Richard J. Gross
Preoperative Planning: Overview
Preoperative evaluation for elective surgery is now done almost entirely in the ambulatory setting, because most surgery is now performed in outpatient surgical units. For inpatient surgery, most patients are admitted on the day of surgery. The primary care practitioner invests substantial time in establishing a diagnosis for the initial complaint, arriving at the decision to recommend surgery, and discussing the findings with the patient and family. The practitioner then evaluates the medical risks of surgery from factors unrelated to the primary surgical problem and consults on the care of the patient's medical problems in the perioperative period.
The principal reasons for office-based preoperative assessment are that health care insurers reimburse only for
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same-day surgery for many procedures, insurers do not reimburse for admission the day before surgery for preoperative assessment, office assessment eliminates the costs and inconvenience associated with unanticipated cancellation of surgery after the patient has been admitted, and better planning of care and higher patient satisfaction are often achieved.
Generally, the surgeon expects the referring clinician to have made an independent assessment of the need for surgery and of the medical acceptability of the patient for surgery. Although the surgeon obtains the actual consent for the surgical procedure, the patient's decision is based in part on the counseling provided by the referring practitioner. The referral itself is usually assumed by a patient and the family to be an endorsement of the consulting surgeon and of the surgeon's opinion. For these reasons, it is important for referring practitioners to know the place of surgery in the management of a broad array of conditions.
Table 93.1 summarizes general guidelines on eligibility for same-day ambulatory surgery, based on the patient's medical status (1,2).
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TABLE 93.1 General Guidelines on Patient Eligibility for Ambulatory Surgery Based on Medical Condition (Not Considering Type of Surgery) |
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Laparoscopic techniques, though more comfortable to the patient, do not necessarily carry a lower medical, anesthetic, or surgical risk. General, spinal, and epidural anesthesia carry similar mortality risks in terms of medical problems. Local and regional anesthesia (usually a block, such as an axillary block) presumably carry lower risk, although data to prove this impression are lacking. Surgery involving the thoracic and abdominal cavities and vascular surgery carry higher medical risks than other types of surgery, with certain exceptions, such as radical head and neck surgery and hip replacement.
In counseling the patient and family, the patient's primary care practitioner and the consulting surgeon should explain clearly the diagnosis; natural history (prognosis) of the disease; and the objective, expected outcome, limitations, potential complications, and alternatives for the operation. This is especially important for surgical procedures that are undertaken for asymptomatic conditions (e.g., elective cholecystectomy) and for procedures that may be disfiguring (e.g., mastectomy or amputation). Preoperative counseling should be documented in the patient's record, including any special issues raised by the patient and how they were resolved (e.g., obtaining additional consultations or providing supportive counseling).
Approximately 50% of adults who undergo surgery are ostensibly in good general health; the other 50% have various medical problems (the percentages vary depending on the age of the population). In perhaps 5% to 10% of patients, new medical problems are identified during preoperative evaluation; a small proportion of these problems have implications for the planning of surgery.
The role of the primary care practitioner in relation to the surgeon and anesthesiologist will vary depending on the setting. In many university hospitals, the anesthesiologist will be more involved in the preoperative evaluation and postoperative care and the surgeon more involved in the postoperative care of medical problems than in community hospitals, but there is wide variation in practices, even among physicians within one institution. The primary care practitioner should be sensitive to the roles of the anesthesiologist and surgeon, usually making recommendations as a consultant rather than mandating management. Perioperative management works best when the primary practitioner, surgeon, and anesthesiologist agree on their individual roles, coordinate care, and work cooperatively. Changes to preoperative medical management before admission will usually be made directly by the primary care practitioner. These changes should be communicated to the anesthesiologist and surgeon before the day of surgery.
Whenever surgery is planned, the patient's referring practitioner should complete an appropriate preoperative evaluation (see General Preoperative Evaluation) to ensure optimal control of existing medical conditions that may affect the outcome of surgery and should communicate
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specific recommendations to the surgeon and anesthesiologist regarding the care of the patient's medical problems during the perioperative period, including recommendations for office or telephone followup. This chapter provides guidelines for these steps in the management of patients with common medical problems.
General Preoperative Evaluation
There is no consensus on the makeup of a general preoperative evaluation. The recommendations below are based on current clinical practices at several institutions and the literature on preoperative testing. For adult patients undergoing general or spinal anesthesia, the “comprehensive” history and physical examination has mostly been replaced by an examination focused on medical risk factors for anesthesia and surgery. Similarly, ordering an extensive number of routine preoperative tests has been replaced by fewer tests, with additional testing guided by specific risk factors identified for the individual patient.
The previously used comprehensive workup has been criticized for having a low yield and being unnecessarily costly (1). The large number of factors that influence the preoperative evaluation make a consensus unlikely. The patient's age, the nature of the planned surgery (major or minor), the type of anesthesia to be used (general, spinal, regional, or local), and the interval since the patient's last comprehensive evaluation are relevant in the preoperative evaluation of every patient. Additionally, one or more of the following considerations are often pertinent: estimating operative risk, establishing a baseline for expected postoperative changes or possible complications, avoiding harm to other patients or medical personnel (e.g., hepatitis, tuberculosis, or human immunodeficiency virus [HIV] infection), documenting selected information for medicolegal reasons, determining drug dosages, detecting rare but potentially catastrophic circumstances (e.g., thrombocytopenia in a patient scheduled for a craniotomy), evaluating further the surgical problem, and establishing a database in a new patient.
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TABLE 93.2 General Preoperative Evaluationa |
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TABLE 93.3 Additional Preoperative Screening Tests for Common High-Risk Situations |
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Tables 93.2 and 93.3 summarize a practical approach for the individual patient including history and examination and tests, respectively. The history and examination focus on those items that are important in preoperative evaluation, rather than a “comprehensive” evaluation as
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in the past. Additional items in the history or examination should be asked or done based on the patient's history, risk factors, and type of surgery. Additional tests are added as indicated by the individual patient's medical and surgical problems or risk factors. Selected screening tests should also be added to the workup to avoid potential catastrophes associated with certain high-risk situations (Table 93.3). Routine HIV screening of preoperative patients is currently not recommended; instead, the universal precautions described in Chapter 39 are recommended.
A common approach is to use a grid to select tests based on individual patient characteristics and type of surgery (3). A number of such grids have been published, but recommendations are not uniform (1). Most hospitals or surgical centers have their own grids, which either are sent by the surgical center with the request for preoperative evaluation or may be requested by the referring practitioner. Because of nonuniformity of recommendations, the primary care practitioner should review the grid.
Table 93.4 lists commonly overlooked aspects of evaluation and planning in the assessment of the outpatient presurgical patient.
Current Medications and Known Allergies
Any known drug allergies or adverse drug reactions, reactions to latex, radiocontrast, and prior local or general anesthesia should be included in the preoperative report. All prescribed and nonprescribed drugs that a patient is taking should be communicated to the responsible anesthesiologist, surgeon, or preoperative unit at the surgical center. Over-the-counter (OTC) medications and certain herbal supplements are particularly important. This information is critical for optimal perioperative management (Table 93.5). Some drugs may have to be discontinued days to weeks in advance of surgery. Some are withheld immediately before surgery, whereas others are taken immediately preoperatively. Withholding of important medications may increase the postoperative medical complication rate, especially for cardiovascular medications (4). For most patients it is appropriate to give a dose of medication, with a small amount of water (1 ounce or less), in the early morning before the induction of anesthesia; there is little risk of aspiration as long as there is normal gastric emptying. Many patients can resume their oral medication 6 to 12 hours later. When important oral medications cannot be continued throughout the perioperative period, alternate medications or routes of administration are used.
In addition to the patient's list of current prescribed medications, the referring practitioner should remember to communicate important related information to the anesthesiologist, surgeon, or surgical center. The patient should be asked specifically about nonprescription drug use that, although common, is often not mentioned spontaneously (e.g., aspirin-containing compounds and nonsteroidal anti-inflammatory drugs [NSAIDs], which may potentiate postoperative bleeding, and sedatives, which may interact with anesthetic drugs); and herbal supplements. The use of recreational substances that may affect the patient's course during or after surgery (alcohol, tobacco, illicit drugs) should be documented. The following should also be noted: prior allergic reactions to local and general anesthetic agents (e.g., halothane) and to drugs used for medical conditions, prior reactions to blood products, and a family history of reactions to anesthesia or blood transfusions. Finally, chronic corticosteroid use at any time within the past year should be reported, because perioperative steroids may be required to cover the stresses of surgery.
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TABLE 93.4 Commonly Forgotten or Underestimated Items in the Office Evaluation and Management of the Surgical Patient |
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TABLE 93.5 Recommended Perioperative Management of Medicationsa |
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Preoperative Donation for Autologous Transfusion
Donation of one or more units of autologous blood for transfusion for elective surgery is now widely practiced. The risks of autologous transfusion are lower than the risks with bank blood, but bacterial contamination and transfusion of the wrong unit remain small possibilities.
Current blood preservation methods limit autologous donation to about three units. Single units are donated beginning about 4 weeks before surgery, at weekly intervals. In preoperative planning, it is important to leave sufficient time for donation of the required units but not so much time that the units expire if there is a minor delay in the scheduled surgery. Usually this is arranged by the surgeon, but the patient's primary care practitioner may want to discuss this option with the patient, including the time necessary (depending on the number of units needed) and any medical contraindications or limitations to autologous donations.
Medical problems that are potential contraindications or that limit the number of units donated (depending on the severity of the situation) include anemia, cardiovascular disease, hypertension and antihypertensive medication, lung disease with significant hypoxia, orthostatic hypotension, certain infectious diseases (including hepatitis and HIV infection), very frail or debilitated patients, and far advanced age. Despite this list of limitations, most patients, including most elderly patients with chronic diseases, are able to donate blood for autologous transfusion. The patient's practitioner may want to plan for partial volume repletion with saline at the time of donation for some patients who may be very sensitive to the volume loss. Most patients are prescribed iron (see Chapter 55) beginning about 1 week before the first donation and continuing for 2 to 3 months after donation (depending on the number of units donated). Some surgeons administer erythropoietin
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preoperatively to limit the degree of postoperative anemia, although the utility of this approach is not yet well established.
Surgery in the Elderly Patient
Risk
The mortality risk associated with anesthesia and surgery is increased in the elderly. However, the risk in elderly patients has fallen substantially over the past 10 to 20 years. The overall mortality risk for major surgery in patients younger than 65 is approximately 1%; the risk is approximately 5% between ages 65 and 80. Patients older than the age of 80 years have a 10% risk, although mortality rates as low as 6% to 8% have been reported (1,6,7).
Several factors are more important than age itself in increasing surgical risk in older patients (7). The most important of these factors are general overall health, nutrition, type of surgery (body cavity versus non–body cavity; emergency versus elective), type of anesthesia, coexisting conditions (cardiac, infectious, renal, pulmonary, central nervous system [CNS]), and psychosocial status (attitude toward surgery, will to live, cognitive level, social situation). Common perioperative causes of death include uncorrectable surgical lesions such as infarcted bowel or ruptured aneurysm, coexisting cardiac disease, infections (especially pneumonia), renal disease, and pulmonary disease. In the preoperative evaluation, attention should be focused on managing or preventing these conditions.
Certain common procedures can be performed at low risk in the elderly, often without general anesthesia. These low-risk operations include cataract surgery, simple hernia repair, and transurethral prostate resection. The risks of some major surgical procedures in the elderly have fallen greatly over the past few years; examples include elective abdominal aortic aneurysm repair and repair of hip fractures. Laparoscopic surgery, such as for cholecystectomy, produces fewer medical complications but has not yet been shown to be associated with a lower mortality rate than does open surgery in the elderly.
Perioperative Management
The elderly patient undergoing major surgery may require a more extensive preoperative evaluation than given in Table 93.2 because of the wide variety of coexisting, often unrecognized, medical conditions found in older patients. The workup should be reviewed specifically for the risk factors listed above. Any major preoperative risks must be weighed against the benefits of the operation, with attention to the fact that quality of life may be as important as longevity in this age group. An accurate estimation of average future longevity for the patient's age group is important; this is often underestimated (see Chapter 12, Table 12.1).
Preoperative cardiac evaluation is discussed in Patients with Cardiovascular Disease. Manifestations of infection (including simple upper respiratory infections) should be carefully sought because classic signs may not be present in the elderly. Spirometry should be performed in patients older than age 65 if there is pulmonary disease, because of the increased incidence of pulmonary complications in older patients. It should be remembered that serum creatinine may be falsely low in elderly patients because of their reduced muscle mass; therefore, a calculated or measured creatinine clearance should be obtained if the state of the patient's renal function is not certain, because of the importance in determining drug dosages. If there is hearing impairment caused by cerumen impaction preoperatively, this problem should be corrected.
Elderly patients often have limitations of understanding because of memory deficits and hearing problems. Because these are often known to the primary care practitioner, informing the surgeon, anesthesiologist, and surgical center of these limitations can improve communication and management at each of these levels. A baseline mental status examination (see Chapter 26) should be completed because postoperative changes in mental status are common in the elderly. Explanation of what to expect during hospitalization and surgery is especially important in the elderly not only because of the above factors, but because elderly patients may be less likely to ask questions of the surgeon and may have outdated conceptions of the nature of surgery.
Simple measures planned before admission may help reduce the high incidence of postoperative confusion in older patients, including correction of reversible hearing or vision deficits, planning to allow family members to stay beyond visiting hours, avoiding placing the patient unnecessarily in an intensive care unit, returning the patient to the same room postoperatively, allowing the presence of familiar objects, leaving a night-light on, and avoiding unnecessary instrumentation. Early mobilization, uninterrupted sleep, and frequent orientation to time, place, and current events are also important. Tranquilizers, sedatives, hypnotics, and pain medications should be used in reduced dosages and for appropriate indications, not routinely.
Postoperative mobilization of the elderly patient should be planned and anticipated by the patient, preoperatively. Generally, the patient should expect to resume ambulation as early as possible.
Surgery in the Pregnant Patient
Risk
Up to 2% of women require nonobstetric surgery during pregnancy. Risks posed to the mother and fetus include complications from the surgical problem, effects of anesthesia and medication (including teratogenicity), risks of
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radiographs and other diagnostic procedures, precipitation of premature labor, and fetal death. Because of these problems, women of child-bearing age who are not known to be pregnant should be screened for pregnancy before surgery. History and sensitive serum human chorionic gonadotropin pregnancy tests usually suffice, but very early pregnancy may still be missed. If it is uncertain whether a woman is pregnant, nonurgent surgery should be postponed for 2 to 3 weeks until the situation is clarified; more urgent surgery requires judgment on an individual basis.
Table 93.6 lists physiologic alterations in pregnancy that may complicate anesthetic and surgical management. Two common changes of pregnancy should be taken into account when evaluating the patient preoperatively: The normal serum creatinine concentration is lower in pregnancy and an S3 gallop, systolic murmur, or edema is commonly present in the pregnant patient without cardiac disease.
Perioperative Management
Preoperative planning and perioperative management for the pregnant surgical patient involves a number of complex issues, considered below.
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TABLE 93.6 Physiologic Alterations in Pregnancy and Their Relevance to the Surgical Patient |
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Urgency
Can the surgery be postponed until after delivery or is it urgent (e.g., acute appendicitis), when delay will increase fetal–maternal mortality? Generally, emergency surgery should not be delayed because of pregnancy, but totally elective surgery should be postponed until the postpartum period. In intermediate situations, the duration and risk to the mother of waiting must be balanced against the risk of immediate surgery.
Testing
Tests should be carefully planned to allow a precise diagnosis with minimal risk, especially risk from radiograph exposure. Whenever possible, other tests should be substituted for radiologic procedures (e.g., renal sonogram instead of computed tomography [CT] scan in suspected renal disease). Routine radiographs, such as chest films or flat abdominal films, should be avoided. When these radiographs are unavoidable, use of lead screening, collimated equipment with minimal exposure, and few films can minimize fetal exposure.
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Medications
Drugs required during the perioperative period should be anticipated. The potential effects on the fetus should be ascertained from obstetric colleagues or available reference sources, and the least toxic alternative should be used. Postoperative medications should be avoided unless they are deemed to be necessary and risk to the fetus has been assessed.
Anesthesia
A decision on the type of anesthesia must be left to the anesthesiologist and obstetrician. Local or regional anesthesia would presumably be safer than general or spinal anesthesia, but no data exist to support this impression.
Monitoring of Fetal Status
Monitoring of fetal status by the obstetrician should be planned throughout the perioperative period.
Problems After Discharge
During the weeks and months after surgery, patients often have questions about incisional pain, various symptoms in the system that was operated on, restrictions of activity, and return to work. These questions are best answered by the surgeon. Additionally, patients who have major surgery often complain of postoperative fatigue, a problem that can usually be handled by the patient's primary care practitioner.
Postoperative Fatigue
Patients with postoperative fatigue may describe a number of symptoms, including the need for increased sleep, weakness of the arms and legs when resuming usual activity, symptoms of orthostatic hypotension, and loss of interest in resuming usual activities (8). The symptoms of postoperative fatigue often last for 1 or more months. The physiologic changes responsible for these symptoms have not been well defined.
The primary care practitioner should also be aware of specific, often treatable, conditions that may contribute to or cause postoperative fatigue. Sleepiness may be related to sedatives, tranquilizers, or analgesics prescribed at the time of discharge and may improve with discontinuation of these drugs. The patient with orthostatic symptoms may have had a drug prescribed that can produce this problem (diuretics, antihypertensives, long-acting nitrates, antidepressants). Because bed rest alone may cause orthostasis, such drugs should be resumed cautiously in a patient who has had recent major surgery, and blood pressure should be checked in the lying and standing positions. Dosage reduction or discontinuation of the drug should be considered when orthostatic hypotension is documented or orthostatic symptoms persist. Loss of interest may also be secondary to drugs prescribed after surgery (see Chapter 24 for a list of drugs that may cause a depressed mood). Alternatively, this symptom may represent a minor mood disturbance in a patient who has had similar problems at previous times of stress (see Chapter 21), or it may represent a reactive depression, similar to a grief reaction (see Chapter 24), that is related to disfiguring surgery. Because other medical problems related to surgery may occasionally cause postoperative fatigue, a hematocrit value, serum urea nitrogen or creatinine, electrolytes, glucose, liver enzymes, and other tests indicated by clinical findings should be checked if fatigue persists.
When evaluation of postoperative fatigue does not disclose contributing factors that can be treated, patients should be reassured that the problem will gradually resolve; they should also be given a rough timetable for a return to regular activities that is realistic in terms of both the surgical procedure and the fact that postoperative fatigue may take a number of months to resolve entirely. Chapter 89 illustrates simple exercises for patients convalescing from bed rest. For selected patients, these or similar exercises can be recommended during the period of recovery from postoperative fatigue.
Patients with Cardiovascular Disease
Most forms of general anesthesia can cause cardiovascular stresses (decreased myocardial contractility, peripheral vasodilatation, arrhythmias, hypotension), and spinal or epidural anesthesia can cause hypotension. These factors and the stresses associated with surgery itself probably account for the greatly increased risk of surgery for patients with underlying cardiovascular disease (9).
Ischemic Heart Disease
Risk
Ischemic heart disease poses four major risks perioperatively in the patient undergoing general anesthesia: myocardial infarction (MI), ischemic pulmonary edema, life-threatening arrhythmias, and cardiac death. These risks depend on the patient's preoperative status. Overall, the risks for patients with arteriosclerotic heart disease are two or three times those of patients of the same age without cardiac disease; patients who have had a prior MI may be at particularly increased risk.
The increased risk posed by ischemic heart disease is partially dependent on the patient's preoperative cardiac
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status. Stable mild to moderate angina pectoris alone represents only a small increase in risk. The risk attending severe or unstable angina cannot be estimated accurately because of varying definitions and the small number of patients reported in the medical literature, but there is a significantly increased risk. An MI during the 6 months preceding surgery represents a high risk, particularly an MI 3 months or less before surgery. There is some evidence (9,10) that aggressive perioperative management may significantly lower cardiovascular risk (e.g., reduce recurrent MI risk from 30% to 4%). By 6 months after an infarction, the risk of a perioperative MI has plateaued but remains larger than the risk in a control population.
In addition to a recent MI, a number of factors contribute to the risk of perioperative cardiac complications or mortality. The most important of these factors are age older than 70, decompensated congestive heart failure (CHF), arrhythmias, and other organ system disease (11, 12,13, 14, 15, 16). These and other factors were incorporated in 1977 into a Cardiac Risk Index; in 1986 into a Modified Cardiac Risk Index; and in 1999 into a Revised (Simple) Cardiac Risk Index (Table 93.7), all of which have been validated (11, 12, 13, 14). The Revised Cardiac Risk Index is used here because it performed slightly to moderately better than the other indices in a single prospective study (14).
The joint American College of Cardiology/American Heart Association (ACC/AHA) Task Force on perioperative cardiovascular evaluation also provided a qualitative index of cardiac risk (“Clinical Predictors”) (Table 93.8) (15).
Two algorithms are available (15,16) that provide guidelines on diagnostic and therapeutic approaches (7) based on a patient's level of cardiac risk established by one of the indices. The algorithms were established by expert consensus; neither has been validated. The ACC/AHA algorithm (Fig. 93.1) (15) is used here since it has been updated more recently than the other algorithm from the American College of Physicians (ACP).
Clinical assessment of the cardiac patient is approximately 75% sensitive for detecting high-risk patients. In intermediate- or high-riskvascular surgery patients, dipyridamole–thallium or other types of stress tests can accurately identify those with ischemia who have an increased operative risk. In nonvascular surgery patients, the usefulness of preoperative stress testing for risk assessment has not been definitely demonstrated (15). Detailed discussion of the use of noninvasive testing for preoperative decision-making is contained in the ACC/AHA guidelines and in other publications (9,15,16).
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TABLE 93.7 Revised (Simple) Cardiac Risk Indexa |
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TABLE 93.8 Clinical Predictors of Cardiac Risk (from ACC/AHA Guidelines) |
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Perioperative Management
Patients with established ischemic heart disease should have a preoperative evaluation (Table 93.2) with emphasis on established cardiac risks for surgery. A baseline electrocardiogram (ECG) should be obtained before surgery for all patients with known coronary artery disease (CAD) and for all patients older than 40 to 50 years of age. Noninvasive tests of cardiac function, including echocardiography, nuclear scanning, and stress tests, should generally be reserved for situations where the evidence for the presence or severity of cardiovascular disease is questioned or in certain high-risk situations, such as vascular surgery, where precise information about the degree of severity is desired (see above).
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Based on the preoperative evaluation, the risk of general anesthesia and surgery should be estimated for each patient. For patients with an MI within the last 6 months, unstable angina, or less severe CAD and multiple other risk factors (Fig. 93.1 and Tables 93.7 and 93.8), only urgent life-saving surgery should be undertaken until the risk is lowered. Surgery may be done 3 months after infarction when the risk of waiting the additional 3 months is thought to be significant (e.g., recurrent cholecystitis). Patients with stable angina or uncomplicated recovery from MI more than 6 months previously have a small increase in risk that does not decline further with time; thus, there is no need to postpone necessary operations.
Coronary artery bypass surgery or angioplasty should be considered before elective noncardiac surgery, in consultation with a cardiologist, in patients who have other indications for coronary revascularization (see Chapter 62). Although guidelines do not generally recommend bypass surgery or angioplasty prophylactically before noncardiac surgery without other indications, these interventions may need to be considered in an occasional high risk patient. Coronary revascularization in stable non–high-risk patients with CAD undergoing vascular surgery has not been shown to lower cardiac morbidity and mortality (17). Assessing the benefit of coronary angioplasty and stenting before noncardiac surgery is complicated by the need for anticoagulation with antiplatelet agents for 1 month to 1 year or more depending on the type of procedure (18).
Postoperative ECGs should be obtained in high-risk patients, (e.g., those with known CAD or who develop hypotension during surgery.) The yield of useful information from postoperative ECGs is low in low and intermediate risk patients.
For patients taking a long-acting oral nitrate for angina, the drug should be administered on the morning of surgery with a sip of water. If the patient is unable to take medications orally, nitroglycerin paste or a transdermal patch can be substituted at a dosage equivalent to the oral nitrate (or by using an intermediate dose equivalent to 1 to 2 inches of paste every 4 to 6 hours).
For patients taking a β-blocking agent for CAD, small intravenous dosages of an intermediate duration β-blocker (such as propranolol or metoprolol titrated to maintain a pulse of ≤80) can be substituted, while the patient is unable to take medications by mouth. This requires cardiac monitoring, usually in an intensive care unit. This should protect the patient from the risk of acute cardiac ischemia, which occasionally follows abrupt cessation of β-blocking agents. Patients able to resume oral intake within 12 to 24 hours and not at high cardiac risk usually can be observed without intravenous β-blockers, particularly if a long acting β-blocker was administered preoperatively.
For patients who are not already taking a β-blocking agent, who have CAD, who are intermediate to high risk, and who are undergoing major surgery, a β-blocker should be started preoperatively and continued during the perioperative period, based on a randomized controlled trial (RCT) (19). Although only patients undergoing vascular surgery were studied, it is reasonable to extend the use of β-blockers to other major surgery until data are available. The authors recommended a β-blocker dose sufficient preoperatively to lower the heart rate to less than 70 beats per minute in the immediate postoperative period and to less than 80 beats per minute (19); this degree of β-blockade may not be achievable in some patients. β-Blockers should be initiated 1 to 2 weeks preoperatively and the patient's response evaluated in the office before surgery. Consideration should be given to chronic β-blockers after surgery because of their efficacy in coronary disease (see Chapters 62 and 63). If β-blockers are not going to be continued indefinitely for chronic indications, they should be continued for a minimum of 2 to 4 weeks postoperatively, longer if there are ongoing cardiac stresses, and then tapered.
Calcium-blocking agents can usually be given on the morning of surgery. Another type of antianginal medication can be used postoperatively until the patient can resume oral intake. Diltiazem and verapamil are available in intravenous form, but maintenance regimens are not established and the cost is high.
Intensive intraoperative monitoring using pulmonary artery and radial artery catheters should be planned in consultation with the anesthesiologist and surgeon for patients who are very sensitive to volume changes, such as those in CHF (see Congestive Heart Failure); for operations when loss and replacement of large volumes of fluid are expected (e.g., aneurysm repair); and for patients with a recent MI (less than 6 months), severe unstable coronary disease, or at very high risk. Routine invasive monitoring of unselected high-risk patients has not been shown to lower perioperative risk.
Hypertension
Risk
Controversy still exists about whether mild to moderate hypertension (diastolic blood pressures less than 110 mm Hg) increases anesthetic and surgical risks. The only prospective study showed no correlation between uncontrolled diastolic pressures in this range and the risk of perioperative cardiac, renal, or cerebrovascular events (20). Patients in this study often had other cardiac risk factors that did correlate with the incidence of perioperative cardiac morbidity (Table 93.10).
Too few patients have been studied to define adequately the risk for patients operated on when their diastolic pressure exceeds 110 mm Hg, but there is probably an increased risk (20). Likewise, risk is probably increased in selected patients with hypertension who also have significant cardiac, renal, or cerebrovascular disease (CBV).
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TABLE 93.9 Cardiac Riska Stratification of Noncardiac Surgical Procedures |
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FIGURE 93.1. ACC/AHA algorithm for diagnostic and therapeutic management based on patient cardiac risk. The ACC/AHA algorithm (Fig. 93.1) first addresses three factors (Steps 1–3): need for noncardiac surgery (emergency versus urgent/elective), coronary revascularization within 5 years, and recent coronary evaluation, any of which can lead directly to a cardiac work-up or surgery. If none of these factors is present, the algorithm divides depending on whether major, intermediate, or minor/no clinical predictors are present (Steps 4 and 5). Decision points for Steps 6–8 include functional status (less or more than 4 METS) and cardiac risk of the surgical procedure. The ACC/AHA algorithm gives an estimated cardiac risk for surgery (Table 93.9). From ACC/AHA Task Force. Guidelines for perioperative cardiovascular evaluation for noncardiac surgery. J Am Coll Cardiol 2002;39:545. *Subsequent care may include cancellation or delay in surgery, coronary revascularization followed by noncardiac surgery, or intensified care. |
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Perioperative Management
The basic preoperative evaluation in the hypertensive patient should establish whether there is end-organ damage (renal: serum creatinine concentration and urinalysis; cerebrovascular:history, neurologic, and neurovascular examination; cardiovascular: history, cardiac examination, chest radigoraph, and ECG). Blood pressure and pulse measurements should be made with the patient lying, sitting, and standing (and after brief exercise, to identify the maximal orthostatic fall in patients taking antihypertensive drugs); the preoperative status of blood pressure control may then be classified as untreated, hypertensive despite therapy, or controlled. The antihypertensive medications being given should be reviewed and evaluated for side effects, particularly orthostatic hypotension, electrolyte disturbances, and changes in renal function (especially with diuretics, angiotensin-converting enzyme [ACE] inhibitors, and angiotensin receptor blockers [ARBs]).
Patients whose hypertension is controlled or partially controlled with diastolic pressures 110 mm Hg or lower should be continued on their prescribed antihypertensive and other medications. Three exceptions to this rule are reserpine, guanethidine, and monoamine oxidase inhibitors (MAOI). A patient taking any of these infrequently used drugs should be switched to different drugs during the 2 weeks preceding surgery, because each of these drugs may cause markedly labile blood pressure during anesthesia.
Untreated patients with diastolic pressures 110 mm Hg or lower may undergo surgery, with institution of antihypertensive therapy after convalescence from surgery, if there are no other complicating cardiovascular risks. Alternatively, as long as adequate time is allowed to measure full effects of antihypertensive medication, there is no reason not to treat hypertension preoperatively. Because for most antihypertensive medications this requires several weeks, a decision may need to be made about delaying surgery versus instituting antihypertensives postoperatively.
Individual judgments must be made about patients with diastolic pressures that are repeatedly above 110 mm Hg, depending on the severity and duration of hypertension, the presence of end-organ damage, and the extent of planned surgery. Most patients with diastolic blood pressure above 110 mm Hg should have their blood pressure at least partly controlled before admission for nonurgent surgery, although there are no randomized studies proving that such control modifies risks. Attempts to control blood pressure too rapidly (e.g., with addition of or increases in doses of diuretics, ACE inhibitors, or ARBs over several days) may result in volume depletion, hypotension, or disturbances in electrolytes or renal function at the time of surgery. Therefore, these patients should have their blood pressure stabilized during the 1 to 2 weeks before admission for surgery. There are no data on the perioperative risk of isolated systolic hypertension, but it seems reasonable to aim for a systolic pressure of 160 mm Hg or below (see Chapter 67).
For all hypertensive patients, significant intravascular volume expansion or contraction should be avoided, because these conditions may either cause a significant rise in blood pressure (volume expansion) or fall in blood pressure (volume contraction, especially in the patient who is taking antihypertensive drugs).
Current antihypertensive medications should be continued through the morning of surgery (diuretics are usually withheld the morning of surgery) and resumed
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postoperatively when the patient is stable and can take oral medications. Because bed rest and inactivity during convalescence can lower blood pressure, some patients require less antihypertensive medication postoperatively and during the first few weeks after major surgery. Because antihypertensive effects may be amplified when a postoperative patient changes position from recumbent to standing, blood pressure should be measured in these positions postoperatively and after antihypertensive treatment has been instituted or resumed.
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TABLE 93.10 Risk of Perioperative Cardiac Complications in Patients with Mild to Moderate Hypertension |
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In some patients, the diastolic pressure exceeds 110 mm Hg postoperatively before oral medication can be resumed. When patients remain severely hypertensive despite control of secondary causes, such as pain, and the hypertension poses immediate health risks, the blood pressure can be controlled by the careful use of parenteral or transcutaneous agents. These include intravenous propranolol, labetalol, hydralazine, enalapril, diuretics, methyldopa, nitroprusside, intravenous or transcutaneous nitroglycerin, and transcutaneous clonidine (especially for patients who were taking clonidine before surgery who are at risk of rebound hypertension and tachycardia if clonidine is withdrawn).
Valvular Heart Disease
Risk
The risk of surgery in the patient with valvular heart disease varies with the valve affected (aortic versus mitral) and the nature (stenosis versus insufficiency) and severity of the lesion (9,12). The severity of valvular lesions as judged clinically by New York Heart Association classification (see Chapter 66) provides a reasonable indication of surgical risk except in patients with aortic stenosis.
Valvular heart disease poses two major surgical risks: cardiac death and CHF. The presence of aortic stenosis of any degree of hemodynamic significance poses a high risk of surgical mortality. Mild to moderate mitral lesions or aortic insufficiency pose only slightly increased risk of cardiac death; however, hemodynamically severe valvular disease (New York Heart Association class 3 or 4) caused by these lesions creates major risks. In addition to increasing the risk of perioperative mortality, significant valvular disease poses an increased risk of decompensated heart failure.
Little specific information exists regarding the risks associated with prolapsed mitral valve or hypertrophic cardiomyopathy. It is reasonable to assume that the risk in patients with prolapsed mitral valve depends on the degree of mitral regurgitation. Patients with hypertrophic cardiomyopathy may be very sensitive to volume contraction and are probably best managed with a pulmonary artery catheter in place during major procedures associated with rapid volume changes.
Patients with artificial heart valves, patients with any evidence of valvular heart disease (including mitral prolapse and hypertrophic cardiomyopathy), and patients with congenital structural defects (e.g., patent ductus arteriosus, ventricular septal defect) have a small but definite risk of acquiring bacterial endocarditis when they undergo procedures in the oral cavity and upper respiratory, gastrointestinal (GI), or genitourinary tracts (21).
Perioperative Management
The basic cardiac evaluation should delineate the nature and severity of the valvular disease and should identify any associated cardiac conditions. Chapter 65 describes the uses of echocardiography and cardiac catheterization
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to evaluate valvular heart disease. Patients with severe valvular disease should have corrective cardiac surgery followed by a period of convalescence before they undergo major elective noncardiac operations. The preoperative management of CHF, arrhythmia, or anticoagulant therapy (in patients with artificial valves) is described in subsequent sections of this chapter.
Patients with valvular disease undergoing procedures attended by a risk of endocarditis (Table 93.11) should receive antimicrobial prophylaxis (as summarized in Tables 93.11 and 93.12). The information in Table 93.12 is available from the AHA in a wallet-sized card for patients. These recommendations are not based on randomized controlled trials and should not be substituted for clinical judgment (21).
Congestive Heart Failure
Risk
Information on the risk of developing CHF perioperatively is limited because there have been few prospective studies (12, 13, 14, 15). The most significant risk factors for postoperative CHF are decompensated failure preoperatively and, to a lesser extent, prior CHF that is clinically stable preoperatively (Table 93.13) (12, 13, 14, 15). However, only 40% of patients who develop perioperative CHF have had prior failure. The best predictors for the other 60% of patients are older than 60 years of age, major surgery (especially abdominal aortic aneurysm repair or major abdominal surgery), and nonspecific ECG abnormalities.
Patients with postoperative pulmonary edema have a high total mortality (20% to 57%), most of which is cardiac. Patients who develop less severe postoperative CHF do not have an increased risk of postoperative cardiac death, although the overall mortality from all causes is increased. Most postoperative CHF occurs during or within several hours of surgery.
Perioperative Management
Patients with compensated CHF should have a preoperative evaluation (Table 93.2) with an emphasis on established cardiac risk factors for surgery. This evaluation should include an assessment of volume status (lying and standing blood pressures, inspection of neck veins, determination of whether edema is present) and examination for cardiac gallops and rales. Laboratory data should include blood urea nitrogen (BUN), creatinine, electrolytes, and a digoxin level if that drug is being administered. Noninvasive methods for assessing left ventricular function (see Chapter 66) may be useful when the degree of cardiac dysfunction is uncertain.
Although there are no definitive perioperative studies in this regard, it is prudent to administer digoxin to patients with a confirmed history of moderate or severe dilated congestive cardiomyopathy, ideally during the week before admission. Most controversy about preoperative digitalization has concerned the patient who has a history of no or minimal CHF, yet has a risk of developing CHF because of an enlarged heart or because the surgery will involve major volume shifts. Most experts do not recommend digoxin in
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this situation (15). In patients undergoing major surgery, spironolactone probably should be held the day the operation is performed because of the risk of hyperkalemia; it can be continued for those who undergo minor procedures that do not require general anesthesia. β-Blockers should be continued perioperatively, including a dose the morning of surgery and postoperatively. If the patient cannot take an oral β-blocker postoperatively, one should be given intravenously if CAD is present (see Ischemic Heart Disease); in patients without CAD the decision on intravenous β-blockers should be individualized.
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TABLE 93.11 Subacute Bacterial Endocarditis Prophylaxis: Recommendations for Procedures in the Respiratory, Gastrointestinal, and Genitourinary Tracts (See Recommended Antibiotic Regimens, Table 93.12) |
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TABLE 93.12 Prevention of Bacterial Endocarditis in Patients with Valvular Heart Disease, Prosthetic Heart Valves, and Other Abnormalities of the Cardiovascular System |
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Patients with decompensated CHF should have all but life-saving surgery postponed until the failure is controlled, either in the practitioner's office or in the hospital. Patients with controlled CHF should be maintained on their usual oral regimen until midnight before surgery and maintained with intravenous diuretics and digoxin (75% of the oral dosage) during the immediate postoperative period. Perioperative monitoring with a pulmonary artery catheter should be considered in advance in situations where large volume shifts are anticipated during surgery or the heart failure is severe or decompensated.
Arrhythmias
Chapter 1 describes in detail arrhythmias that are most common in ambulatory patients.
Risk
Patients with arrhythmias before surgery have significantly increased risks of cardiac morbidity and death. These risks have not been quantified for subgroups of patients with specific arrhythmias, except for the broad category of rhythms other than sinus or >5 premature
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ventricular contractions (PVCs) on ECG (10,12). Patients with complete heart block, Mobitz type II second-degree block, and a few patients with sick sinus syndrome (see Chapter 64) have a significant risk of complications during anesthesia if a pacemaker is not inserted. On the other hand, there is little or no increased risk associated with bifascicular or trifascicular block on ECG in patients who are asymptomatic.
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TABLE 93.13 Risks of Developing CHF in the Perioperative Period |
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Arrhythmias do occur in approximately 20% or more of adult patients during general anesthesia; however, most of these patients do not have preoperative arrhythmias. Most intraoperative arrhythmias are supraventricular, transient, and related to anesthetic or surgical manipulations and do not require specific therapies. The number of arrhythmias that are detected clinically, without the use of continuous monitoring, is lower; supraventricular arrhythmias are detected clinically in 4% of patients and other arrhythmias in 11% (12,22).
Perioperative Management
Patients with arrhythmias should have a preoperative evaluation (Table 93.2) expanded in several ways. The probable cause of the arrhythmia should be delineated (see Chapter 64). If the arrhythmia is intermittent or control is uncertain, 24-hour Holter monitoring should be done. Levels of antiarrhythmic drugs that are being administered should be obtained. This evaluation should be accomplished before admission for surgery.
Patients with supraventricular arrhythmias should have their ventricular rates controlled or should be converted to more stable rhythms. Except for atrial fibrillation, this usually means conversion either to normal sinus rhythm or atrial fibrillation because other supraventricular arrhythmias are hemodynamically unstable or give an unpredictable ventricular response even with appropriate drug therapy. Patients with atrial fibrillation should have their rates slowed but should be able to accelerate their heart rate under stress as indicated by their ability to raise their pulse rate more than 10 points by mild exercise.
Established indications for preoperative digoxin administration in patients with arrhythmias are control of rate in atrial fibrillation and prophylaxis of supraventricular arrhythmias in selected patients (e.g., some patients with past histories of supraventricular arrhythmias who remain at high risk for recurrence). Patients with ventricular arrhythmias should be treated according to the criteria outlined in Chapter 64.
Antiarrhythmic drugs should be continued orally through the morning before surgery, after which the following intravenous treatment should be substituted until the patient can take oral medications again: intravenous digoxin (75% of the oral dosage) for patients taking digoxin and intravenous lidocaine or procainamide for patients taking quinidine, procainamide, or disopyramide for ventricular arrhythmias. Amiodarone is available in an intravenous preparation; its use may be considered in patients maintained on it, a decision best made with the assistance of a cardiologist.
There is general agreement that patients undergoing general anesthesia should have a prophylactic or therapeutic pacemaker inserted for the following conditions:
Patients with a history suggesting symptomatic bradyarrhythmias (especially a history of syncope or near syncope and an underlying ECG abnormality) probably should have a temporary pacemaker recommended if a full workup to evaluate the cause of the symptoms
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cannot be performed preoperatively. Isolated conditions for which a pacemaker is more controversial, but generally not indicated, include bifascicular block, bundle branch block, first-degree AV block, and asymptomatic sinus bradycardia.
Patients with Pulmonary Disease
Patients with significant pulmonary disease have increased mortality and morbidity during surgery. The increased risks are caused chiefly by the following physiologic changes produced by the effects of anesthesia, sedatives, and analgesics: abnormalities of pulmonary gas exchange, causing hypoxemia; depression of the cough reflex and decrease in clearance of respiratory tract secretions; respiratory depression; and loss of sighing and normal lung inflation. Each of these changes increases the risk of atelectasis and pneumonia. Additionally, normal breathing and voluntary coughing are decreased after surgery because of pain and discomfort, especially after upper abdominal and thoracic surgery. Optimal preoperative treatment of pulmonary disease can reduce perioperative morbidity and mortality.
Chronic Obstructive Pulmonary Disease
Risk
The precise risk of perioperative death from pulmonary causes for patients with chronic obstructive pulmonary disease (COPD) is not known because of the lack of information regarding patients with mild lung disease. In patients with moderate to severe COPD, pulmonary deaths occur in approximately 4% (versus 0% to 2% of unselected patients), postoperative respiratory failure requiring mechanical ventilation in 3%, and total pulmonary complications in 36% (versus 9% of unselected patients) (23, 24, 25, 26).
A smoking history, dyspnea, cough, or abnormal spirometry increases the risk of minor postoperative pulmonary complications (i.e., atelectasis or infection without significant respiratory compromise). The risk of respiratory failure requiring vigorous postoperative respiratory therapy is increased in patients with a forced expiratory volume in 1 second (FEV1) less than 1.5 L. An FEV1 less than 1.0 L or a carbon dioxide pressure (PCO2) greater than 45 mm Hg predicts a substantial increase in perioperative pulmonary mortality and in the incidence of postoperative respiratory failure requiring prolonged mechanical ventilation. However, no study has definitively shown that any pulmonary function test, including FEV1 or arterial blood gases, predicts major pulmonary complications (respiratory failure, need for mechanical ventilation, or death) with enough precision to establish a prohibitive criterion for surgery. The decision for surgery in the presence of pulmonary disease requires consideration of all clinical and laboratory data (23, 24, 25, 26).
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TABLE 93.14 Nonpulmonary Factors that Increase Pulmonary Risks During General Surgery |
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A number of nonpulmonary factors are helpful in predicting postoperative pulmonary complications in patients with COPD (Table 93.14). The greatest risks are in patients who are older than 60 years of age, who undergo upper abdominal and thoracic operations or operations under general anesthesia lasting more than 3 hours, or who have repeated operations within 1 year. A much lower risk is posed by operations on the extremities, back, breast, and central nervous system. Lower abdominal surgery represents an intermediate risk. Combining these factors with the pulmonary factors listed above increases the practitioner's ability to predict operative morbidity.
The type of anesthesia may affect the risk of pulmonary complications. Local anesthesia creates very little risk; if the patient is also sedated (“moderate sedation”), however, there may be temporary deterioration in respiratory control and there may be a suppression of the cough reflex. Spinal anesthesia has been reported to be associated with a low mortality rate in patients with COPD in some studies (25), but not others (24). However, because of the simultaneous use of sedation, lack of control of the airway, less ability to monitor (especially PCO2), and because the patient must ventilate in the supine position, spinal anesthesia creates a significant risk of intraoperative and postoperative respiratory complications; this is especially true of obese patients with chronic pulmonary disease. Because of these problems, general anesthesia, which permits control of ventilation and clearance of secretions, is often preferable to spinal anesthesia in patients with moderate or severe COPD.
A respiratory failure risk index (analogous to the cardiac risk indices) has been developed and validated in a Veteran's Administration Hospital (VA) setting (Table 93.15) (24). This index provides useful guidance for clinical decision making, but should not be used solely until it is validated in other settings.
Perioperative Management
Patients with known COPD should have a preoperative evaluation (Table 93.2) with additional evaluation focused
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on established risk factors described above and the status of their pulmonary disease. If they are taking theophylline, they should have measurement of the serum theophylline concentration and adjustment of the dosage if it is above or below the therapeutic range. Any history of smoking, chronic or intermittent sputum production, recent upper respiratory infection (URI), dyspnea on effort, or concomitant cardiovascular disease is particularly pertinent. Ideally, smokers should stop smoking 8 weeks before admission for surgery to be performed under general or spinal anesthesia, and patients with URIs should have surgery postponed at least 2 weeks, regardless of how minor the episode.
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TABLE 93.15 Respiratory Failure Risk Index |
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For patients undergoing general or spinal anesthesia the principal indications for preadmission spirometry alone (forced vital capacity and FEV1) or for spirometry plus lung volumes and arterial blood gases have not been firmly established.
Pulmonary function testing is indicated when the presence or severity of lung disease is uncertain clinically, for surgery with a high risk of pulmonary complications, and probably in patients with high risk scores on the respiratory failure risk index. Even experienced clinicians can sometimes misjudge the severity of obstructive lung disease. Spirometry is indicated to clarify the presence and severity of lung disease in questionable cases, including patients without a prior diagnosis of pulmonary disease. However, the ability of pulmonary function testing to predict adverse outcomes for high-risk patients has not been clearly established (26). Pulmonary consultation should be obtained for patients whose FEV1 is less than 1.0 L or whose PCO2 is above 45 mm Hg, and for those with less severe pulmonary disease who are being evaluated for thoracic or upper abdominal surgery.
Preoperatively, the patient should be instructed on coughing and deep breathing exercises, as well as on the use of devices such as an incentive spirometer that will be used postoperatively. Patients already taking inhaled or oral bronchodilators and inhaled steroids should continue their regimen through the morning of surgery. Patients who have a history of intermittent airway obstruction should be started on an inhaled bronchodilator before surgery. To prevent bronchospasm, especially in the immediate postoperative period, inhaled (β2-sympathomimetics) and occasionally intravenous aminophylline should be administered (the serum theophylline level should be kept in the therapeutic range [10 to 20 mg/mL]) while the patient cannot take oral medications. Patients who have received corticosteroids for more than 2 weeks during the year before surgery should be appropriately covered for stress with parenteral steroids (see Adrenal Insufficiency and Chronic Steroid Therapy); occasionally steroids may need to be reinstituted or the dose increased to control the pulmonary disease. Patients with chronic purulent sputum production should receive a 5-to 7-day course of a broad-spectrum antibiotic (tetracycline, amoxicillin, trimethoprim–sulfamethoxazole [TMP-SMX], azithromycin, or clarithromycin) to decrease the quantity and purulence of secretions. Finally, arterial blood gases should be checked in patients with moderate to severe COPD before and, as needed, after surgery. Pulse oximetry is usually obtained pre- and postoperatively but does not measure PCO2. There is some dispute about the efficacy of most of these individual measures. However, controlled trials show that the combination, preoperatively, of bronchodilators, antibiotics, lung expansion, and mobilization of secretions decreases the number of perioperative complications (25,26).
Lung Resection and Chronic Obstructive Pulmonary Disease
Overall mortality rates for lung resection are about 5% for lobectomy and approximately 15% for total pneumonectomy. The mortality and morbidity rates for lung surgery vary widely depending on patient factors (particularly age and pulmonary function), type of operation (pneumonectomy, lobectomy, segmental resection), and the experience and skill of the surgical team.
Assessment of pulmonary function in the patient with COPD who has an indication for lung resection (usually a tumor) should be performed in the ambulatory setting. Use of the following criteria to select candidates for lung resection has reduced mortality for patients with COPD:For pneumonectomy, the major criteria for operability are FEV1 of 2 L or more and forced vital capacity 50% of predicted or more. Patients with an FEV1 below 2 L should have quantitative perfusion lung scanning to determine
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the FEV1 that can be expected after pneumonectomy (e.g., if 30% of perfusion and ventilation goes to the affected lung, the patient's pulmonary function will be decreased by approximately 30% postoperatively). Those with a predicted postoperative FEV1 as low as 0.8 to 1 L can undergo pneumonectomy, although their mortality risk is probably increased.
Patients not meeting the criteria for pneumonectomy may tolerate lobectomy or segmental resection. Most patients with a preoperative FEV1of 1.5 L or more can tolerate a lobectomy. The patient may undergo resection of the segment or lobe if the predicted postoperative FEV1 is greater than 0.8 to 1 L by quantitative perfusion lung scanning. Other measures in preoperative planning for the patient with COPD undergoing pulmonary resection are similar to those described for such patients in the preceding section.
Asthma
Risk
Asthma affects approximately 3% of Americans, which makes it one of the most common pulmonary diseases (see Chapter 60). It is difficult to give a firm estimate of the operative risks posed by asthma, because in most reports data on asthma are pooled with results for other types of obstructive airway disease. The most dangerous period for the asthmatic patient is not usually the period during general anesthesia, because the anesthetic may be an effective bronchodilator, but is the immediate postoperative period. The major risks are severe bronchospasm and inspissation of thick secretions.
Perioperative Management
Asthmatic patients should have a preoperative evaluation (Table 93.2) with an emphasis on the severity, stability, and current status of their asthma. The evaluation should be done in the practitioner's office prior to admission to allow adequate time for changes in management. The patient should stop smoking 8 weeks before surgery. Spirometry (FEV1 and forced vital capacity) should be performed on asthmatic patients before operation; peak flows (if normal) are adequate in mild stable asthmatics undergoing minor surgery. Arterial blood gases should be measured in decompensated or severe asthmatics, in asthmatics with substantial abnormalities of spirometry, and when there is clinical concern about hypoxia or hypercarbia. Pulse oximetry is useful when carbon dioxide (CO2) retention is not a concern. Serum theophylline levels should be measured in patients on this medication, because levels on standard doses are frequently subtherapeutic or toxic.
β2-Sympathomimetics and inhaled steroids can be continued as inhaled aerosols until the induction of anesthesia and can be resumed in the recovery room. Planning for the immediate preoperative period should include administration of oral and inhaled bronchodilators on the morning of surgery and scheduling of surgery early in the day. In very severe asthmatic patients who are taking theophylline, a constant infusion of aminophylline may be used in the perioperative period when the patient cannot take medicine by mouth; most patients are adequately treated with intravenous aminophylline or by resuming theophylline orally, in the recovery room. Patients who have taken systemic corticosteroids for more than 2 weeks during the previous year should receive dosages of parenteral steroids sufficient to cover the stress of surgery (see Adrenal Insufficiency and Chronic Steroid Therapy) (27). Some patients will require reinstitution of or an increase in their oral corticosteroid dose to control asthma before surgery.
Patients with Renal Disease
Risk
The size of the operative risk for patients with chronic renal disease depends on the severity of their disease (see Chapter 52). The type of surgery also influences risk; high-risk surgery includes trauma, vascular, and some GI surgery (e.g., when bleeding, jaundice, or infection is present preoperatively) (28). Other risk factors include advanced age, volume depletion, hypotension, sepsis, exposure to nephrotoxins, and CHF (28). Overall, the mortality after major surgery in patients with severe renal disease (i.e., creatinine clearance [CrCl] less than 10 to 15 mL/minute, including patients on dialysis) is approximately 2% to 4% when these cases are managed carefully. In patients not requiring dialysis, postoperative acute renal failure is the gravest complication (28).
The major complications associated with surgery in the patient with moderate to severe renal disease are worsened renal failure, electrolyte disturbances (especially acidosis and hyperkalemia), volume contraction, volume overload, toxicity caused by agents that are nephrotoxic or are excreted by the kidneys, anemia, and bleeding. Volume contraction, with the risk of ischemic cerebral, cardiac, or renal damage, is a particular risk in patients with the nephrotic syndrome; these patients usually have a slightly contracted intravascular volume at baseline and are at risk of hypovolemia if an effort is made to decrease their edema with potent diuretics preoperatively. Toxic renal damage may follow the use of two classes of agents that are often used in the perioperative period: radiocontrast materials and aminoglycoside antibiotics.
Perioperative Management
Before admission for surgery, patients with chronic renal failure should have an evaluation as outlined in
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Table 93.2, and their intravascular volume status should be documented. Weight and orthostatic blood pressure are important in assessing preoperative volume status. Baseline creatinine clearance should be documented by calculation or actual measurement. Radiocontrast studies should be avoided, if at all possible, in the preoperative workup of patients with significantly elevated serum creatinine concentrations or with other risk factors because of the risk of acute renal failure (28). If radiocontrast studies are required, the use of intravenous hydration with 0.45 (half-normal) saline combined with oral acetylcysteine or an intravenous infusion of sodium bicarbonate may reduce this risk (29,30).
The most important consideration in perioperative management of patients who do not require dialysis is avoidance of fluid imbalance. When the surgery carries a risk of significant volume shifts, pulmonary artery catheterization may be considered to ensure close monitoring of the intravascular volume. Administration of antihypertensives should follow the guidelines stated earlier in this chapter. The dosages of some drugs may need to be adjusted for the patient's degree of renal insufficiency as outlined in Chapter 52 (31). BUN, serum creatinine, and electrolytes should be monitored before and after surgery to detect hyperkalemia and deterioration of renal function. Patients with renal failure often have a metabolic acidosis compensated by hyperventilation; postoperatively, continued appropriate hyperventilation is necessary to avoid a potentially precipitous fall in arterial pH. Preoperative prophylactic dialysis is not generally recommended in the patient not already on chronic dialysis. Patients with chronic anemia secondary to renal failure usually are well compensated and do not require preoperative transfusion unless they are symptomatic from the anemia or a large blood loss is expected during surgery; preoperative use of erythropoietin is a consideration to avoid transfusion.
Generally, the nephrologist caring for patients on chronic dialysis should coordinate the medical management of these patients throughout the surgical episode. Although these patients have a very high postoperative complication rate (caused by hyperkalemia, bleeding, arteriovenous fistula thrombosis, pneumonia, wound infection, and arrhythmias), their risk of dying from surgery remains in the 2% to 4% range if complications are carefully managed (28).
Patients with Endocrine Disease
Diabetes Mellitus
Risk
Total surgical mortality for all diabetic patients is approximately 2% to 4%; less than 0.3% die as a result of poor control of their diabetes. Approximately 15% of diabetic patients have postoperative complications that may be related to diabetes, particularly wound infection.
Two recent consensus statements have concluded that tight glycemic control during the perioperative period (premeal glucoses ≤110 to 126) reduces surgical morbidity and mortality (32,33). Clear guidelines on how to achieve this difficult goal were not offered, except that sliding scale insulin alone is not considered sufficient.
Perioperative Management
Each diabetic patient should have a preoperative evaluation as outlined in Table 93.2, with particular attention to determining diabetes control and the presence of cardiovascular disease. Patients who are responsible can monitor their own glucose, and patients who are compliant are good candidates for outpatient surgery. Relative contraindications to outpatient surgery include significantly uncontrolled diabetes, extremely labile diabetes, and noncompliant diabetic patients requiring insulin.
Measurement of fasting glucose, electrolytes, serum urea nitrogen, and creatinine should be obtained at the time of the preoperative office evaluation. If the patient is monitoring glucose at home, these values should be reviewed, as well as any recent hemoglobin A1Cmeasurements. The patient should be told to call if his or her home glucose measurements are higher or lower than predetermined values (specific values should be given to the patient in writing) between the time of the office medical evaluation and surgery and also postoperatively. The patient or nurse should do a bedside glucose determination on arrival at the hospital. The state of hydration should be determined to ensure that the diabetic is not significantly volume contracted. Elective surgery should not be undertaken if diabetes is uncontrolled (fasting blood glucoses more than 200 to 250 mg/100 mL); better control may decrease perioperative risks, and tight control with pre-meal glucoses less than 110 to 126 are optimal. Table 93.16 summarizes the appropriate perioperative treatment of diabetes, which depends on the type of surgical procedure planned and the preadmission regimen. Diabetic patients who are controlled by diet can be monitored with daily fasting blood glucose levels throughout the operative episode and treated with insulin if unacceptable rises in glucose occur.
Treatment of patients taking oral agents varies because they represent a heterogeneous group. Patients with mild elevations of glucose who are undergoing minor procedures that will allow them to eat the same day can take their oral hypoglycemic drug on the day before surgery and resume it when they begin eating after surgery. If the patient is to undergo a major procedure, oral agents (including thiazolidinediones) should be discontinued beginning on the morning of surgery and not continued postoperatively
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because they have relatively long half-lives, control is less predictable, and because the drugs cannot be given parenterally postoperatively. Therefore, such patients should be switched to management by diet only or to insulin. Human insulin is preferred for the patient who has not taken insulin previously. An exception is the patient taking chlorpropamide (Diabinese), which should be withheld 2 to 3 days before surgery because of its particularly long half-life. Metformin (Glucophage) should be withheld at least 48 hours before elective surgery. It should not be restarted (except for minor procedures) until 48 hours postoperatively, and when the patient is stable and eating, and for major procedures, until a postoperative serum creatinine has been measured. Metformin should also be withheld for 48 hours before and after any preoperative imaging procedure involving administration of radiocontrast. It is especially important to withhold metformin in major procedures that carry a risk of hypotension or renal failure (e.g., vascular surgery) because of the risk of lactic acidosis.
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TABLE 93.16 Management of Diabetes on Day of Surgery |
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For the patient who is taking insulin before surgery, one of several strategies is recommended for the preoperative period (Table 93.16). Because of its simplicity and the small risk of hypoglycemia, the first regimen (giving one half to two thirds of the usual total daily dosage of long-acting insulin preoperatively) is preferred. Postoperative inpatient management of diabetes is beyond the scope of this text (32,33).
Adrenal Insufficiency and Chronic Steroid Therapy
Risk
It is generally agreed that patients who are currently taking a pharmacologic dosage of corticosteroids (more than the equivalent of 20 to 30 mg of hydrocortisone daily), who have taken corticosteroids at a pharmacologic dosage for 2 or more weeks in the past year, or who are receiving replacement dosages for adrenal insufficiency, are at risk of developing perioperative adrenal insufficiency because of the stress of surgery. Patients in each of these groups should therefore receive extra corticosteroids in the perioperative period (see Chapter 81 for additional details) (34).
Perioperative Management
These patients should have an evaluation before admission (Table 93.2) with an emphasis on signs of adrenal insufficiency. For patients with adrenal insufficiency, the evaluation should include particular attention to factors that may reflect the adequacy of corticosteroid replacement (i.e., lying and standing blood pressure, concentration of serum urea nitrogen or serum creatinine, glucose, and electrolytes). Adrenocorticotropic hormone stimulation or insulin-hypoglycemia testing to determine the need for steroid coverage in patients previously on steroids is
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not recommended for routine use because there is not adequate evidence that a normal response precludes the need for steroid coverage during surgery.
Patients on chronic steroid therapy may receive the usual steroid dosage by mouth the day before surgery. On the day of surgery, hydrocortisone 100 mg should be administered intravenously at 6 a.m. A second 100-mg dose should be given intravenously during surgery and then a 100-mg dose should be given intravenously every 6 hours for the first 24 hours after surgery, followed by 50 mg every 6 hours for the second 24 hours after surgery, and 25 mg every 6 hours for the third 24-hour period. Alternatively, a continuous infusion of hydrocortisone after an initial bolus dose preoperatively may be given (34). The patient may then return to the preoperative medical regimen.
There are two exceptions to these guidelines. First, the regimen is based on the assumption that there is no prolonged stress after surgery; if this occurs, higher dosages of corticosteroids must be continued for a longer time postoperatively. Second, for minor procedures, patients may return to their usual dosage within 24 to 48 hours postoperatively. For outpatient surgery, equivalent dosages of oral prednisone may be given as an outpatient for the postoperative care (preoperative dosage should still be given intravenously).
Hypothyroidism
Risk
The major potential complications of surgery in hypothyroid patients are increased sensitivity to and prolonged half-life of anesthetic agents, hypoventilation and respiratory arrest in the immediate postoperative period, hyponatremia caused by decreased free water clearance, and myxedema coma. The risks of surgery in patients with mild to moderate hypothyroidism are probably not as high as once thought (35). Nonetheless, hypothyroid patients should delay elective surgery for 4 to 6 weeks and should be treated with thyroxine (seeChapter 80).
Perioperative Management
Hypothyroid patients should be evaluated carefully before admission for surgery. The patient should have the evaluation outlined in Table 93.2, and the serum thyroid-stimulating hormone concentration should be checked (unless a value from the past 2 months is available; seeChapter 80 for details).
Specific recommendations for preoperative management depend on the status of the patient's hypothyroidism. Patients with previously known and adequately treated hypothyroidism can undergo surgery. The half-life of administered thyroxine is about 7 days. Therefore, oral thyroxine can usually be omitted on the day of surgery and resumed when the patient is able to take oral medication. The stress of major surgery or severe infection may accelerate the turnover of thyroxine, occasionally necessitating daily treatment with intravenous thyroxine (50% of the oral dosage) in patients in either of these situations.
If the hypothyroidism has been effectively treated for a long period (as indicated by no or only minor symptoms or a normal or only a slightly increased thyroid-stimulating hormone), the patient can usually tolerate surgery and thyroid replacement can be adjusted postoperatively. For hypothyroid patients who have not been treated or who remain significantly hypothyroid because of inadequate replacement therapy, elective surgery should be postponed because of the risks listed above. Such patients should receive adequate thyroid replacement for a minimum of 1 to 2 months before elective surgery (4 to 6 months for patients with profound myxedema). Surgery required before this period in mild to moderately hypothyroid patients may be considered, especially if minor surgery under local anesthesia is being performed, if the patient can be started on a total replacement dosage immediately, and if there is prompt improvement in signs and symptoms of hypothyroidism (see Chapter 80). When a patient with previously undiagnosed hypothyroidism requires immediate major surgery, an endocrinologist should be consulted regarding perioperative treatment and monitoring.
Hyperthyroidism
Risk
The major risk of operation in patients with uncontrolled hyperthyroidism is thyroid storm (see Chapter 80). In an old series, there were only 25 episodes of thyroid storm after 1,383 operations on thyrotoxic patients (36). However, surgery accounts for up to one third of the cases of thyroid storm reported, probably in patients with unrecognized hyperthyroidism.
Perioperative Management
The patient with known hyperthyroidism should be reassessed clinically and with thyroid function tests before admission for surgery. In previously undiagnosed patients, the usual approach should be used in evaluation and management (see Chapter 80).
The treatment of the hyperthyroid patient during surgery depends on the patient's current thyroid status. Patients previously diagnosed and adequately treated should take their current treatment until midnight the night before surgery and should resume treatment when they can take medications by mouth again. Patients with new,
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known, or recurrent hyperthyroidism who are not euthyroid should be brought to an euthyroid state with thyroid-blocking agents or iodides (see Chapter 80). Ideally, surgery should be postponed for several months in these patients until a consistent euthyroid state is attained. An endocrinologist should be consulted regarding the treatment and monitoring of any patient with uncontrolled hyperthyroidism who requires urgent surgery.
Obese Patients
Risk
Massive obesity significantly increases the risk of mortality associated with surgery. In one study, for example, women undergoing surgery for adenocarcinoma of the uterus had a 20% operative mortality if they weighed more than 300 pounds (136 kg), compared with a 1.5% mortality for obese women weighing between 200 and 240 pounds (91 and 110 kg) (37). Less severe obesity probably does not increase mortality risks.
Moderate or massive obesity also increases the risk of a number of perioperative problems, including difficult intubation, difficulty in ventilating the patient during anesthesia, the need for a large amount of anesthesia during induction, potential delay in anesthesia washout because of slow release of anesthetic agents from adipose tissue, postoperative atelectasis and pneumonia, thromboembolism, difficult postoperative mobilization, nosocomial wound infection (particularly when there is increased moisture caused by pannus adjacent to the surgical incision), wound dehiscence, and late incisional hernia.
Perioperative Management
For massively obese patients, a program of gradual weight reduction (see Chapter 83) should be planned, if the patient is amenable, before any elective operation; this may require up to 6 months. When prompt surgery is needed, these patients should have an evaluation (Table 93.2) with the addition of assessment for complications of obesity, particularly cardiopulmonary complications. Particularly, these patients should be checked for uncontrolled diabetes mellitus and significant hypoventilation (sleep apnea), two common complications of obesity that increase the risk of surgery. Either of these two problems should be managed preoperatively, as discussed above.
Massively obese patients should be given preoperative instruction in deep breathing and in the use of the incentive spirometer or other devices designed to prevent pulmonary complications postoperatively. Prophylaxis of thromboembolic disease should be given (see Chapter 57). Other recommendations for perioperative management depend on obesity-associated conditions, such as diabetes, that the patient may have.
Patients with Gastrointestinal or Hepatic Disease
Peptic Ulcer Disease
Risk
Data are lacking on the risk and the management of surgery in patients with active peptic ulcer disease.
Perioperative Management
Patients with active ulcer disease should have elective nonulcer surgery postponed until the ulcer heals. The average time required for the healing of uncomplicated ulcers is 4 to 6 weeks for duodenal ulcer and 6 weeks for gastric ulcer (see Chapter 43). There is no consistent relationship between disappearance of ulcer symptoms, ulcer healing, and recurrence. Therefore, it is best to wait several weeks after all symptoms have disappeared and 6 weeks to 3 months from the beginning of an episode before admission for elective nonulcer surgery. If surgery cannot be deferred this long or if ulcer recurrence is suspected, endoscopy should be considered preoperatively. Before surgery, these patients should also have the medical evaluation summarized in Table 93.2, and multiple stool samples should be checked to exclude active bleeding.
No empiric data confirm these guidelines or indicate whether surgery can be done safely as soon as an ulcer has healed (as shown by endoscopy). If urgent abdominal surgery must be performed in a patient with active ulcer disease, consideration should be given to whether surgical treatment is needed for the ulcer as well (see Chapter 43 for detailed discussion of indications for and types of surgery). Patients with remote or inactive ulcer disease require no special therapy preoperatively or postoperatively.
Patients with recently active ulcer disease should continue their current therapy until midnight the day before surgery. Both H2 blockers (cimetidine, ranitidine, famotidine) and proton pump inhibitors (lansoprazole, pantoprazole) can be given intravenously or via nasogastric tube. One of these should be used throughout the period when the patient cannot take medications by mouth; nasogastric suctioning may also be recommended during this period.
Hepatitis
Risk
General anesthesia and surgery during acute hepatitis are associated with high rates of mortality and morbidity (38). The major problem accounting for these risks is postoperative hepatic encephalopathy and its complications. The catabolic effects of surgery, hypotension during anesthesia,
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and hepatic toxicity from anesthetic agents are the principal factors that may precipitate hepatic encephalopathy.
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TABLE 93.17 Child's Classification of Operative Mortality Risk in the Cirrhotic Patient |
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Perioperative Management
Patients with a history of acute hepatitis should have an evaluation (Table 93.2) with the addition of assessment of the severity and complications of the liver disease. Liver function tests (serum aminotransferases, bilirubin, alkaline phosphatase, albumin, and prothrombin time [PT]) should be obtained before admission for surgery. Serologic tests for hepatitis B and hepatitis C should also be performed (seeChapter 47), if they have not been done previously.
Ideally, surgery should be postponed for a minimum of 6 to 12 months after all laboratory evidence of active liver disease has returned to normal. This cautious approach is advised because there is a risk of exacerbating hepatic injury if surgery is performed earlier. Only urgent life-saving surgery should be performed during the acute phase of hepatitis, whatever its cause.
Anticipation of postoperative complications (particularly bleeding and encephalopathy) is important in the patient with active hepatitis who must undergo surgery. For the patient with an abnormal PT, fresh frozen plasma can be given throughout the immediate perioperative period. When immunologic tests or epidemiologic information indicates infectious hepatitis (see Chapter 47), the surgical team should be notified in order to minimize the risk of spreading infection.
Cirrhosis
Risk
Data regarding the risks of surgery in the cirrhotic patient are available from trials of portal–systemic shunts and from more recent studies in general surgical patients (39). The most widely used measure of the mortality risk is the Child index, which incorporates measurements of serum bilirubin, albumin, ascites, encephalopathy, and nutrition (Table 93.17). Elevated PT is also a predictor of bad outcome (39). The perioperative complications encountered in these patients are those associated with chronic cirrhosis: encephalopathy, jaundice, gastrointestinal hemorrhage, infection, and hepatorenal syndrome.
Regional and spinal anesthesia do not entirely eliminate the risks of complications in cirrhotic patients. For example, increased morbidity and mortality caused by liver disease have been associated even with hernia repair under local anesthesia in some patients. The stress of the procedure itself, decreased hepatic blood flow, and complications such as hypotension and wound infection may worsen hepatic function, even in the absence of toxic general anesthetics.
Perioperative Management
In addition to the preoperative evaluation (Table 93.2), patients with cirrhosis should have an assessment of the severity and complications of their liver disease and liver function tests (serum amino transferase, bilirubin, alkaline phosphatase, albumin, and PT). Liver biopsy is indicated in selected patients to establish the presence of cirrhosis, provide an additional indicator of the severity of liver damage, or exclude active hepatitis. CT or sonogram is only occasionally needed to evaluate hepatomegaly. In the history and physical examination, a search should be made for complications of cirrhosis, especially encephalopathy, bleeding, varices, and ascites.
The expected benefits of surgery must be weighed carefully against the risks in patients with cirrhosis. Generally, risks are higher and only essential surgery should be performed. Stable patients with mild cirrhosis, however, who have no ongoing injury (e.g., due to removal of a toxin or discontinuation of alcohol) may tolerate surgery without significant complications.
A number of precautions should be emphasized in the cirrhotic patient who does require surgery. Local (or, as a second choice, spinal) anesthesia may be safer than
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general anesthesia, although data are lacking. Therapy to prevent complications of liver disease, such as postoperative bleeding (fresh frozen plasma for the patient with an abnormal PT or partial thromboplastin time) and encephalopathy (see Chapter 47), should be established and maintained throughout the operative period, and the patient should be repeatedly checked for evidence of these two problems. The occasional patient who is taking chronic corticosteroid therapy for liver disease should have the steroid dosage increased during the perioperative period as described in Adrenal Insufficiency and Chronic Steroid Therapy.
Patients with Iatrogenic Impairment of Hemostasis
All anticoagulants and platelet inhibitors increase the risk of intraoperative and postoperative bleeding and should be discontinued before any type of surgery. Patients receiving drugs in these classes should have a preoperative evaluation (Table 93.2) before admission for surgery, and an appropriate plan for perioperative management of anticoagulation should be communicated to the surgeon, anesthesiologist, or surgical center.
Anticoagulants
On the basis of critical assessment of risks and benefits, recommendations for the perioperative management of patients taking oral anticoagulants have been revised (40). Warfarin (Coumadin) should be stopped 4 to 7 days before surgery, depending on the patient's current international normalized ratio (INR). In patients maintained at a high INR, warfarin should be discontinued earlier. The INR should be measured the day before surgery. If the INR remains elevated, 1 mg of vitamin K1 should be administered subcutaneously. Within 12 hours, this dose will usually normalize the INR of a patient who has been off warfarin for 4 to 7 days. The larger doses of oral vitamin K1previously recommended (e.g., 10 mg) are believed not to be necessary and to increase, possibly, the risk of thromboembolism (40).
Preoperative use of intravenous heparin, while the INR is subtherapeutic, is recommended only for patients at very high risk of thromboembolism, such as those with recent (within 1 month) venous thromboembolism or arterial embolism (40). Postoperatively, intravenous heparin is also recommended in these high-risk patients and in patients who have had venous thromboembolism within the 3 months preceding surgery. An alternative to intravenous unfractionated heparin preoperatively is subcutaneous low-molecular-weight heparin (LMWH) in therapeutic or prophylactic doses depending on the underlying diagnosis. Intravenous heparin should be stopped about 6 hours before surgery; the last dose of low-molecular-weight heparin should be given at least 24 hours before surgery. An INR and, if the patient is taking unfractionated heparin, a partial thromboplastin time and a platelet count should be checked before surgery (40). A number of new anticoagulants (e.g., direct thrombin inhibitors and factor X inhibitors) have been developed in recent years. In general, they should not be prescribed perioperatively until more experience is gained with their use.
These recommendations for use of preoperative and postoperative heparin are much more limited than previous recommendations. Other authors recommend preoperative or postoperative intravenous or LMWH for other high-risk patients, such as those with mechanical valves and multiple risks (e.g., mechanical valve, atrial fibrillation, or history of embolization).
Preoperative placement of a vena caval filter is an option in patients with recent venous thromboembolism or patients for whom the risk of bleeding because of heparin is unacceptably high (40). Warfarin ordinarily can be resumed 24 to 72 hours after surgery, at the preoperative dosage, if all surgical bleeding is controlled; the INR usually reaches 2.0 after 3 days. Patients who have undergone intracranial, spinal, or ophthalmologic operations probably should not be anticoagulated for 48 hours to several weeks after surgery. For patients with a high risk of thromboembolism (see above), continuous-infusion heparin can be reinstituted 12 to 24 hours postoperatively without a bolus, if the surgeon is confident that hemostasis is ensured, and continued until full anticoagulation with warfarin has been re-established (40).
Antiplatelet Agents
Aspirin prolongs the bleeding time and may increase blood loss during and after operation in some patients. Generally, if aspirin is not being used as a critical therapy, it should be discontinued 7 or more days before surgery because the effect of aspirin on platelets continues for this period of time. Discontinuation of aspirin is particularly important before procedures for which hemostasis is critical, such as neurosurgical operations or some ophthalmologic surgery. Aspirin may be continued when its indication is important (e.g., CAD) and the risk of bleeding is low (e.g., breast biopsy, some peripheral vascular surgery). Because some NSAIDs other than aspirin also may impair platelet function, it is prudent to advise patients to discontinue NSAID use 1 week before surgery, especially surgery for which increased bleeding would be especially harmful (Table 93.4). Ticlopidine (Ticlid) and clopidogrel (Plavix), platelet aggregation inhibitors, should be discontinued at least 2 weeks before surgery to ensure that the bleeding time is not prolonged in the perioperative period.
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Patients with a Chronic Infection
Two types of chronic bacterial infection pose risks to the patient and to others in the operating room: staphylococcal skin infections and pulmonary tuberculosis. They require appropriate management before surgery.
Skin Infections
Chronic bacterial skin infections (usually caused by staphylococci) pose a high risk for wound sepsis and may be the source of infections in other patients. Therefore, they should be suppressed or eradicated before admission of the patient for an elective operation. Chapter 32describes strategies for accomplishing this.
Tuberculosis
Active pulmonary tuberculosis poses a problem for the surgical patient because of the general debilitation it causes. It also creates the risk of infection for others in the operating room. Therefore, adult patients with a history of unexplained chronic cough or a history of tuberculosis should be evaluated for active tuberculosis before admission for surgery. Patients with active pulmonary tuberculosis should be stable and have negative sputum cultures before admission for elective surgery. Chapter 34 describes the ambulatory treatment of tuberculosis.
Human Immunodeficiency Virus Infection
Acquired immunodeficiency syndrome (AIDS) poses many problems in preoperative evaluation that are beyond the scope of this chapter but are addressed elsewhere (see http://www.hopkinsbayview.org/PAMreferences and Chapter 39). Several important issues are summarized here.
The risk of transmission to health care workers is very small, but it does exist. Universal precautions are recommended in the care of all patients, not just known HIV-positive patients (see Chapter 39). Screening of all surgical patients for HIV infection is not currently recommended by expert consensus, but this issue continues to be controversial.
HIV-infected patients pose challenges in addition to the usual preoperative evaluation. Decision-making is complicated by the wide spectrum of morbidity in HIV infection, ranging from the lack of symptoms in the recently infected patient to the debilitation in the preterminal patient. Decision-making should balance the status and prognosis of the patient's HIV infection (asymptomatic, symptomatic), mean life expectancy, the patient's wishes, the increased risk for the specific operation posed by the HIV infection, and the indications for and expected benefit of the surgery during the patient's expected length of survival.
Patients with Neuropsychiatric Disease
Neuropsychiatric problems present ill-defined risks during surgery and the postsurgical period. The major concerns are worsening of mental status caused by both metabolic changes and psychologic stresses. The patient with psychiatric disease may decompensate postoperatively, making care difficult and jeopardizing wound healing.
Cerebrovascular Disease
Risk
Patients with recent strokes have a significant risk of worsening focal deficits during carotid artery surgery, but this risk cannot necessarily be extrapolated to other types of surgery. Patients with recent strokes (less than 6 weeks preoperatively) also have a risk of deterioration in their general mental status, regardless of the status of their focal deficits, if they undergo major surgery; however, firm data are lacking on the size of this risk.
Perioperative Management
Patients with recent strokes should have a preoperative evaluation (Table 93.2), emphasizing documentation of the preoperative neurologic impairment and the detection of treatable underlying causes of the stroke. The data regarding the course of the patient's stroke should be reviewed, and additional testing (see Chapter 91) should be performed if necessary to exclude a treatable cause.
No specific perioperative therapy for the patient with a stable completed stroke is needed. In general, it is prudent to delay elective noncarotid surgery for at least 6 weeks after a completed stroke, although no firm data are available to support this practice.
Asymptomatic Cervical Bruit
Risk
Cervical bruits are present in approximately 4% of people older than the age of 45 years. These bruits may be caused by a number of processes (see Chapter 91), including common or internal carotid stenosis. In the patient with an asymptomatic cervical bruit, there is slight or no increased risk of stroke during surgery (41).
Perioperative Management
Apart from a careful history and physical examination to exclude evidence of a prior stroke or transient ischemic
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attack related to the cervical bruit, no special approach is needed for these patients. Duplex carotid ultrasound can help establish whether the cervical bruit is caused by carotid stenosis and the degree of stenosis; its value has not been established for estimating risk of postoperative stroke. Hypotension and excessive neck manipulation should be avoided during surgery in patients known to have carotid bruits. The patient with a history of symptoms possibly related to the bruit should be evaluated as described in Chapter 91.
Data summarized in Chapter 91 show that patients with high-grade asymptomatic and symptomatic carotid stenosis have a lower long-term stroke rate if carotid endarterectomy is performed. When patients such as these require elective surgery for another condition, a decision must be made on which of the two surgeries to do first. Whether prophylactic carotid endarterectomy should be done before vascular surgery is controversial, but few patients require prophylactic carotid endarterectomy before general surgery who would not require it anyway.
Parkinson Disease
Risk
The perioperative risks in patients with Parkinson disease (PD) are caused by musculoskeletal rigidity, which may impair voluntary postoperative ventilation, mobilization, and swallowing. These patients are also subject to postoperative delirium. The rigidity of patients taking antiparkinson medication may worsen after the patient has missed one or more doses (see Chapter 90). Despite this potential problem, most patients with PD tolerate anesthesia and temporary omission of medications.
Perioperative Management
The patient should have a preoperative evaluation (Table 93.2), and the antiparkinsonian regimen should be tailored to provide the best possible relief of symptoms (see Chapter 90). For patients taking an anticholinergic agent, the drug may be continued until midnight before surgery and resumed when the patient is able to take oral medications. L-Dopa or Sinemet (L-dopa/carbidopa) should be continued until induction of anesthesia, and the drug should be resumed as soon as possible after surgery. Postoperative physical therapy to maintain range of motion may help these patients until they are able to take oral medication. Parkinsonian patients should be observed for postoperative delirium and aspiration.
Dementia and Organic Brain Syndrome
Risk
Patients with dementia have an increased risk of mortality and morbidity during surgery. The increase in mortality is caused largely by lack of cooperation (e.g., with postoperative respiratory care). Much of the morbidity is related to the development of delirium caused by anesthesia, perioperative medications, and surgical stress. Because surgery is always a difficult process for a demented patient and because the degree of increased risk is ill defined, the potential benefits of surgery should be carefully reviewed before a final decision to operate is made.
Perioperative Management
The patient should have an evaluation (Table 93.2) before admission for surgery. Formal mental status testing should be done (see Mini-Mental Status Examination, Chapter 26) so that a baseline is established for postoperative comparison. The patient should be checked for metabolic abnormalities that may worsen cerebral function before admission, just before surgery, and throughout the postoperative period. Emphasis should be placed on detecting and correcting hypovolemia, electrolyte abnormalities, and hypoxia. See Surgery in the Elderly Patient, above, for simple measures to decrease the incidence of postoperative delirium. When demented patients undergo major procedures, constant observation is recommended for the first 24 to 48 hours after surgery.
Other Psychiatric Problems
Risk
The major problems associated with general surgery in psychiatric patients are lack of cooperation with postoperative care, postoperative psychosis, and interactions between psychotropic medications and anesthetic agents. The degree of cooperation that can be expected postoperatively can generally, but not always, be predicted on the basis of the patient's past behavior and preoperative mental status. Obtaining informed consent is also an issue.
Perioperative Management
A careful history of the patient's past psychiatric illness should be obtained. The patient's mental status should be documented preoperatively (see Chapter 26) so that it can be compared with postoperative changes. The patient's ability to give informed consentshould be evaluated (see Chapter 26); involvement of a designated decision-maker other than the patient may be required. A psychiatric consultation should be obtained in all patients with psychosis or other severe psychiatric problems. An additional issue that must be dealt with by the patient's primary care practitioner and surgeon is the likely effect of the patient's psychiatric state on the surgical evaluation and outcomes (e.g., evaluating symptoms in a patient with one of the somatoform disorders, described in Chapter 21, or evaluating the need for cosmetic surgery).
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Careful explanation of the operation is especially crucial to management of patients with psychiatric disorders or with anticipated stress reactions to surgery. The procedure should be explained in language the patient can understand. After the explanation, the patient should be asked to express any concerns about the planned surgery, and the patient's comprehension of the planned surgery should be assessed and documented. The need to ventilate about anxiety associated with disfiguring surgery (e.g., mastectomy, amputation) and with the fear of not waking up is particularly common in both anxiety-prone patients and those who are usually free of anxiety.
Patients with severe psychosis should be in a stable manageable state before admission for elective surgery. This should be accomplished through close collaboration between the patient's primary care practitioner, the surgeon, and psychiatrist.
Patients with mild to moderate anxiety or depression can be managed by supportive counseling, use of support by family members, selective use of antidepressants or minor tranquilizers, and careful explanation of the procedure to the patient. These interventions should be initiated before hospital admission, not at the last minute before surgery.
The patient's use of psychotropic drugs should be communicated to the anesthesiologist. Neuroleptics and tricyclic antidepressants can interact with anesthetics to cause increased sedation, hypotension or hypertension, and arrhythmias. Small to moderate dosages of phenothiazines, haloperidol, and tricyclic antidepressants should be continued until about 12 hours before surgery. In the occasional patient taking a very high dosage of these agents, it is recommended that the drug is stopped about 24 hours before surgery, except in patients who have severely decompensated in the past when their medication has been changed. The dosage of benzodiazepines does not need to be changed unless it is very high.
Lithium carbonate may prolong the action of muscle relaxants and cause myocardial depression and hypernatremia. Lithium should be discontinued 24 hours preoperatively; however, the anesthesiologist should be aware that it has been administered recently. A blood lithium level and electrolyte measurements should be obtained before surgery as a guideline. Chapter 24 provides additional information about lithium.
MAOI antidepressants can enhance the effect of sympathomimetic agents and sympathetic responses to anesthesia and can decrease the rate of elimination of certain anesthetic agents. Because of these problems, MAOIs should be discontinued at least 2 weeks before surgery, and the anesthesiologist must be informed of their recent administration.
Specific References*
For annotated General References and resources related to this chapter, visit http://www.hopkinsbayview.org/PAMreferences.
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