Initial and ongoing assessment of the patient and continuous monitoring of dialysis equipment are among the most vital functions of dialysis personnel. Both registered nurses and patient care technicians (PCTs) have defined roles and responsibilities. State boards of nursing regulate the practice of nursing, including the direct supervision of nonprofessionals to whom specific tasks may be delegated. Readers are advised to review the regulations guiding practice in the states in which they practice.
In some states, only registered nurses are allowed to perform assessment as described by the Nurse Practice Acts. Some states, however, have special laws that allow unlicensed dialysis PCTs to perform certain tasks. In many states, PCTs are permitted by the state to infuse normal saline intravenously for priming and hypotension, to inject intradermal lidocaine (Xylocaine) before insertion of dialysis needles into the vascular access, and to administer intravenous heparin for anticoagulation per protocol or physicians’ orders. These tasks are allowed under the direct supervision of a registered nurse.
In this chapter, assessment refers to the nurses’ role. Monitoring or collection of data is the role of the PCT. After data are collected, the nurse and the PCT work together to initiate changes in the dialysis treatment per physicians’ orders or protocols.
What is patient monitoring?
Patient monitoring is a series of repeated or continuous observations and documentation of the patient’s physiologic state and response to dialysis. Machine monitoring is continuous and includes the following: arterial and venous pressures, blood flow rate, transmembrane pressure (TMP), ultrafiltrate removed, dialysate temperature, dialysate flow and conductivity, and remaining treatment time. Dialysis personnel are responsible for reading, documenting, and evaluating these parameters. Vital signs are measured at least every hour or more frequently in unstable patients or where facility policy dictates. Assessments determine the appropriate dialysis intervention to attain the goals of treatment.
What are dialysis treatment outcome standards?
The National Kidney Foundation (NKF) Kidney Disease Outcomes Quality Initiative (KDOQI) provides guidelines with indicators for outcomes. Four different clinical practices guidelines—hemodialysis adequacy, peritoneal dialysis adequacy, treatment of anemia, and vascular access—are used to assess and improve the outcome of each dialysis. Other guidelines have been developed, including nutrition, dyslipidemia, bone disease, and hypertension. Additional guidelines for pediatrics have also been developed. (See Appendix A for additional information on NKF KDOQI.)
What are the different types of hemodialysis assessment?
Types of assessment include the following: physical assessments, laboratory data analysis and interpretation, first dialysis assessment, intradialytic assessment (predialysis, postdialysis, and monitoring of hemodialysis procedure), and the interdisciplinary team (IDT) assessment using the Centers for Medicare & Medicaid Services (CMS) clinical practice guidelines. The IDT must develop and implement a written and individualized comprehensive plan of care. The plan of care should reflect changes in the patient’s condition and must include measurable and expected outcomes within a defined time frame.
General assessment parameters
Assessment involves collecting data through interviews, physical examination, performance of laboratory tests, and interpretation of patient observation. These data directly affect the patient’s care.
What does physical assessment include?
Physical assessment consists of the following: assessing weight, blood pressure (BP), temperature, pulse, and respiratory rate; evaluating respiratory effort and extent of edema; auscultating for quality of heart sounds and breath sounds; comparing apical and peripheral pulses; assessing skin integrity, skin color, and jugular vein distension (JVD); and evaluating vascular access.
When are patients weighed?
Dialysis patients are weighed before and after each dialysis treatment. Some patients follow their weights at home to guide the adjustment of their fluid intake between dialyses.
Why is measurement of weight important?
Weight is a good indicator of how well the patient is controlling fluid balance between dialyses. Predialysis weight indicates how much ultrafiltration (UF) is required during the treatment. Postdialysis weight is the best indication of how much UF occurred during the hemodialysis procedure.
What is meant by the patient’s dry weight?
Dry weight is the ideal postdialysis weight after the removal of all or most excess body fluid. Patients who are at dry weight are usually normotensive. If the postdialysis weight suggests that volume status is too high, the patient may be on the borderline for fluid overload and may be hypertensive. If postdialysis weight is too low, the patient may be hypovolemic and at risk for hypotension and clotting of the vascular access.
How much weight gain is permissible between dialysis treatments?
Weight gained between dialysis procedures is due to fluid retention. Most dialysis units encourage patients to limit their weight gain to 0.5 kg (or 1 lb) per day. (Refer to Chapter 14 for further discussion and calculation of fluid restrictions.)
Why is blood pressure measurement important?
Blood pressure is often volume related. Hypertension may indicate volume overload. Hypotension may indicate dehydration. Blood pressure is measured while the patient is sitting and standing to evaluate orthostatic changes requiring intervention. It is important to monitor and treat hypertension in the patient with chronic kidney disease (CKD) to reduce the risk of cardiovascular disease and other complications. Hypertension occurs in more than 80% of patients with CKD stage 5.
What is normal blood pressure?
Hypertension is very common in CKD and as many as 75% of patients with a glomerular filtration rate (GFR) < 60 mL/min have a BP > 140/90 mm Hg. Normal BP is an individual matter. In the CKD patient, BP is analyzed for trends rather than absolute values. The KDOQI 2003 Guidelines on Goals of Antihypertensive Therapy for CKD recommend a target BP of < 130/80 mm Hg.
Where can the cuff be placed for blood pressure measurement?
The upper arm is the most common cuff placement site but there are two alternative placements. A large thigh cuff can be applied around the midthigh area. The pulse is audible via a stethoscope at the popliteal space. As well, a regular cuff may be applied above the ankle with auscultation over the posterior tibial or dorsalis pedis artery. This usually yields an audible BP, but the readings obtained will be 20 to 40 mm Hg higher than arm pressures. A notation should be made on the patient’s chart whenever leg pressures are taken. Blood pressure cuffs should never be placed on an extremity with a deep vein thrombosis, grafts, ischemic changes, or AV fistula or graft.
Why are temperature, pulse, and respiration monitored?
Temperature, pulse, and respiration (TPR) observations serve as a baseline at the start of dialysis. Temperature elevation suggests infection or complicating illness. An elevated temperature is often a sign of vascular access infection. Fever during dialysis may be caused by high dialysate temperature or by a pyrogen reaction. A rapid pulse may result from anemia or fluid overload. Irregular heart rate (arrhythmia) may indicate cardiac complications, including those associated with serum potassium levels. An increase in pulse rate during dialysis may be associated with falling blood volume (from UF) and may occur just before a drop in BP. Increased respiratory rate may indicate excessive fluid gain. Any unexpected findings should be reported to the physician.
What is edema?
Edema is the excessive accumulation of fluid in the tissue spaces. Excessive weight gain between dialyses results in edema. Edema appears in different areas of the body in different patients. It may present at the ankle or sacrum, facial or periorbital areas, or peripherally. The jugular veins are often distended when the patient is fluid overloaded. Fluid status assessment determines the amount of UF required during dialysis.
Are there other physical assessments?
The predialysis assessment includes a subjective analysis of the patient’s health since the previous dialysis treatment. Ask whether the patient has experienced such symptoms as headaches, hypotension, bleeding, or diarrhea. Dialysis personnel can assess changes in mentation, speech, or thought processes while patients describe their health and any problems between dialysis sessions.
First hemodialysis assessment
Why is the first hemodialysis procedure so important?
The first hemodialysis is critical because it sets the atmosphere for all future treatment procedures. The first dialysis is sometimes performed in the hospital. The patient may be unstable and feel sick. The information the nurse gives the patient during this first dialysis is often forgotten or misunderstood. Therefore the nurse and dialysis personnel must reiterate teaching instructions regarding medications or access care again and again. Written manuals and instructions are helpful so that patients have a reference as needed. Sometimes the first dialysis is performed in an outpatient dialysis facility. When this is the case, it is imperative that the dialysis personnel be cognizant of the emotional status of the new patient. The patient may be fearful because of the myths about dialysis he or she has heard, or because of the equipment’s appearance. These fears, combined with the fact that the patient is chronically ill, are strong reasons for the patient to be in emotional shock and to not recall instructions given during the first dialysis. The dialysis nurse and personnel must make the first dialysis as smooth and uneventful as possible.
What procedures take place before the first hemodialysis?
The physician evaluates and prescribes the dialysis orders for the new patient. The nurse reviews the orders and, after the fluid composition and machine settings are programmed, starts predialysis assessment. Before the first meeting with the patient, medical records should be reviewed. This information will be helpful during the physical assessment. After introductions, a brief tour around the facility should be conducted. The first visit should be as simple and as pleasant as possible. Remember that instructions will have to be repeated many times.
Make certain that a signed consent for the dialysis treatment is completed and retained in the patient’s medical records. The physical assessment begins with the patient’s weight, BP, temperature, pulse, and respiratory rate. A general assessment of the patient’s fluid status and overall well-being follows. Some questions that should be asked include the following: Is there edema? Is the patient in any respiratory distress or experiencing any pain? Is there any bleeding or bruising? Is there residual renal function? Are bowel movements regular? Are there sleep problems? Many units have assessment forms that offer guidelines to the caregiver.
During this first procedure some of the dialysis parameters will be set: for example, heparin requirements, tolerance of fluid removal, arterial and venous pressure readings, saline requirements, tolerance to the dialyzer, and the dialysate composition. Because the first dialysis is so critical, the physician usually prescribes a slow blood flow and only two hours of dialysis.
Predialysis assessment
What is predialysis assessment?
Before initiation of hemodialysis, the patient and machine are both evaluated. The patient’s physiologic status is assessed to ascertain the need to adjust dialysis orders or prescribed medications. The machine parameters are assessed to ensure that the prescribed procedure is implemented correctly.
What is included in the patient’s predialysis assessment?
Predialysis assessment includes the following:
• Fluid status (respiratory rate and effort, JVD, heart sounds, breath sounds, presence of edema)
• Weight
• BP, sitting and standing
• TPR, including apical and peripheral pulse evaluation
• Skin color, temperature, turgor, and integrity
• Vascular access patency and freedom from bleeding and infection
• Interpretation of physical assessment and laboratory data for appropriate intervention and medication administration
What other checks should be done on the dialysis machine before patient use?
It is necessary to ensure that machine functions have been checked and that they work correctly. All extracorporeal alarms should be tested to ensure that they respond appropriately. Arterial pressure, venous pressure, and air detector alarms should all cause the blood pump to stop and the venous line clamp to close. In addition, conductivity and temperature of the dialysate should be tested to ensure that they are within the proper range. These alarms must be working at all times so that, if any problems arise, the dialysate will be diverted from the dialyzer and a major complication will be avoided. Finally, there should be an adequate amount of dialysate concentrate to complete the patient’s treatment.
What is included in machine preassessment?
Machine preassessment includes the following:
• Dialyzer membrane check for patency and integrity
• Blood tubing intact without leaks
• Appropriate prescribed dialyzer
• Dialysate fluid composition as ordered and within safe limits (12.8 to 14.8 mho) as read by a Myron-L meter
• Appropriate prescribed dialysate potassium and calcium
• Temperature within limits (35°C to 37°C)
• Correlation of machine conductivity with an external meter reading of dialysate (Myron-L or pHoenix)
• Dialysate delivery system free of sterilant or disinfectant agents
• Extracorporeal blood circuit free of air
• Blood pump properly occluded
• Dialyzer bloodline tubing free of kinks or crimps
• Blood pump segment of tubing properly seated in the pump segment
• Physician’s orders reviewed to ensure adherence to dialysis prescription
• All alarms programmed and set within limits
• Dialysis quality water evaluated for chlorine and chloramines
What is sodium modeling or sodium variation, and when is it applicable?
During dialysis small solutes, primarily urea, are removed from the extracellular fluid (ECF), resulting in a fall in ECF osmolality. This fall in ECF osmolality causes a shift of water into cells, aggravating hypotension. One way of preventing this phenomenon is by replacing the lost osmoles (urea) with sodium. This can be done automatically by the dialysis machine and may prevent or minimize hypotension.
Sodium variations allow the dialysis treatment to be modified by increasing the concentrate-to-water ratio slightly, resulting in a rise in dialysate sodium. This feature allows the dialysis staff to initiate hemodialysis with a high-dialysate sodium concentration and use progressively lower sodium-containing dialysate, decreasing to the original baseline level in a programmed time and profile. These maneuvers are intended to reduce the incidence of hypotension and cramping. By varying the level of sodium in the dialysate, the drop in osmolality of the patient’s serum is more gradual. The fluid that is in the interstitial spaces in the tissues does not transfer into the vascular spaces as fast as the dialysis machine is able to remove it. The result of this is fluid depletion of the vascular space and the resultant side effects of hypotension. The sodium variation system keeps the vascular space filled enough to prevent this fluid depletion from occurring. There are several machines available to perform this treatment function. The Fresenius 2008H has three sodium variation system profiles: step decrease, linear decrease, and exponential decrease. Fig. 13-1 illustrates these system profiles. The baseline is determined by the basic setting of the mechanical acid/acetate and bicarbonate concentrate pumps. With this method of sodium modeling there is a significant variation in the dialysate potassium level. If the dialysate sodium is increased from 140 to 160 mEq/L (about 14%), the dialysate potassium concentration will also increase by 14%. If the baseline concentrate has 3 mEq/L of potassium and is increased by 14%, the new potassium concentrate would be 3.4 mEq/L. If there is a decrease in the dialysate sodium to 120 mEq/L (decrease of 14%), the new potassium concentrate will be 2.6 mEq/L. Increasing sodium in the dialysate has assisted many patients in the prevention of hypotension, cramping, and disequilibrium syndrome during dialysis. The physician writes the orders for the sodium modeling for each patient.
Figure 13-1 Sodium variation system profiles. The exponential program causes the conductivity to decrease toward the baseline over the programmed time in a smooth curve. The linear program is a straight-line reduction from the program maximum to the baseline level. The step program allows for a single large step to be performed.
(From Gotch FA, et al: Measurement of whole body UF on urea mass transfer coefficients: implications for Na+ urea modeling in dialysis, Presentation at the American Society of Nurses, 1984.)
Are there complications of sodium modeling?
Some patients experience increased interdialytic thirst, weight gain, and BP when sodium modeling is used. Adjustment of the dialysate sodium concentration may be required.
Why is it necessary to do such a thorough assessment of the patient and the machine before initiation of the dialysis treatment?
The accuracy of assessment and the appropriateness of the interventions directly affect the patient’s outcome and will ensure that the goal of adequacy of dialysis is achieved.
What is ultrafiltration?
UF is the removal of fluid during dialysis. It is the result of hydrostatic force across the dialysis membrane. The difference in hydrostatic pressure, blood to fluid, is the TMP. The rate of UF is the sum total of positive and negative pressures plus the filtration factor, known as the UF coefficient (kUF), of each individual dialyzer. The kUF ranges from 0.5 to 80.0 mL/h/mm Hg, depending on specific dialyzer characteristics (see Chapter 6).
What information is needed to calculate the rate of ultrafiltration?
All of the following questions must be answered to calculate the rate of ultrafiltration:
• What is the patient’s dry weight?
• What weight loss is needed (in kilograms)?
• What is the target postdialysis weight?
• How much fluid will the patient receive orally and/or intravenously during the treatment?
• What is the kUF of the dialyzer?
• How much saline will be infused to rinse the blood circuit?
• What is the length of time the patient will be dialyzed?
How is fluid removal calculated?
The following steps are taken in calculating fluid removal:
1. Add Amount of weight to be removed in milliliters
Amount of fluid intake in milliliters during treatment
+ Amount of IV fluid to be removed in milliliters
________________________________________
Total amount of fluid to be removed in milliliters
2. Divide
3. Divide
An example of how to calculate fluid removal follows. Dialyze for 3 hours; remove 2.3 kg; conventional dialyzer kUF equals 4.
1. Add Weight to be removed in milliliters 2300 mL
Oral intake 600 mL
+ Saline rinsed back 100 mL
________________________________________
Total amount of fluid to be removed 3000 mL
2. Divide
3. Divide
In a conventional dialysis delivery machine, the TMP must be set manually. Most systems now provide a programmable function for controlled UF. This controlled UF allows the machine to adjust and control the fluid removal.
What is sequential ultrafiltration and dialysis?
The application of UF as a means of fluid removal during dialysis was instituted by Alwall in 1947. The concept of convective transport rather than diffusion (see Chapter 7) is currently put to use in the hemofiltration approach. Several dialyzers have membranes or fibers of sufficient permeability and strength to give UF of several liters per hour at safe TMPs.
Application of UF alone before conventional dialysis with minimal UF is known as sequential or isolated UF and dialysis. During the UF phase blood circulates normally through the dialyzer, but the dialysis fluid does not. The UF resulting from the negative pressure gradient across the membrane is collected at the outflow side and measured. Patients tolerate fluid removal by this method at a rate and quantity greater than with conventional dialysis without hypotension or symptoms. Severely hypertensive patients are able to achieve better BP control than would otherwise be obtainable. This therapy is particularly useful for maintenance dialysis patients with chronic large fluid gains (see Chapter 18 for more information).
What is ultrafiltration profiling and how is it used in the dialysis treatment?
UF profiling is an option on some dialysis machines; it varies the rate of fluid removal during the patient’s dialysis treatment. The Fresenius 2008H has four preset profiles and four blank screens for customizing profiles. With UF profiling, the entire UF goal is removed, but at a variable rate. An example of this would be removing the greater proportion of fluid during the first half of the treatment. The greatest amount of available fluid volume is available at this time in the treatment. As the treatment progresses and the patient is ultrafiltrated, the rate of fluid removal is decreased, allowing time for the intravascular space to refill. This can help to prevent complications, such as hypotension and cramping. UF profiling is helpful for patients with either high or low predialysis blood pressure, patients with large interdialytic weight gain, and patients (such as those with diabetes mellitus) who have difficulty with plasma refilling. The UF profile system works well in conjunction with the sodium variation system.
What is high-efficiency dialysis?
High-efficiency dialysis is performed with a dialyzer with a large surface area. This dialyzer has a permeable membrane that allows solutes of low to middle molecular weight and up to 5000 Da to be removed. The kUF ranges from 5 to 15 mL/h/mm Hg. With this higher kUF, a UF control system is essential to control fluid loss. In addition, cardiovascular instability becomes more of a problem because of the rapid fluid removal and accompanying hypotension. Therefore a bicarbonate delivery system is imperative to allow for fluid removal while maintaining cardiovascular stability. Blood flow rates are from 300 to 500 mL/h and dialysate flow is from 500 to 1000 mL/h.
What is high-flux dialysis?
High-flux dialysis is performed with a special dialyzer with a synthetic, highly permeable membrane that allows low and high molecular weight solutes to be convected across the membrane. The major difference between high-efficiency dialysis and high-flux dialysis is the membrane. High-flux membranes have solute clearance in the molecular weight range of 5000 Da (insulin) to 12,000 Da (β2-microglobulins). The membrane surface area ranges from 0.6 to 2.0 m2. Water permeability is much higher in high-flux membranes than in high-efficiency membranes and much higher than with conventional membranes, thus resulting in possible backflow of dialysate. The kUF for high-flux membranes ranges from 20 to 80 mL/h/mm Hg. A fluid delivery system with UF control is required. High-flux dialysis requires a blood flow rate of 300 to 500 mL/min. Bicarbonate dialysate is required for cardiovascular stability. Usually dialysate flow is at 500 or 800 mL/min. Because the membrane is so permeable, very stringent water quality is imperative (see Chapter 6 on dialyzers, Chapter 8 on water treatment, and Chapter 9 on dialyzer preparation and reprocessing). The equipment and bicarbonate dialysate containers must be disinfected regularly.
Intradialytic assessment and monitoring
What is intradialytic monitoring?
Intradialytic monitoring is the ongoing assessment of the patient and equipment during the hemodialysis treatment. The patient and the machine are monitored at least every half hour by the caregivers. Monitoring is done more frequently in unstable patients. The vital signs and machine monitors are assessed. Machine parameters are listed in Box 13-1.
Box 13-1 Machine Parameters
Arterial pressure
Venous pressure
Fluid removal
Dialysate flow
Blood flow
Visual check of the dialyzer, blood tubing, and connections
Visual check of the machine monitor setting
Heparin pump
Visual check of the air/foam detector alarm status
Visual check of the patient’s access to ensure that needles are visible and secure
The patient must also be monitored for consciousness, and the caregiver must always do a visual check to ensure that the patient’s access is visible and the needles and lines are secure.
These parameters are adjusted as needed in accordance with the treatment goals. All assessments are logged on the dialysis flow records. In computerized fluid delivery systems, the machine parameters are automatically monitored and recorded on the dialysis flow sheets.
Are any other patient assessments done during dialysis?
An important assessment, not subject to numerical recording, is the general condition and response of the patient during the procedure. Nausea, apprehension, shortness of breath, restlessness or agitation, irritability, itching, flushing, twitching, irrational behavior, sensation of faintness, and complaints of pain are some of the many signs or symptoms that can occur. A person on regular dialysis has an individual pattern of response, and any change in this pattern is significant. Acute dialysis patients must be evaluated more often because of their less stable condition and unknown response to therapy. All observed clinical conditions are documented on the chart and reported to the physician. Sometimes reactions or complications are reported to the continuous quality improvement (CQI) committee for the purpose of ongoing monitoring or corrective action.
Is there any way to know how well you are cleaning a patient’s blood during a treatment?
There is a noninvasive assessment tool that can monitor the amount of clearance the patient is receiving during the actual dialysis treatment. One such tool is the OnLine Clearance Adequacy Monitoring Program, which is available on several types of machines in the market today. For example, the Fresenius 2008H and 2008K machines use a monitoring system called OnLine Clearance. This monitoring tool uses sodium chloride, which has a molecular weight of 58, as a surrogate marker for urea, which has a molecular weight of 60. Sodium can move across the dialyzer membrane similarly to urea. The OnLine Clearance test occurs in two phases. The first phase or half of the test involves raising the dialysate sodium above the normal sodium concentration in the blood. The dialysate sodium is raised as high as 15.5 mS/cm. Because of the concentration gradient now created, sodium will cross the dialyzer membrane into the blood. The second half of the OnLine Clearance test involves lowering the dialysate sodium to 13.5 mS/cm, allowing diffusion to take place again with the sodium moving from the blood compartment into the dialysate compartment. Conductivity monitors are at both the dialyzer inlet and the dialyzer outlet flow paths. The difference between the two conductivity readings generates a clearance value. Because of the similarities in urea and sodium chloride, a prediction of the degree of urea removal can be made. The machine performs up to six OnLine Clearance tests during a four-hour treatment. This allows the dialysis nurse or technician to see how well the treatment prescription is working for that patient. The patient’s volume of urea distribution is entered into the OnLine Clearance program before treatment is initiated because this is used to determine effective clearance. Certain variables contribute to the patient not being dialyzed optimally, including poor needle positioning, clotting of the dialyzer, access recirculation, or blood/dialysate flow rates incorrectly set. The OnLine Clearance program is a tool that can greatly improve the adequacy of patients’ treatment, which will in turn help to improve the quality of their lives. One advantage of using these types of tools is that the dialysis caregiver will know during treatment whether optimal adequacy is being provided and also be able to troubleshoot early in the treatment to correct any problems.
What are potential hemodialysis complications?
During the hemodialysis procedure many potential complications can occur to both the patient and the equipment. These complications may result from the process itself or from complex interactions between the patient and the dialysis procedure.
What is the most common complication during the hemodialysis treatment?
The most common complication during dialysis treatment is hypotension related to rapid decrease of circulating blood volume caused by UF. Lack of vasoconstriction caused by antihypertensive medications or other cardiac factors is another cause of hypotension.
The ingestion of food during the dialysis treatment may contribute to hypotension due to splanchnic vasodilation. This is commonly referred to as postprandial hypotension and usually occurs about two hours after eating. It is prudent for the patient to not eat during treatment for this reason; as well, loss of consciousness may occur with untreated hypotension, placing the patient at risk for obstruction of the airway if he or she is eating.
What causes hypotension as dialysis is begun?
Hypotension at the beginning of dialysis occurs in some patients with a relatively small blood volume (children and small women). This is the result of volume shifts as the dialyzer is filled with the patient’s blood. It is much less frequent with small-volume dialyzers than with larger ones. This type of reaction is rarely serious and usually does not last long. It will respond to the infusion of small amounts of saline or albumin. Careful technique in starting the dialysis will minimize the occurrence of these episodes.
What about hypotension occurring later during dialysis?
Later hypotension is usually attributable to removal of fluid from the vascular space (UF) in excess of the patient’s ability to compensate for this. The hypotension may be asymptomatic until there has been a fall of 40 to 55 mm Hg in systolic pressure. It usually responds to fluid replacement. Most modern dialysis machines remove fluid at a steady rate set by the practitioner. Removing more than 1% of a patient’s dry body weight as fluid per hour often results in hypotension.
Why do some patients with gross edema become hypotensive early during a dialysis?
Patients with gross fluid overload may have heart failure or a low serum albumin. The dialysis removes fluid from the vascular compartment, but the low serum protein does not exert sufficient oncotic pressure to mobilize fluid from the interstitial space. There is another group of patients for whom cardiac failure or hypoproteinemia are not obvious causes, but who have problems with overhydration and who have vascular instability during dialysis. These people, during conventional dialysis with UF, become symptomatically hypotensive with tachycardia, nausea, and vomiting. The causes are likely to be multifactorial. Changes in serum osmolality, effects of acetate if this is used as the buffer, and norepinephrine depletion have been suggested or demonstrated. Infusion of hypertonic saline or mannitol or use of a higher than usual sodium in the dialysis fluid may be beneficial. Sequential UF followed by dialysis may also give good results.
How is hypotension prevented and treated intradialytically?
Sodium modeling and UF profiling, discussed earlier, are excellent methods of preventing severe hypotension. BP monitoring, with careful observation and/or the use of an in-line hematocrit monitor, is also helpful in reducing hypotensive episodes. If hypotension is treated early by placing the patient in the Trendelenburg position, by decreasing the UF pressures, or by giving replacement fluid, more serious complications may be avoided. It is helpful to be aware of the signs of hypotension, such as the patient complaining of feeling hot or light-headed. Some patients will complain of blurred vision or nausea. It is prudent to check a patient’s BP whenever he or she complains of these symptoms. The treatment for hypotension is administering a normal saline bolus, placing the patient in Trendelenburg position, decreasing the UF rate, and using a volume expander if ordered.
What is the crit-line instrument?
The Crit-Line monitor is an arterial in-line medical instrument that provides continuous measurement of absolute hematocrit, percent blood volume change, and oxygen saturation in real time. It measures blood volume change based on the hematocrit because these two values have an inverse relationship. As fluid is removed from the intravascular space, the blood density increases. This is displayed in percent blood volume change on a gridlike graph on the Crit-Line screen (Fig. 13-2). With this device it is possible to maximize UF safely and prevent hypotension, cramping, and other intradialytic complications associated with volume depletion. A disposable blood chamber is attached to the arterial side of the dialyzer and a photometric technology is used. This device will also measure access recirculation. The Crit-Line monitor is exempt from the Clinical Laboratory Improvement Act (CLIA).
Figure 13-2 A, (black line) Absolute hematocrit. B, (gray line) Percent of blood volume change.
(Courtesy In-Line Diagnostics, Farmington, UT.)
Does hypertension occur during dialysis?
A small minority of patients develop a rise in BP during dialysis. Some experience a gradual rise in BP throughout the dialysis, whereas others experience an elevation soon after starting. In some patients the rise in BP is the result of increased cardiac output as fluid overload is relieved. In other instances there may be an increase in peripheral vascular resistance on a reflex or hormonal basis. Angiotensin-converting enzyme (ACE) inhibitor therapy or bilateral nephrectomy may be indicated in cases where high renin levels are present, whereas the hypertension in very young and elderly patients may respond to a lower blood flow rate and the use of a smaller surface area dialyzer.
Are arrhythmias common during dialysis?
As more older patients and persons with complicating diseases enter end-stage renal disease (ESRD) programs, arrhythmias become frequent. They are most often caused by underlying heart disease. The physician should make the presence of such problems and their significance known to the dialysis personnel. Evaluation of a new, or different, rhythm developing during dialysis requires an electrocardiogram. The patient should be queried as to medications, and a review of recent serum potassium, calcium, and magnesium values should be made. Patients with myocardial damage may develop arrhythmias of various types in response to volume change or a shift in electrolytes, particularly potassium. Patients receiving digitalis may pose particular problems.
What if a patient develops chest pain during dialysis?
Some patients have chest pain that comes on during dialysis. Often these persons have a history of underlying heart disease, and the pain must be presumed to be angina. It may go away if blood flow is slowed or saline is infused. Some patients on occasion have a vague chest distress or low back pain. The mechanism is obscure but often seems related to blood volume change or decreased hematocrit. When new or unexpected chest pain occurs in a patient with no known history of cardiac disease, it is always advisable to notify the physician.
What causes muscle cramping during dialysis?
Muscle cramping during dialysis is probably caused by fluid shift or osmolar change, although pH change may play a role. Use of sodium modeling may be preventive, and infusion of hypertonic saline or a 50% dextrose solution usually brings relief when cramps occur. Heat and pressure over the painful area are temporary measures.
What are other serious complications during dialysis?
Other complications that can occur during dialysis are hemolysis and air embolism.
What is hemolysis?
Hemolysis is the lysis (breakup) of red blood cells resulting in the release of intracellular potassium. Hemolysis may be caused by chemical, thermal, or mechanical events. Chemical causes of hemolysis include exposure of the blood to chemicals, such as sodium hypochlorite, formaldehyde, copper, or nitrates. Thermal hemolysis is caused by the exposure of blood to overheated dialysate. Dialysate temperatures greater than 42°C are considered dangerous. Mechanical causes of hemolysis include kinking of the bloodlines, overoccluded blood pumps, excessive negative pressure from a small-gauge needle with a high blood flow rate, or a poorly positioned needle. Other causes of hemolysis include dialyzing the patient against a hypotonic bath and blood transfusions. Hemolysis may be either acute or chronic. It may be slight and require no immediate treatment, or it may be a life-threatening emergency. Acute hemolysis during the dialysis treatment is a medical emergency. The patient may also experience symptoms after returning home from dialysis treatment and present in the emergency department. For unknown reasons, pancreatitis will sometimes occur following an episode of acute hemolysis.
What are the symptoms of hemolysis?
With hemolysis, the blood in the extracorporeal circuit may appear transparent and “cherry soda pop” in color; however, the blood also may appear very dark and opaque. Other symptoms of hemolysis are burning sensation in the access extremity, usually the venous needle, from the release of large amounts of potassium from the ruptured red blood cells. The patient will often complain of abdominal pain or cramping, low back pain, chest pain, nausea and vomiting, shortness of breath, or indigestion. Cardiac changes may be seen as the potassium is released from the cells, causing arrhythmias and bradycardia with hypotension or hypertension. An acute drop in hematocrit will be seen as the red blood cells rupture.
What steps should be taken if you suspect hemolysis in a patient?
Monitors should detect a hypotonic dialysate solution or high dialysate temperature; however, machines are not infallible. Careful monitoring by dialysis personnel is essential to avoid this potentially life-threatening complication. If hemolysis is suspected, the bloodlines should be clamped immediately, the blood pump stopped, and the patient’s symptoms treated. The dialysate should be sampled for pH and conductivity. A blood sample from the patient should be obtained and checked for hematocrit, electrolytes, free hemoglobin, and haptoglobin. If hemolysis is suspected, a blood sample in a serum separator tube when centrifuged will have red serum. It is important to remember to never reinfuse hemolyzed blood cells. Returning hemolyzed blood could cause hyperkalemia. The patient’s symptoms should be treated and the physician should be notified.
What is an air embolism?
Air embolism occurs when air or a large amount of foam (microbubbles) is introduced into a patient’s vascular system. Air embolism can occur when arterial or venous lines become disconnected or when blood or saline infusion bags run dry. The resultant vacuum causes microbubbles, or foam. Dialysis personnel are responsible for setting and monitoring the air/foam detector throughout the entire dialysis procedure.
What symptoms are associated with an air embolism?
The patient may complain of chest pain or tightness or shortness of breath, and may cough. If the patient is sitting upright, air may be introduced into the cerebral venous system and cause neurologic symptoms, such as visual problems, loss of consciousness, and convulsions.
What action is taken if a patient receives an infusion of air?
When a patient receives air, treatment must be immediate. The bloodlines are clamped and dialysis is stopped. The patient is placed on the left side in the Trendelenburg (head down) position. This position decreases the movement of air to the brain and traps air in the right atrium above the tricuspid valve. This minimizes foaming, which occurs primarily in the right ventricle of the heart. It is important to maintain the patient’s airway and to administer oxygen if needed. The patient must be moved as little as possible and must be maintained in the Trendelenburg position. It takes several hours for all of the air, particularly the nitrogen, to be totally reabsorbed. A chest x-ray examination should be done to evaluate the amount of air present in the heart.
What is disequilibrium syndrome?
Disequilibrium syndrome is a situation that produces neurologic and other symptoms soon after a patient begins dialysis treatments. Urea has the ability to move freely between the cells and the serum. Theories suggest that when a patient who is very uremic is dialyzed for the first time, as the urea is removed, the plasma becomes more hypotonic, causing water to shift from the plasma into the brain tissue, which is less hypotonic and contains higher amounts of urea. This usually occurs in patients with very high blood urea nitrogen levels or in those with acute renal failure. As the water flows to the higher urea concentration, the brain cells begin to swell, causing neurologic symptoms ranging from headache, nausea, vomiting, restlessness, and twitching to the more severe tremors, disorientation, and convulsions. Treatment includes the administration of a hypertonic solution, such as hypertonic saline, 50% dextrose, or mannitol. The patient’s symptoms should be treated. Delivering a less effective treatment by using lower blood and dialysate flow rates, decreasing treatment time, or running the patient with a concurrent flow will help to minimize these symptoms until the blood urea nitrogen levels stabilize.
What happens during a dialyzer reaction?
Dialyzer reactions are sometimes referred to as “first-use syndrome” because some patients, when exposed to the dialyzer membrane for the first time, develop allergic-type symptoms. Dialyzer reactions are now more commonly referred to as type A and type B reactions.
Type A reactions are the more severe of the two and often present with anaphylactic-type symptoms. These reactions usually occur within the first five minutes of treatment, with the patient experiencing the following symptoms: dyspnea, chest and back pain, feeling of warmth, sense of impending doom, and cardiac arrest. Less threatening symptoms include itching, urticaria, coughing, sneezing, watery eyes, and abdominal cramping. Type A reactions are usually caused by the factory sterilant ethylene oxide (EtO). This type of reaction is less common today because some dialyzer manufacturers are using alternative sterilization methods such as gamma irradiation as a sterilant, E-Beam sterilization, or steam sterilization. For those using dialyzers sterilized with EtO, proper priming of the dialyzer may help to prevent pockets of EtO remaining in the fibers to be released during the patient’s dialysis treatment.
Type B reactions are less threatening but more commonly seen. The symptoms usually occur as soon as the patient’s blood is exposed to the dialyzer and returned to the patient. Symptoms include chest pain, hypotension, and occasionally back pain. The treatment for both types of reactions is based on symptoms. The dialysis treatment should be discontinued until a determination is made as to the cause of the symptoms and the physician is notified. Oxygen is generally administered for difficulty breathing. Intravenous antihistamines may be ordered or epinephrine may be ordered for anaphylaxis. BP support may also be necessary for hypotension.
What is a formaldehyde reaction?
A formaldehyde reaction occurs when the patient’s blood is exposed to the sterilant. This may occur when a formaldehyde-filled dialyzer is incorrectly rinsed of the sterilant or from improper testing for the presence of residual formaldehyde. Symptoms include a bitter peppery taste in the mouth, anxiety, burning in the venous needle, numbness around the mouth or lips, chest and back pain, and shortness of breath. It is important to recognize and treat formaldehyde reactions immediately because hemolysis of red blood cells may also occur. The dialysis treatment should be stopped and the patient’s symptoms should be taken care of. Approximately 10 mL of blood should be removed from each needle so that the patient receives no further formaldehyde. Proper rinsing of the system and attention to safety testing for residual formaldehyde will help alleviate this complication.
What causes a pyrogen reaction to occur?
A pyrogen reaction may occur from an improperly sterilized dialyzer, bacteria in the water system or dialysate, a break in aseptic technique, or improper access preparation. A pyrogen is a fever-producing substance, usually an endotoxin, that is a by-product of dead bacterial cell walls. Bacteria are too large to cross the dialyzer membrane, but an endotoxin is small enough to cross, causing the symptoms. A patient will experience chills after the commencement of the dialysis treatment along with a decrease in the systolic BP. Headache, fever, myalgia (muscle pain), nausea, and vomiting may also be experienced. The symptoms will usually subside after the patient’s treatment is discontinued. The hypotension and fever may need to be treated. Blood cultures may be ordered. It is imperative to practice scrupulous infection control technique when accessing your patient’s catheter or internal access. Dialyzers should never be used if they have been recirculating for longer than the manufacturer’s directions and the facility’s policy allow. Care must be taken to disinfect dialysate jugs, mixing tanks, and machines per the facility’s policy. It is important to rule out septicemia because the symptoms are very similar to those of a pyrogen reaction.
What are potential problems with hemodialysis equipment?
Hemodialysis equipment is designed to protect the patient from complications that may occur during the treatment. However, machines are not infallible and will periodically malfunction. A malfunction of the temperature control device can cause hyperthermia, resulting in hemolysis. If not detected, this condition could cause death. Its opposite, hypothermia, can also occur; this condition can cause extreme chills and violent shaking.
Are there other equipment complications?
Other equipment complications may occur when dialyzers and bloodlines become disconnected, leak, or clot. Most machine complications can be prevented by careful monitoring. Machine maintenance also plays an important role in the prevention of machine-related accidents. Chapter 6 discusses the equipment and its preventive maintenance.
What is arterial pressure?
Arterial pressure is a measurement of the extracorporeal blood circuit pressure between the patient’s needle site and a site proximal to the blood pump. It is not the equivalent of the patient’s systemic arterial pressure but the negative pressure created by the blood pump. Arterial monitoring guards against excessive suction on the vascular access. For example, if the patient’s arterial pressure has been reading -100 mm Hg and it suddenly increases to -200 mm Hg, this could indicate a clotted or dislodged needle, a drop in the patient’s systemic BP, or a kink in the arterial line. If the arterial negative pressure increases or decreases, as long as the monitor is properly set, the alarm will be activated and the blood pump will shut off. This audible and visual alarm alerts the caregiver to a dialysis complication and always requires immediate attention. The alarm will remain activated and the blood pump will not work until the abnormality is corrected. A high negative arterial pressure must always be assessed and steps must be taken to correct the problem. High negative arterial pressure may be damaging to the vascular access and may cause hemolysis in the patient.
What is venous pressure?
Venous pressure is a measurement of the extracorporeal blood circuit pressure at some point after the dialyzer and before the blood reenters the patient’s body. The monitoring line is usually attached to the top of the venous bubble trap. Venous extracorporeal pressure measures the resistance of the blood returning to the patient via the venous needle. For example, if the patient’s venous pressure reading suddenly increases from 50 to 150 mm Hg, this increase would indicate that the venous line may be kinked, the bubble trap may be clotted, the venous needle may be clotted or misaligned, or the vascular access may be in danger of failing. If, however, there is a sudden and dramatic decrease in venous pressure, the venous needle may have been pulled out, the transducer may be wet, or the arterial chamber may be clotted. The venous pressure alarm is similar to the arterial pressure alarm in that, when activated, the abnormal condition must be corrected before the machine will allow the blood to continue through the blood circuit.
Note that all alarms must be set properly at the initiation of dialysis. This ensures that if any complication occurs, an audible and visual alarm will activate and alert caregivers to a potential problem.
What effect does the dialysis solution (dialysate) flow rate have on the dialyzer clearance?
Dialysis solution flow rate affects clearance of small solutes, such as urea. The usual dialysis solution flow rate is 500 mL/min, although some types of dialysis equipment (e.g., Sorb System’s Redy 2000) use 250 mL/min. The slower flow rate leads to slightly lower dialyzer urea clearance. Dialysis solution flow rates of greater than 500 mL/min are used to increase clearance for high-efficiency dialysis. Higher dialysate flow rate can be used to enhance urea clearance when the blood flow rate is reduced for any reason. According to Nissenson, “little clinical benefit is achievable using presently available equipment at blood flow rates greater than 500 mL/min. There is a point where the relationship between dialysis solution flow rate and dialyzer clearance levels off with the higher dialysis solution flow rates.” (Nissenson & Fine, 2008.)
Why should patients with chronic kidney disease control their food and oral fluid intake during dialysis treatment?
There are several reasons for controlling food and oral intake during dialysis treatment. First, the amount of fluid removed by UF is the net change in weight from the predialysis weight to the postdialysis weight. If the patient consumes large amounts of food and drink during dialysis, this net weight change does not reflect a realistic fluid loss. The quantity of food or fluid ingested during dialysis should always be taken into consideration when calculating how much fluid to ultrafiltrate during the dialysis procedure. If it is permissible for patients to eat during dialysis, it is best to limit this to very small snacks. Food in the digestive tract causes pooling of blood and may cause hypotension, vomiting, and increased risk of aspiration. Still, with more efficient dialysis and removal of fluid, CKD patients have fewer restrictions with respect to oral intake than formerly. See Chapter 14 for more on nutrition.
What about the consumption of ice chips as a water substitute?
Ice has two advantages: (1) its coldness and (2) the time required for it to melt in the mouth. These factors make ice more effective in alleviating the sensation of thirst. A 200-mL cup filled with ice chips yields about 150 mL of water. Therefore the patient will consume less fluid by consuming ice chips than by drinking water.
Postdialytic therapy assessment
What is postdialytic assessment?
Postdialytic assessment is the total evaluation of the patient and the treatment, and an interpretation of the predialytic goals. Factors to be included are listed in Box 13-2.
Box 13-2 Patient Parameters Evaluated after Dialysis
Patient’s weight and weight loss
Vital signs, e.g., temperature, pulse, and respiration (TPR) and blood pressure (BP)
Resolution or improvement of problematic predialysis parameters (improvement of fluid status)
Total of infusions given, both saline and blood
Patient’s subjective physical assessment, e.g., any pain or complaints
Access assessment
Bleeding status
Are there other postdialytic assessments?
The dialysis prescription plan is assessed for any changes that will be implemented in the next dialysis. Finally, the date for the next dialysis is scheduled.
Monthly assessments
What is the purpose of monthly assessments for patients with chronic kidney disease?
Each patient’s dialysis prescription plan should be evaluated monthly to review his or her status and to determine the adequacy of dialysis treatment (Box 13-3).
Box 13-3 Items for Monthly Evaluation of Patients with Chronic Kidney Disease
Nutritional status, dry weight control, diet and fluid control
Kt/V* and/or urea reduction ratio (URR): dialyzer, blood flow, hours of treatment
Chemistries: dialysate K and Ca
Vital signs and blood pressure: sodium modeling
Access: complications, aneurysm
Any bleeding in relation to heparin dose
Physical assessment
Bowel habit changes
Sleep habits
Sexuality
Medication review
Psychosocial review for general problems (social or financial)
* Kt/V: K, dialyzer clearance of urea; t, dialysis time; V, volume of distribution of urea, approximately equal to patient’s total body water