Jonathan A. Maisel
EPIDEMIOLOGY
Although nausea and vomiting is typically caused by gastrointestinal disorders, the clinician must consider systemic causes as well.
Neurologic, infectious, cardiac, endocrine, renal, obstetric, pharmacologic, toxicologic, and psychiatric disorders may all be the cause of nausea and vomiting.
A comprehensive history and physical examination, as well as the use of various diagnostic modalities, are needed to determine the cause and its complications.
PATHOPHYSIOLOGY
Vomiting is a complex, highly coordinated activity involving the gastrointestinal tract, the central and autonomic nervous system, and the vestibular system.
Three stages of vomiting have been described: nausea, retching, and emesis. With nausea comes hypersaliva-tion and tachycardia. Retching occurs with gastric relaxation and repetitive simultaneous contraction of the diaphragm and abdominal muscles, which allows for the development of a pressure gradient. Finally, in response to changes in intra-abdominal and intratho-racic pressure, emesis occurs, expelling gastric contents from the stomach.
CLINICAL FEATURES
History is essential in determining the cause of vomiting. Important features to elicit include the following:
The onset and duration of symptoms
The frequency and timing of episodes
The content of the vomitus (eg, undigested food, bile-tinged, feculent)
Associated symptoms (eg, fever, abdominal pain, diarrhea)
Exposure to foodborne pathogens
The presence of sick contacts
A thorough past medical and abdominal surgical history can also be valuable.
The physical examination should initially focus on determining the presence or absence of a critical, life-threatening condition.
Hypotension, tachycardia, lethargy, poor skin turgor, dry mucous membranes, and delayed capillary refill suggest significant dehydration.
A careful abdominal examination will help clarify the presence or absence of a primary GI etiology.
The extent to which the balance of the physical examination will be of value will be dictated by the history. In the event that a reliable history is not available (eg, drug overdose, cognitive impairment), a comprehensive physical examination is warranted.
DIAGNOSIS AND DIFFERENTIAL
Vomiting with blood could represent gastritis, peptic ulcer disease, or carcinoma. However, aggressive non-bloody vomiting followed by hematemesis is more consistent with a Mallory-Weiss tear.
The presence of bile rules out gastric outlet obstruction, as from pyloric stenosis or strictures.
The presence of abdominal distension, surgical scars, or an incarcerated hernia suggests a small bowel obstruction.
The presence of fever suggests an infectious (eg, gastroenteritis, appendicitis, cholecystitis) or inflammatory cause.
Vomiting with chest pain suggests myocardial infarction.
Post-tussive vomiting suggests pneumonia.
Vomiting with back or flank pain can be seen with aortic aneurysm or dissection, pancreatitis, pyelonephritis, or renal colic.
Headache with vomiting suggests increased intracra-nial pressure, such as with subarachnoid hemorrhage, tumor, or head injury.
The presence of vertigo and nystagmus suggests either vestibular or CNS pathology.
Vomiting in a pregnant patient is consistent with hyperemesis gravidarum in the first trimester; but in the third trimester, could represent preeclampsia if accompanied by hypertension.
Associated medical conditions are also useful in discerning the cause of vomiting: diabetes mellitus suggests ketoacidosis, peripheral vascular disease suggests mesenteric ischemia, and medication use or overdose (eg, lithium or digoxin) suggests toxicity
The physical examination in a vomiting patient includes a careful assessment of hydration status; the gastrointestinal, pelvic, and genitourinary systems; and selected additional systems as dictated by the history. The potential causes of vomiting, based on physical examination findings, are summarized in Table 38-1.
All women of childbearing age warrant a pregnancy test.
In vomiting associated with abdominal pain, liver function tests, urinalysis, and lipase or amylase determinations may be useful.
Electrolyte determinations and renal function tests are usually of benefit only in patients with severe dehydration or prolonged vomiting. In addition, they may confirm the presence of Addisonian crisis, with hyperkalemia and hyponatremia.
Obtain specific drug levels for acetaminophen, sali-cylates, and digoxin when toxicity is suspected, and urine and/or serum toxicology screens when ethanol or illicit drug use is suspected.
The electrocardiogram and chest radiograph can be reserved for patients with suspected cardiac ischemia or pulmonary infection.
Abdominal radiograph can be used to confirm the presence of intestinal obstruction.
If plain radiographs are unrevealing, CT scan of the abdomen and pelvis with IV and PO contrast is helpful for revealing the location of a mechanical obstruction and may also clarify alternative explanations for the patient’s symptoms.
CT scan of the brain will be helpful if a CNS lesion is suspected.
Measuring intraocular pressure is useful if glaucoma is suspected.
TABLE 38-1 Differential Diagnosis Based on Physical Examination Findings
EMERGENCY DEPARTMENT CARE AND DISPOSITION
The treatment of nausea and vomiting consists of correcting fluid and electrolyte problems. In addition, one must initiate specific therapy for any life-threatening cause identified in the initial workup.
Resuscitation of seriously ill patients requires intravenous boluses of normal saline 20 mL/kg. Boluses may be repeated as necessary, targeting euvolemia. Caution should be used in the elderly, and those with compromised left ventricular function.
Mildly dehydrated patients may tolerate an oral rehy-dration solution containing sodium, as well as glucose to enhance fluid absorption. Many commercial products (eg, Pedialyte) are available. The World Health Organization advocates a mixture of 4 oz orange juice, 8 tsp sugar, and 1 tsp salt in 1 L boiled water.
Nutritional supplementation should be started as soon as nausea and vomiting subside. Patients can quickly advance from clear liquids to solids, such as rice and bread. Patients may benefit from avoiding raw fruit, caffeine and lactose, and sorbitol-containing products.
Antiemetic agents are useful in actively vomiting patients with dehydration.
Ondansetron 4 to 8 milligrams IV or ODT (children 0.15 milligram/kg) is very effective and well tolerated, and can be administered to pregnant women (category B).
Promethazine 25 milligrams (0.25–1 milligram/kg in children over 2 years) IM or PR every 4 to 6 hours can be effective.
Prochlorperazine 5 to 10 milligrams IM every 6 hours, or 25 milligrams PR every 12 hours is effective.
Metoclopramide 10 milligrams (children 0.1 milligram/kg) IV/IM every 6 to 8 hours is useful and can be administered to pregnant women (category B).
Meclizine 25 milligrams PO every 6 hours is effective for vomiting associated with vertigo.
Patients with a life-threatening cause of vomiting require admission. In addition, toxic or severely dehydrated patients, particularly infants and the elderly, or those still intolerant of oral fluids following hydration, warrant admission.
Patients with an unclear diagnosis, but favorable examination findings following hydration, can be discharged home safely with antiemetic medication.
Work excuses are indicated for patients in the food, day care, and health care industries.
For further reading in Tintinalli’s Emergency Medicine: A Comprehensive Study Guide, 7th ed., see Chapter 75, “Nausea and Vomiting,” by Susan Bork, Jeffrey Ditkoff, and Bophal Sarha Hang.