Nausea and vomiting

Nausea, an unpleasant feeling of the urge to vomit, is an afferent vegetative impulse (including an increase in parasympathetic tone) of the medullary vomiting center. Vomiting is a forced removal of gastric contents due to an unintentional contraction of the abdominal wall muscles during the lowering of the fundus of the stomach and relaxation of the esophageal sphincter. Vomiting should be distinguished from regurgitation, belching of gastric contents not associated with nausea or forced contraction of the abdominal muscles.

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Causes and pathophysiology of nausea and vomiting

Nausea and vomiting occur in response to stimulation of the vomiting center and originate in the gastrointestinal tract (eg, gastric or intestinal obstruction, acute gastroenteritis, peptic ulcer disease, gastrostasis, cholecystitis, choledocholithiasis, perforation of an internal organ or acute abdomen of other etiologies, ingestion of toxic substances); some causes are localized in other parts of the body (eg, pregnancy, systemic infection, radiation exposure, drug toxicity, diabetic ketoacidosis, cancer) or the central nervous system (eg, increased intracranial pressure, vestibular stimulation, pain, meningitis, head injury, brain tumor).

Psychogenic vomiting may be spontaneous or develop unintentionally in stressful or unusual situations. Psychological factors causing vomiting may be identified separately (e.g., the repulsive nature of food). Vomiting may be an expression of rejection, for example, if vomiting occurs in a child as a reaction to hardening, or be a symptom of conversion disorder.

Cyclic vomiting syndrome is an unexplored disorder characterized by severe, discrete episodes of vomiting or sometimes only nausea that develop at variable intervals with relative health between episodes of vomiting. It is common in childhood (age 5 and up) and tends to persist into adulthood. Causes may be related to migraine headaches, possibly representing a variant of migraine.

Acute, severe vomiting can lead to general dehydration and electrolyte imbalances. Chronic vomiting can lead to malnutrition, weight loss, and metabolic disturbances.

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Evaluation of nausea and vomiting

History and physical examination

Diarrhea and fever suggest infectious gastroenteritis. Vomiting undigested food suggests achalasia or Zenker's diverticulum. Vomiting partially digested food several hours after ingestion suggests pyloroduodenal stenosis or gastrostasis. Headache, mental status changes, or papilledema suggest CNS pathology. Tinnitus or dizziness suggests labyrinthine disease. Stool retention and abdominal distension suggest intestinal obstruction.

Vomiting that occurs when thinking about food or is temporarily not associated with food has a psychogenic cause, which suggests an individual or family history of functional nausea and vomiting. Patients should be asked about the possible connection between vomiting and stressful situations, as patients may not consider this relationship or may not even report feelings of distress at the time.

Survey

All women of childbearing potential should have a urine pregnancy test. Patients with severe vomiting, vomiting for more than 1 day, or signs of dehydration should have other laboratory tests (eg, electrolytes, blood urea nitrogen, creatinine, glucose, urinalysis, and sometimes liver function tests). Patients with symptoms or signs of obstruction or perforation should have flat and upright abdominal radiographs. Evaluation of chronic vomiting typically includes upper GI endoscopy, small bowel radiography, gastric passage studies, and antral-duodenal motility studies.

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Treatment of nausea and vomiting

Certain conditions involving dehydration require treatment. Even without evidence of significant dehydration, intravenous fluid resuscitation (0.9% saline 1 L or 20 mL/kg in children) often relieves symptoms. In adults, antiemetics (eg, prochlorperazine 5 to 10 mg IV or 25 mg rectally) are effective for most acute vomiting. Additional medications include metoclopramide (5 to 20 mg orally or IV 3 to 4 times daily) and sometimes scopolamine (1 mg every 72 hours). These medications should generally not be given to children because of their side effects. Antihistamines (eg, dimenhydrinate 50 mg orally every 4 to 6 hours and meclizine 25 mg orally every 8 hours) are effective for vomiting due to labyrinthine lesions. Emesis secondary to chemotherapeutic agents may require the use of 5HT ₃ antagonists (eg, ondansetron, granisetron); when chemotherapeutic agents that cause severe emesis are used, a new drug, prepitant, a substance-P neurokinin 1 inhibitor, may be added to the treatment.

In psychogenic vomiting, reassuring talk creates an understanding of the cause of the discomfort and a willingness to cooperate in minimizing symptoms, regardless of the cause. Comments such as “nothing fits” or “the problem is emotions” should be avoided. Short-term symptomatic therapy with antiemetics may be tried. If long-term monitoring is necessary, friendly, regular visits to the physician may help resolve the underlying problem.