Electrogastrography (EGG) is performed by placing electrodes over the abdominal skin and recording the frequency and regularity of gastric myoelectrical activity in the fasting state and after a test meal. Gastric dysrhythmias have been observed in patients with idiopathic and diabetic gastroparesis, nausea of pregnancy, and motion sickness. Gastric dysrhythmias have been recorded on occasion in those with unexplained nausea and vomiting in the absence of altered gastric emptying. MRI of the brain should be considered also in those with chronic unexplained nausea and vomiting. Once common organic causes and GI dysmotility have been excluded, consider psychogenic vomiting as a possibility.
Treatment of vomiting should begin with restoration of normal fluid and electrolyte balance. If possible, underlying causes should be treated. When the specific cause of vomiting cannot be determined, antiemetic agents should be used to suppress the symptoms. Scopolamine is used as a transdermal patch principally for prophylaxis and treatment of motion sickness. However, other anticholinergic side effects are not uncommon. Antihistamine drugs with histamine 1 (H1) receptor antagonists have central antiemetic properties. H1 receptor antagonists (meclizine or promethazine) are useful in treatment of motion sickness and vestibular disturbances. Neuroleptic agents (e.g., prochlorperazine, chlorpromazine, and haloperidol) are effective in treating nausea and vomiting induced by medications, radiation, or gastroenteritis. Prokinetic agents that are useful in the treatment of nausea and vomiting include dopamine 2 (D2) receptor antagonists, selective 5-HT3 receptor antagonists, and motilin receptor agonists. Metoclopramide, a D2 receptor antagonist, is useful in treating chemotherapy-induced emesis, gastroparesis, or pseudoobstruction. Domperidone is another selective dopamine antagonist with fewer side effects because it does not cross the blood-brain barrier. Selective 5-HT3 receptor antagonists such as ondansetron and granisetron are effective in controlling chemotherapy-induced emesis refractory to conventional therapy. Erythromycin has been shown to accelerate gastric emptying in patients with diabetic gastroparesis. It acts on motilin receptors on GI smooth-muscle membranes; this effect is unrelated to antibiotic properties. Corticosteroids, especially dexamethasone, have been used in combination with other agents such as metoclopramide and ondansetron in the treatment of chemotherapy-related nausea and vomiting, acting perhaps by reducing prostaglandin formation. Benzodiazepines such as lorazepam and diazepam have also been shown to be effective in the treatment of chemotherapy-related nausea and vomiting. Gastric pacing can be considered in patients with intractable nausea and vomiting related to gastroparesis.