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Chapter 039. Nausea, Vomiting, and Indigestion

Indigestionis a nonspecific term that encompasses a variety of upper abdominal complaints including nausea, vomiting, heartburn, regurgitation, and dyspepsia (the presence of symptoms thought to originate in the gastroduodenal region). Some individuals with dyspepsia report predominantly epigastric burning, gnawing discomfort, or pain. Others with dyspepsia experience a constellation of symptoms including postprandial fullness, early satiety (an inability to complete a meal due to premature fullness), bloating, eructation (belching), and anorexia. . | Chapter 039. Nausea Vomiting and Indigestion Indigestionis a nonspecific term that encompasses a variety of upper abdominal complaints including nausea vomiting heartburn regurgitation and dyspepsia the presence of symptoms thought to originate in the gastroduodenal region . Some individuals with dyspepsia report predominantly epigastric burning gnawing discomfort or pain. Others with dyspepsia experience a constellation of symptoms including postprandial fullness early satiety an inability to complete a meal due to premature fullness bloating eructation belching and anorexia. Nausea and Vomiting Mechanisms Vomiting is coordinated by the brain stem and is effected by neuromuscular responses in the gut pharynx and thoracoabdominal wall. The mechanisms underlying nausea are poorly understood but likely involve the cerebral cortex as nausea requires conscious perception. This is supported by electroencephalographic studies showing activation of temporofrontal cortical regions during nausea. Coordination of Emesis Several brain stem nuclei including the nucleus tractus solitarius dorsal vagal and phrenic nuclei medullary nuclei that regulate respiration and nuclei that control pharyngeal facial and tongue movements coordinate the initiation of emesis. Neurotransmitters involved in this coordination are uncertain however roles for neurokinin NKi serotonin 5-HT3 and vasopressin pathways are postulated. Somatic and visceral muscles exhibit stereotypic responses during emesis. Inspiratory thoracic and abdominal wall muscles contract producing high intrathoracic and intraabdominal pressures that facilitate expulsion of gastric contents. The gastric cardia herniates across the diaphragm and the larynx moves upward to promote oral propulsion of the vomitus. Under normal conditions distally migrating gut contractions are regulated by an electrical phenomenon the slow wave which cycles at 3 cycles min in the stomach and 11 cycles min in the duodenum. With emesis there is .