Doctor Medicine about 2 years ago

Nausea and vomitting

Nausea is the unpleasant sensation that often but not always is followed by retching (dry heaves) and then vomiting – the forceful expulsion of gastric contents. Nausea and vomiting result from a complex interplay between: • the gut, • the peripheral nervous system, • the brain. Largely mediated by 5 neurotransmitters: acting on muscarinic, dopamine, histamine, serotonin, and neurokinin receptors. Vomiting is a physiological defense that removes noxious substances. Pathologically, however, the basis for nausea and vomiting extends from GI diseases, intracranial events (from strokes to an inner ear infection), and a slew of drugs, toxins and metabolic diseases. Think gut, brain and systemic conditions. A careful history provides diagnostic clues. Determine: 1. The onset relative to meals, time of day, or a history of ingesting a potential toxin. 2. The nature of the vomitus – does it contain blood, bile, food or feculent material? 3. Is there abdominal pain? . The physical exam looks for any complications of vomiting – either acutely like hypovolemia or chronically as weight loss. Are there red flags to indicate either urgent intra-abdominal process (peritonitis or an abdominal mass) or a CNS event such as a stroke? Investigations must include a pregnancy test for younger women. Assessment seeks to determine and treat the cause, manage any consequences, and suppress symptoms. If mild without marked consequences and especially if short-lived – diet and symptomatic treatment suffice. Conversely, “red flags” with features suggesting an acute abdomen, upper GI bleeding or an intracranial event warrant immediate attention. . When vomiting is severe or prolonged, anti-nausea agents become necessary. These generally antagonize one or more of the 5 key neurotransmitters, particularly dopamine and serotonin. .