nausea
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Introduction
An unpleasant, but not painful sensation generally perceived in the upper abdomen.
It is generally accompanied by hypersalivation & the desire to vomit or the feeling that vomiting is imminent.
It may be brief, prolonged & sometimes occurs in waves.
See vomiting.
Etiology
- gut wall dilation -constipation, bowel obstruction, ileus (GUT)*
- gut mucosal injury
- radiation therapy, chemotherapy, infection, inflammation (gastritis), direct tumor invasion (GUT)*
- drugs, metabolites, bacterial toxins (CTZ)*
- motion sickess, labyrinthine disorders (vesibular)*
- anticipatory nausea (cerebral cortex)*
- increased intracranial pressure (?)*
* see pathology for mechanism at site or origin
Pathology
- mediated by
- dopamine D2 receptors or 5-HT3 receptors in GI tract
- dopamine D2 receptors, 5-HT3 receptors or neurokinin-1 receptors in the chemoreceptor trigger zone (CTZ)
- histamine H1 receptors & muscarinic receptors in the vestibular system
- unknown mediators in the cerebral cortex (putative)
Management
- sucking of hard candy or popsicle especially in children
- anticholinergics for motion sickness - scopolamine
- antihistamines - inner ear dysfunction or motion sickness
- dimenhydrinate (Dramamine) 50 mg PO/IV/IM every 4 hours
- promethazine (Phenergan) 25-50 mg PO/IV/IM every 4-6 hours
- dopaminergic antagonist (metochlopramide, prochlorperazine, haloperidol) for dopamine D2 receptor mediated nausea
- antacids for nausea due to gastritis[2]
- serotonin antagonists (ondansetron, granisetron) for 5-HT3 receptor (chemotherapy) mediated nausea
- aprepitant for resistant chemotherapy-induced nausea[2]
- benzodiazepines for anticipitory nausea
- glucocorticoids for increased intracranial pressure
- octreotide for nausea due to bowel obstruction
- do not use topical agents for treatment of nausea[2]
- treatment of nausea in palliative care
- if due to constipation, bowel obstruction, ileus
- if due to chemotherapy, radiation, inflammation, cancer
- if due to drugs, metabolites, bacterial toxins
- if due to labyrinthine disorder, motion sickness
- anticholinergic agents: scopolamine, diphenhydraine, promethazine
- increased intracranial pressure: glucocorticoids
- also see vomiting