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Nausea and Vomiting

Vocabulary

Nausea: subjective feeling of a need to vomit.

Vomit: the oral expulsion of upper GI contents resulting from contractions of gut and thoracoabdominal wall musculature.

MOA

Vomiting is coordinated by the brain stem and is affected by NT responses in the gut, pharynx, and thoracoabdominal wall

Nausea is requires conscious perception, the sensation is probably mediated by the cerebral cortex.

N/V caused by condition within and outside the gut as well as by drug and circulating toxins

Coordination of Emesis

Vomiting was coordinated by a single locus in the medullary reticular formation.

NT in coordinate:

Neurokinin NK, serotonin, vasopressin

somatic and visceral muscle

inspiratory thoracic and abdominal wall muscles contract

producing high intrathoracic and intraabdominal pressures that facilitate expulsion of gastric contain

it then across diaphragm and larynx then oral propulsion vomitus

Activator of emesis

cerebral cortex

emesis noxious thoughts or smells originates

cranial nerves

vomiting after gag reflex act.

Labyrinthine apparatus

motion sickness and inner ear disorders

gastroduodenal vagal afferent nerves

gastric irritant and anticancer agents cisplatin

chemoreceptor trigger zone(medulla nucleus or postrema)

chemotherapy, uremia, hypoxia, ketoacidosis

Neurotransmitter

Labyrinthne disorder sti

vestibular cholinergic muscarinic M1

histaminergic H1

Gastroduodenal vagal afferent sti

serotoin 5-TH3

Postrema

5-TH3, M1, H1, and dopamine D2

Differential diagnosis

Intraperitoneal disorders

obstruction

enteric infections

inflammatory diseases

gastroparesis

extraperitoneal disorders

MI

motion sickness

malignancy

medications and metabolic disorders

drugs, chemo, antbiotic, pregnancy, OH

Approach to the patient

History ad physical examination

Diagnostic testing

Treatment

antiemetic medication

selected clinical setting

History and physical examination

Acute symptom

drug or toxins

intestinal obstruction

emesis in the late after meal

pyloric obstruction

within 1 hour of eating

abdominal auscultation

absent bowel sound

intravascular fluid lost

lightheadedness with orthostatic hypotension

Diagnostic testing

Upper endoscopy; ulcer disease

barium radiography; small bowel obstruction

colonoscopy; colonic obstruction

ultrasound; intraperitoneal inflammatory

gastrointestinal motility testing; function

gastroparesis; gastric scintigraphy endoscopy

Treatment

General principles

severe dehydration needs to be hospitalized

once oral intake is tolerated, nutrient are restarted as liquid that are low in fat, because lipid delay gastric emptying

food high in indigestible residues are avoided because these also prolong gastric retention

Antiemetic medication

Labyrinthine-activated pathway

antihistamine

meclizine

dimenhydrinate

anticholinergic

scopolamine

serotonin antagonist

ondansetron and granisetron

treatment of postoperative vomiting

mainly in chemos

postrema

phenothiazine and butyrophenone dopamine D1 antagonists

Gastrointestinal motor stimulants

Drugs that stimulate gastric emptying are indicated for gastroparesis

cisapride

serotonin 5th4 agonist sti cholinergic nerves in the stomach, has because prefer drug of outpt. SE, fetal cardiac arrhythmias, p450 substrate

metoclopramide:

combine 5TH4 ag and D2 antag is antidopaminergic SE limit it use in 20% of patient

Erythromycin:

macrolide, inc gastro motility by action on receptors for motilin, and endogenous stimulant of fasting motor activity

Chemotherapy

Prophylactically 5-TH3 antagonist prevent chemo acute vomiting in most cases

with combination of glucocorticoid

benzodiazepine: lorazepam

reducing anticipatory N/V

cannabinoids: tetrahydrocannabinol

cancer associated emesis