6. Nausea and Vomiting Flashcards
What is nausea?
An inclination to vomit or a feeling in the throat or epigastric region alerting the individual that vomiting is imminent.
What is vomiting/emesis?
The ejection or expulsion of gastric contents through the mouth - often a forceful event.
What is the dynamic threshold?
An ever-changing point at which an individual experiences nausea.
What is regurgitation?
gastric or esophageal contents rise to the pharynx because of pressure differences caused by an incomplete lower esophageal sphincter, for example.
What is retching?
labored movement of abdominal and thoracic muscles before vomiting
What are the clinical consequences of vomiting?
- dehydration
- aspiration
- electrolyte or acid/base imbalance
- Mallory-Weiss Syndrome
Vomiting is controlled via central emesis in the __-____ _____.
mid-brain stem
What are the receptors involved with visceral stimulation?
serotonin and dopamine
What are the receptors involved with vestibular stimulation?
histamine and acetylcholine
What are the receptors involved with CTZ stimulation?
serotonin, dopamine, and substance P
What is the result of visceral stimulation?
GI tract upset
What is the result of vestibular stimulation?
motion sickness
What is the result of CTZ stimulation?
vomiting
What autonomic nervous system symptoms are present?
- sweating
- pale
- hyper-salivation
- high BP
- tachycardia
- decreased gastric motility
What endocrine system symptoms are present?
increased vasopressin (ADH) level
What GI system symptoms are present?
gastric dysrhythmias
When should you refer patients to seek other help?
- severe dehydration
- protracted vomiting (> 1-2 days)
- infants or frail elderly
- severe headache
- recent head injury
- blood in vomit
- severe abdominal pain
- ingestion
- AMS
What symptomatic anomalies need to be corrected?
- electrolyte abnormalities
- dehydration
- malnutrition
What recommendation should be given to a patient with mild symptoms and no alarm signs?
- dietary modification
- symptomatic therapy with antiemetic or prokinetic
What recommendation should be given to a patient with significant symptoms +/- warning signs or complications?
- initiate symptomatic medication
- lab testing
- plain abdominal films
- upper endoscopy
If no diagnosis is determined in a patient with significant symptoms +/- warning signs or complications, what are the next steps?
consider
- gastric scintigraphy
- electrogastrography
If a patient with significant symptoms +/- warning signs or complications has abnormal gastric scintigraphy or electrogastrography results, what is the next step?
- prokinetic therapy
- consider cause of gastroparesis
What is the mechanism of action of ondansetron (Zofran)?
- primarily block central serotonin receptors in the CTZ
- also block peripheral receptors in vagal and spinal afferent nerves
In what formulations is ondansetron available?
PO (IR and orally disintegrating tablet)
solution
IV
What are ADRs of ondansetron?
QT-interval prolongation
serotonin syndrome
What is the mechanism of action of metoclopramide (Reglan)?
centrally blocks the dopaminergic receptors in the CTZ
involves vagal and central serotonin and dopamine receptor antagonism with prokinetic properties
What are the clinical results of metoclopramide?
- increases lower esophageal sphincter tone
- aids gastric emptying
- accelerates transit through small bowel
What are ADRs of metoclopramide?
dose-dependent irreversible tardive dyskinesia
What is the mechanism of action for prochlorperazine (Compazine)?
antipsychotic which centrally blocks D1 and D2 receptors
In what population is prochlorperazine contraindicated?
patients
What is the mechanism of action for promethazine (Phenergan)?
centrally blocks the postsynaptic mesolimbic dopaminergic receptors in the brain
In what formulations is promethazine available?
PO (IR and solution)
IM
IV
rectal
In what population is promethazine contraindicated?
patients
Promethazine is _______ protein bound.
highly
What is the mechanism of action for diphenhydramine (Benadryl) or pyridoxine-doxylamine (Diclegis)?
- H1 receptor antagonist on effector cells in the GI tract, blood vessels, and respiratory tract
- anticholinergic effects are also seen
What are the most common uses of antihistamines in NV?
motion sickness
pregnancy
What is the mechanism of scopolamine?
anticholinergic
What benzodiazepine is used for NV?
lorazepam
What cannabinoid is used for NV?
Dronabinol
What is the mechanism of Aprepitant?
substance P antagonist
What is first line therapy for NV in pregnant patients?
non-pharmacological
What is second line therapy for NV in pregnant patients?
antihistamine or possibly ginger
What is first line therapy for NV in pediatrics?
non-pharmacological
What is second line therapy for NV in pediatrics?
ondansetron
What medications do we avoid in pediatric patients?
metoclopramide
prochlorperazine
promethazine
antihistamines
