Ex5 Antiemetics Flashcards
N/V occurring within 24h of surgery
Postop Nausea and vomiting (PONV)
Early PONV
Within 6h of emergence of anesthesia
Late PONV
Within 6-24h of emergence from anesthesia
PDNV
Post discharge nausea and vomiting
From 24h post-discharge up to 72h
Forceful expulsion of gastric contents through nose/mouth
Vomiting
Similar to vomiting but no gastric contents enter pharynx
Retching
“Dry heaves”
Retching
Emetic episode
> or = 1 episode of vomiting and/or retching separated by no more than 1 minute
Consequences of PONV
Prolonged stay in PACU Aspiration of gastric contents Unplanned hospital admissions Decreased patient satisfaction Dehydration Electrolyte imbalance Wound dehiscence Bleeding Esophageal rupture Airway compromise SubQ emphysema Pneumothorax Increased abdominal pressure Increased parasympathetic response or sympathetic response
Leading cause of unplanned hospital admissions in outpatient surgery
PONV
Emesis center lies in the
Medulla oblongata
How does the emesis center receive information?
Receives impulses from sensory centers
Sensory centers
- Chemoreceptor trigger zone (CTZ)
- Vagal input from gut/pharynx
- Cerebral cortex
Location of CTZ
Bottom of 4th ventricle
CTZ contains
Receptors that module activity
CTZ detects
Noxious chemicals in bloodstream + activates emesis center in brainstem
Once emesis center detects input, what occurs?
Sends impulse to salivation center, respiratory center, pharyngeal, GI, abdominal muscles —> vomiting
What is located in emesis center/CTZ/GI tract?
Neurotransmitters
Neurotransmitters located in emesis center
Cholinergic, histaminic, dopamine 2, opiate, serotonin-5HT, neurokinin type 1, benodiazepine
Patient risk factors for PONV
Women Previous episode of PONV Non smokers History of motion sickness History of migraine Age < 50 years
Surgical risk factors for PONV
Length of procedure
Certain surgeries: gynecological surgery, laparoscopic procedures, ENT, breast, plastics, orthopedic
Anesthetic risk factors for PONV
Volatile anesthetics (dose dependent, <6h postop)
Duration of anesthetic
Intra/postop opioids
Nitrous oxide
Large doses of neostigmine (>2.5mg, controversial)
General anesthesia
Each ________ in duration of anesthesia increases risk for PONV
30 minute increase
Independent factors predictive of PONV
Women Previous episode of PONV Younger age (<50y/o) Opioid use in PACU Nausea in PACU Non-smokers
