PONV, or postoperative nausea and vomiting, is the most common problem patients experience after surgery requiring anesthesia. It occurs in approximately 30% of patients and is caused by stimulation of various neurotransmitter receptors in the brain and gut. Risk factors include a history of PONV, non-smoking status, age under 50, and certain surgical procedures like cholecystectomy or gynecological surgery. Prophylaxis involves reducing baseline risk factors, administering antiemetics that target the 5-HT3, glucocorticoid, anticholinergic, and neurokinin 1 receptors, and meeting specific discharge criteria once patients have sufficiently recovered.

1. PONV
 PONV: postoperative nausea and vomiting
 Most common problem in PACU
 In 30% of patient; mostly in general anesthesia
 Neurotransmitter/receptor involved:
1) muscarinic receptor 1 (M1)
2) dopamine receptor 2 (D2)
3) histamine 1 (H1)
4) 5-HT3R
5) neurokinin 1 (NK1) receptor - substance P

2. Mechanism
Central:
perioperative fear, anxiety,
pain, stimulation of
vestibular system
↓
Substance P
↓
NK1 receptor
↓
central pattern generator
(CPG)

3. Mechanism
Peripheral:
GI stimuli
(trauma, blood, toxin)
↓
5-HT
↓
5-HT3R
↓
Brainstem nucleus tractus
solitarius (NTS)
(near Area Postrema (AP), base of 4th
ventricle, chemoreceptor trigger zone)

4. Mechanism
Drug, toxin:
Opioid, inhalation
↓
Area Postrema (AP)
↓
DA, 5-HT
↓
central pattern generator
(CPG)

5. Risk factors
Preoperative N/V
Non-smoking
<50 y/o
Cholecystectomy
Gynecologic
Laparoscopic procedures

6. Risk factors
 High-risk patients: 4
 Moderate-risk patients: 2-3
 Low-risk patients: 0-1

8. Prophylaxis
1. Reduce baseline risk:
 Adequate hydration (20 ml/kg)
 Multimodal post-OP pain control:
 Regional anesthesia, acetaminophen, NSAID, etc.
 Modification of anesthesia:
 Regional anesthesia or TIVA with propofol

10. Prophylaxis
1. Reduce baseline risk:
 Adequate hydration (20ml/kg)
 Multimodal post-OP pain control:
 Regional anesthesia, acetaminophen, NSAID, etc.
 Modification of anesthesia:
 Regional anesthesia or TIVA with propofol

11. Prophylaxis
2. Antiemetics (↓ 25% of PONV)
1) 5-HT3 receptor antagonist
 Ondansetron: 4 mg, onset: immediately; use at the end of surgery
 Granisetron: 1 mg
 Dolasetron: 12.5 mg, onset: 15 min
 Palonosetron: 0.075 mg; use at the end of surgery
2) Glucocorticoid - dexamethasone: 4-10 mg
 Antiemetics and analgesic
 Use after induction

12. Prophylaxis
3) Anticholinergics: transdermal scopolamine
 Long-acting: several hours
 Use 2hrs before induction
 Side effect: sedation, dysphoria, dry mouth, blurred vision, urinary
retention, glaucoma
4) Dopamine receptor antagonist
 Butyrophenone
 Droperidol: 0.625-1.25 mg
 SE: QT prolong

13. Prophylaxis
5) Neurokinin 1 (NK1) receptor antagonist:
 Aprepitant: oral, 40 mg
 Use 3 hrs before induction

14. Discharge criteria
 Recovery stage:
Phase 1 (early recovery): recovery room
↓ Aldrete score
Phase 2 (intermediate recovery): day care center
↓ PADS
Phase 3 (late recovery): home

15. Reference
 Morgan & Mikhail’s Clinical Anesthesiology, 5th
edition.
 Uptodate