General Principles

• Many patients undergoing anesthesia will experience post-operative nausea and vomiting
• Anti-emetic medications are given routinely during anesthesia.
• Combining agents of different classes reduces side effects and improves anti-emetic action

Clinical Pathway

graph TB
A["`**Patient Factors**
-Female
-Hx of PONV
-Non-smoker
-Post-op Opioids`"];
B["`**Surgical Factors**
-Laparoscopy 
-Cholecystectomy
-Gynecologic Surgery
-Strabismus`"];
N[Nausea Risk];
AN["`**Anesthetic Technique**
-TIVA
-Regional`"];
M["`**Medications** 
-5-HT3 Antagonists
-Steroids
-Anti-psychotics
-NK inhibitors
-Dopaminergic Agents`"];
RM["`**Rescue Medications**`"];




subgraph Pre-operative
A -->N
B-->N
end
subgraph Intra-operative
N-->AN
N-->M
end
subgraph Recovery
AN --> RM
M--> RM
end

graph LR
A["`**Apfel Score**`"];
B1["`**1-2 Risk Factors**`"];
B2["`**3-4 Risk Factors**`"];
C1["`**2 Antiemetics**`"];
C2["`**3-4 Antiemetics**`"];

A --> B1
A --> B2
B1 --> C1
B2 --> C2

Risk Factors for Nausea

Patient Risk Factors – Apfel Score ¹

• Female
• Non-smoker
• history of PONV/motion sickness
• post-operative opioids

Apfel Score Points	Risk of PONV
0	10%
1	20%
2	40%
3	60%
4	80%

Surgical Risk Factors

• Cholecystectomy
• laparoscopic
• gynecologic

Anesthetic Risk Factors

• Duration of anesthesia
• use of volatile anesthetics / nitrous oxide

Medications to Prevent PONV

5-HT₃ Antagonists

OndansetronOndansetron
Mechanism of Action 12

Ondansetron is a selective 5-HT₃ receptor antagonist that blocks serotonin receptors in the chemoreceptor trigger zone (CTZ), preventing the initiation of the vomiting ref...

Antidopaminergics

HaloperidolHaloperidol
Mechanism of Action 12

Haloperidol is an antipsychotic that acts primarily as a dopamine D2 receptor antagonist.
By blocking dopamine receptors, it inhibits the vomiting reflex, making it effe... Metoclopromide Private or Broken Links
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NK1 Receptor Antagonists

AprepitantAprepitant
Mechanism of Action 1

Aprepitant is a neurokinin-1 (NK1) receptor antagonist. NK receptors in the brain are involved in nausea.


Pharmacology 1

Half-life: Approximately 40 hours
Indicat...

Corticosteroids

DexamethasoneDexamethasone
What is Dexamethasone?

Dexamethasone is a glucocorticoid used in the perioperative period for Post-operative Nausea and Vomiting and airway swelling.


Mechanism of Action 12

Dexamethason...