What PONV (postoperative nausea and vomiting) prophylaxis regimen is recommended for a 29-year-old female with a history of PONV after appendectomy, undergoing surgical intervention for a broken femur?

PONV Prophylaxis for a 29-Year-Old Female with History of PONV

Dexamethasone 4 mg IV at the time of anesthesia induction and ondansetron 4 mg IV at the end of the procedure is the recommended PONV prophylaxis regimen for this patient based on her Apfel Simplified Risk Score. 1, 2

Apfel Risk Score Assessment

This patient has multiple risk factors for PONV:

• Female gender
• History of PONV after previous surgery (appendectomy)
• Non-smoker
• Likely to receive postoperative opioids for femur fracture pain

These factors give her an Apfel score of 3-4, placing her in the high-risk category with approximately 60-80% risk of developing PONV without prophylaxis.

Recommended Prophylaxis Strategy

For patients with 3 or more risk factors, a multimodal approach using two or more antiemetic medications from different classes is strongly recommended 1:

1. Dexamethasone 4 mg IV at induction of anesthesia

   • Provides long-lasting antiemetic effect
   • Meta-analyses show 4-5 mg dose is as effective as higher doses 1
   • Should be administered early in the procedure for maximum benefit

2. Ondansetron 4 mg IV at the end of the procedure

   • 5HT3 receptor antagonist effective for immediate postoperative period
   • Timing at the end of surgery optimizes the duration of action 2

Why This Regimen Is Superior

• Single-agent prophylaxis (dexamethasone alone) would be inadequate given her high-risk status 2
• No prophylaxis would be inappropriate as she has multiple risk factors and a history of PONV 1
• Triple therapy with aprepitant would be excessive for initial prophylaxis and should be reserved for cases where standard dual therapy has failed or for extremely high-risk patients 3

Clinical Considerations

• Each antiemetic class provides approximately 25% relative risk reduction when used alone, but combination therapy has additive effects 1
• The combination of dexamethasone and ondansetron targets different antiemetic pathways (anti-inflammatory and 5HT3 antagonism)
• If PONV occurs despite prophylaxis, rescue medication should be from a different class than those used for prophylaxis 1

Potential Pitfalls

1. Timing matters: Dexamethasone should be given at induction to allow time for onset of action, while ondansetron is more effective when given near the end of surgery 2

2. Dose considerations: Higher doses of dexamethasone (8-10 mg) have not shown additional benefit over 4 mg for PONV prophylaxis but may increase side effect risk 1

3. Monitoring: Despite prophylaxis, this patient should still be monitored closely for PONV given her high-risk status

4. Rescue plan: Have a rescue antiemetic from a different class (such as promethazine or droperidol) available if needed 2

This evidence-based approach balances efficacy with safety and is supported by current guidelines for high-risk PONV patients undergoing major surgery.