What is the recommended management for postoperative nausea?

Management of Postoperative Nausea and Vomiting

A multimodal approach to postoperative nausea and vomiting (PONV) prophylaxis should be implemented for all surgical patients, with antiemetic agents selected based on patient risk factors and administered in combination for those at moderate to high risk. 1, 2

Risk Assessment

• PONV affects 30-50% of all surgical patients and up to 80% of high-risk patients 1
• Key risk factors include: female gender, history of PONV or motion sickness, non-smoking status, use of volatile anesthetics, and postoperative opioid administration 1, 2
• Risk assessment using validated tools like the Apfel score should guide prophylaxis strategy 1, 2

Prophylactic Management

First-Line Antiemetics:

• 5-HT3 antagonists (ondansetron, granisetron): Ondansetron 4mg IV is highly effective, reducing PONV by approximately 25% when used alone 1, 3
• Corticosteroids (dexamethasone): A 4-5mg dose has similar clinical efficacy to 8-10mg doses 1, 4
  • The DREAMS Trial with 1350 patients showed a single 8mg dose reduced PONV at 24 hours and decreased rescue antiemetic needs for up to 72 hours 1
• Dopamine (D2) antagonists (droperidol, metoclopramide): Effective as part of multimodal therapy 1

Risk-Stratified Approach:

• Low risk (0-1 factors): Single antiemetic agent may be sufficient 2, 5
• Moderate risk (1-2 factors): Two-drug combination using first-line antiemetics 1, 2
• High risk (≥2 factors): 2-3 antiemetics from different classes 1, 2

Optimal Combination:

• Ondansetron 4mg IV plus dexamethasone 4-5mg IV provides superior prevention compared to either agent alone 2, 6
• For cesarean delivery, this combination has shown high efficacy in reducing PONV 1

Treatment of Established PONV

• If PONV occurs despite prophylaxis, administer a rescue antiemetic from a different class than those used for prophylaxis 1, 2
• Ondansetron 4mg IV is effective as rescue treatment for established PONV 3
• For persistent symptoms, a multimodal approach using different classes of drugs should be implemented 1, 2

Additional Preventive Measures

• Anesthetic techniques: Total intravenous anesthesia (TIVA) with propofol rather than volatile anesthetics 1, 7
• Fluid management: Adequate hydration can reduce PONV incidence 1
• Hemodynamic control: Preventing hypotension through fluid preloading and vasopressors (ephedrine, phenylephrine) reduces PONV risk, particularly in cesarean delivery 1
• Analgesic strategies: Prophylactic analgesia with intravenous acetaminophen can reduce nausea incidence 1
• Alternative therapies: Some evidence supports acupressure, acupuncture, and other non-pharmacological approaches 1

Common Pitfalls to Avoid

• Using only a single agent in high-risk patients is often insufficient 2, 5
• Underdosing dexamethasone (doses <4mg may be less effective) 4, 2
• Failing to administer prophylaxis to patients with multiple risk factors 1
• Using the same antiemetic class for rescue that was used for prophylaxis 1, 2
• Overlooking the potential immunosuppressive effects of dexamethasone on long-term oncological outcomes in cancer surgery 1, 2

Special Considerations

• For cesarean delivery, fluid preloading, vasopressors, and lower limb compression effectively reduce hypotension-induced PONV 1
• In pediatric patients, ondansetron dosing should be weight-based (0.1mg/kg for those ≤40kg) 3
• Second-line agents (antihistamines, anticholinergics) may cause sedation, dry mouth, blurred vision, or dyskinesia 1