What are the guidelines for managing postoperative nausea and vomiting (PONV)?

Guidelines for Postoperative Nausea and Vomiting Management

A multimodal approach using at least two antiemetic drugs from different classes should be used for postoperative nausea and vomiting (PONV) prophylaxis, with medication selection based on patient risk factors. 1, 2

Risk Assessment and Stratification

Risk factors for PONV include:

• Female gender
• Non-smoking status
• History of PONV or motion sickness
• Postoperative opioid use
• Type of surgery (e.g., abdominal, breast, gynecologic)

Risk-Based Prophylaxis Approach:

• 0-1 risk factors: Consider single antiemetic
• 1-2 risk factors: Use two-drug combination
• ≥2 risk factors: Use three-drug combination 2

First-Line Pharmacological Interventions

Recommended Antiemetic Combinations:

1. High-Risk Patients (≥3 risk factors):

   • General anesthesia with propofol and remifentanil (avoid volatile anesthetics)
   • Dexamethasone 4-8 mg IV at beginning of surgery
   • PLUS a serotonin receptor antagonist (e.g., ondansetron 4 mg IV) at end of surgery
   • PLUS droperidol or metoclopramide 25-50 mg 30-60 minutes before end of surgery 1

2. Moderate-Risk Patients (2 risk factors):

   • Dexamethasone 4-8 mg IV at induction
   • OR a serotonin receptor antagonist (e.g., ondansetron, tropisetron) at end of surgery 1

Specific Antiemetic Medications

5-HT3 Receptor Antagonists:

• Ondansetron: 4 mg IV (standard dose), provides ~25% relative risk reduction when used alone 2, 3
• Granisetron: Highly effective for preventing PONV for 24 hours postoperatively 3
• Ramosetron: Effective for long-term (up to 48 hours) prevention of PONV 3, 4

Corticosteroids:

• Dexamethasone: 4-8 mg IV, reduces PONV with a risk ratio of 0.51 compared to placebo 2, 3
  • 4 mg dose is as effective as higher doses (8-10 mg) for PONV prophylaxis
  • Note: Use with caution in diabetic patients due to potential for worsened glycemic control 1

NK1 Receptor Antagonists:

• Aprepitant: 32 mg IV prior to induction of anesthesia 5
• Fosaprepitant: Highly effective for PONV prevention 3

Dopamine Antagonists:

• Droperidol: Effective for PONV prevention, similar efficacy to 5-HT3 antagonists 2, 3
• Metoclopramide: 10-20 mg IV, particularly useful as rescue therapy 2

Rescue Treatment for Breakthrough PONV

If PONV occurs despite prophylaxis:

1. Administer rescue medication from a different class than those used for prophylaxis
2. Options include:
   • Promethazine
   • Droperidol
   • Metoclopramide 10 mg IV
   • Ondansetron (if not previously used) 2
3. For persistent symptoms, add scopolamine transdermal patch 2

Non-Pharmacological Strategies

• Minimize opioid use through multimodal analgesia approaches
• Ensure adequate hydration and correct electrolyte abnormalities
• Consider total intravenous anesthesia (TIVA) with propofol instead of volatile anesthetics 2
• Early mobilization from the operative day until hospital discharge 1

Special Considerations

• Elderly patients: Use lower doses of benzodiazepines 2
• Patients with cardiac conditions: Monitor with ECG when using certain antiemetics like droperidol 2
• Pregnant patients: Consider tropisetron 2 mg and metoclopramide 20 mg for cesarean delivery 2

Common Pitfalls to Avoid

1. Monotherapy for high-risk patients: Single antiemetic agents are often inadequate for high-risk patients 2
2. Delayed treatment: Administering antiemetics only after symptoms appear rather than prophylactically 2
3. Using rescue medications from the same class as prophylactic agents: This reduces efficacy
4. Ignoring non-pharmacological approaches: Multimodal strategies should include both pharmacological and non-pharmacological interventions
5. As-needed dosing: Around-the-clock administration of antiemetics is more effective than as-needed dosing for established PONV 2

By following these evidence-based guidelines for PONV management, clinicians can significantly reduce the incidence and severity of this common postoperative complication, improving patient comfort, satisfaction, and potentially reducing length of hospital stay.