What is the best approach for managing postoperative nausea?

Management of Postoperative Nausea and Vomiting

A multimodal approach using 2-3 antiemetics from different drug classes should be administered prophylactically to all patients with risk factors for postoperative nausea and vomiting, with first-line agents including ondansetron (4 mg IV), dexamethasone (4-8 mg IV), and droperidol. 1

Risk Stratification and Prophylaxis Strategy

Identify patient risk factors:

• Female sex 1
• Non-smoking status 1
• History of PONV or motion sickness 1
• Postoperative opioid use 1
• Major abdominal surgery 1

Prophylactic antiemetic regimen based on risk:

• Patients with 1-2 risk factors: Administer two-drug combination prophylaxis using first-line antiemetics 1

• Patients with ≥2 risk factors: Administer 2-3 antiemetics from different classes 1

First-Line Antiemetic Agents

Each first-line agent provides approximately 25% relative risk reduction when used individually: 1

Serotonin (5-HT3) Antagonists

• Ondansetron 4 mg IV at the end of surgery 1, 2
• FDA-approved for PONV prevention in patients aged 1 month and older 2
• Can be used for both prophylaxis and rescue treatment 1, 2
• In placebo-controlled trials, ondansetron 4 mg prevented postoperative vomiting in 59% vs 45% placebo (P<0.001) 2

Corticosteroids

• Dexamethasone 4-5 mg IV at induction of anesthesia 1
• Meta-analysis of 6,696 patients showed 4-5 mg has clinical effects similar to 8-10 mg 1, 3
• The DREAMS trial (1,350 patients) demonstrated that 8 mg dexamethasone reduced PONV at 24 hours and reduced rescue antiemetic needs up to 72 hours 1
• Important caveat: Immunosuppressive effects on long-term oncological survival remain unknown 1

Dopamine (D2) Antagonists

• Droperidol (dose varies by protocol) 1
• Metoclopramide 25-50 mg IV administered 30-60 minutes before end of surgery 1

Combination Therapy

Combining antiemetics from different classes is significantly more effective than single agents: 1, 4

• Ondansetron + dexamethasone: Provides superior efficacy compared to ondansetron alone 1, 4

• In laparoscopic surgery, combination therapy achieved 92% complete response vs 76% with ondansetron alone 4

• Ondansetron + droperidol: Meta-analysis of 33 trials (3,447 patients) showed combination regimens significantly more effective than 5-HT3 antagonists alone 1

Anesthetic Modifications to Reduce PONV

High-risk patients (≥3 risk factors) should receive: 1

• General anesthesia with propofol and remifentanil (avoid volatile anesthetics) 1
• Avoid nitrous oxide 1
• Multimodal opioid-sparing analgesia 1

Prophylactic IV paracetamol (acetaminophen) reduces nausea incidence in meta-analysis of 2,364 patients, correlating with pain reduction 1

Second-Line Agents

Use when first-line agents are contraindicated or for rescue therapy:

• Antihistamines (promethazine): Limited by sedation 1
• Anticholinergics (scopolamine transdermal): More effective for postoperative than intraoperative nausea 1, 5, 6
• Gabapentin/pregabalin: Reduce nausea but increase risk of visual disturbance (pregabalin) and sedation (both) 1
• NK1 receptor antagonists (aprepitant): Not superior to ondansetron 1

Rescue Therapy

If PONV occurs despite prophylaxis: 1

• Administer a different class of antiemetic than used for prophylaxis 1
• Use multimodal approach with drugs from different pharmacologic classes 1
• Ondansetron 4 mg IV is effective for rescue treatment in patients who did not receive prophylaxis 2

Important caveat: Repeat dosing with the same agent (e.g., second dose of ondansetron 4 mg) does not provide additional control if initial prophylaxis fails 2

Special Populations

Cesarean Delivery

• Address maternal hypotension (common cause of intraoperative nausea/vomiting) with fluid preloading, ephedrine/phenylephrine, and lower limb compression 1, 5, 7
• Multimodal antiemetic prophylaxis strongly recommended 1, 5

Pediatric Patients (aged 2-12 years)

• Ondansetron 0.1 mg/kg IV (maximum 4 mg) for patients ≤40 kg 2
• Ondansetron 4 mg IV for patients >40 kg 2
• Significantly more effective than placebo in preventing nausea and vomiting 2

Common Pitfalls to Avoid

• Do not use single-agent prophylaxis in high-risk patients – multimodal approach is essential 1
• Do not repeat the same antiemetic class for rescue therapy – switch to different mechanism of action 1
• Do not rely solely on pharmacologic prophylaxis – incorporate anesthetic modifications (propofol-based TIVA, opioid-sparing analgesia) 1
• Avoid routine prophylaxis in low-risk patients – reserve for those with expectation of PONV or when PONV must be avoided 2