Low doses of haloperidol combined with ondansetron are not effective for prophylaxis of postoperative nausea and vomiting in susceptible patients.

BACKGROUND In this observational study we reviewed the efficacy and side effects of different antiemetic combinations used in our hospital for postoperative nausea and vomiting (PONV) prophylaxis in high-risk women undergoing highly emetogenic surgery. METHODS After reviewing retrospectively the medical records of patients undergoing highly emetogenic elective surgeries under general anaesthesia, we selected 368 women whose Apfel risk score was ≥ 3 and receiving a combination of 2 antiemetics for PONV prophylaxis. We analysed the incidence of PONV at 2, 6, 12 and 24h after surgery, antiemetic rescue requirements, pattern of occurrence of PONV, side effects and level of sedation were also assessed. The main goal was complete response defined as no PONV within 24h after surgery. RESULTS Ondansetron 4mg i.v. plus dexamethasone 8mg i.v. (O&Dex), haloperidol 1mg i.v. (O&Hal1), haloperidol 2mg i.v. (O&Hal2) or droperidol 1.25mg i.v. (O&Dro) were the combinations most frequently used. The complete response was better in groups O&Dex: 68.5% (CI: 58-78), O&Hal2: 64.1% (CI: 53-74) and O&Dro 63% (CI: 52-73) than in group O&Hal1: 41.3% (CI: 31-52) (p<0,01). Peak incidence of PONV occurred within the 2-6h period. The incidence of side effects was higher in group O&Hal2. CONCLUSION In high risk patients for PONV who underwent highly emetogenic surgeries, the efficacy of low-dose haloperidol (1mg) in combination is limited. Higher doses (2mg) are more effective but its use is associated with a high incidence of side effects.