ANTIEMETIC EFFECT OF SUBHYPNOTIC DOSES OF PROPOFOL AFTER THYROIDECTOMY

Postoperative nausea and vomiting (PONV) are unpleasant, often underes timated side effects of anaesthesia and surgery, not devoid of medical complications, Prevention with antiemetics is only partially effectiv e. Propofol has been shown recently to possess antiemetic properties i n several situations. In this prospective, randomized, controlled tria l, we have compared the antiemetic efficacy of subhypnotic doses of pr opofol, with Intralipid as placebo, after thyroidectomy. We studied 64 patients of both sexes, aged 22-71 yr, ASA I or II, undergoing thyroi dectomy. After premedication with a benzodiazepine, balanced anaesthes ia was produced with isoflurane and nitrous oxide in oxygen, and suppl ementary analgesia with fentanyl i.v. as required. Postoperative analg esia was provided with non-opioids, and piritramide 0.25 mg kg(-1) i.m . on demand. Patients were allocated randomly and blindly to receive a 20-h infusion of either propofol or 10% Intralipid 0.1 ml kg(-1) h(-1 ). Intralipid, the excipient of propofol, was chosen as placebo as it is devoid of antiemetic effects. Sedation scores, respiratory and card iovascular variables, and incidence of PONV were assessed every 4 h fo r 24 h. Pulse oximetry and ECG were monitored continuously. Both group s were comparable in characteristics, surgical and anaesthesia procedu res, amount of opioids given during and after operation, and total amo unt of the study drug infused after operation. Occurrence of PONV was similar before the start (propofol 41%, Intralipid 50%) and after comp letion (propofol 0.64%, Intralipid 1.6%) of infusion and decreased wit h time in both groups during the infusion. However, symptoms were redu ced to nil with propofol but persisted and were more severe with Intra lipid during infusion (P less than or equal to 0.01). The overall inci dence of PONV during infusion was 10% (three of 32 patients) in the pr opofol group and 65% (21 of 32 patients) in the Intralipid group. Card iovascular and respiratory variables, and Sp(O2) were unaltered, and s edation decreased similarly with time in both groups. We conclude that propofol, given at subhypnotic doses, effectively reduced the inciden ce of PONV without untoward sedative or cardiovascular effects.