The effects of tramadol on postoperative nausea, vomiting and headache after ENT surgery. A placebo-controlled comparison with equipotent doses of nalbuphine and pethidine

Background: Opioids given as adjuncts to balanced inhalational anaesthesia augment postoperative nausea and vomiting (PONV). Tramadol, equipotent to pethidine, does not depress respiration, but can cause an increase in blood pressure and headache via its monoaminergic actions. Nalbuphine, ten times as potent as pethidine, has a ceiling respiratory depressant and ceiling analgesic effect at >0.3 mg · kg^?1. We compared the effects of equipotent doses of tramadol and nalbuphine (3.0 and 0.3 mg · kg^?1, respectively) given as analgesic with induction of anaesthesia on emesis during recovery from anaesthesia and on PONV and headache until 24 h after ENT surgery, using saline (0.2 ml · kg^?1) and an equipotent dose of pethidine (1.5 mg · kg^?1) as controls. Method: The study population (N=281) comprised 4 comparable subgroubs (N=69 to 71 each). Anaesthetic medications were standardised. Emesis during recovery from anaesthesia and nausea, vomiting, retching, headache and administrations of antiemetic and analgesics until 24 h after surgery were recorded. Results: Emesis and antiemetic requirements during recovery from anaesthesia were similar and infrequent in each group, as were the incidences of nausea alone (3 to 5%), vomiting alone (17 to 31%), and nausea with vomiting (10 to 22%) during the first 24 h after surgery. However, any complaint of PONV was least frequent in the saline and pethidine groups (32% and 37%, respectively) and most frequent in the tramadol and nalbuphine groups (49% and 52%, respectively; P<0.05 versus saline, both comparisons; P=NS versus pethidine, both comparisons). The times to onset and severity of PONV were similar in each group, but patients given nalbuphine most frequently (P<0.025) needed rescue antiemetic to treat PONV. Headache occurred with similar frequency in each group. Conclusion: It is concluded that tramadol, nalbuphine and pethidine have similar emetic effect in the doses and manner used, and that tramadol does not increase the incidence of postoperative headache when used as peroperative analgesic.