[The significance of tramadol as an intraoperative analgesic. A randomized double-blind study in comparison with placebo].

Tramadol-N2O anaesthesia as recommended by Stoffregen was studied in 40 patients (ASA I-II) undergoing elective orthopaedic or lower abdominal surgery. Fentanyl and droperidol (Thalamonal)/atropine were given as i.m. premedication, induction was performed using methohexitone, succinylcholine and pancuronium, ventilation was controlled by means of a Takaoka respirator (N2O/O2 79:21, 4 breaths/min). Intraoperative analgesia was provided by a biphasic tramadol infusion. However, half the patients were given placebo infusion (0.9% NaCl) instead of tramadol in a randomized and double-blind manner in order to evaluate tramadol efficacy as one component of balanced anaesthesia. Whenever anaesthetic depth appeared to be insufficient enflurane (0,5-1.5 vol.%) was administered for short periods. Blood pressure, pulse rate as well as cumulative enflurane dose were documented; postoperative analgesic requirement and awareness of intraoperative events (tape recorder music offered via earphones) were further used to assess tramadol effects. Anaesthesia proved to be quite comparable in both groups; patients felt satisfied without exception. Relative cumulative enflurane times (vol.% . min, related to duration of anesthesia) did not differ significantly (tramadol 5.9%, placebo 4.9%). When enflurane had not been necessary (tramadol n = 13, placebo n = 10), mean percentage rises of blood pressure or pulse rate, related to preoperative values, were found to be slightly higher in the tramadol group. Postoperative analgesic requirement was reduced significantly after tramadol. Striking differences between the two groups, on the other hand, were shown with respect to intraoperative awareness: while patients receiving placebo proved to be amnaesic, 65% of tramadol patients were aware of intraoperative music.(ABSTRACT TRUNCATED AT 250 WORDS)