Intraoperative loading attenuates nausea and vomiting of tramadol patient‐controlled analgesia. (Show‐Chwan Memorial Hospital, Changhua, Taiwan) Can J Anaesth 2000;47:968–973.

Sixty adult patients scheduled for elective abdominal surgery were enrolled into this prospective, randomized, double‐blinded study. The patients were anesthetized in a similar manner. At the beginning of wound closure, the patients were randomly allocated to receive tramadol (Group 1) or normal saline (Group 2). Pain control and adverse effect assessments were done in the PACU and every 6 h for 48 h post drug by an independent observer. The loading dose was 290 ± 45 mg in Group 1 and 315 ± 148 mg in Group 2. In PACU, more nausea and vomiting both in terms of incidence and severity were observed in patients with postoperative loading than in those with intraoperative loading of tramadol. Conclude that administering the loading dose of tramadol during surgery decreases the nausea and vomiting associated with a high dose of tramadol and improves the quality of tramadol PCA in the relief of postoperative pain. Comment by Lian‐Kah Ti, M.D. The clinical application and conclusions of this study have to be questioned. It was not surprising that a loading dose of tramadol could effectively be given intraoperatively. What was surprising was that the authors chose not to give any analgesics either preoperatively or intraoperatively for relatively major surgery in an older population, potentially risking morbidity. Indeed, analgesics were withheld in the control group until the patients were extubated, awake, responsive, and complained of pain. Another source of concern was the large loading dose used. Based on their own experience, the authors gave doses of 300 mg of tramadol, which far exceeded the maximum recommended single dose of 100 mg as stated in the manufacturer's instruction for use. The authors did not report any intraoperative hemodynamic consequences from the loading dose, although they noted that the amount of isoflurane required was decreased. The authors concluded that the decreased nausea and vomiting seen in the patients receiving tramadol intraoperatively resulted from the patients being anesthetized at the point when peak plasma levels were achieved. An alternative explanation could be that the patients in the control group had greater postoperative pain (initial VAS of 5.9), and that pain itself resulted in the increased nausea and vomiting. Therefore, the value of this study is doubtful.