No abstract

Thoracotomy is often responsible for chronic pain, possibly of neuropathic origin. To confirm preclinical studies, the preventive effects of perioperative ketamine were tested in a randomized, double-blind, placebo-controlled clinical trial on persistent neuropathic pain after thoracotomy. Eighty-six patients scheduled for thoracotomy under standardised general anaesthesia were randomised to receive either ketamine (1 mg kg(-1) at the induction, 1 mg kg(-1) h(-1) during surgery, then 1 mg kg(-1) during 24 h; n=42) or normal saline (n=44). Postoperative analgesia included a single dose of intrapleural ropivacaine, intravenous paracetamol and nefopam, and patient-controlled intravenous morphine. Vital parameters and analgesia were recorded during the 48 first postoperative hours. Seventy-three patients were followed up. The patient's chest was examined 1-2 weeks, 6 weeks and 4 months after surgery. At the last two observations, spontaneous pain score over a one-week period (visual analogue scale), neuropathic pain score (NPSI), and intake of analgesics, were assessed. No drug affecting neuropathic pain (except opiates) was given during the follow-up. Two patients in each group were lost to follow-up after the 6 week visit. Ketamine improved immediate postoperative pain, but the groups were similar in terms of neuropathic pain and intake of analgesics, 6 weeks (NPSI score: ketamine: 1.25 [0-4.125]; placebo: 1 [0-4]) and 4 months after surgery. Thus, ketamine given in 24-h infusion failed to prevent chronic neuropathic pain after thoracotomy. Other perioperative preventive long-lasting treatments or techniques could be tested in this context.

SummaryWe compared the duration of analgesia produced by a mixture of lignocaine and bupivacaine, either alone or combined with morphine (75 mg.kg ¹1 ), buprenorphine (3 mg.kg ¹1 ) or sufentanil (0.2 mg.kg ¹1 ) in 80 patients after brachial plexus block for orthopaedic surgery of the upper limb. The characteristics of analgesia were evaluated hourly using a visual analogue scale. The analgesia was considered satisfactory for scores of 30 or less. The median duration (range) of satisfactory analgesia was: 11.5 (8-15) h without an opioid, 21 (9-27) h with morphine, 20 (14-34) h with buprenorphine and 24.5 (11-38) h with sufentanil. We conclude that the addition of an opioid to a local anaesthetic mixture lengthens the duration of analgesia. The demonstration that opioid receptors are present in the peripheral nervous system [1] prompted recent investigations of the effects of using opioids, alone or combined with local anaesthetics, for regional analgesia procedures like brachial plexus block. Several authors have investigated the efficacy of injecting opioids into the brachial plexus sheath [2][3][4][5][6][7][8][9][10][11][12][13][14], but the results remain inconclusive. Some authors did not observe any benefit from adding opioids [6,7,[9][10][11], but the drugs and doses of opioids and local anaesthetics and the populations of patients, were different in the various studies. Lipid solubility and the affinity of the different opioids for their receptors seemed to be important factors [1]. The aim of this study was to evaluate the effects of different opioids which have either different receptor affinities or different lipid solubilities in patients scheduled for osteosynthesis of a fractured upper limb, without any signs of inflammation. For this purpose, we compared the quality and the duration of the analgesia produced by a brachial plexus block with a mixture of lignocaine and bupivacaine, either alone or combined with morphine, buprenorphine or sufentanil. MethodsThe study was approved by our local ethics committee and informed consent was obtained from the 89 participating ASA grade 1 or 2 patients who were less than 65 years old. They were scheduled to undergo osteosynthesis of the upper limb under brachial plexus anaesthesia. After oral medication with hydroxyzine 100 mg given 2 h before surgery, the brachial plexus block was performed with the aid of a nerve stimulator, using the supraclavicular technique. The patients were randomly allocated into four groups: the control group (group C), which was given a mixture of 1 mg.kg ¹1 of bupivacaine 0.5% and 2 mg.kg ¹1of lignocaine 1% with 1 : 200 000 adrenaline and groups M, B and S, which were all given the same mixture, combined with either morphine 75 mg.kg ¹1 , buprenorphine 3 mg.kg ¹1 or sufentanil 0.2 mg.kg ¹1 . The opioids were diluted in the bupivacaine, in order to obtain the same volume per kilogram in all the groups. In all cases, there was an interval of more than 45 min between the injection of the anaesthetic solution and the surgical procedure.