Continuous interscalene infusion and single injection using levobupivacaine for analgesia after surgery of the shoulder - A double-blind, randomised controlled trial

We performed a double-blind, randomised controlled trial to assess the effectiveness of a continuous-infusion brachial plexus block with levobupivacaine compared with that of a standard single injection for the management of post-operative pain after surgery on the shoulder. Eight patients were randomised to receive a pre-operative brachial plexus block using 30 ml of levobupivacaine 0.5% with adrenaline 1:200 000 followed by insertion of a 20-gauge polyamide catheter. This was connected to a disposable elastometric pump, set immediately after surgery to administer a continuous flow of levobupivacaine 0.25% at a rate of 5 ml per hour. The other eight patients were randomised to receive only the initial injection of 30 ml. The study was double-blinded with the aid of sham catheters and clamped pumps. All patients were given regular paracetamol and were prescribed morphine through a patient-controlled analgesia pump. Motor and sensory block assessments, visual analogue scale pain scores and consumption of morphine were recorded after the operation and then at 6,12 and 24 hours after administration of the block. Satisfactory motor and sensory block was achieved in all patients. The mean visual analogue scale pain score at 12 hours and consumption of morphine at 24 hours after injection were significantly lower (p < 0.05) in the continuous-infusion group. This group also took longer to request their first additional analgesia and reported a significantly higher overall level of satisfaction. Our study has shown that continuous interscalene infusion of levobupivacaine is an effective method of post-operative analgesia after major surgery of the shoulder.