Effect of morphine, verapamil or morphine plus verapamil on lidocaine brachial block anaesthesia for orthopaedic surgery

ABSTRACT

Calcium channel blockers [CCBs] potentiate the analgesic properties of both local anaesthetics and opioids. We examined the analgesic effects of administering morphine, verapamil or its combination into the brachial plexus sheath with lidocaine in 64 unpremedicated patients of physical status 1 or 11, aged 20 - 55 yr and weighing 50 - 80 kg, undergoing upper extremity orthopaedic surgery. All patients received brachial plexus anaesthesia with 40 ml of 1.5% lidocaine and epinephrine 5 ug/ml. in addition, patients were randomly allocated to 1 of 4 groups; Group 1 patients received lidocaine solution, Group 2; patients received morphine 5 mg was added to lidocaine solution; Group 3; patients received verapamil 2.5 mg was added to lidocaine solution and Group 4; patients received morphine 5 mg and verapamil 2.5 mg were added to lidocaine solution. Onset of sensory block, duration of anaesthesia and analgesia were recorded. Postoperatively patients rated their pain [0 - 10] at 1, 6, 12, and 24 hr. Patients were instructed to take paracetamol tablets, every 6 hrs when pain score exceeded 3, and total postoperative analgesia requirements was recorded. Onset of sensory block was similar in the four treatment groups. Duration of anaesthesia [time of abolition of pinprick response] was significantly [p<0.001] increased in those patients receiving brachial plexus blocks with verapamil [groups 3 and 4]. Analgesic duration was significantly increased [p<0.001] in those patients receiving brachial plexus block with morphine [groups 2 and 4]. The total 24hr paracetamol use was also less in those groups [2 and 4], which was significant [p<0.05]. We conclude that, the addition of verapamil to brachial plexus block with lidocaine can prolong the duration of sensory anaesthesia, but it had no effect on analgesic duration of morphine used when both were administered with lidocaine via a brachial plexus route