Evaluation of the Effect of Addition of Different Doses of Verapamil to 1.5% Lidocaine on Sensory and Motor Axillary Block

Studies showed that Verapamil as a calcium channel blocker, potentiates the analgesic effects of local anesthesia; however there is controversy regarding the dosage of Verapamil in this regard. In this study, we evaluated the effect of two doses of Verapamil (5 and 10 mg) in combination with Lidocaine, on quality of local axillary blockage in comparison with placebo. The present study was a double blind placebo –controlled clinical trial. Ninety two patients candidate for upper limb orthopedic and plastic surgery with axillary block were enrolled and divided in three groups randomly. In group A, the patients received only lidocaine 1.5%; in group B, the patients received Verapamil 5 mg plus lidocaine 1.5%; and in group C, the patients received Verapamil 10 mg plus lidocaine 1.5%. Time of onset and duration of analgesia, sympathetic, sensory and motor blocks as well as hemodynamic changes (heart rate, blood pressure and mean arterial pressure) before, during and after surgery were evaluated and compared in the three groups. SPSS V.13, Chi2 and One way ANOVA tests were used for data analysis. P= 0.05 was considered as statistically significant. Systolic, diastolic and mid arterial blood pressures significantly decreased during 15-60 min in both groups receiving Verapamil (5 and 10 mg); after which the blood pressure remained similar in the three groups. Mean onset of sympathetic, sensory and motor block was shorter in patients who received Verapamil (5 and 10 mg) than those who received Lidocaine alone (p<0.001). There was no difference in regard to the onset of sympathetic block in the groups receiving Verapamil (p=0.18). Meanwhile duration of motor and sensory block in Verapamil groups was greater than Lidocaine group. Patients who received Verapamil experienced less post-operative (6 hours) pain than those in placebo group, which was statistically significant. Our finding showed that Verapamil 10 mg could amplify quality of axillary blockage (prolonged duration of analgesia, sensory and motor block and reduced post operation pain) without significant changes in hemodynamic situations in comparison with patient who received Verapamil 5 mg.