RESUMO
Disadvantages of intravenous regional anesthesia [IVRA] include slow onset, poor muscle relaxation, tourniquet pain, and rapid onset of pain after tourniquet deflation. In this randomized, double-blind study, we evaluated the effect of addition of nitroglycerine [NTG] to lidocaine for improvement of IVRA. Forty six patients [20-50 yrs] were randomly assigned into 2 equal groups. Under identical conditions, the control group received 3 mg/kg of lidocaine 0.5% diluted with saline, and the study group received an additional 200 microgram NTG. Vital signs and tourniquet pain were measured on the basis of VAS score and recorded before applying tourniquet and 5, 10, 15, 20, and 30 min after administration of anesthetic solution. The onset of sensory and motor block was measured and recorded for all patients. Severity of pain was measured at 5 min, 2, 4, 6, 12, 24, hours after deflation of tourniquet and the total dosage of pethidin injected in the first 24 hours after operation was calculated. Sensory and motor block began more rapidly in study group than control group [2.61 vs. 5.09 and 4.22 vs. 7.04 min., respectively] [p<0.05]. Recovery from sensory and motor block and onset of tourniquet pain were delayed [7.26 vs. 3.43, 9.70 vs. 3.74 and 25 vs. 16.65min., respectively] [p<0.05]. Duration of analgesia after tourniquet deflation was more prolonged and tourniquet pain intensity was lower in study group [p<0.05]. Fentanyl requirement during operation and meperidine used during first postoperative day and pain intensity at 4, 6, 12 and 24hr postoperatively were lower in study group p<0.05. No significant side effect was noted in the patients of both groups. Addition of NTG to lidocaine in intravenous regional anesthesia accelerates the onset of anesthesia and decreases the tourniquet and postoperative pain, without any side effect