Background: Pneumatic arterial tourniquet is a very commonly used technique in limb surgeries to provide bloodless field to facilitate dissection and decrease blood loss. However, arterial tourniquet has many deleterious effects including hemodynamic changes, serum lactate and potassium level changes and tourniquet-induced pain which sometimes can be severe and intolerable. Aim of the study: To evaluate the effect of different regional blocks: femoralsciatic, spinal and epidural blocks on serum lactate and potassium levels and the degree of arterial tourniquet-induced pain in patients undergoing lower limb orthopedic surgeries. Methods: 60 patients underwent lower limb orthopedic surgery with application of tourniquet for duration not more than 90 minutes. Patients were assigned randomly to one of three groups (20 each) Group I had sciatic-femoral block, Group II: patients had spinal anesthesia and Group III: patients had epidural anesthesia. Intraoperative hemodynamics, changes in serum potassium and lactate levels and tourniquet pain after tourniquet inflation & deflation, were recorded. Results: There was no statistically significant difference among the three groups regarding tourniquet pain after tourniquet inflation (p = 0.872) and deflation (p = 0.902), and regarding serum levels changes of potassium (p = 0.067) and lactate (p = 0.051). However, each group showed statistically significant increase in post deflation tourniquet pain (p = 0.003, 0.002, 0.003, in groups F, S, E respectively) and serum potassium (p = 0.004, 0.006, 0.000, in groups F, S, E respectively) and lactate levels (p = 0.004, 0.000, 0.000, in groups F, S, E respectively) when compared to the pre-deflation values, and the increase was
89directly proportional to the duration of tourniquet. Conclusion: the three different types of anesthesia (femoral-sciatic, spinal and epidural block) have the same effect on serum lactate and potassium levels and the degree of tourniquet pain, which were related to the duration of tourniquet inflation.