The Effect of Tourniquet Inflation Time on the Pharmacodynamics of Cisatracurium During Surgery: A Randomized Clinical Trial

Background: Pneumatic tourniquets are commonly used in orthopedic surgeries to minimize bleeding. However, they may alter the pharmacokinetics and pharmacodynamics of neuromuscular blocking agents such as cisatracurium. Objectives: This study aimed to evaluate the impact of tourniquet inflation on neuromuscular blockade by assessing the train-of-four (TOF) response when cisatracurium was administered before or after tourniquet inflation. Methods: Twenty-seven patients undergoing general surgery, aged 20 to 65, were randomly assigned to two groups. All patients received midazolam, lidocaine, fentanyl, and propofol for anesthesia induction. In group A (n = 13), cisatracurium 0.5 mg/kg was administered after tourniquet inflation, while in group B (n = 14), it was given before inflation. The TOF responses of the ulnar nerve were recorded in both arms every 15 seconds. The times to complete blockade (TOF count = 0) and recovery to TOF counts of 1 and 2 were measured in both perfused and tourniquet-isolated limbs. Data were analyzed using SPSS software, with P < 0.05 considered statistically significant. Results: In group A, no complete neuromuscular blockade was observed in the limb isolated by the tourniquet; TOF count remained at 4 with only a minor decrease in TOF ratio. In contrast, group B exhibited complete blockade in both limbs (P = 0.82), although the block duration was significantly longer in the tourniquet-isolated limb than the perfused one (P = 0.001). Conclusions: Administering cisatracurium before tourniquet inflation does not affect the onset of neuromuscular blockade but prolongs its duration in the isolated limb. However, if the drug is administered after tourniquet inflation, neuromuscular blockade does not occur in the limb that has been isolated. Therefore, administering additional or maintenance doses of cisatracurium while the tourniquet remains inflated will not affect blockade in that limb.