BACKGROUND: A pneumatic tourniquet is commonly used in orthopedic surgery. However, neuromuscular blocking agent can be sequestered in the isolated limb and be reabsorbed into the systemic circulation after tourniquet release, potentially delaying extubation. To investigate the change in the train-of-four (TOF) ratio after tourniquet release and correlate the TOF ratio change with the extubation time. METHODS: Forty patients undergoing unilateral total knee arthroplasty were enrolled. Before and after the pneumatic tourniquet release, 10 measurements of the TOF ratio were averaged and compared. Additionally, we investigated the correlation between the percentage change in the TOF ratio before and after tourniquet release and the extubation time. RESULTS: Among the 40 patient subjects, 30 showed a TOF ratio before tourniquet release and 10 showed only a TOF count. Of the 30 patients with a TOF ratio, 21 showed a TOF ratio increase after tourniquet release and 9 showed a TOF decrease; both increase and decrease were statistically significant (P < 0.001 and P = 0.008, respectively). The extubation time showed a weak negative correlation with the percentage change in the TOF ratio after tourniquet release (P = 0.004). CONCLUSIONS: In orthopedic surgery using a pneumatic tourniquet, neuromuscular function monitoring may be required to monitor the change in the effect of neuromuscular blocking agent before and after tourniquet release, which may help to improve anesthesia safety.
Anesthesia ; Arthroplasty* ; Extremities ; Humans ; Knee* ; Neuromuscular Blockade ; Neuromuscular Blocking Agents ; Neuromuscular Monitoring ; Orthopedics ; Tourniquets*