Optimal degree of neuromuscular blockade for inhibiting obturator nerve-muscle responses induced by transurethral resection of bladder tumor with general anesthesia

Abstract

Objective To evaluate the optimal degree of neuromuscular blockade for inhibiting obturator nerve-muscle responses induced by transurethral resection of bladder tumor (TURBT) with general anesthesia. Methods Ninety American Society of Anesthesiologists physical status Ⅰ-Ⅲ patients of both sexes, aged 26-64 yr, weighing 50-80 kg, scheduled for elective TURBT for lateral bladder wall tumors with general anesthesia, were divided into 3 groups (n=30 each) using a random number table: low-dose mivacurium group (group L), medium-dose mivacurium group(group M)and high-dose mivacurium group (group H). After mivacurium 0.15 mg/kg was injected intravenously during anesthesia induction, mivacurium was continuously infused at a rate of 0.2, 0.3 and 0.4 mg·kg-1·h-1 in L, M and H groups, respectively, until the end of operation.Neuromuscular blockade was continuously monitored during operation.When T1% and TOF count(TOFC)disappeared, post tetanic count(PTC)was used.ROC curve was applied to analyze the relationship between the occurrence of obturator nerve-muscle responses and degree of neuromuscular blockade. Results T1% and TOFC were recorded in 16 patients (15 cases in group L, 1 case in group M) during the resection of tumor, and the obturator nerve-muscle response was observed in all of these patients.In the other 74 patients, T1% and TOFC disappeared, and PTC recorded was 10.0±3.1 (group L, n= 15), 6.0 ± 3.5 (group M, n=29) and 4.0±2.2 (group H, n=30). Among the 74 patients, the obturator nerve-muscle response was found in 18 patients (8 cases in group L, 10 cases in group M). The area under the ROC curve of PTC value in predicting the occurrence of obturator nerve-muscle responses was 0.882 with a PTC cut-off of 9(P<0.05). The sensitivity and specificity were 87.3% and 72.2%, respectively. Conclusion In order to inhibit the obturator nerve-muscle response during TURBT with general anesthesia, the optimal degree of neuromuscular blockade should be kept not more than 9 for PTC. Key words: Anesthesia, general; Obturator nerve; Urologic surgical procedures; Neuromuscular blockade