Does Deep Neuromuscular Blockade Improve Operating Conditions during Minimally Invasive Anterolateral Total Hip Replacements?: A Randomized Controlled Trial

Background Neuromuscular blockade (NMB) is thought to improve operative conditions during certain procedures. Published descriptions of minimally invasive hip replacement techniques specify the need for "excellent relaxation", however, the optimal degree of NMB required for such cases has not been studied. We performed a randomized, single-blind study comparing the effect of moderate and deep neuromuscular blockade on surgical conditions and operating time during minimally invasive anterolateral hip replacement. Vecuronium was administered to maintain moderate NMB (train-of-four count of 1-2) or deep NMB (train-of-four count of 0, post-tetanic count of 1-2). Methods In this study, 116 patients were randomized to receive moderate or deep neuromuscular blockade; depth of blockade was monitored using acceleromyography. The primary outcome was the number of requests from the surgeon for additional blockade intraoperatively. Secondary outcomes included operative times and assessment of the operative conditions by the surgeon utilizing the Leiden-Surgical Rating Scale. Results Cases with additional requests for blockade did not differ between the deep and moderate NMB groups (11/58, 19.0% vs 8/58, 13.8%); relative risk, 1.22 (95% CI [confidence interval], 0.70-2.15), p=0.62. Neither time from incision to prosthesis reduction (33.8±1.2 min vs. 32.6 ±1.2 min; difference in geometric mean, 0.96 [95% CI, 0.90-1.04] minutes, p=0.33), nor the surgeon's assessment of operative conditions (p=0.88), differed between the deep or moderate NMB groups, respectively. Conclusions Deep NMB did not produce significantly improved operative conditions compared with moderate NMB. Routine use of deep NMB during minimally invasive anterolateral hip arthroplasty is not supported by this study.