In reference to Reversal of rocuronium-induced neuromuscular blockade by sugammadex allows for optimization of neural monitoring of the recurrent laryngeal nerve.

We read with interest the study by Lu et al. about routine sugammadex reversal in patients with rocuroniuminduced neuromuscular blockade undergoing thyroidectomy. This study showed that after a single intubating dose of rocuronium, sugammadex 2 mg/kg was effective to restore sufficient neuromuscular function, allowing intraoperative neuromonitoring (IONM). Also, this article concluded that implementation of this enhanced neuromuscular blockade recovery protocol would assure optimal conditions for both tracheal intubation and subsequent IONM during thyroid surgery. Although we commend authors for these data validated in both porcine modeling and clinical human application, we also believe that several points should be discussed further. First, we agree that adequate neuromuscular blockade is essential for tracheal intubation, especially in patients undergoing thyroid surgery. Indeed, a relaxantfree induction technique has been shown to increase significantly postoperative laryngeal morbidity with a number needed to harm for postoperative hoarseness and vocal cord sequelae of 2.7 and 3.5, respectively. However, the use of neuromuscular blockade for tracheal intubation does not preclude IONM. Intraoperatively, anesthesiologists typically assess depth of neuromuscular block at the adductor pollicis muscle while the laryngeal muscles are in the focus of IONM. Of interest in this context, it has been shown that recovery from rocuronium neuromuscular blockade was significantly faster at the laryngeal muscles compared to the adductor pollicis muscle, 22 6 3 minutes and 37 6 4 minutes, respectively. Consequently, time duration between rocuronium injection and V1 signal is crucial regarding this issue and corresponds to about 25 to 35 minutes in our experience (506 patients with rocuronium-induced neuromuscular blockade at intubation with IONM since January 2014), thus allowing appropriate intraoperative neuromonitoring in most patients while the adductor pollicis is still paralyzed. In this setting, the need for sugammadex to restore neuromuscular function allowing adequate IONM is rather infrequent and observed approximately in less than 20% of patients. Consequently, compared to routine reversal of rocuronium neuromuscular blockade with sugammadex, a selective reversal approach may be sufficient and more cost-effective. Finally, whether that mean V1 amplitude may be artificially lowered by residual paralysis is currently not completely understood and should be addressed in further studies. In conclusion, the decision of sugammadex reversal in patients requiring IONM should be based on riskbenefit analysis, that is, risks of sugammadex injection in patients with no need for reversal of neuromuscular blockade versus risks of no sugammadex injection in patients with residual paralysis needing IONM.