LAUSR

We would like to deliberate upon the manuscript of Koo et al. [1] on the effects of deep neuromuscular blockade (NMB) on surgical conditions during TURB. The authors adapted the Leiden Surgical Rating Scale (L-SRS) that was developed and validated for laparoscopic surgery [2], to evaluate the endoscopic field, movements and bladder contractions during TURB. Deep NMB improves surgical space conditions during laparoscopic surgery [3, 4], however, it is crucial to note that the transurethral endoscopic field has very different characteristics. The wall of the bladder consists of detrusor muscle, smooth muscle cells under autonomic control [5]. Rocuronium selectively competes for acetylcholine receptors at the neuromuscular junction of skeletal muscle. Deep muscle relaxation induced by rocuronium will consequently not widen the endoscopic field or prevent bladder contractions. Conceivably, inhibition of gross patient movements, pelvic floor contractions or prevention of the obturator reflex may improve surgical conditions. However, in spite of decreased occurrence of the obturator reflex, more surgical complications occurred (4 versus 1) in the deep NMB group, indicating the (perceived) improvement of the surgical field did not contribute to prevention of complications. Results were presented without neuromuscular monitoring data. Strikingly, the dose of rocuronium is nearly equal in both groups. A 4 mg difference in the average total rocuronium dose (42 versus 46 mg) is highly unlikely to account for a clinical difference between a moderate (train of four response of 1–2) and deep (post tetanic count of 2) NMB. Previous studies comparing moderate and deep NMB that provide concomitant neuromuscular monitoring data use 40 versus 70 mg [6] and 21 versus 80 mg [7]. Regulating the desired level of NMB remains complex, due to a large dose–response variability between patients [8] and various monitoring methods. Reliable measurement of the posttetanic count requires at least a 5-min interval, which makes titration of the level of muscle relaxation challenging, especially during short procedures. We advocate the importance of comprehensive protocols and training for anesthesiology teams in achieving and maintaining deep NMB. Including NMB monitoring data in future publications will strengthen internal validity and allow for a solid comparison between studies. This will aid in development of guidelines and allow for a reliable evaluation of the effect of deep NMB on patient outcomes.