A modified TOF-ratio to assess rocuronium-induced neuromuscular block: a comparison with the usual TOF-ratio

• Published in: Anaesthesia critical care & pain medicine 2022-08, Vol.41 (4), p.101088-101088, Article 101088
• Main Authors: Schmartz, Denis, Bernard, Paul, Sghaier, Raouf, Fils, Jean-Francois, Fuchs-Buder, Thomas
• Format: Article
• Language: English
• Subjects: Neuromuscular blocking agents; Neuromuscular transmission: monitoring; TofScan
• ISSN: 2352-5568; 2352-5568
• DOI: 10.1016/j.accpm.2022.101088

The TOFscan is an acceleromyographic neuromuscular monitor that calculates and displays two measurements: first, a train-of-four (TOF) ratio, or ratio of the fourth twitch in the TOF-sequence, T4, and the first twitch, T1 (T4/T1). In addition, a second, modified ratio is displayed (T4/Tr), which refers to the ratio between T4 and a reference twitch (Tr), calculated as the mean value of the four twitches in a TOF-sequence [Tr = (T1 + T2 + T3 + T4)/4]. T4/Tr is calculated before establishment of neuromuscular block. This prospective observational study included 35 adult patients. NMB induced by a rocuronium bolus of 0.6 mg/kg was continuously monitored at the adductor pollicis with the TOFscan and both TOF-ratios were simultaneously assessed. Primary outcome was the comparison of recovery to a TOF-ratio ≥ 0.9 calculated as T4/T1 and T4/Tr. The first value of the T4/T1 ≥ 90% was 90.9 (1.1) % and the simultaneously calculated T4/Tr was 69.6 (9.3) %, P