The interest of 100 versus 200Hz tetanic stimulations to quantify low levels of residual neuromuscular blockade with mechanomyography: a pilot study.

Abstract

A more sensitive method than the train-of-four ratio seems required to detect low levels of residual neuromuscular blockade before tracheal extubation. The goal of the study was to determine the potential benefit of 5s of 100 versus 200Hz tetanic stimulation to quantify the residual block with mechanomyography in anesthetised patients. Twenty informed and consenting 18- to 80-year-old patients undergoing nose surgery were included. On the left hand, neuromuscular transmission was continuously monitored by acceleromyography. On the right side, a new mecanomyographic device (Isometric Thumb Force©) recorded the force of thumb adduction (N) developed during 5s of 100- and 200Hz tetanic stimulations of the ulnar nerve at three consecutive times: baseline before inducing the neuromuscular blockade, at the time of contralateral train-of-four ratio 0.9 recovery, and 3min after additional sugammadex reversal. Tetanic Fade Ratios (TFR = F residual/F max) were compared between 100 and 200Hz stimulations using Student's t test. At the time of TOF ratio 0.9 recovery, both 100 and 200Hz TFR were significantly decreased compared to baseline (0.61 and 0.16 on average, respectively, p < 0.0001). The 200Hz TFR was significantly lower than the 100Hz TFR (p < 0.0001). There were no differences between baseline and post-reversal TFR. The 200Hz TFR has the potential to better describe low levels of residual neuromuscular blockade than the TOF ratio and 100Hz TFR and would benefit from further investigations. Retrospectively registered in the Australian and New Zealand Clinical Trials Registry ACTRN12619000273189.