Comparison of compressomyography and electromyography during the spontaneous recovery from rocuronium-induced neuromuscular blockade

In this interventional study, we compare the compressomyography (CMG) to the electromyography (EMG), the latter being the control arm. The nerve stimulation patterns used in this study are the train-of-four (TOF) and the post-tetanic count (PTC), both are standard methods in the monitoring of the neuromuscular blockade. During the TOF-stimulation, four quick stimulation is given to a nerve and the muscle response is monitored. The TOF-measurements use two different assessments: the train-of-four ratio (TOF-ratio) is the ratio of the fourth muscle response to the first one and the train-of-four count (TOF-count) is the number of the detected muscle responses. Once the TOF-ratio is below 10%, the TOF-count is calculated. When the TOF-count reaches zero, the PTC is used to assess the degree of neuromuscular blocade. During PTC, 20 single twitch stimulations are applied after a tetanic stimulus and the muscle response is assessed. Description of the intervention: In one arm, the Stimpod NMS450X (Xavant Technology, Pretoria, South Africa) is installed for the collection of the EMG data: the wrist’s skin is cleaned with diethyl-ether and the electrode array designed for the nerve stimulation and EMG-recording (Xavant Technology, Pretoria, South Africa) is placed above the ulnar nerve, above the adductor pollicis muscles and on the distal phalanx of the thumb. Then the electrode array is connected to the Stimpod Research Unit. The hand is carefully placed in a TOF-tube. In the opposite arm, the VisionDUO (RGB Barcelona, Spain) is installed for the collection of the CMG data: the skin and the electrodes are cleaned and moisted with water, the electrodes are placed over the humeral canal and the cuff is tightened around the arm. Both arms are installed alongside the body with soft padding. After anesthesia induction and the loss of consciousness, manual ventilation is started and the Stimpod and the VisionDUO are calibrated. On the Stimpod side, supramaximal stimulation determination and initial calibration are performed using the Stimpod’s internal automatic sequence. Then, TOF-stimulations are applied every 15 second intervals during a five minutes baseline period (20 measurements) before rocuronium administration. On the VisionDUO side, the stimulation intensity is fixed to 40 mA as a default setting. The Auto Pilot mode is initiated, and neuromuscular block measurements is recorded every 15 seconds during the baseline period and until the TOF-count 0 is reached. After 5 minutes of baseline registration, 0.6 mg/kg rocuronium is administered for neuromuscular block. Once the Stimpod reaches the TOF-count 0, the patient is intubated. For the Stimpod, measurements of TOF-count or TOF-ratio continue every 15 seconds up until the spontaneous recovery of TOF-count 1 and also 10 minutes additional data registration is performed after reaching the complete recovery. In the absence of muscular response to TOF, the PTC-sequence is automatically applied every 5 minutes. For the VisionDUO, neuromuscular measurements are recorded every minute after the onset is completed (TOF-count 0). In the absence of muscular response to TOF, the PTC-sequence is automatically applied every 5 minutes. No reversal agents is administered to not to interfere with the spontaneous recovery of neuromuscular blockade.