Gentle Skin Abrasion and EMG-Based Neuromuscular Blockade Monitoring

Neuromuscular blocking agents are commonly used during adult surgical procedures. Quantitative neuromuscular blockade monitoring is used to assess the effects of these drugs and to guide clinical management of neuromuscular blockade and recovery. The TwitchView electromyographic monitor is routinely used for this purpose and uses surface electrodes placed over the ulnar nerve and hand muscles to generate train-of-four measurements. In some patients, the electromyographic signal obtained with routine electrode application may be poor or inadequate for continuous monitoring. This may be related to skin condition, such as callouses, oily skin, or other factors that affect signal quality. Gentle skin abrasion is a technique commonly used in electrophysiology settings to improve the quality of physiologic electrical signals. This study will compare electromyographic signals obtained from routinely applied TwitchView electrodes with signals obtained from TwitchView electrodes placed after gentle skin abrasion using 3M Red Dot Trace Prep abrasive strips. After consent is obtained and the participant is moved into the operating room, TwitchView electrodes will be applied to both wrists. One wrist will receive routine electrode application without skin preparation, while the opposite wrist will undergo gentle skin abrasion before standard TwitchView electrodes are applied. Two TwitchView monitors will be used, one for each electrode strip. After induction of anesthesia, both TwitchView devices will be started. Other than a brief device start-up period, anesthetic and surgical management, including neuromuscular blocking drug dosing and timing, will be determined by the clinical care team and not by the investigators. The devices will record neuromuscular monitoring data during the procedure. The primary outcome is the amplitude of recorded electromyographic responses to train-of-four stimulation after induction of anesthesia but before administration of a paralytic drug. Secondary outcomes include the supramaximal stimulus current determined by the device and electromyographic signal amplitudes after administration of neuromuscular blocking drugs.