Neuromuscular blockade: electromyographic and mechanical versus visual interpretation

Anesthetists frequently provide intraoperative muscle relaxation in addition to general anesthesia. However, visual interpretation of the effect of neuromuscular blocking drugs is not always possible. This study examined two alternative methods (electromyography/electrocardiography [EMG/ECG] and mechanical/ECG) of interpreting neuromuscular blockade and compared these methods to visual interpretation. EMG/ECG and mechanical/ECG methodologies were found to provide reliable valid intraoperative interpretation of nondepolarizing neuromuscular blockade for single-twitch and train-of-four stimuli. EMG/ECG and mechanical/ECG measures of neuromuscular blockade were performed with an electrocardiographic monitor and a pressure transducer, respectively. Both EMG/ECG and mechanical/ECG, when compared to visual interpretation, were found to be equally, and usually more, valid indicators of neuromuscular blockade. The clinical significance of this study is its contribution to quality care and patient safety. When visual monitoring of neuromuscular blockade is not feasible, either EMG/ECG or mechanical/ECG provide an alternative method of monitoring neuromuscular blockade.