Electromyographic Monitoring and Postoperative Recovery

Residual neuromuscular blockade (weakness) is a common occurrence in the postanesthesia care unit when muscle relaxant drugs have been used in the operating room. The only method of reliably detecting residual neuromuscular blockade is through the use of quantitative neuromuscular monitors. These devices measure and quantify the degree of muscle weakness and display the results on a screen. When using train-of-four (TOF) nerve stimulation, the ratio of the fourth muscle contraction (twitch) to the first twitch will be displayed; when this ratio is 90% (or 0.9) or greater, full recovery of muscle strength is present, and the endotracheal tube can be safely removed. At the present time, there is only one commercially available quantitative monitor produced in the United States -the TOF-Watch. The TOF-Watch is not used by many clinicians because it requires experience to obtain accurate results, is expensive, and is subject to interference by factors in the operating room. The aim of this investigation is to examine a new quantitative monitor (the TetraGraph, an electromyography (EMG) device) in the clinical setting. Patients will be randomized to receive either electromyography monitoring (EMG group-using the TetraGraph) or qualitative peripheral nerve stimulator monitoring (PNS group-the standard type of neuromuscular monitoring used at NorthShore University HealthSystem). The primary endpoint of the investigation is the incidence of postoperative residual blockade (defined as a TOF ratio < 0.9 with TOF-Watch, the current "gold standard quantitative monitor). Secondary endpoints include a variety of standard clinical recovery variables.