Background The dose of sugammadex recommended by the manufacturer for reversal of rocuronium is 2 mg/kg when the train-of-four count is 2 or more and 4 mg/kg when it is less than 2 but there is a post-tetanic count of at least 1. The purpose of this dose-finding study was to titrate sugammadex to produce a train-of-four ratio ≥0.9 at the conclusion of cardiac surgery, and to continue monitoring neuromuscular blockade in the ICU to identify recurrent paralysis. The hypothesis was that many patients would require less than the recommended dose of sugammadex, but that some would require more, and that recurrent paralysis would not occur. Methods Neuromuscular blockade was monitored using electromyography during cardiac surgery. Administration of rocuronium was at the discretion of the anesthesia care team. During sternal closure, sugammadex was titrated in 50 mg increments every 5 minutes until a train-of-four ratio ≥0.9 was obtained. Neuromuscular blockade was monitored with electromyography in the ICU until sedation was discontinued prior to extubation or for a maximum of 7 hours. Results Ninety-seven patients were evaluated. The dose of sugammadex required to achieve a train-of-four ratio of ≥0.9 varied from 0.43 to 5.6 mg/kg. There was a statistically significant relationship between the depth of neuromuscular blockade and the sugammadex dose required for reversal, but there was a large variation in dose required at any depth of neuromuscular blockade. Eighty-four of 97 patients (87%) required less than the recommended dose, and 13 (13%) required more. Two patients required additional sugammadex administration for recurrent paralysis. Conclusions When sugammadex was titrated to effect, the dose was usually less than the recommended dose, but it was more in some patients. Therefore, quantitative twitch monitoring is essential for ascertaining that adequate reversal has taken place following sugammadex administration. Recurrent paralysis was observed in 2 patients.

No abstract

Background Mechanomyography is the traditional gold standard research technique for quantitative assessment of neuromuscular blockade. Mechanomyography directly measures the isometric force generated by the thumb in response to ulnar nerve stimulation. Researchers must construct their own mechanomyographs since commercial instruments are no longer available. We constructed a mechanomyograph and compared its performance against an archival mechanomyography system from the 1970s that utilized an FT-10 Grass force transducer, hypothesizing that train-of-four ratios recorded on each device would be equivalent. Methods A mechanomyograph was constructed using 3D printed components and modern electronics. An archival mechanomyography system was assembled from original components, including an FT-10 Grass force transducer. Signal digitization for computerized data collection was utilized instead of the original paper strip chart recorder. Both devices were calibrated with standard weights to demonstrate linear voltage response curves. The mechanomyographs were affixed to opposite arms of patients undergoing surgery, and the train-of-four ratio was measured during the onset and recovery from rocuronium neuromuscular blockade. Results Calibration measurements exhibited a positive linear association between voltage output and calibration weights with a linear correlation coefficient of 1.00 for both mechanomyography devices. The new mechanomyograph had better precision and measurement sensitivity than the archival system, 5.3mV vs. 15.5mV and 1.6mV vs. 5.7mV, respectively (p<0.001 for both). Seven hundred sixty-seven pairs of train-of-four ratio measurements obtained from 8 patients had positive linear association (R2 = 0.94; p<0.001). Bland Altman analysis resulted in bias of 3.8% and limits of agreement of -13% and 21%. Conclusions The new mechanomyograph resulted in similar train-of-four ratio measurements compared to an archival mechanomyography system utilizing an FT-10 Grass force transducer. These results demonstrated continuity of gold standard measurement of neuromuscular blockade spanning nearly 50 years, despite significant changes in the instrumentation technology.