Desert Island TOF part deux

Myron Yaster MD, Lynne Maxwell, MD and Debra Faulk MD

Original Article:

Nemes R, Lengyel S, Nagy G, Hampton DR, Gray M, Renew JR, Tassonyi E, Fülesdi B, Brull SJ: Ipsilateral and simultaneous comparison of responses from acceleromyography- and electromyography-based neuromuscular monitors. Anesthesiology 2021; 135:597–611

Editorial (reviewed yesterday):

Bowdle, A. & Michaelsen, K. (2021). Quantitative Twitch Monitoring: What Works Best and How Do We Know?. Anesthesiology, 135 (4), 558-561. PMID: 34499107

In yesterday’s PAAD, we discussed the editorial by Bowdle et al. and presented an overview of quantitative TOF monitors. Residual neuromuscular blockade is and has been a significant problem in everyday anesthetic practice and should be preventable with objective quantitative monitoring. Until very recently quantitative monitors have not been readily available or easy to use. In today’s PAAD we discuss a “shoot out” in which the authors compared 2 methods of quantitative monitoring, namely acceleromyography vs. electromyography by simultaneously contracting the same adductor pollicis muscle. We think that all of you need to pay very close attention to this because formal ASA guidelines mandating quantitative TOF monitors will be released in less than a year. When that happens, these monitors will become mandatory whenever paralysis is used and will be as essential to the safe practice of anesthesia as our other desert island monitors pulse oximetry and capnography.

The authors did just about everything they could do to ensure study validity. Temperature, end-tidal CO2, and blood pressure (perfusion) were tightly controlled, drugs that could augment NMB were avoided (aminoglycosides, vapor anesthetics, etc.) and a special cable was built to synchronize nerve stimulation. The results: Both monitors work but the EMG based monitor “had higher precision and greater repeatability than acceleromyography”. They concluded that “the EMG monitor is a better indicator of adequate recovery from NMB and readiness for safe tracheal extubation than the acceleromyography monitor”.

Beyond the results of this study, as we discussed yesterday, we think EMG will be better suited to pediatrics because it does not require baseline measurements prior to administration of the NMBA. In our pediatric practices, it’s hard enough to get a pulse oximeter probe and other monitors on and an IV started before tracheal intubation. We just don’t think placing the acceleromyograhy components AND obtaining a baseline measurement will be possible. This is not required with EMG. An additional benefit of EMG not discussed in this paper is that the patients’ arms can be tucked and out of view. This is not possible with acceleromyography.

The editorial and the paper describe an important limitation. The devices were compared to each other not to the “standard” mechanography, which is a force of contraction measure. Unfortunately, these mechanography devices are no longer commerically available so we are not sure how these comparisons could be made. Another issue which was clearly stated in the conflict of interest statement: the senior author is both the inventor and CMO of the company making the EMG device used in the study. We don’t think this changes the results and applaud the authors and the journals for disclosing this conflict.

The paper was published with this accompanying infographic