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Your 27-year-old female patient has been receiving general endotracheal anesthesia for a 3-hour laparoscopic cholecystectomy. Paralysis has been maintained using vecuronium. At the end of the anesthetic, the quantitative train-of-four count is 1. Based on the recent guideline for neuromuscular blockade by the American Society of Anesthesiologists, which of the following is MOST likely a recommendation?
(A) Monitoring should occur at the eye muscles. X(B) Sugammadex should be used at this depth of block. ✔
(C) Clinical signs are sufficient to verify acceptable recovery. X
Gain insight on this topic, and many others, with Summaries of Emerging Evidence (SEE) 2024 – now available. The content is aggregated from 30 international medical journals to streamline your learning and improve your practice.
Neuromuscular blocking drugs revolutionized the practice of surgery and anesthesia by providing a reliable means to temporarily ensure immobility and facilitate airway management. However, unrecognized residual neuromuscular blockade is a source of postoperative morbidity and mortality. In 2021, a group of experts convened to develop evidence-based recommendations on monitoring neuromuscular blockade and the use of drugs to antagonize the effects of neuromuscular blockers and minimize the risk of residual weakness. The American Society of Anesthesiologists Practice Guidelines for Monitoring and Antagonism of Neuromuscular Blockade represent the results of a systematic review of literature published between 1990 and 2022. These guidelines contain 8 recommendations (Table 1). Strength of recommendations were classified by the corresponding quality of evidence, using the Grading of Recommendations, Assessment, Development, and Evaluation (GRADE) system.
Table 1. Recommendations from the Task Force on Neuromuscular Blockade. Used with permission, from Thilen SR, Weigel WA, Todd MM, et al. 2023 American Society of Anesthesiologists Practice Guidelines for Monitoring and Antagonism of Neuromuscular Blockade: a report by the American Society of Anesthesiologists Task Force on Neuromuscular Blockade. Anesthesiology. 2023;138(1):13-41. doi:10.1097/ALN.0000000000004379
The rate of residual neuromuscular blockade after surgery may be as high as 64%. This is likely the result of many factors, one of which is overreliance on clinical or subjective rather than quantitative assessment of neuromuscular blockade. Healthy patients have demonstrated that a sustained 5-second head lift is possible with a train-of-four ratio as low as 0.45. Furthermore, subjective fade in the train-of-four ratio may represent anywhere from a train-of-four ratio as low as 0.4 to as high as 1.0. Based on moderate evidence from randomized trials and observational studies, the authors strongly recommended the use of quantitative monitoring rather than clinical or qualitative assessment to reduce the risk of residual neuromuscular blockade.
The adductor pollicis muscle is relatively sensitive to neuromuscular blockade; therefore, time to a train-of-four ratio of 0.9 or greater is longer at the adductor pollicis than at the orbicularis oculi, corrugator supercilii, or flexor hallucis brevis. For this reason, the adductor pollicis is the preferred muscle at which to monitor neuromuscular blockade. Monitoring at a muscle relatively sensitive to neuromuscular blocking drugs increases the probability that other muscle groups—including those that protect the airway—have recovered when a train-of-four ratio of 0.9 or greater is achieved.
Although neostigmine has historically been the antagonist drug of choice to reverse the effects of vecuronium or rocuronium, the authors endorsed a preference for the use of sugammadex at shallow (train-of-four count of 4, train-of-four ratio < 0.4), moderate (train-of-four count of 1–3), and deep (train-of-four count of 0, posttetanic count ≥ 1) levels of block because it has been associated with a lower rate of residual neuromuscular blockade and a shorter time to reversal. Regarding adverse effects, such as postoperative nausea and vomiting, there was no obvious advantage of one drug over the other.
For benzylisoquinolinium neuromuscular blockers (eg, atracurium and cisatracurium), neostigmine remains the reversal drug of choice because sugammadex is not effective at reversing the effects of these agents. Although recovery time varies, in general when quantitative neuromuscular blockade monitoring is not used, the authors recommended neostigmine administration at least 10 minutes before extubation in the context of 4 visible twitches without fade. Reversal was not recommended at deeper levels of block, except when using quantitative monitoring with a confirmed train-of-four ratio of 0.9 or greater before extubation.
The authors recognized that the recommendation for quantitative monitoring of neuromuscular blockade is a departure from traditional reliance on qualitative assessments and requires peer-to-peer teaching and investment in quantitative monitors, which are currently infrequently available in most clinical settings.
Reference
Date of last update: January 17, 2024
