S004: QUANTITATIVE NEUROMUSCULAR MONITORING: ACCELEROMYOGRAPHY VS. ELECTROMYOGRAPHY ACROSS OR, PACU, AND ICU
Aaron E LaMont, BS1; Mani Vindhya, MD1; Thomas Moroney, MD2; Mukesh Patel, MD2; Tonni Bacoat-Jones, DO, MPH1
1Nova Southeastern University; 2BayCare Medical Group
Background: Quantitative neuromuscular transmission (NMT) monitoring is essential to avoid residual neuromuscular blockade (RNMB) and postoperative respiratory complications. The 2025 American Society of Anesthesiologists (ASA) guidelines prioritize objective monitoring, including quantitative train-of-four (TOF) assessments, to minimize RNMB.
Acceleromyography (AMG) and electromyography (EMG) are two common monitoring modalities. AMG estimates neuromuscular recovery by measuring muscle acceleration, whereas EMG directly measures compound muscle action potential. Pharmacologic reversal has traditionally relied on anticholinesterases (e.g., neostigmine), but increasing adoption of sugammadex has shifted reversal practices for aminosteroid neuromuscular blocking agents.
As quantitative monitoring and sugammadex use expands, understanding the comparative performance of monitoring and reversal modalities is essential to optimizing patient safety and outcomes.
Methods: This project was conducted as a quality improvement development study. The objective was to synthesize existing evidence to inform a standardized set of quality metrics for quantitative NMT modalities and reversal.
We conducted a structured literature search (January 2021-December 2025) using PubMed as the primary database. Keyword combinations included "quantitative neuromuscular monitoring" AND "acceleromyography" AND "electromyography" OR "train-of-four" OR "residual neuromuscular block" AND "sugammadex."
Inclusion criteria were English-language human randomized controlled trials, systematic reviews, scoping reviews, meta-analyses, adults age 19+, and society guidelines.
Primary outcomes included RNMB, achievement of recovery based on TOF ratios, and postoperative respiratory events when using AMG versus EMG modalities, as well as reversal agent utilization and cost differences between neostigmine and sugammadex.
Results: Contemporary studies confirm that use of quantitative monitoring and reversal significantly lowers RNMB. In a recent observational study (N=500) with 77.6% intraoperative monitoring, only 2.2% of patients had RNMB. Those with documented TOF≥0.9 at surgery end almost never showed RNMB, while older series without routine quantitative monitoring reported RNMB in up to 50% of patients.
Comparing modalities, EMG monitors outperform AMG in precision. EMG provided more repeatable TOF ratios and more accurately indicated true recovery than AMG. AMG proved to be variable, including higher baseline TOF readings, which can give false reassurance of recovery.
Regarding reversal, sugammadex was associated with faster, more complete neuromuscular recovery than neostigmine. Sugammadex consistently provided superior recovery of diaphragmatic and expiratory muscle strength at TOF≥0.9 compared to neostigmine. Fewer pulmonary complications were seen in patients reversed with sugammadex versus neostigmine.
Economic analyses suggest that, although sugammadex has a higher acquisition cost, its use is associated with downstream cost savings through faster neuromuscular recovery and lower rates of postoperative complications.
Discussion: Our data suggests that institutions adopt the 2025 ASA guidelines, standardizing monitoring equipment, training staff, and setting benchmarks based on these metrics. For example, targeting RNMB rates <5% and TOF≥0.9 in >95% of cases would align with current guideline goals.
EMG is preferred over AMG due to its direct measurement of neuromuscular electrical activity, which provides more accurate and reproducible TOF ratios and reduces the risk of falsely reassuring assessments of neuromuscular recovery. Future practice should necessitate EMG monitoring, or systematic calibration of AMG devices, and routine use of sugammadex for rapid, reliable reversal in opposed to neostigmine and other anticholinesterases when feasible.