While necessary for monitoring deep neuromuscular blockade, short tetanic stimulation during posttetanic count monitoring may induce nociception. We sought to explore the effects of short tetanic stimulation on hemodynamic variables and electroencephalography (EEG) band powers, while identifying associated risk factors. In this retrospective cohort study, we included adult patients undergoing ophthalmic or otolaryngologic surgery with quantitative neuromuscular blockade monitoring from October 2022 to October 2023. Nociceptive responses were evaluated using hemodynamic changes and EEG band power analysis. Patients were classified as responders based on a 20% or greater increase in heart rate after 5 sec of tetanic stimulation. We used multivariable logistic regression to identify risk factors for nociceptive responses. Of the 732 patients, 11% (78/732) were categorized as responders. Among responders, mean (95% confidence interval CI) heart rates increased from 67 (64 to 70) to 88 (85 to 92) min −1 (+33%; P < 0.001), and mean (95% CI) systolic blood pressure rose from 107 (102 to 112) to 119 (114 to 124) mm Hg (+12%; P < 0.001). EEG analysis showed significant mean (95% CI) alpha band power loss in responders (−5.9 dB −6.4 to −5.4 to −6.6 dB −7.1 to −6.0 dB; −14%; P = 0.003). These nociceptive changes were significantly associated with lower remifentanil effect-site concentrations and body weight in multivariable logistic regression analysis (odds ratio OR, 0.90; 95% CI, 0.85 to 0.95; P = 0.001 and OR, 0.74; 95% CI, 0.52 to 0.95; P = 0.04). Short tetanic stimulation during posttetanic count monitoring induced nociceptive responses as evidenced by changes in hemodynamics and EEG band powers. While lower remifentanil concentrations were associated with nociception, the retrospective design, exclusion of total intravenous anesthesia cases, and lack of assessment regarding clinical outcomes may limit the generalizability and clinical implications of these findings. Prospective studies are needed to confirm these results.
Yoon et al. (Thu,) studied this question.