The arousal effect of sugammadex reversal of neuromuscular blockade differs with anesthetic depth in propofol-remifentanil anesthesia: a randomized controlled trial

Sugammadex reverses neuromuscular blockade by encapsulating steroidal neuromuscular blockers; therefore, it does not pharmacologically affect sedation levels. However, some clinicians avoid using it because of sudden unwanted acting out or patient arousal. Previous studies suggested sugammadex-induced awakening, but frontal muscle contraction after sugammadex administration compromised reliability of results obtained from EEG-based anesthesia depth monitoring tools like bispectral index (BIS). We hypothesized that sugammadex would affect patients' arousal depending on their baseline levels of sedation. We evaluated arousal signs after sugammadex administration with BIS between 25-35 and 45-55 under steady-state propofol-remifentanil anesthesia at the end of a surgery (n=33 in each group). After sugammadex administration, twelve patients with a BIS of 45-55 showed clinical signs of awakening but none with a BIS of 25-35 (36.4% vs. 0%, P=0.001). The distribution of the modified observer's assessment of alertness/sedation scale scores was also significantly different between the two groups (P<0.001). Changes in the BIS were significantly greater in the BIS 45-55 than in the 25-35 group (median difference, 7; 95% CI 2-19, P=0.002). Arousal after sugammadex was affected by patient sedation levels, and clinical signs of awakening appeared only in those with BIS 45-55. Unwanted arousal of the patient should be considered when using sugammadex under shallow anesthesia.Clinical trial registry number: Clinical Trial Registry of Korea (https://cris.nih.go.kr; Principal investigator: Jieae Kim; Registration number: KCT0006248; Date of first registration: 11/06/2021).