There were insufficient researches of the comparison between Bispectral Index (BIS) and Patient State Index (PSI) values during the recovery of moderate NMB. We investigated the response of these indices during neuromuscular blockade (NMB) reversal by sugammadex under steady-state total intravenous anesthesia (TIVA) using propofol/remifentanil. In this prospective, observational study, patients undergoing laparoscopic cholecystectomy were enrolled. At the end of surgery, after confirming that train-of-four (TOF) count as 1 or 2, we maintained a steady state (BIS value of 40–50). After administration of 2 mg kg−1 sugammadex, BIS, PSI, and electromyography (EMG) signal values were recorded at one-minute intervals for 10 min. The primary outcome was the difference between the changes in BIS and PSI from baseline to a TOF ratio (TOFR) of 90 after sugammadex administration in steady-state TIVA. A total of 48 patients completed this trial. There was no significant difference between the changes in BIS and PSI values from baseline to TOFR 90 (− 0.333 ± 4.955 vs. − 0.188 ± 4.616; 95% confidence interval [CI] − 2.095 to 1.803; p = 0.882). Both BIS-EMG and PSI-EMG values at baseline and TOFR 90 were not statistically different (95% CI − 0.550 to 1.092; p = 0.510, 95% CI − 1.569 to 0.527; p = 0.322, respectively). No patient experienced any complications. Changes in BIS and PSI values after NMB reversal during steady-state TIVA were not significantly different. Both BIS and PSI provide trustworthy values for monitoring anesthetic depth during NMB reversal under TIVA.Trial Registration: This study was registered in the Clinical Trial Registry of Korea (https://cris.nih.go.kr: KCT 0003805).

The degree of neuromuscular blockade reversal may affect bispectral index (BIS) value. One possible reason is that the reverse of neuromuscular blockade affects electromyographic (EMG) signals of fascial muscle. Another reason is, the afferentation theory, the reverse of neuromuscular blockade relieves block signals generated in muscle stretch receptors from accessing the brain through afferent nerve pathways and induces arousal. Inaccurate BIS value may lead to overdose of drugs or the risk of intraoperative awareness. We compared changes in BIS and EMG values according to neuromuscular blockade reversal agents under steady-state desflurane anesthesia. A total of 65 patients were randomly allocated to receive either neostigmine 0.05 mg/kg, sugammadex 4 mg/kg, or pyridostigmine 0.25 mg/kg for neuromuscular blockade reversal under stable desflurane anesthesia, and 57 patients completed the study. The primary outcome was change in BIS and EMG values before and after administration of neuromuscular blockade reversal agents (between train-of-four [TOF] count 1–2 and TOF ratio 0.9). The change in BIS and EMG values before and after administration of neuromuscular blockade reversal agents were statistically different in each group (BIS: Neostigmine group, P < 0.001; Sugammadex group, P < 0.001; Pyridostigmine group, P = 0.001; EMG: Neostigmine group, P = 0.001; Sugammadex group, P < 0.001; Pyridostigmine group, P = 0.001; respectively). The BIS and EMG values had a positive correlation ( P < 0.001). Our results demonstrate that the EMG and BIS values have increased after neuromuscular blockade reversal under desflurane anesthesia regardless of the type of neuromuscular blockade reversal agent. BIS should be applied carefully to measure of depth of anesthesia after neuromuscular blockade reversal.

The perfusion index (PI) is an objective tool used to assess a successful nerve block. Epinephrine is a widely used adjuvant to local anesthetics, and it may affect PI values because of the vasoconstrictive property. The aim of this study was to investigate the influence of epinephrine on PI as an indicator of a successful block in ultrasound-guided supraclavicular brachial plexus block (SCBPB). In this randomized controlled trial, 82 adult patients underwent upper limb surgery under SCBPB were recruited between July 2018 and March 2019 in a single tertiary care center. Participants were randomly assigned to one of two groups: non-epinephrine group (n = 41) or epinephrine group (5 mcg ml −1 , n = 41). The primary outcome was the comparison of the "PI ratio 10," which was defined as the ratio of the PI 10 to the baseline. Receiver operating characteristic (ROC) curves were constructed to determine the accuracy of the PI in predicting the block success at each time interval. The PI ratio 10 was 2.7 (1.9-4.0) in non-epinephrine group and 3.3 (2.2-4.4) in epinephrine group (median difference: 0.4; 95% confidence interval [CI] − 1.1 to 0.2; P = 0.207). The ROC curves compared without group identification were not significantly different over time. The cutoff value for the PI and PI ratio at 5 min (PI ratio 5) were 7.7 (area under the ROC [AUROC]: 0.89, 95% CI 0.83-0.94) and 1.6 (AUROC: 0.94, 95% CI 0.90-0.98), respectively. The perineural epinephrine did not affect the PI following a SCBPB. The PI ratio 5 > 1.6 might be considered as a relatively accurate predictor of a successful SCBPB. Trial registration: This study was registered at the Clinical Trial Registry of Korea (https ://cris.nih.go.kr. CriS No. KCT0003006).