Breteler MJM, Leigard E, Hartung LC
… +9 more, Welch JR, Brealey DA, Fritsch SJ, Konrad D, Hertzberg D, Bell M, Rienstra H, Rademakers FE, Kalkman CJ
J Clin Monit Comput
· 2025 Oct · PMID 40100556
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Continuous vital signs monitoring with wearable systems may improve early recognition of patient deterioration on hospital wards. The objective of this study was to determine whether the wearable Checkpoint Cardio's CPC1...Continuous vital signs monitoring with wearable systems may improve early recognition of patient deterioration on hospital wards. The objective of this study was to determine whether the wearable Checkpoint Cardio's CPC12S, can accurately measure heart rate (HR), respiratory rate (RR), oxygen saturation (SpO2), blood pressure (BP) and temperature continuously. In an observational multicenter method comparison study of 70 high-risk surgical patients admitted to high-dependency wards; HR, RR, SpO2, BP and temperature were simultaneously measured with the CPC12S system and with ICU-grade monitoring systems in four European hospitals. Outcome measures were bias and 95% limits of agreement (LoA). Clinical accuracy was assessed with Clarke Error Grid analyses for HR and RR. A total of 3,212 h of vital signs data (on average 26 h per patient) were analyzed. For HR, bias (95% LoA) of the pooled analysis was 0.0 (-3.5 to 3.4), for RR 1.5 (-3.7 to 7.5) and for SpO2 0.4 (-3.1 to 4.0). The CPC12S system overestimated BP, with a bias of 8.9 and wide LoA (-23.3 to 41.2). Temperature was underestimated with a bias of -0.6 and LoA of -1.7 to 0.6. Clarke Error Grid analyses showed that adequate treatment decisions regarding changes in HR and RR would have been made in 99.2% and 92.0% of cases respectively. The CPC12S system showed high accuracy for measurements of HR. The accuracy of RR, SpO2 were slightly overestimated and core temperature underestimated, with LoA outside the predefined clinical acceptable range. The accuracy of BP was unacceptably low.
Tanaka et al. suggested that the increase in high-frequency variability index (HFVI) after peripheral nerve block (PNB) may result from autonomic effects mediated by the stellate ganglion block when an interscalene brach...Tanaka et al. suggested that the increase in high-frequency variability index (HFVI) after peripheral nerve block (PNB) may result from autonomic effects mediated by the stellate ganglion block when an interscalene brachial plexus block (ISB) is performed. To investigate this, we analyzed patients receiving PNB with (ISB group; n = 8) or without ISB (non-ISB group; n = 22). HFVI increased significantly in both groups to a similar extent. These findings suggest that ISB's direct autonomic influence on HFVI is minimal. Additionally, laterality effects could not be assessed due to limited cases. We conclude that HFVI elevation is more likely due to PNB's analgesic effects rather than ISB's autonomic influence. Further studies are needed to confirm these findings.
The aim of this study was to compare the supramaximal currents obtained simultaneously by acceleromyography (AMG) TOF-Watch SX and electromyography (EMG) AF-201P in pediatric patients. Patients aged 2-11 years who underw...The aim of this study was to compare the supramaximal currents obtained simultaneously by acceleromyography (AMG) TOF-Watch SX and electromyography (EMG) AF-201P in pediatric patients. Patients aged 2-11 years who underwent elective surgery under general anesthesia were enrolled. AMG and EMG monitors were placed on opposite arms of the patient to stimulate the ulnar nerve and monitor the adductor pollicis muscles following the induction of general anesthesia. After the monitors were calibrated, rocuronium 0.6 mg/kg was administered. Endotracheal intubation was performed when the EMG showed a train-of-four (TOF) count of 0. The primary outcome was the supramaximal current set by each device's calibration. The secondary outcomes were the time from the administration of rocuronium to a TOF count of 0, the baseline and final TOF ratios, and the conditions surrounding intubation. The paired t test and the Wilcoxon signed-rank test were used to analyze parametric and nonparametric data. A P value < 0.05 indicated statistical significance. Clinical data from 25 pediatric patients were analyzed. The supramaximal current was significantly lower with EMG than with AMG (27.4 ± 6.1 vs. 54.2 ± 8.4 mA, p <.001). The time to a TOF count of 0 was significantly shorter with EMG than with AMG (58 [24-170] vs. 75 [26-236] seconds, p <.001). Both the baseline and final TOF ratios were significantly lower with EMG than with AMG. The ease of laryngoscopy was rated as excellent for all patients. The vocal cords were abducted in 76% of patients, and no movement to insertion of the endotracheal tube was confirmed in 96% of patients. We found that the supramaximal current was significantly lower with EMG than with AMG.
This study explores the feasibility of continuous pulse wave velocity (PWV) monitoring during general anaesthesia (GA), particularly in response to blood pressure fluctuations. Our aim is to evaluate whether dynamic PWV...This study explores the feasibility of continuous pulse wave velocity (PWV) monitoring during general anaesthesia (GA), particularly in response to blood pressure fluctuations. Our aim is to evaluate whether dynamic PWV can provide new insight to detect cardiovascular risks. From December 2022 to February 2023, continuous carotid and femoral Doppler monitoring was performed on patients scheduled for surgery with GA, to collect PWV data at awakening (PWV) and during GA (PWV). The study investigated PWV's response to MAP fluctuations using the α-angle, a dynamic stiffness parameter. We evaluated PWV and α-angle efficacy in discriminating between low (CVR-) and high (CVR+) cardiovascular risk patients. Among 43 patients, 41 (95%) had successful PWV measurements. PWV was significantly higher than PWV (8.1 vs. 7.4 m.s, p < 0.0001). This difference vanished after matching MAP levels. A strong correlation was found between PWV and PWV (r = 0.88, and r = 0.97 at the same MAP levels). PWV, α-angle and their product (α x PWV) were significantly higher in CVR + patients (8.1 vs. 6.9 m.s, p < 0.01; 2.6 vs. 1.3 degrees, p < 0.001; 21.8 vs. 8.1 degrees.m.s, p < 0.001, respectively), with AUC values indicating good predictive capabilities for cardiovascular risk (PWV: AUC [95%CI] = 0.80 [0.65-0.95]; α-angle: 0.83 [0.69-0.96]; product: 0.86 [0.74-0.97]). Measurement of PWV under GA using carotid and femoral Doppler is a feasible method to continuously assess arterial stiffness under general anaesthesia. Further studies are required to validate the α-angle parameter in different physiological conditions.
Despite advances made toward the automation of medical treatments, existing work has predominantly focused on the automation of individual medical treatments while overlooking interferences between them. In our prior wor...Despite advances made toward the automation of medical treatments, existing work has predominantly focused on the automation of individual medical treatments while overlooking interferences between them. In our prior work, we developed an automation architecture to administer interfering medical treatments with safety, which (i) monitors internal physiological state of a patient using an extended Kalman filter, (ii) mediates medical treatments to bound the estimated internal state within a prescribed safe regime based on control barrier functions, and (iii) treats the patient to a prespecified treatment target through a number of intermediate targets derived from reachability analysis. The goal of this work was to investigate the scalability of this automation architecture in more complex and challenging medical treatment scenarios with a number of conflicts. Using a critical care resuscitation scenario including fluid resuscitation and intravenous sedative-vasopressor infusion, we examined if our automation architecture can achieve treatment goals while ascertaining the safety of internal state in a large number of diverse in silico patients. The results suggested that (i) the extended Kalman filter could continuously monitor a patient's internal physiological state, (ii) the control barrier functions could mediate interfering medical treatments and protect patients against unsafe internal physiological state, and (iii) the reachability analysis could treat a patient as closely as possible to a treatment target while ensuring the safety of the patient's internal physiological state, all despite complex and entangled conflicts between them. Our automation architecture may provide a viable means to autonomously de-conflict interfering medical treatments.
J Clin Monit Comput
· 2025 Oct · PMID 40050564
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Wearables and Internet of Things (IoT) technologies are increasingly incorporated into healthcare, including perioperative settings. These devices offer continuous non-invasive monitoring of vital signs, patient position...Wearables and Internet of Things (IoT) technologies are increasingly incorporated into healthcare, including perioperative settings. These devices offer continuous non-invasive monitoring of vital signs, patient position, and mobilization. Nonetheless, there is currently little information about tolerance and acceptance of wearables in postoperative patients. We therefore assessed opinions and user experience in postoperative patients who used three popular fitness trackers during their entire hospital stay. Specifically, we evaluate the Apple Watch 7, Garmin Fenix 6 Pro, and Withings ScanWatch. We used an investigator-designed patient questionnaire with 11 questions to quantify patient experience and opinions regarding inpatient and home monitoring. Secondarily, we evaluated compliance and the incidence of associated adverse events during daily patient visits. Data were analyzed using descriptive statistics and non-parametric tests. The majority of the answers to the questions (82.1%) were rated positively defined as Likert-Scale Scores 4 or 5 by the 33 analyzed patients, ranging between 72.7 and 97.0% agreement rate. Specific questions related to data sharing for research and overall user experience received high agreement rates (97.0 and 84.8%, respectively). Women reported slightly higher satisfaction with device comfort, as compared to men (LS-Score 4.8 vs. 4.0). No significant differences were found based on the device model or length of hospitalization. The use of wearable devices in healthcare is rated positively by postoperative inpatients, paving the way for future implementation of these devices in healthcare. However, besides validating the measurement accuracy and demonstrating clinical benefits, several regulatory hurdles must be overcome before implementing wearables in routine clinical care.
Azuma S, Asamoto M, Akabane S
… +3 more, Ezaka M, Otsuji M, Uchida K
J Clin Monit Comput
· 2025 Aug · PMID 40050563
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Electroencephalogram-derived monitors are affected by various artifacts. HeartMate 3™ operates at frequency bands that overlap with those used for calculating the electromyographic index (EMG) and bispectral index (BIS)...Electroencephalogram-derived monitors are affected by various artifacts. HeartMate 3™ operates at frequency bands that overlap with those used for calculating the electromyographic index (EMG) and bispectral index (BIS) on the Bispectral Index™ monitor. This study investigated whether HeartMate 3 elevates these values, a change not predicted with HeartMate II™. This retrospective observational study included data from patients who underwent HeartMate 3 or II implantation between April 2008 and December 2023 as extracted from our institutional database. Patient-wise median EMG and BIS were compared between the pre-LVAD period (from the start of surgery to initiation of cardiopulmonary bypass) and the post-LVAD period (from the end of cardiopulmonary bypass to end of surgery). Data were obtained from 33 and 43 patients who underwent HeartMate 3 and HeartMate II implantation, respectively. Patients with HeartMate 3 implantation showed significant elevation in the EMG (pre-LVAD, mean ± standard deviation, 26.1 ± 1.0 dB; post-LVAD, 39.5 ± 2.8 dB; P < 0.001) without a significant change in the BIS (pre-LVAD, 44.5 ± 8.1; post-LVAD, 45.5 ± 7.1; P = 0.35). In contrast, patients with HeartMate II implantation did not show significant changes in either the EMG (pre-LVAD, 26.1 ± 1.2 dB; post-LVAD, 27.1 ± 4.1 dB; P = 0.16) or BIS (pre-LVAD, 45.1 ± 9.2; post-LVAD, 43.0 ± 8.1; P = 0.071). HeartMate 3 significantly elevates EMG. Anesthesiologists should be aware of this to appropriately interpret EMG elevation in patients with HeartMate 3.Trial registration: Japan Registry for Clinical Trials identifier: jRCT1030230549 (date of registration: January 10, 2024.
The administration of propofol for sedation or general anesthesia presents challenges due to the complex relationship between patient factors and real-time physiological responses. This study explores the application of...The administration of propofol for sedation or general anesthesia presents challenges due to the complex relationship between patient factors and real-time physiological responses. This study explores the application of deep reinforcement learning (DRL) to automate propofol dosing, aiming to maintain multiple physiological parameters including bispectral index (BIS), heart rate (HR), respiratory rate (RR), and mean arterial pressure (MAP) within safe and desired ranges. A multi-variable pharmacokinetic-pharmacodynamic (PK/PD) simulation environment was developed to model the effects of propofol on the physiological parameters. An adjustable reward system was designed for multi-target anesthetic infusion. The DRL agent was trained using Twin Delayed Deep Deterministic Policy Gradient (TD3), interacting with the simulation environment and receiving rewards for maintaining physiological parameters close to their targets and above safety thresholds. The performance of the TD3 agent was compared to other DRL algorithms and traditional control methods. The TD3 algorithm demonstrated superior performance in achieving precise and safe control of multiple physiological parameters during propofol administration, outperforming other DRL algorithms and traditional control methods. The application of DRL, particularly TD3, offers a promising approach for automating propofol dosing, ensuring better management of physiological parameters and enhancing the safety and effectiveness of sedation and general anesthesia.
J Clin Monit Comput
· 2025 Oct · PMID 40011398
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To assess the efficacy of electrical impedance tomography (EIT)-guided positive end-expiratory pressure (PEEP) titration in improving outcomes for patients with acute respiratory distress syndrome (ARDS). A systematic re...To assess the efficacy of electrical impedance tomography (EIT)-guided positive end-expiratory pressure (PEEP) titration in improving outcomes for patients with acute respiratory distress syndrome (ARDS). A systematic review and meta-analysis was conducted following Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Randomized controlled trials and observational studies with a control group comparing EIT-guided PEEP titration to other strategies were included. Endpoints analysed included mortality, days of mechanical ventilation (MV), intensive care unit (ICU) length of stay (LOS), weaning success rate, barotrauma, driving pressure (∆P), mechanical power (MP), Sequential Organ Failure Assessment (SOFA) score and adverse events. Pooled results were presented as Risk Ratio (RR) for dichotomous outcomes and standardized difference in means (SMD) for continuous outcomes. A total of 4 studies were identified (3 randomized controlled trials and one observational study). All studies were single-center studies (N total = 271 patients). The main limitations were related to potential bias in selecting reported outcomes. EIT-guided PEEP titration was associated with a significant reduction in mortality among critically ill patients with ARDS (RR = 0.64, 95% CI: 0.45-0.91). No significant differences were found in other outcomes. Our findings suggest that EIT may be a valuable tool for PEEP titration in critically ill patients with ARDS. By optimizing lung mechanics, EIT-guided PEEP titration may potentially reduce mortality rates. While larger, multicenter studies are needed to definitively establish the clinical role of EIT in ARDS management, our results provide promising evidence for its potential clinical impact.
Descamps A, Jacquet-Lagrèze M, Aussal T
… +2 more, Fellahi JL, Ruste M
J Clin Monit Comput
· 2025 Oct · PMID 40011397
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Capillary Refill Time (CRT) is a valuable metric to assess cutaneous perfusion. Its prognostic value in patients with acute circulatory failure has been reported as improved when the measurement is standardized. The DiCA...Capillary Refill Time (CRT) is a valuable metric to assess cutaneous perfusion. Its prognostic value in patients with acute circulatory failure has been reported as improved when the measurement is standardized. The DiCART™ device is a fully automated CRT measurement tool requiring validation. We conducted a comparative interventional single-center study including 25 patients with acute circulatory failure, to evaluate the agreement between CRT measured by an automated measurement device (CRT) and CRT measured clinically (CRT). CRT was measured on the fingertip, chest, and knee. Three measurements were performed at each location to obtain an average for each site. The measurements were conducted both clinically and using the DiCART™ device by two different operators, each blinded to the results. Agreement was determined using intraclass correlation coefficient (ICC) and Bland and Altman analysis. The ICC between CRT and CRT was 0.46 (95% Confidence Interval (CI) 0.32, 0.59) across all measurement sites; the mean bias was 0.23s (95% CI -0.17, 0.64), with upper Limit of Agreement (LoA) 2.77s (95% CI 2.44, 3.20) and lower LoA - 2.30s (-2.73, -1.97). Intra observer ICC was 0.85 (95% CI 0.74, 0.91) for CRT and 0.43 (95% CI 0.15, 0.64) for CRT. Inter observer ICC was 0.86 (95% CI 0.76, 0.92) for CRT and was 0.41 (95% CI 0.14, 0,63) for CRT. The DiCART™ device showed poor agreement with clinical CRT in patients with acute circulatory failure, which does not support its use in routine practice.
Improvement in anesthesia and surgical practices has enabled more patients, including those undergoing higher-risk surgeries, to be treated in outpatient settings. This shift creates a need for reliable postoperative mon...Improvement in anesthesia and surgical practices has enabled more patients, including those undergoing higher-risk surgeries, to be treated in outpatient settings. This shift creates a need for reliable postoperative monitoring at home. Wearable devices like the Biobeat offer continuous, real-time monitoring of vital signs have remained largely untested for home use in this context.A prospective, single-center observational study was conducted at the Centre hospitalier de l'Université de Montréal (CHUM) from February to August 2023. Fifty eligible patients underwent continuous monitoring with the Biobeat device for five days post-surgery, with data transmitted to CHUM's telehealth service. Feasibility was assessed by the percentage of patients without data loss during consecutive 2-hour intervals.Of the 50 patients enrolled, 49 completed the study, but all experienced some level of data loss. While 39.6% of patients maintained connectivity without complete data loss for 6-8-hour intervals, challenges included device discomfort, Bluetooth disconnection, and connectivity issues. Thirteen patients removed the device early due to discomfort or technical issues. Of the 3 patients who experienced post-operative complications, no data was available within 24 h prior to the episodes. Continuous vital signs monitoring is feasible for high-risk outpatient surgery patients; however, significant improvements are required in device reliability and data accessibility. Further studies are needed to refine the technology and develop reliable protocols for postoperative monitoring in the home setting.
One-lung ventilation (OLV) is crucial for collapsing the lung and improving access to the operative field during lung surgery. Intraoperative OLV may increase the intrapulmonary shunt, potentially leading to intraoperati...One-lung ventilation (OLV) is crucial for collapsing the lung and improving access to the operative field during lung surgery. Intraoperative OLV may increase the intrapulmonary shunt, potentially leading to intraoperative hypoxemia. The Oxygen Reserve Index (ORI) is a continuous, noninvasive parameter that provides a broader range of oxygen reserve data than conventional oxygen saturation measurements. We aimed to determine whether ORI values measured during OLV before pleural opening are reliable predictors of intraoperative hypoxemia. We included 113 adult patients who underwent lung resection surgery at a tertiary medical center between January 2024 and April 2024. Patients were positioned laterally for surgery, and preemptive OLV was performed with a tidal volume of 5 mL/kg and a fraction of inspired oxygen (FiO) of 60% for at least 5 min before pleural opening, with concurrent ORI measurements. ORI values obtained during this period were analyzed using ROC curve analysis to predict intraoperative hypoxemia (SaO ≤ 90%). AUC values were compared using DeLong's test. Among the 113 patients, 13 (11.5%) developed intraoperative hypoxemia. The predictive power of ORI measured 5 min after initiating OLV for intraoperative hypoxemia was reflected by an AUC of 0.955 (95% CI: 0.899-1.000). Additionally, the predictive power of the change in ORI over 5 min for intraoperative hypoxemia was demonstrated by an AUC of 0.966 (95% CI: 0.935-0.997). The optimal cut-off values for the ORI and its change measured 5 min after preemptive OLV to predict intraoperative hypoxemia were 0.040 and 0.110, respectively. In patients receiving OLV during lung surgery, ORI values and their changes measured during preemptive OLV before pleural opening can predict intraoperative hypoxemia. These findings support an individualized approach to intraoperative FiO management, which may help prevent unnecessary oxygen overdose and enable early identification and intervention in patients at high risk of hypoxemia during OLV.
Kumagai et al. provided valuable insights into the effects of postoperative peripheral nerve blocks (PNB) on the high-frequency variability index (HFVI), a surrogate for nociception monitoring. However, the analysis excl...Kumagai et al. provided valuable insights into the effects of postoperative peripheral nerve blocks (PNB) on the high-frequency variability index (HFVI), a surrogate for nociception monitoring. However, the analysis excluded the impact of different brachial plexus block techniques, particularly the interscalene brachial plexus block (ISB), and role of laterality in HFVI variability. ISB produces a stellate ganglion block-like effect through local anesthetic diffusion, influencing autonomic function and heart rate variability, independent of nociceptive modulation. Provided that this study included various brachial plexus block approaches, stratifying HFVI changes according to technique and laterality could enhance their clinical relevance. Right-sided ISB may have a more pronounced autonomic effect than left-sided ISB. Further research is needed to clarify these effects and optimize the interpretation of HFVI during perioperative monitoring.
Regional cerebral oxygen saturation (rSO) is used to monitor cerebral perfusion with emerging evidence that optimization of rSO may improve neurological and non-neurological outcomes. To manipulate rSO an understanding o...Regional cerebral oxygen saturation (rSO) is used to monitor cerebral perfusion with emerging evidence that optimization of rSO may improve neurological and non-neurological outcomes. To manipulate rSO an understanding of the variables that drive its behavior is necessary, and this can be accomplished using supervised machine learning. This study aimed to establish a hierarchy by which various hemodynamic and ventilatory variables contribute to intraoperative changes in rSO. A post-hoc analysis 146 patients undergoing high risk surgery. rSO was partitioned into segments with a change of at least 3% points over 5 min. Features from hemodynamic and ventilatory variables were used to train a machine learning classification algorithm (XGBoost) for prediction of association with either up or down-sloping rSO. The classifier was optimized and validated using five-fold cross validation. Feature importance was quantified based on information gain and permutation feature importance. The optimized classifier demonstrated a mean accuracy of 77.1% (SD 8.0%) and a mean area-under-ROC-curve of 0.86 (SD 0.06). The most important features based on information gain were the slope of the associated ETCO signal, the slope of the SPO signal, and the mean of the MAP signal. CO is a significant mediator of changes in rSO in an intraoperative setting, through its established effects on cerebral blood flow. This study furthers our overall understanding of the complex physiologic process that governs cerebral oxygenation by quantifying the hierarchy by which rSO is affected. Clinical Trial Number NCT01838733 (ClinicalTrials.gov).
Flick M, Vokuhl C, Bergholz A
… +3 more, Boutchkova K, Nicklas JY, Saugel B
J Clin Monit Comput
· 2025 Oct · PMID 39920502
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The "Cellular Oxygen METabolism" (COMET) system (Photonics Healthcare, Utrecht, The Netherlands) non-invasively measures mitochondrial oxygen tension (mitoPO) in the skin. The effects of general anesthesia and major non-...The "Cellular Oxygen METabolism" (COMET) system (Photonics Healthcare, Utrecht, The Netherlands) non-invasively measures mitochondrial oxygen tension (mitoPO) in the skin. The effects of general anesthesia and major non-cardiac surgery on mitoPO remain unknown. In this pre-planned pilot substudy of the "Intraoperative blood pressure Management based on the individual blood PRessure profile: impact on postOperatiVE organ function" (IMPROVE) trial, we measured mitoPO from induction of general anesthesia until the end of surgery in 19 major non-cardiac surgery patients (10 assigned to personalized and 9 to routine intraoperative arterial pressure management). In the overall cohort, the median (25th to 75th percentile) preoperative awake mitoPO was 63 (53 to 82) mmHg and mitoPO after induction of general anesthesia was 42 (35 to 59) mmHg. The intraoperative average mitoPO was 39 (30 to 50) mmHg. Thirteen patients (68%) had intraoperative mitoPO values below 20 mmHg and the median percentage of surgical time with mitoPO < 20 mmHg was 17 (0 to 31)%. MitoPO was weakly correlated with mean arterial pressure (repeated measures correlation (r(n); r(984) = 0.26, 95% confidence interval 0.20 to 0.32; P < 0.001), but not meaningfully with heart rate (r(984) = -0.05, 95% confidence interval -0.11 to 0.01; P = 0.117). There was no important difference in intraoperative average mitoPO between patients assigned to personalized or to routine intraoperative arterial pressure management (P = 0.653). MitoPO under general anesthesia was about a quarter lower than preoperative awake mitoPO, substantially fluctuated during major non-cardiac surgery, and transiently decreased below 20 mmHg in about two-thirds of the patients. Personalized - compared to routine - intraoperative arterial pressure management did not increase intraoperative mitoPO. Whether intraoperative decreases in mitoPO are clinically meaningful warrants further investigation.
Kumagai M, Yamada N, Wakimoto M
… +4 more, Ogawa S, Watanabe S, Sato K, Suzuki KS
J Clin Monit Comput
· 2025 Oct · PMID 39881086
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PURPOSE: The analgesia nociception index (ANI), also referred to as the high frequency variability index (HFVI), is reported to be an objective measure of nociception. This study investigated changes in ANI after periphe...PURPOSE: The analgesia nociception index (ANI), also referred to as the high frequency variability index (HFVI), is reported to be an objective measure of nociception. This study investigated changes in ANI after peripheral nerve blocks (PNB) under general anesthesia. Understanding these changes could enhance assessment of PNB efficacy before emergence from general anesthesia. METHODS: This study enrolled 30 patients undergoing elective upper limb surgery. After surgery, median and maximum ANI values were recorded during two periods: a 5-minute period before PNB and a 20-minute period after PNB. The numeric rating scale (NRS) for pain was assessed twice: immediately after emergence from general anesthesia (N1) and the maximum pain experienced by the following morning after PNB effects subsided (N2). The difference in ANI before and after PNB was tested using the Wilcoxon signed-rank test. Statistical significance was set at P < 0.05. RESULTS: The ANI significantly increased after PNB in both the median (pre vs. post PNB value: 53.5 [44.0-68.0] vs. 59.0 [47.0-78.3], median [interquartile range]; P < 0.05) and maximum values (64.0 [56.3-79.5] vs. 74.5 [61.5-85.3]; P < 0.01). Secondary analysis revealed that significant ANI increases in both median (48.0 [42.3-66.5] vs. 61.0 [50.0-76.5]; P < 0.01) and maximum values (58.5 [50.3-75.3] vs. 76.0 [71.8-83.5]; P < 0.01) in the 18 cases with N2 ≥ 4 whereas no statistical differences were observed in the 12 cases with N2 < 4. CONCLUSION: The increased ANI value after PNB under propofol anesthesia may be a valuable indicator for assessing PNB efficacy. TRIAL REGISTRATION NUMBER: UMIN000050334. DATE OF REGISTRATION: February 28, 2023.