The use of prescription opioids has risen dramatically in South Korea in recent years; however, there is no standardized Korean-language instrument to assess opioid withdrawal. The Clinical Opiate Withdrawal Scale (COWS) is a widely used clinician-rated measure for assessing the severity of opioid withdrawal. We aimed to validate the Korean version of the COWS (K-COWS) among patients receiving opioid therapy. We translated and culturally adapted the 11-item COWS into Korean. A total of 66 adult patients with opioid use disorder who were experiencing withdrawal symptoms were assessed. Each patient was evaluated using the K-COWS and completed the Subjective Opiate Withdrawal Scale (SOWS), the brief 3-item Opioid Craving Scale (OCS-3), and the single-item Opioid Craving Visual Analog Scale (OC-VAS). We examined the internal consistency, factor structure [through exploratory factor analysis (EFA) and confirmatory factor analysis (CFA)], and convergent/discriminant validity of the K-COWS. The K-COWS showed good internal consistency (Cronbach's α = 0.79; 95% CI = 0.71-0.86). EFA supported a two-factor structure (physical vs. autonomic clusters) that explained 39% of the variance. In CFA, the two-factor model showed a marginally acceptable fit (χ2  = 47.76, CFI = 0.915, RMSEA = 0.082), whereas the unidimensional alternative showed a poor fit. The K-COWS strongly correlated with the SOWS (r = 0.74, 95% CI = 0.61-0.83, p < 0.001), indicating good convergent validity for withdrawal. In contrast, correlations with the craving measures were weak (OCS-3: r = 0.19, p > 0.05; OC-VAS: r = 0.20, p > 0.05), supporting discriminant validity. The K-COWS is reliable and has demonstrated construct validity for withdrawal severity in Korean clinical settings. Given the preliminary nature of the factor structure, the total score is recommended for clinical decision-making. Future studies should assess inter-rater reliability and confirm the structure in larger, more diverse samples.
In the gynecology field, robotic laparoscopic surgery is increasingly being used to enhance the quality of care. The Enhanced Recovery After Surgery (ERAS) program, which improves patient outcomes, is becoming the standard of care, but its impact on gynecological patients remains unclear. We compared the effect of ERAS implementation and conventional care for robotic gynecological surgery. This parallel-group, randomized controlled trial included patients aged 20-70 years undergoing robotic gynecological surgery at a single tertiary medical center in the Republic of Korea. Patients were randomized to conventional care and ERAS groups in a 1:1 ratio. The customized ERAS protocol encompassed minimized fasting, pre-emptive analgesia, transversus abdominis block, and early ambulation. The primary outcome was the Quality of Recovery-15 (QoR-15) score at 24-h and 1-week postoperatively. Secondary outcomes included postoperative pain, ClavienDindo grade ≥ 3 complications, readmission, and length of hospital stay. Of the 66 enrolled patients, data of 65 were analyzed (conventional care, n = 32; ERAS, n = 33). Compared with conventional care, ERAS resulted in a significantly better quality of recovery at 24-h (QoR-15 scores: 93 [71117] vs. 124 [103135], P < 0.001) and 1-week postoperatively (QoR-15 scores: 135 [131142] vs. 142 [136148], P = 0.002). Additionally, the ERAS group had less severe postoperative pain and a shorter length of hospital stay. Complication and readmission rates were comparable between the groups. ERAS implementation in robotic gynecological surgery enhanced the quality of recovery and provided better pain control than conventional care, without affecting patient safety.
Halogenated anesthetics such as sevoflurane have a high global warming potential (GWP) and should be degraded before atmospheric release. We hypothesized that sevoflurane undergoes oxidative degradation when mixed with ozone and some degradation products can be captured using a water trap. In Experiment 1, sevoflurane and its degradation products were monitored in real-time using liquid chromatography-mass spectrometry under three conditions: air control, ozone mixing, and ozone mixing followed by passage through a water trap. In Experiment 2, sevoflurane (7-8%) was delivered into a closed anesthesia circuit, and concentration changes were recorded every 10 s under ozone-present and ozone-absent conditions (six trials each). In Experiment 3, proton nuclear magnetic resonance (¹H NMR, Bruker Ascend 400, 20.1°C) was performed on heavy-water samples from the water trap used in Experiment 2 to assess the solubility of ozone-exposed sevoflurane. In Experiment 1, ozone accelerated sevoflurane degradation; however, the concentration of the degradation products was not increased in the water trap. In Experiment 2, ozone mixing caused a rapid decline in sevoflurane concentration, decreasing from 7.3% to < 1% within 25-28 s and reaching 0% within 265-288 s, whereas no decrease was found in the ozone-absent trials (P < 0.001). In Experiment 3, ¹H NMR spectra showed clearer sevoflurane signals and minor new peaks after ozone exposure, suggesting enhanced apparent solubility and limited decomposition. Ozone mixing accelerated sevoflurane degradation and increased its water solubility, suggesting a practical approach for reducing the environmental impact of sevoflurane.
This study aimed to investigate the impact of hospital volume on severe complications and mortality rates following gastrectomy for gastric cancer using nationwide survey data and propensity score weighting to adjust for baseline differences. Data were collected from 68 institutions through a nationwide survey by the Korean Gastric Cancer Association encompassing 14,076 patients who underwent surgery for gastric adenocarcinoma in 2019. After exclusion, data from 12,244 patients were included in the analysis. Hospitals were categorized into 3 volume groups: group A (≤99 cases/year), group B (100-199 cases/year), and group C (≥200 cases/year). Propensity score weighting balanced the variables (age, sex, tumor-node-metastasis stage, comorbidities, American Society of Anesthesiologists score, approach methods, and extent of resection) among the hospital groups. The overall complication rate was 14%, with a severe complication rate (Clavien-Dindo grade IIIa or higher) of 4.9% and a mortality rate of 0.2%. After propensity score weighting, there was no statistically significant difference in the severe complication rates among the 3 groups (P = .058). However, the mortality rates were significantly lower in groups B (0.2%) and C (0.2%) than in group A (0.7%) (P < .001). Specific complications such as intra-abdominal abscess and mechanical ileus were more prevalent in low-volume hospitals. Although hospital volume did not significantly affect severe postoperative complication rates after adjusting for patient characteristics, higher mortality rates were observed in lower-volume hospitals. These findings call for standardized protocols and training programs, along with the maintenance of more than 100 operations per hospital, to reduce mortality.
Hypertensive patients tend to have an increased risk of hypotension during anesthesia induction, which can result in adverse outcomes. This study aimed to compare hemodynamic stability with remimazolam versus propofol in hypertensive patients. This meta-analysis analyzed randomized controlled trials investigating the hemodynamic parameters of remimazolam versus propofol during anesthesia induction in hypertensive adults. A systematic search of electronic databases was conducted in November 2024. Six studies were included in the final analysis. The administration of remimazolam significantly lowered the risk of hypotension (risk ratio [RR] 0.711; 95% CI 0.545 to 0.929; I2 = 67.54%) and bradycardia (RR 0.256; 95% CI 0.101 to 0.649; I2 = 0.0%). It also resulted in a higher minimum mean arterial pressure (mean difference [MD] 9.023 mmHg; 95% CI 0.243 to 17.802; I² = 97.50%) and higher minimum heart rate (MD 7.200 beats/min; 95% CI 1.960 to 12.441; I² = 86.40%). Despite these findings, substantial heterogeneity was observed in continuous outcomes. The trial sequential analysis revealed that none of the outcomes reached the required information size. The administration of remimazolam showed a trend toward superior hemodynamic stability compared with propofol during anesthesia induction in hypertensive patients, especially in minimizing the incidence of hypotension and bradycardia. However, the trial sequential analysis results remain inconclusive, the current evidence is limited by small sample sizes, and larger trials are needed to confirm our findings.
To evaluate the risk of developing psychiatric disorders within three years after non-cardiac surgery in patients exposed to fentanyl analogs versus other opioids. Retrospective observational study. Postoperative period. The study included 52,640adult patients who underwent non-cardiac surgery at Samsung Medical Center, Seoul, Korea, between January 2011 and June 2019. Patients were divided into those exposed to fentanyl analogs and those exposed to other opioids. Propensity score matching and Cox regression analysis were used to compare the incidence of psychiatric disorders between the groups. Psychiatric outcomes, including depression, anxiety, stress-related disorders, substance use disorders, and psychotic disorders, were assessed. The study included 52,640 patients, evenly split between the fentanyl and other opioid groups. Fentanyl exposure was associated with a higher incidence of composite psychiatric outcomes (hazard ratio [HR] 1.28 [1.13-1.46]; P < 0.001), including depression (HR 1.25 [1.08-1.45]; P = 0.003) and stress-related disorders (HR 1.45 [1.02-2.04]; P = 0.036). Subgroup analyses indicated increased risks in males, females, patients without alcohol history, and those not undergoing emergency surgeries. Perioperative fentanyl use is linked to a higher risk of psychiatric disorders compared to other opioids. These findings emphasize the need for careful use and monitoring of fentanyl in surgical patients, considering both immediate and long-term mental health effects.
In this paper, we provide a conceptual introduction to linear mixed-effects models (LMMs), statistical approaches that are used for analysis of longitudinal repeated-measure data, for clinical researchers with a limited statistical background. We begin by contrasting LMMs with repeated-measures analysis of variance, and highlight the limitations of the latter approach, including its restrictive assumption of sphericity and its sensitivity to dropout. We show that LMMs overcome these limitations by providing valid inferences under the missing-at-random assumption, accommodating unbalanced designs, and offering flexible options for modeling covariance structures. Beyond addressing the core assumptions of LMMs, we evaluate the implications of modeling time as a numerical versus as a categorical factor. We discuss approaches for handling baseline values, including longitudinal data analysis, constrained longitudinal data analysis, and analysis of covariance, and describe their relative strengths and limitations in both randomized and observational studies. We explain the roles of random effects and residual covariance structures and provide practical guidance for selecting candidate models by using exploratory plots and information criteria, such as the Akaike and Bayesian information criteria. Overall, by providing a clear and accessible conceptual framework, we hope to enable clinical researchers to understand, evaluate, and apply LMMs effectively.
Preoperative comorbidities are associated with postoperative acute kidney injury (AKI). However, whether this association is direct or mediated by intraoperative hypotension (IOH) is unclear. We hypothesized that IOH mediates the relationship between preoperative comorbidities and postoperative AKI. Data from adult patients undergoing non-cardiac surgery under general anesthesia were analyzed. Inverse probability of treatment weighting (IPTW) was applied to achieve a balance between the exposure groups by reducing the baseline differences in the measured covariates. Structural equation modeling (SEM)-based mediation analysis was conducted using the American Society of Anesthesiologists physical status (ASA-PS) classification ≥ 3 as an input and postoperative AKI as an outcome. IOH (duration of mean arterial pressure [MAP] < 60 mmHg), along with albumin and hemoglobin levels, was considered a mediator. We also performed interaction analysis between patient sex and age. After IPTW, 8643.9 (10.8%) patients had an ASA-PS of ≥ 3. AKI occurred more frequently (4.5% vs. 6.9%, P < 0.001) in patients with ASA-PS ≥ 3. ASA-PS ≥ 3 was associated with a total effect estimate of 0.02 on the log-odds of postoperative AKI (P < 0.001). Of the total effect of ASA-PS ≥ 3 on postoperative AKI, 48% was significantly mediated by IOH (26%) and hypoalbuminemia (26%), though anemia showed no significance. The effect of high ASA-PS scores on postoperative AKI was significantly modified by sex, but not by age. High ASA-PS scores increase AKI risk after non-cardiac surgery, a relationship partially mediated by statistically significant pathways involving IOH and hypoalbuminemia.
This study aims to evaluate the global burden of adverse effects of medical treatment (AEMT) using data from the Global Burden of Disease Study (GBD) 2021. Data were extracted from the GBD 2021, covering 204 countries/territories from 1990 to 2021. AEMT was defined using ICD-9 and ICD-10 codes, encompassing complications from medical procedures, treatments, or healthcare exposures. Estimates were categorized into fatal and non-fatal outcomes and stratified by age, sex, year, and covariates, including the Socio-demographic Index (SDI). Mortality-incidence ratios (MIRs), defined as the ratio of mortality calculated by dividing the number of deaths by the total incident cases, were analyzed. In 2021, the global age-standardized prevalence, incidence, disability-adjusted life years (DALYs), and mortality rates of AEMT were 11.48 (95% uncertainty interval [UI], 8.86-14.13), 150.44 (131.19-171.81), 64.19 (51.06-73.11), and 1.53 (1.29-1.68) per 100,000 population, respectively. DALY rates were highest in the early neonatal group (4,789.47 per 100,000 population [95% UI, 3,682.00-5,963.30]), while mortality rates followed a U-shaped pattern across age groups. In 2021, MIRs were highest at both ends of the age range: the early neonatal group (0.58 [95% UI, 0.55-0.58]) and the 95+ age group (0.05 [0.04-0.06]). This pattern was consistent across all SDI quintiles, with higher MIRs observed in lower SDI quintiles. The significantly higher prevalence and incidence rates of AEMT among the older population in high SDI quintiles, compared to lower SDI quintiles, could be attributed to the healthcare overutilization, highlighting the need for policy adjustments.
Inhalational anesthetics have long been the cornerstone of general anesthesia in noncardiac surgery owing to their reliable pharmacokinetics, ease of administration, and cardiopulmonary benefits such as bronchodilation and myocardial preconditioning. Total intravenous anesthesia (TIVA), achieved using short-acting agents such as propofol and remifentanil, and supported by target-controlled infusion systems and depth-of-anesthesia monitors, has emerged as a widely adopted alternative. TIVA is associated with improved recovery profiles, reduced incidence of postoperative nausea and vomiting, and potential neuroprotective and immunomodulatory effects. In this review, we compared the pharmacological mechanisms and clinical implications of inhalational anesthesia and TIVA, focusing on myocardial injury after noncardiac surgery and other perioperative outcomes. We summarized evidence from randomized controlled trials, large-scale observational studies, and health system-level analyses across multiple outcome domains: all-cause mortality, cardiovascular complications, pulmonary and renal outcomes, oncological prognosis, and system-level factors, such as cost-effectiveness and environmental impact. While inhalational agents demonstrated advantages in terms of cardioprotection and airway management, TIVA was found to offer potential benefits in select populations, particularly in cancer surgery and neuroanesthesia. No single technique demonstrated consistent superiority across all clinical contexts. Therefore, the selection of anesthetic technique should be personalized based on surgical risk, patient comorbidities, institutional infrastructure, and clinician expertise. Emerging trends in sustainability and precision medicine further underscore the need for individualized evidence-based strategies. By combining mechanistic insights with evidence from clinical practice, this review aimed to provide a balanced framework to guide optimal anesthetic decision-making in noncardiac surgery.
Coughing and hemodynamic fluctuations during emergence from anesthesia after a craniotomy can result in serious complications. This study evaluated whether the ultrasound-guided superior laryngeal nerve block (SLNB) attenuates these tracheal tube-related responses. Eighty patients scheduled for elective craniotomy were randomized into the control (Group C, 2 ml 0.9% saline per side) and SLNB (Group S, 2 ml 1% lidocaine per side) group. The primary outcome was the incidence of coughing during the recovery period. Secondary outcomes included the severity of coughing, hemodynamic fluctuations, need for rescue interventions, anesthesia-related parameters, and complications. Compared to controls, the patients in Group S experienced a significantly reduced incidence (78.9% vs. 48.6%; P = 0.006) and severity (P < 0.001) of coughing during emergence. The mean arterial pressure and heart rate were also more stable during and after extubation in Group S than in Group C. Furthermore, Group S required a significantly lower dose of nicardipine during the emergence period (P = 0.032), and both the incidence of and visual analog scale (VAS) scores for postoperative sore throat at 6 h after extubation were markedly reduced (P = 0.035). No significant differences were noted between the groups in terms of propofol consumption, emergence agitation, extubation time, post-anesthesia care unit stay duration, or complications. The SLNB significantly suppressed extubation-related responses during anesthetic emergence after craniotomy by reducing coughing and attenuating hemodynamic fluctuations, thereby contributing to a smoother emergence profile.
In February 2024, a nationwide medical crisis erupted in South Korea following the mass resignation of over 90% of trainee physicians in protest against the government's healthcare reform policy. Amid the ongoing crisis, the government initiated a series of restructuring activities aimed at concentrating high-complexity surgeries and critical care at tertiary hospitals, while redistributing low-complexity procedures to hospitals and clinics. However, the nationwide impact of the reform policy on high-complexity surgical practices, particularly in terms of institutional type, departmental specialty, and regional distribution, has not yet been assessed. Using national insurance claims data from the Korean Health Insurance Review and Assessment Service, we analyzed 914 high-complexity surgical procedures across tertiary hospitals (n = 47), general hospitals (n = 331), and hospitals/clinics (n = 37,888). Claims data from February to July 2023 (pre-crisis) were compared with those from February to July 2024 (post-crisis), stratified by institutional type, medical specialty, and geographic region. After the medical crisis, overall high-complexity surgical claims decreased by 10% (P < 0.001), with a 19% decrease in tertiary hospitals (P < 0.001), 6% increase in general hospitals (P = 0.115), and 27% increase in hospitals/clinics (P < 0.001). The decreased capacity for oncological surgery in tertiary hospitals by 16% (P < 0.001) was partly compensated by increased volume in general hospitals by 23% (P = 0.001). In terms of medical specialty, shifts from tertiary to general hospital in cardiothoracic surgery (1%, P = 0.636), neurosurgery (1%, P = 0.765), and interventional radiology (0%, P = 0.186) were negligible. Oncological surgery in the capital region, which is home to a higher concentration of tertiary hospitals, decreased by 17%, while oncological surgery in around-capital and non-capital regions increased by 11% and 5%, respectively. During the Korean medical crisis in 2024, nationwide surgical capacity and systems for maintaining competency were significantly compromised. Although some procedures were offset by redistribution to lower-tier institutions or regional hospitals, most high-complexity surgeries-particularly those requiring critical care-did not recover.
Laparoscopic surgery in the lateral decubitus position can alter pulmonary mechanics and oxygenation. Although positive end-expiratory pressure (PEEP) may alleviate these effects, the optimal level remains unclear. This study evaluated whether electrical impedance tomography (EIT)-guided PEEP titration improves oxygenation compared to a fixed PEEP of 5 cmH2O. In this randomized controlled trial, 74 adult patients undergoing robot-assisted or laparoscopic urologic surgery in the lateral decubitus position were assigned to either the EIT-guided or standard care group. The EIT-guided group underwent decremental PEEP titration to determine and maintain optimal PEEP throughout surgery. The standard care group received a fixed PEEP of 5 cmH2O. The primary outcome was ratio of partial pressure of arterial oxygen to fraction of inspired oxygen (PaO2/FiO2) at the end of surgery. Secondary outcomes included intraoperative respiratory mechanics and postoperative pulmonary complications (PPCs) until discharge. Seventy-one patients completed the study (EIT-guided: 35, standard care: 36). The PaO2/FiO2 ratio at the end of surgery was higher in the EIT-guided group than in the standard care group (523.8 ± 82.4 vs. 414.6 ± 96.7 mmHg, P < 0.001). Driving pressure was lower in the EIT-guided group at 30 min after pneumoperitoneum initiation (15.8 [12.5, 17.4] vs. 19.9 [17.2, 22.5] cmH2O, P < 0.001) and at the end of surgery (9.1 [8.0, 10.4] vs. 10.0 [8.8, 12.6] cmH2O, P = 0.033). PPCs did not differ between groups. EIT-guided PEEP titration improved intraoperative oxygenation. Further studies are needed to assess clinical outcomes.
Placement of an intraoperative urinary catheter frequently leads to catheter-related bladder discomfort (CRBD) in the immediate postoperative period. We assessed the efficacy of a fixed-dose combination (FDC) of acetaminophen/ibuprofen in alleviating CRBD. In this double-blinded, active-controlled, randomized trial, adults aged 20-79 years undergoing elective robot-assisted laparoscopic radical prostatectomy were randomly assigned to one of three groups: intravenous acetaminophen 1 g/ ibuprofen 300 mg (FDC), 1 g acetaminophen alone, or 100 mL normal saline (placebo). The intervention was administered when fascial closure was initiated. The primary outcome was moderate-to-severe grade CRBD (grade ≥3) incidence in the post-anesthesia care unit (PACU). Secondary outcomes included moderate-to-severe CRBD incidence at 1, 2, and 6 h; CRBD grade distribution; pain scores; 24-h opioid requirements; postoperative nausea and vomiting (PONV); medication-related complications; patient satisfaction; and Quality of Recovery-15K (QoR-15K) scores. Overall, 172 patients were analyzed (FDC, n = 58; acetaminophen, n = 57; and placebo, n = 57). Moderate-to-severe CRBD incidence at PACU was 46.6% in the FDC group and 59.6% in both the acetaminophen and placebo groups (P = 0.3). In repeated-measures analysis, CRBD incidence decreased significantly over time across all groups. Between-group differences at individual postoperative time points were limited and not consistently reproduced across assessments. No significant differences were observed in pain score, PONV, opioid consumption, medication-related complications, patient satisfaction, or QoR-15K. Perioperative acetaminophen/ibuprofen FDC administration was well tolerated but did not significantly reduce moderate-to-severe CRBD incidence in the immediate postoperative period. Further studies with scheduled-dosing and investigations in other surgeries are warranted for applicability.
Discharge management and workflow efficiency in a postanaesthesia care unit (PACU) can be improved with specific tools assessing discharge readiness. Several authors have found tools to reduce the PACU length of stay (PACU LOS), but results have remained inconsistent. We analysed the effects of the Post-ANaesthesia Discharge Assessment tool (PANDA) on PACU LOS, operating room (OR) holds, PACU nurses' confidence with the discharge decision and their perception of the tools' implementation. This pre-post study with a propensity-matched historical control group evaluated the impact of the semi-automatic PANDA tool in a single primary-level hospital. The tool supports discharge decisions in the PACU. Median PACU LOS pre- and post-implementation was compared using nearest-neighbour propensity score matching and weighted linear regression. OR holds were analysed over 20 consecutive days. A structured nurse survey assessed confidence in discharge decisions and perceptions of the tool's implementation. The study included 8475 patients (pre n = 4509; post n = 3966) and 19 nurses. Median PACU LOS before implementing the PANDA tool was 114 min (IQR 89-144) compared to 103 min (IQR 79-136) after the implementation. The weighted linear model showed an estimated difference in PACU LOS of -16 min (95% CI from -20 to -12 min, p < 0.001). There were too few OR holds for comparison. PACU nurses' confidence in their discharge decision remained unchanged before and after implementation. The PANDA tool received high ratings for acceptability, appropriateness, compatibility and feasibility. Implementing the semi-automated PANDA discharge tool significantly decreased PACU LOS. In addition, PACU nurses reported high acceptance, usefulness and feasibility of the tool. The PANDA discharge tool may optimise routine clinical practice to streamline PACU workflows, support resource allocation and decision-making and promote standardisation. Reducing PACU LOS may also improve patient flow and capacity planning in high-volume settings. The semi-automated PANDA tool was well received by nurses who perceived it as useful and feasible. Given the significant reduction in PACU length of stay, integrating PANDA into clinical practice may enhance post-surgical patient flow and resource allocation, while its main added value lies in improving standardisation, supporting decision-making and PACU workflow.
Given propofol's antioxidant and anti‑inflammatory properties compared with volatile/inhalational agents, we aimed to evaluate the association between anesthetic technique and both in‑hospital mortality and postoperative complications following spinal surgery. In this retrospective, population‑based cohort study, we used South Korea's National Health Insurance Service database to identify adult patients (≥ 18 years) who underwent spinal surgery between January 1, 2016 and December 31, 2021. Primary outcomes were in‑hospital mortality and postoperative complications. Propensity score (PS) matching (1:1) was employed to balance baseline characteristics between the total intravenous anesthesia (TIVA) and volatile/inhalational anesthesia (INH) groups. Among 708,387 patients, 264,728 (37.4%) received TIVA and 443,659 (62.6%) received INH. After PS matching, 460,654 patients remained (230,327 per group). In the PS‑matched cohort, TIVA was associated with significantly lower odds of in‑hospital mortality (OR 0.85; 95% CI 0.80-0.89; P = 0.004) and postoperative complications (11.8% vs. 14.2%; OR 0.81; 95% CI 0.80-0.82; P < 0.001) compared with INH. In the full cohort, multivariable logistic regression confirmed these findings: TIVA remained linked to reduced in‑hospital mortality (OR 0.74; 95% CI 0.63-0.87; P < 0.001) and fewer postoperative complications (OR 0.71; 95% CI 0.70-0.73; P < 0.001). In this nationwide cohort, propofol‑based TIVA was associated with lower in‑hospital mortality and fewer postoperative complications than volatile/inhalational anesthesia in adult spinal surgery patients. Prospective trials are warranted to confirm these findings. Not applicable.
Continuous variables are often dichotomized or categorized in clinical research to improve interpretability or to align with clinical thresholds. However, arbitrary or poorly justified cut-off points can cause substantial information loss, reduced statistical power, and potentially misleading conclusions. In this article, we describe commonly used approaches for determining cut-off points, including guideline-based thresholds, median, or quantile splits, and statistically derived methods, such as receiver operating characteristic (ROC) curve-based approaches (e.g., Youden Index and related criteria). We also discuss the clinical and methodological implications of these approaches using illustrative examples and offer practical recommendations to support the transparent and appropriate use of cut-offs in anesthesia and perioperative research.
Spinal anesthesia in older patients can be technically challenging due to degenerative spinal disease. The L5-S1 interspace often remains accessible and is a useful fallback; however, it has been associated with higher rates of therapeutic failure due to inadequate block height. Injection of hypobaric local anesthetic may promote cranial intrathecal spread and address this limitation. We investigated this by evaluating the efficacy and block characteristics of low-dose hypobaric bupivacaine injected at the L5-S1 level in a prospective observational study. Fifty-four patients undergoing elective total hip or knee arthroplasty received ultrasound-assisted spinal anesthesia at L5-S1 with 10 mg of 0.33% hypobaric bupivacaine. The primary outcome was surgical completion without conversion to general anesthesia, supplemental opioids, or local anesthetic infiltration. Secondary outcomes included adequate anesthesia for surgical incision, block pharmacodynamics, hemodynamic stability, adverse effects, patient satisfaction, and surgeon-perceived quality of anesthesia. Surgical completion without anesthetic supplementation was successful in 50 patients (92.6%, 95% CI 82.1-97.8%). Adequate anesthesia for surgical incision was achieved in 53 patients (98.2%, 95% CI 90.1-100%). Four patients required supplemental opioids: one for surgical incision, and three for surgical completion following prolonged injection-to-incision intervals (47-59 minutes) due to unanticipated delays in operating room readiness. No patients required conversion to general anesthesia. Full motor recovery occurred within 198 ± 53 minutes. Patient and surgeon satisfaction with quality of anesthesia was high. Hypobaric 0.33% bupivacaine injected at L5-S1 may be a useful fallback option in lower-extremity arthroplasty if challenging spinal anatomy renders other interspaces inaccessible.
Diabetes mellitus (DM) is prevalent among adults, many of whom require surgical interventions. Although metformin may improve postoperative outcomes by reducing inflammation, its effects on postoperative mortality and complications remain unclear. This study aimed to determine whether preoperative metformin use is associated with improved postoperative outcomes after noncardiac surgery. This retrospective study included adult patients with type 2 DM who underwent noncardiac surgery between 2011 and 2019. Patients were assigned to one of two groups based on the use of preoperative metformin at admission. To evaluate dose-related effects, patients in the metformin group were further divided into low- and high-dose groups based on daily dose (< or ≥ 1,000 mg). The primary outcome was one-year mortality after surgery, and the secondary outcomes were 30-day mortality, five-year mortality, and postoperative complications in major organs within 7 d. Among 22 944 patients, 12 536 (54.6%) were exposed to preoperative metformin. After inverse probability of treatment weighting, preoperative metformin use was associated with a reduced one-year mortality (hazard ratio: 0.76, 95% CI [0.68-0.85]). For secondary outcomes, metformin use decreased postoperative complications in respiratory (odds ratio [OR]: 0.76, 95% CI [0.61-0.93]) and renal systems (OR: 0.66, 95% CI [0.58-0.74]). In a dose-related analysis, both doses were associated with a lower risk of postoperative mortality, with reductions in respiratory complications primarily due to high-dose metformin (OR: 0.69, 95% CI [0.54-0.89]). Preoperative use of metformin is associated with reduced postoperative mortality and complications in diabetic patients undergoing noncardiac surgery.
Despite various available methods for monitoring a patient's respiratory system, conventional monitors provide limited ventilatory function information. This study explored the feasibility of intraoperative lung sound patterns to discriminate preoperatively diagnosed ventilatory dysfunction. Forty-five patients who had undergone preoperative pulmonary function testing were enrolled for analysis, comprising 15 patients per normal, obstructive, and restrictive group. High-fidelity lung sounds were recorded intraoperatively using esophageal stethoscopes equipped with digital microphone devices. After signal processing, morphological features of the acoustic data, including the inhale/exhale peak ratio (I/Ep), were extracted. Their discriminative abilities for obstructive and restrictive types were assessed and compared with conventional monitoring parameters. I/Ep showed strong discriminative performance, with an area under the receiver operating characteristic curve of 0.950 (95% CI: 0.887-0.991) for obstructive and 0.950 (95% CI: 0.867-0.995) for restrictive types. The median values of I/Ep were 2.9 in the restrictive, 2.2 in the normal, and 1.5 in the obstructive group (P < 0.001). Conventional ventilatory parameters (compliance, peak inspiratory pressure, and slope of end-tidal CO2) did not significantly differ among the groups. Our study demonstrated that the I/Ep derived from intraoperative acoustic data differed according to preoperatively diagnosed ventilatory dysfunction. Hence, acoustic inhale and exhale patterns contain clinically useful information not captured by conventional ventilator parameters. Further studies are warranted to explore the clinical application of acoustic feature analysis for real-time intraoperative monitoring.