Multicentre validation of a machine learning model for predicting respiratory failure after noncardiac surgery.

BACKGROUND: Postoperative respiratory failure is a serious complication that could benefit from early accurate identification of high-risk patients. We developed and validated a machine learning model to predict postoperative respiratory failure, defined as prolonged (>48 h) mechanical ventilation or reintubation after surgery. METHODS: Easily extractable electronic health record (EHR) variables that do not require subjective assessment by clinicians were used. From EHR data of 307,333 noncardiac surgical cases, the model, trained with a gradient boosting algorithm, utilised a derivation cohort of 99,025 cases from Seoul National University Hospital (2013-9). External validation was performed using three separate cohorts A-C from different hospitals comprising 208,308 cases. Model performance was assessed by area under the receiver operating characteristic (AUROC) curve and area under the precision-recall curve (AUPRC), a measure of sensitivity and precision at different thresholds. RESULTS: The model included eight variables: serum albumin, age, duration of anaesthesia, serum glucose, prothrombin time, serum creatinine, white blood cell count, and body mass index. Internally, the model achieved an AUROC of 0.912 (95% confidence interval [CI], 0.908-0.915) and AUPRC of 0.113. In external validation cohorts A, B, and C, the model achieved AUROCs of 0.879 (95% CI, 0.876-0.882), 0.872 (95% CI, 0.870-0.874), and 0.931 (95% CI, 0.925-0.936), and AUPRCs of 0.029, 0.083, and 0.124, respectively. CONCLUSIONS: Utilising just eight easily extractable variables, this machine learning model demonstrated excellent discrimination in both internal and external validation for predicting postoperative respiratory failure. The model enables personalised risk stratification and facilitates data-driven clinical decision-making.

Effect of a repeated verbal reminder of orientation on emergence agitation after general anaesthesia for minimally invasive abdominal surgery: a randomised controlled trial.

BACKGROUND: An orientation strategy providing repeated verbal reminders of time, place, and person has been widely used for the non-pharmacological management of delirium. We hypothesised that using this strategy could reduce emergence agitation and improve recovery profiles. METHODS: This prospective observer-blinded RCT included male and female patients aged 18-70 yr undergoing minimally invasive abdominal surgery. During emergence from general anaesthesia, subjects in the orientation group (n=57) were provided a repeated reminder, including orientation: '(Patient's name), you are now recovering from general anaesthesia after surgery at Seoul National University Hospital, open your eyes!' via noise-cancelling headphones, whereas those in the control group (n=57) only heard their name: '(Patient's name), open your eyes!'. The primary outcome was the incidence of emergence agitation (Riker sedation agitation scale [SAS] ≥5). The incidence of dangerous agitation (SAS=7), maximal SAS score in the operating room, and recovery profile until 24 h postoperatively were evaluated as secondary outcomes. RESULTS: The incidence of emergence agitation in the operating room was significantly lower in the orientation group than in the control group (16/57 [28.1%] vs 38/57 [66.7%]; relative risk [95% confidence interval], 0.5 [0.3-0.7]; P<0.001). The incidence of dangerous agitation (0 [0.0%] vs 10 [17.5%], P=0.001) and the median maximal SAS score (4 [4-5] vs 5 [4-6], P<0.001) were also lower in the orientation group. Secondary outcomes, other than agitation-related variables, were comparable between the two groups. CONCLUSIONS: Repeated verbal stimulation of orientation may serve as a simple and easily applicable strategy to reduce emergence agitation after general anaesthesia. CLINICAL TRIAL REGISTRATION: NCT05105178.

Effect of driving pressure-guided positive end-expiratory pressure on postoperative pulmonary complications in patients undergoing laparoscopic or robotic surgery: a randomised controlled trial.

BACKGROUND: Individualised positive end-expiratory pressure (PEEP) improves respiratory mechanics. However, whether PEEP reduces postoperative pulmonary complications (PPCs) remains unclear. We investigated whether driving pressure-guided PEEP reduces PPCs after laparoscopic/robotic abdominal surgery. METHODS: This single-centre, randomised controlled trial enrolled patients at risk for PPCs undergoing laparoscopic or robotic lower abdominal surgery. The individualised group received driving pressure-guided PEEP, whereas the comparator group received 5 cm H2O fixed PEEP during surgery. Both groups received a tidal volume of 8 ml kg-1 ideal body weight. The primary outcome analysed per protocol was a composite of pulmonary complications (defined by pre-specified clinical and radiological criteria) within 7 postoperative days after surgery. RESULTS: Some 384 patients (median age: 67 yr [inter-quartile range: 61-73]; 66 [18%] female) were randomised. Mean (standard deviation) PEEP in patients randomised to individualised PEEP (n=178) was 13.6 cm H2O (2.1). Individualised PEEP resulted in lower mean driving pressures (14.7 cm H2O [2.6]), compared with 185 patients randomised to standard PEEP (18.4 cm H2O [3.2]; mean difference: -3.7 cm H2O [95% confidence interval (CI): -4.3 to -3.1 cm H2O]; P<0.001). There was no difference in the incidence of pulmonary complications between individualised (25/178 [14.0%]) vs standard PEEP (36/185 [19.5%]; risk ratio [95% CI], 0.72 [0.45-1.15]; P=0.215). Pulmonary complications as a result of desaturation were less frequent in patients randomised to individualised PEEP (8/178 [4.5%], compared with standard PEEP (30/185 [16.2%], risk ratio [95% CI], 0.28 [0.13-0.59]; P=0.001). CONCLUSIONS: Driving pressure-guided PEEP did not decrease the incidence of pulmonary complications within 7 days of laparoscopic or robotic lower abdominal surgery, although uncertainty remains given the lower than anticipated event rate for the primary outcome. CLINICAL TRIAL REGISTRATION: KCT0004888 (http://cris.nih.go.kr, registration date: April 6, 2020).

Driving pressure-guided ventilation and postoperative pulmonary complications in thoracic surgery: a multicentre randomised clinical trial.

BACKGROUND: Airway driving pressure, easily measured as plateau pressure minus PEEP, is a surrogate for alveolar stress and strain. However, the effect of its targeted reduction remains unclear. METHODS: In this multicentre trial, patients undergoing lung resection surgery were randomised to either a driving pressure group (n=650) receiving an alveolar recruitment/individualised PEEP to deliver the lowest driving pressure or to a conventional protective ventilation group (n=650) with fixed PEEP of 5 cm H2O. The primary outcome was a composite of pulmonary complications within 7 days postoperatively. RESULTS: The modified intention-to-treat analysis included 1170 patients (mean [standard deviation, sd]; age, 63 [10] yr; 47% female). The mean driving pressure was 7.1 cm H2O in the driving pressure group vs 9.2 cm H2O in the protective ventilation group (mean difference [95% confidence interval, CI]; -2.1 [-2.4 to -1.9] cm H2O; P<0.001). The incidence of pulmonary complications was not different between the two groups: driving pressure group (233/576, 40.5%) vs protective ventilation group (254/594, 42.8%) (risk difference -2.3%; 95% CI, -8.0% to 3.3%; P=0.42). Intraoperatively, lung compliance (mean [sd], 42.7 [12.4] vs 33.5 [11.1] ml cm H2O-1; P<0.001) and Pao2 (median [inter-quartile range], 21.5 [14.5 to 30.4] vs 19.5 [13.5 to 29.1] kPa; P=0.03) were higher and the need for rescue ventilation was less frequent (6.8% vs 10.8%; P=0.02) in the driving pressure group. CONCLUSIONS: In lung resection surgery, a driving pressure-guided ventilation improved pulmonary mechanics intraoperatively, but did not reduce the incidence of postoperative pulmonary complications compared with a conventional protective ventilation. CLINICAL TRIAL REGISTRATION: NCT04260451.

Effect of Hospital Case-Volume on Mortality after Ovarian Cancer Surgery: A Population-Based Retrospective Cohort Study.

OBJECTIVES: The goal of ovarian cancer surgery has recently shifted from optimal cytoreduction to more complete resection. This study attempted to reassess and update the association between surgical case-volume and both in-hospital and long-term mortality after ovarian cancer surgery using recent data. DESIGN: This study is a population-based retrospective cohort study. Participants/Material: Data from all adult patients who underwent ovarian cancer surgery in Korea between 2005 and 2019 were obtained from the national database. A total of 24,620 patients underwent ovarian cancer surgery in 362 hospitals during the period. SETTING: In-hospital and 1-, 3-, 5-year mortality were set as primary and secondary outcomes. METHODS: Hospitals were categorized into high-volume (>90 cases/year), medium-volume (20-90 cases/year), and low-volume (<20 cases/year) centers considering overall distribution of case-volume. Postoperative in-hospital and long-term mortality were analyzed using logistic regression after adjusting for potential risk factors. RESULTS: Compared to high-volume centers (0.54%), in-hospital mortality was significantly higher in medium-volume (1.40%; adjusted odds ratio, 2.92; confidence interval, 1.82-3.73; p < 0.001) and low-volume (1.61%; adjusted odds ratio, 2.94; confidence interval, 2.07-4.17; p < 0.001) centers. In addition, 1-year mortality was 6.26%, 7.06%, and 7.94% for high-volume, medium-volume, and low-volume centers, respectively, and the differences among the groups were significant. However, case-volume effect was not apparent in 3- and 5-year mortality after ovarian cancer surgery. LIMITATIONS: Lacking clinical information such as staging or histologic diagnosis due to the nature of the administrative data should be considered in interpreting the data. CONCLUSIONS: Case-volume effect was observed for in-hospital and 1-year mortality after ovarian cancer surgery, while it was not clearly found in 3- or 5-year mortality. Dilution of the case-volume effect might be attributed to the high accessibility to care.

Remimazolam for General Anesthesia in a Patient with Severe Aortic Stenosis Undergoing High-Risk Surgery: A Case Report.

High-risk surgeries for patients with severe aortic stenosis (AS) are challenging for anesthesiologists and can result in hemodynamic deterioration and even mortality. We describe a case in which remimazolam was used to induce and maintain general anesthesia for a high-risk, noncardiac surgery accompanied by ongoing bleeding. An 86-year-old man with severe AS was scheduled to undergo proximal gastrectomy due to ongoing gastrointestinal bleeding and severe anemia. Remimazolam, a novel, ultra-short-acting benzodiazepine, was administered along with remifentanil for the induction and maintenance of general anesthesia. Throughout the anesthetic process, the patient's cardiac index and systemic vascular resistance were well preserved without any vasopressor support. Remimazolam seems to have possible effectiveness as a relatively safe agent for the induction and maintenance of general anesthesia in patients with severe AS who are undergoing high-risk, noncardiac surgery with bleeding.

The impact of total intravenous anesthesia versus inhalation anesthesia on acute kidney injury after major abdominal surgery: a propensity score analysis.

PURPOSE: The effect of anesthetic types on postoperative acute kidney injury (AKI) remains unclear particularly in patients undergoing non-cardiac surgery. The purpose of this retrospective study was to compare total intravenous anesthesia (TIVA) and inhalation anesthesia in terms of the risk of AKI after open major abdominal surgery (MAS). METHODS: Adult patients who underwent open MAS (gastrectomy, hepatectomy, colectomy, or pancreatectomy) at our institute from 2016 to 2018 were included. Using the multivariable logistic regression, the risk of postoperative AKI was compared among patients who underwent TIVA (TIVA group) and inhalation anesthesia (inhalation group) both in the total cohort and in the propensity score-matched cohort. Additional multivariable logistic regression analysis was performed with inverse probability of treatment weighting (IPTW) using the propensity score. RESULTS: In total, 3616 patients were analyzed. The incidence of postoperative AKI was 5.0% (77/1546) and 7.8% (161/2070) in the TIVA and inhalation groups, respectively. The risk of AKI was significantly higher in the inhalation group [adjusted odds ratio (aOR) 1.72; 95% confidence interval (CI) 1.27-2.35; P = 0.002] than the TIVA group. In the matched cohort (n = 1518 in each group), the inhalation group also had a higher risk of AKI (aOR 1.66; 95% CI 1.20-2.31; P = 0.002). The multivariable logistic regression with IPTW showed similar results (aOR 1.59; 95% CI 1.30-1.95; P < 0.001). CONCLUSIONS: The risk of AKI after open MAS differed significantly according to the anesthetic used. Patients receiving inhalation anesthesia may have a greater risk of postoperative AKI than those undergoing TIVA.

Pharmacokinetics of human antithrombin III concentrate in the immediate postoperative period after liver transplantation.

AIMS: Antithrombin III (AT-III) concentrates have been used to prevent critical thrombosis in the immediate post-liver transplantation period without clear evidence regarding the optimal dose or administration scheme. The relationship between the AT-III dosage and the plasma activity levels during the period was evaluated in this study. METHODS: The plasma AT-III activity levels and clinical data obtained from patients who received liver transplantation from January 2017 to September 2018 were retrospectively analysed. A population pharmacokinetic (PK) model was developed using nonlinear mixed-effects method and externally validated thereafter. Several dosing scenarios were simulated to maintain the plasma AT-III activity level within the normal range using the developed PK model to search for an optimal AT-III dosing regimen. RESULTS: The plasma AT-III activity levels were best described by a single compartment model with first order elimination kinetics. The recovery of endogenous AT-III level during the postoperative days was modelled using an Emax model. The typical values (95% confidence interval) of volume of distribution and clearance were 3.86 (3.40-4.32) L, and 0.129 (0.111-0.147) L h-1 , respectively. Serum albumin and body weight had significant effect on clearance and were included in the model. External validation of the proposed model demonstrated adequate prediction performance. Furthermore, simulation of previously suggested or modified dosing scenarios showed successful maintenance of AT-III activity level within the normal range. CONCLUSION: A population PK model of AT-III concentrate was developed using data from liver recipients. Dosing scenarios simulated in our study may help establish a practical guide for AT-III concentrate titration after liver transplantation.

Lung ultrasound score to determine the effect of fraction inspired oxygen during alveolar recruitment on absorption atelectasis in laparoscopic surgery: a randomized controlled trial.

BACKGROUND: Although the intraoperative alveolar recruitment maneuver (RM) efficiently treats atelectasis, the effect of FIO2 on atelectasis during RM is uncertain. We hypothesized that a high FIO2 (1.0) during RM would lead to a higher degree of postoperative atelectasis without benefiting oxygenation when compared to low FIO2 (0.4). METHODS: In this randomized controlled trial, patients undergoing elective laparoscopic surgery in the Trendelenburg position were allocated to low- (FIO2 0.4, n = 44) and high-FIO2 (FIO2 1.0, n = 46) groups. RM was performed 1-min post tracheal intubation and post changes in supine and Trendelenburg positions during surgery. We set the intraoperative FIO2 at 0.4 for both groups and calculated the modified lung ultrasound score (LUSS) to assess lung aeration after anesthesia induction and at surgery completion. The primary outcome was modified LUSS at the end of the surgery. The secondary outcomes were the intra- and postoperative PaO2 to FIO2 ratio and postoperative pulmonary complications. RESULTS: The modified LUSS before capnoperitoneum and RM (P = 0.747) were similar in both groups. However, the postoperative modified LUSS was significantly lower in the low FIO2 group (median difference 5.0, 95% CI 3.0-7.0, P < 0.001). Postoperatively, substantial atelectasis was more common in the high-FIO2 group (relative risk 1.77, 95% CI 1.27-2.47, P < 0.001). Intra- and postoperative PaO2 to FIO2 were similar with no postoperative pulmonary complications. Atelectasis occurred more frequently when RM was performed with high than with low FIO2; oxygenation was not benefitted by a high-FIO2. CONCLUSIONS: In patients undergoing laparoscopic surgery in the Trendelenburg position, absorption atelectasis occurred more frequently with high rather than low FIO2. No oxygenation benefit was observed in the high-FIO2 group. TRIAL REGISTRATION: ClinicalTrials.gov, NCT03943433 . Registered 7 May 2019.

Randomized Trial Comparing Early and Late Administration of Rocuronium Before and After Checking Mask Ventilation in Patients With Normal Airways.

BACKGROUND: During induction of general anesthesia, it is common practice to delay neuromuscular blockade until the ability to deliver mask ventilation has been confirmed. However, the benefits of this approach have never been scientifically validated. We thus compared the early and late administration of rocuronium before and after checking mask ventilation to investigate the efficiency of mask ventilation and the time to tracheal intubation in patients with normal airways. METHODS: Patients (n = 114) were randomized to receive IV rocuronium either before (early rocuronium group, n = 58) or after (late rocuronium group, n = 56) checking mask ventilation. Expiratory tidal volumes (VTs) were measured at 10, 20, 30, 40, 50, and 60 seconds after apnea during mask ventilation. We graded the ease of mask ventilation and measured the time from apnea to tracheal intubation. The primary outcome was the average of mask VTs measured at 10, 20, 30, 40, 50, and 60 seconds after apnea. The main secondary outcome was the time from apnea to tracheal intubation. STATA was used for statistical analysis. RESULTS: The average of mask VTs measured at 10, 20, 30, 40, 50, and 60 seconds after apnea was larger in the early rocuronium group than in the late rocuronium group (552 mL breath [165 mL breath] vs 393 mL breath [165 mL breath], mean difference, 160 mL breath; 95% CI, 98-221 mL breath; P < .001, unpaired t test). Because the interaction between time and group was significant in mask VTs measured at 10, 20, 30, 40, 50, and 60 seconds after apnea (P < .001, linear mixed effects model), pairwise comparisons were performed at the 6 time points. The differences in VTs between the groups were significant at 10, 20, 30, 40, and 50 seconds after apnea (P < .001 each, contrast statements in STATA). The time from apnea to tracheal intubation was shorter in the early rocuronium group than in the late rocuronium group (116 seconds [42 seconds] vs 195 seconds [41 seconds]; mean difference, -79 seconds; 95% CI, -96 to -64 seconds, P < .001). CONCLUSIONS: The early administration of rocuronium before checking mask ventilation resulted in a larger mask VT and earlier tracheal intubation than the late administration of rocuronium after checking mask ventilation in patients with normal airways.

Effect of head position on laryngeal visualisation with the McGrath MAC videolaryngoscope in paediatric patients: A randomised controlled trial.

BACKGROUND: The McGrath MAC video laryngoscope can improve visualisation of the glottis compared with the Macintosh direct laryngoscope. However, good visualisation of the glottis does not guarantee rapid or successful intubation because of difficulty in handling the McGrath device. OBJECTIVE: We evaluated the effect of head elevation, aligning the positions of the external auditory meatus and sternal notch in the horizontal plane, on visualisation of the glottis and handling of the McGrath laryngoscope in paediatric patients. DESIGN: A randomised controlled trial. SETTING: The operating rooms of our tertiary care hospital. PATIENTS: Forty-six children, American Society of Anaesthesiologists' physical status 1 or 2, aged 3 to 7 years. INTERVENTION: Videolaryngoscopy using the McGrath device was performed with the head either flat or elevated. MAIN OUTCOME MEASURES: The percentage of glottis opening score, the use of optimisation manoeuvre and time to successful tracheal intubation were recorded. RESULTS: The median (IQR) percentage of glottis opening score was higher after head elevation than when the head was flat in all patients [100 (100 to 100)% vs. 100 (90 to 100)%, P = 0.0001). The need for use of optimisation procedures (50 vs. 9%, P = 0.004) and mean (SD) time to intubation (17 ±â€Š4 s vs. 15 ±â€Š3 s, P = 0.008) were lower in the head-elevated group. CONCLUSION: Visualisation of the glottis and handling of the McGrath MAC video laryngoscope were significantly better when the external auditory meatus and sternal notch were aligned in the horizontal plane. TRIAL REGISTRATION: http://cris.nih.go.kridentifier:KCT0001443.

Practical strategies for the prevention and management of chronic postsurgical pain.

Chronic postsurgical pain (CPSP) is a multifactorial condition that affects a significant proportion of patients undergoing surgery. The prevention and management of CPSP require the identification of preoperative risk factors to screen high-risk patients and establish appropriate perioperative pain management plans to prevent its development. Active postoperative pain management should be provided to prevent CPSP in patients with severe pain following surgery. These tasks have become important for perioperative team members in the management of CPSP. This review article provides a comprehensive overview of the latest research on the role of perioperative team members in preventing and managing CPSP. Additionally, it highlights practical strategies that can be employed in clinical practice, covering the definition and risk factors for CPSP, including preoperative, intraoperative, and postoperative factors, as well as a risk prediction model. The article also explores various treatments for CPSP, as well as preventive measures, including preemptive analgesia, regional anesthesia, pharmacological interventions, psychoeducational support, and surgical technique modification. This article emphasizes the importance of a comprehensive perioperative pain management plan that includes multidisciplinary interventions, using the transitional pain service as an example. By adopting a multidisciplinary and collaborative approach, perioperative team members can improve patient outcomes, enhance patient satisfaction, and reduce healthcare costs. However, further research is necessary to establish targeted interventions to effectively prevent and manage CPSP.

Continuous versus intermittent infusion of human antithrombin III concentrate in the immediate postoperative period after liver transplantation.

Antithrombin-III (AT-III) concentrates have been used in the immediate postoperative period after liver transplantation to prevent critical thrombosis. We aimed to investigate a more appropriate method for AT-III concentrate administration to maintain plasma AT-III activity level within the target range. In this randomized controlled trial, 130 adult patients undergoing living-donor liver transplantation were randomized to either the intermittent group or continuous group. In the intermittent group, 500 international units (IU) of AT-III concentrate were administered after liver transplantation and repeated every 6 h for 72 h. In the continuous group, 3000 IU of AT-III were continuously infused for 71 h after a loading dose of 2000 IU over 1 h. Plasma AT-III activity level was measured at 12, 24, 48, 72, and 84 h from the first AT-III administration. The primary outcome was the target (80%-120%) attainment rate at 72 h. Target attainment rates at other timepoints and associated complications were collected as secondary outcomes. A total of 107 patients were included in the analysis. The target attainment rates at 72 h post-dose were 30% and 62% in the intermittent group and continuous group, respectively (p = 0.003). Compared to the intermittent group, patients in the continuous group reached the target level more rapidly (12 vs. 24 h, median time, p < 0.001) and were more likely to remain in the target range until 84 h. For maintaining the target plasma AT-III activity level after living-donor liver transplantation, continuous infusion of AT-III seemed to be more appropriate compared to the conventional intermittent infusion regimen.

Hospital case-volume and mortality after lung cancer surgery: A population-based retrospective cohort study.

OBJECTIVES: Recent advances in lung cancer treatment warrants reassessment of the volume-outcome association in lung cancer surgery. This study reassessed the relationship between surgical case-volume and both in-hospital and long-term mortality after lung cancer surgery using a current database to reflect recent advances. MATERIALS AND METHODS: Using the database of the National Health Insurance Service in Korea, data of all adult patients who underwent lung cancer surgery in Korea between 2005 and 2019 were obtained. Hospitals were categorized by the annual number of lung cancer surgeries. Risk-adjusted in-hospital and 1, 3, 5-year mortality after surgery were assessed. RESULTS: A total of 84,194 lung cancer surgeries were performed in 163 centers during the study period. High-volume centers were defined as > 200 cases/year, medium-volume centers as 60-200 cases/year, and low-volume centers as < 60 cases/year. After adjustment, in-hospital mortality was significantly lower in high-volume centers (1.03%) compared to medium-volume centers (2.06%, adjusted odds ratio [OR], 1.43; 95% confidence interval [CI], 1.23-1.65; P < 0.001), and low-volume centers (3.08%, OR, 1.32; 95% CI, 1.16-1.51; P < 0.001). Long-term mortality was also significantly lower in high-volume centers compared to the other groups. CONCLUSION: High-volume centers showed lower in-hospital and long-term mortality compared to centers with less case-volume.

Effect of pre-operative carbohydrate loading on aspiration risk evaluated with ultrasonography in type 2 diabetes patients: a prospective observational pilot study.

Owing to concerns about delayed gastric emptying or hyperglycemia, evidence is lacking regarding whether pre-operative carbohydrate loading can be routinely administered to patients with type 2 diabetes. The objective of this study was to determine the aspiration risk and gastric volume after pre-operative carbohydrate loading in patients with type 2 diabetes. A prospective, single-center, observational cohort study. The study was conducted at a tertiary teaching hospital in Seoul, Korea, from May 2020 to May 2021. Patients (n = 49) with type 2 diabetes underwent elective noncardiac surgery. All patients were administered carbohydrate loading two hours before surgery. Once in the operating room, they underwent gastric ultrasonography to determine gastric volume. The anesthesiologists monitored the patients' glucose concentrations during and after surgery. The primary outcome was the predicted risk of aspiration. The secondary outcomes were gastric volume, antral grade, satisfaction score, and perioperative glucose profile. Forty-nine patients were analyzed. All patients had a low risk of aspiration after carbohydrate loading, as follows: 33 (67.3%) patients classified as antral grade 0 and 16 (32.7%) patients classified as antral grade 1. The median time from carbohydrate drink ingestion to ultrasound examination was 120 min (IQR 115-139). After carbohydrate loading, the median gastric volume in the right-lateral position after carbohydrate loading was 2.64 ml (IQR 0.00-32.05). The mean glucose concentrations (SD) were 134 (24) mg/dl, 159 (37) mg/dl, 150 (32) mg/dl, and 165 (36) mg/dl at baseline, after induction, 30 min after surgery, and in the post anesthesia care unit, respectively. The median satisfaction score of the patients was 5 (IQR 4-5). Pre-operative carbohydrate loading may be feasible for patients with type 2 diabetes and without complications.Trial registration: ClinicalTrials.gov (NCT04456166). Registered on 2 July 2020.

Effect of institutional case volume on mid-term mortality after coronary artery bypass grafting surgery.

OBJECTIVE: The impact of center case volume on mid-term postoperative outcome after coronary artery bypass grafting surgery (CABG) is still controversial and requires investigation. The aim of this study was to compare mid-term survival after CABG according to the institutional annual CABG case volume. METHODS: Adult patients (≥ 18 years) who underwent CABG from 2009 to 2016 were identified by searching National Health Insurance database of Korea for CABG procedure codes. Hospitals were classified into three groups based on annual case volume; low-volume centers (< 20 cases/year), medium-volume centers (20-50 cases/year), and high-volume centers (> 50 cases/year). RESULTS: A total of 22,575 CABG were performed in 95 centers during the study period, and 14,697 (65.1%) cases performed at 15 high-volume centers, 5,262 (23.3%) cases at 26 medium-volume centers, and 2,616 (11.6%) cases at 54 low-volume centers. The overall 1-year mortality rate was the lowest in high-volume centers (6.5%), followed by medium-volume centers (10.6%) and low-volume centers (15.2%). Logistic regression identified medium-volume centers (adjusted OR 1.30 [95% CI 1.15-1.49], P < 0.01) and low-volume centers (adjusted OR 1.75 [95% CI 1.51-2.03], P < 0.01) as risk factors for 1-year mortality after CABG compared to high-volume centers. In the Cox proportional hazard model, low- and medium-volume centers were significantly risk factors for poor survival (adjusted HR 1.41 [95% CI 1.31-1.54], P < 0.01 and HR 1.26 [95% CI 1.17-1.35], P < 0.01 for low- and medium-volume centers, respectively). CONCLUSIONS: Higher institutional case volume of CABG was associated with lower mid-term mortality.

Repeated intermittent hypoxic stimuli to operative lung reduce hypoxemia during subsequent one-lung ventilation for thoracoscopic surgery: A randomized controlled trial.

BACKGROUND: An intervention to potentiate hypoxic pulmonary vasoconstriction may reduce intrapulmonary shunt and hypoxemia during one-lung ventilation. Previous animal studies reported that repeated intermittent hypoxic stimuli potentiated hypoxic pulmonary vasoconstriction, but no clinical study has examined the effects of this intervention on hypoxemia during one-lung ventilation. We thus performed a single-center, parallel-group, double-blind, randomized controlled trial to investigate whether repeated intermittent hypoxic stimuli to the operative lung reduce hypoxemia during the subsequent one-lung ventilation for thoracoscopic surgery. METHODS: Patients undergoing one-lung ventilation were randomized into two groups (n = 68 each). Before one-lung ventilation, in the intermittent hypoxia group, the nondependent lung was not ventilated for 2 min and then ventilated for 2 min while the dependent lung was continuously ventilated. This was repeated five times. In the continuous normoxia group, both lungs were ventilated for 20 min. We measured SpO2, PaO2, FiO2, PaCO2, SaO2, and central venous oxygen saturation during one-lung ventilation. The primary outcome was the number of patients with hypoxemia defined as a SpO2 <95% during one-lung ventilation, which was analyzed with a chi-squared test. RESULTS: Hypoxemia was less frequent in the intermittent hypoxia group than in the continuous normoxia group during OLV [6/68 (8.8%) vs 17/68 (25.0%), risk ratio (95% CI) 0.35 (0.15-0.84), p = 0.012]. The PaO2 (p = 0.008 for 30 min and 0.007 for 60 min) and PaO2/FiO2 (p = 0.008 for both) were higher 30 and 60 min after starting one-lung ventilation, and the alveolar-arterial pressure gradient (p = 0.010) and shunt index (p = 0.008) were lower 30 min after starting one-lung ventilation in the intermittent hypoxia group than in the continuous normoxia group. Postoperative adverse events did not differ significantly between groups. CONCLUSIONS: Repeated intermittent hypoxic stimuli to the operative lung seemed to potentiate hypoxic pulmonary vasoconstriction, and thus reduced hypoxemia during the subsequent one-lung ventilation.

The association between hospital case-volume and postoperative outcomes after esophageal cancer surgery: A population-based retrospective cohort study.

BACKGROUND: Recent advances in esophageal cancer treatment require a reevaluation of the relationship between institutional case-volume and patient outcome. The aim of this study was to analyze and update the association between surgical case-volume and both in-hospital and long-term mortality after esophagectomy for esophageal cancer. METHODS: Data of all adult patients who received esophageal cancer surgery in Korea between 2004 and 2017 were extracted from the database of the National Health Insurance Service. Hospitals were categorized into three groups according to the average annual number of esophageal cancer surgery: low-volume (<12 cases/year), medium-volume (12-48 cases/year), and high-volume centers (>48 cases/year). Postoperative in-hospital and 1-, 3-, and 5-year mortality were analyzed according to the categorized groups using logistic regression. RESULTS: In total, 11, 346 esophageal cancer surgeries in 122 hospitals were analyzed. In-hospital mortality in the high-, medium-, and low-volume centers were 3.4%, 6.4%, and 11.1%, respectively. In-hospital mortality was significantly higher in low- volume (adjusted odds ratio, 3.91; confidence interval, 3.18-4.80; p < 0.001) and medium volume (adjusted odds ratio, 2.21; confidence interval, 1.80-2.74, p < 0.001) centers compared to high-volume centers. Patients who received esophageal cancer surgery in a low-or medium-volume center also had higher 1-, 3-, and 5-year mortality compared to patients who received the surgery in a high-volume center. Conclusions Centers with lower case-volume showed higher in-hospital mortality and long-term mortality after esophageal cancer surgery.

Association between hospital liver transplantation volume and mortality after liver re-transplantation.

BACKGROUND: The relationship between institutional liver transplantation (LT) case volume and clinical outcomes after liver re-transplantation is yet to be determined. METHODS: Patients who underwent liver re-transplantation between 2007 and 2016 were selected from the Korean National Healthcare Insurance Service database. Liver transplant centers were categorized to either high-volume centers (≥ 64 LTs/year) or low-volume centers (< 64 LTs/year) according to the annual LT case volume. In-hospital and long-term mortality after liver re-transplantation were compared. RESULTS: A total of 258 liver re-transplantations were performed during the study period: 175 liver re-transplantations were performed in 3 high-volume centers and 83 were performed in 21 low-volume centers. In-hospital mortality after liver re-transplantation in high and low-volume centers were 25% and 36% (P = 0.069), respectively. Adjusted in-hospital mortality was not different between low and high-volume centers. Adjusted 1-year mortality was significantly higher in low-volume centers (OR 2.14, 95% CI 1.05-4.37, P = 0.037) compared to high-volume centers. Long-term survival for up to 9 years was also superior in high-volume centers (P = 0.005). Other risk factors of in-hospital mortality and 1-year mortality included female sex and higher Elixhauser comorbidity index. CONCLUSION: Centers with higher case volume (≥ 64 LTs/year) showed lower in-hospital and overall mortality after liver re-transplantation compared to low-volume centers.

The Effect of Ventilation with Individualized Positive End-Expiratory Pressure on Postoperative Atelectasis in Patients Undergoing Robot-Assisted Radical Prostatectomy: A Randomized Controlled Trial.

For patients undergoing robot-assisted radical prostatectomy, the pneumoperitoneum with a steep Trendelenburg position could worsen intraoperative respiratory mechanics and result in postoperative atelectasis. We investigated the effects of individualized positive end-expiratory pressure (PEEP) on postoperative atelectasis, evaluated using lung ultrasonography. Sixty patients undergoing robot-assisted radical prostatectomy were randomly allocated into two groups. Individualized groups (n = 30) received individualized PEEP determined by a decremental PEEP trial using 20 to 7 cm H2O, aiming at maximizing respiratory compliance, whereas standardized groups (n = 30) received a standardized PEEP of 7 cm H2O during the pneumoperitoneum. Ultrasound examination was performed on 12 sections of thorax, and the lung ultrasound score was measured as 0-3 by considering the number of B lines and the degree of subpleural consolidation. The primary outcome was the difference between the lung ultrasound scores measured before anesthesia induction and just after extubation in the operating room. An increase in the difference means the development of atelectasis. The optimal PEEP in the individualized group was determined as the median (interquartile range) 14 (12-18) cm H2O. Compared with the standardized group, the difference in the lung ultrasound scores was significantly smaller in the individualized group (-0.5 ± 2.7 vs. 6.0 ± 2.9, mean difference -6.53, 95% confidence interval (-8.00 to -5.07), p < 0.001), which means that individualized PEEP was effective to reduce atelectasis. The lung ultrasound score measured after surgery was significantly lower in the individualized group than the standardized group (8.1 ± 5.7 vs. 12.2 ± 4.2, mean difference -4.13, 95% confidence interval (-6.74 to -1.53), p = 0.002). However, the arterial partial pressure of the oxygen/fraction of inspired oxygen levels during the surgery showed no significant time-group interaction between the two groups in repeated-measures analysis of variance (p = 0.145). The incidence of a composite of postoperative respiratory complications was comparable between the two groups. Individualized PEEP determined by maximal respiratory compliance during the pneumoperitoneum and steep Trendelenburg position significantly reduced postoperative atelectasis, as evaluated using lung ultrasonography. However, the clinical significance of this finding should be evaluated by a larger clinical trial.