Electrical Impedance Tomography-based Ventilation Patterns in Patients after Major Surgery.

Rationale: General anesthesia and mechanical ventilation have negative impacts on the respiratory system, causing heterogeneous distribution of lung aeration, but little is known about the ventilation patterns of postoperative patients and their association with clinical outcomes. Objectives: To clarify the phenotypes of ventilation patterns along a gravitational direction after surgery by using electrical impedance tomography (EIT) and to evaluate their association with postoperative pulmonary complications (PPCs) and other relevant clinical outcomes. Methods: Adult postoperative patients at high risk for PPCs, receiving mechanical ventilation on ICU admission (N = 128), were prospectively enrolled between November 18, 2021 and July 18, 2022. PPCs were prospectively scored until hospital discharge, and their association with phenotypes of ventilation patterns was studied. The secondary outcomes were the times to wean from mechanical ventilation and oxygen use and the length of ICU stay. Measurements and Main Results: Three phenotypes of ventilation patterns were revealed by EIT: phenotype 1 (32% [n = 41], a predominance of ventral ventilation), phenotype 2 (41% [n = 52], homogeneous ventilation), and phenotype 3 (27% [n = 35], a predominance of dorsal ventilation). The median PPC score was higher in phenotype 1 and phenotype 3 than in phenotype 2. The median time to wean from mechanical ventilation was longer in phenotype 1 versus phenotype 2. The median duration of ICU stay was longer in phenotype 1 versus phenotype 2. The median time to wean from oxygen use was longer in phenotype 1 and phenotype 3 than in phenotype 2. Conclusions: Inhomogeneous ventilation patterns revealed by EIT on ICU admission were associated with PPCs, delayed weaning from mechanical ventilation and oxygen use, and a longer ICU stay.

Inspiratory Muscle Training Before Esophagectomy Increases Diaphragmatic Excursion: A Randomized Controlled Trial.

BACKGROUND: Inspiratory muscle training (IMT) has preventive effects against postoperative pulmonary complications (PPCs) after upper abdominal surgery. However, its impact on diaphragmatic function has not been evaluated. This study investigated the effect of preoperative IMT on diaphragmatic excursion (DE) and prevention of PPCs for patients with esophageal cancer. METHODS: This study was an unblinded, parallel, randomized controlled trial. Patients with thoracic or abdominal esophageal cancer scheduled for esophagectomy were randomized into the incentive spirometry (IS) or IMT group. During preoperative neoadjuvant chemotherapy, IS or IMT intervention was performed. The inspiratory resistance of the IMT group was consistently set at 50% maximal inspiratory pressure. The primary outcome was the amount of change in DE evaluated with ultrasonography, and the secondary outcome was the incidence of Clavien-Dindo grade II or higher PPCs. RESULTS: This study recruited 42 patients. Among these patients 21 were randomized into the IS or IMT group, and 2 patients dropped out from the study. Finally, 40 patients were included in this analysis. The DE of the IMT group increased significantly after the intervention. The IMT group had significantly larger DE changes than the IS group. Of the 39 patients analyzed for postoperative outcome, 5 experienced grade II PPCs. The IMT group had a lower incidence of PPCs than the IS group. CONCLUSIONS: Patients with thoracic and abdominal esophageal cancer scheduled for surgery who had preoperative IMT have increased DE, which may have an important role in prevention of PPCs.

Association between reversal agents (sugammadex vs. neostigmine) for neuromuscular block and postoperative pulmonary complications: A retrospective analysis.

AIMS: Residual neuromuscular blockade has been linked to pulmonary complications in the postoperative period. This study aimed to determine whether sugammadex was associated with a lower risk of postoperative pulmonary complications (PPCs) compared with neostigmine. METHODS: This retrospective cohort study was conducted in a tertiary academic medical center. Patients ≥18 year of age undergoing noncardiac surgical procedures with general anesthesia and mechanical ventilation were enrolled between January 2019 and September 2021. We identified all patients receiving rocuronium and reversal with neostigmine or sugammadex via electronic medical record review. The primary endpoint was a composite of PPCs (including pneumonia, atelectasis, respiratory failure, pulmonary embolism, pleural effusion, or pneumothorax). The incidence of PPCs was compared using propensity score analysis. RESULTS: A total of 1786 patients were included in this study. Among these patients, 976 (54.6%) received neostigmine, and 810 (45.4%) received sugammadex. In the whole sample, PPCs occurred in 81 (4.54%) subjects (7.04% sugammadex vs. 2.46% neostigmine). Baseline covariates were well balanced between groups after overlap weighting. Patients in the sugammadex group had similar risk (overlap weighting OR: 0.75; 95% CI: 0.40 to 1.41) compared to neostigmine. The sensitivity analysis showed consistent results. In subgroup analysis, the interaction P-value for the reversal agents stratified by surgery duration was 0.011. CONCLUSION: There was no significant difference in the rate of PPCs when the neuromuscular blockade was reversed with sugammadex compared to neostigmine. Patients undergoing prolonged surgery may benefit from sugammadex, which needs to be further investigated.

Association of Myostatin With Complications and Cognition in Lung Cancer Patients With Sarcopenia.

INTRODUCTION: The risk of surgery and postoperative complications increases greatly in frail older patients with sarcopenia. The purpose of this study is to explore the correlation between myostatin (MSTN) levels and cognitive function and postoperative pulmonary complications (PPCs) in older patients undergoing thoracoscopic lobectomy and to determine whether MSTN could be used to predict the risk of postoperative complications and cognitive impairment. METHODS: A prospective observational study was conducted at the First Affiliated Hospital of Bengbu Medical College, China, between January 2023 and June 2023. The risk factors of PPCs and postoperative cognitive impairment were studied using backward stepwise logistic regression analysis. The independent factors were formed into a linear regression equation to construct a risk score model for each patient. The 122 patients who participated in the study were divided into two groups, a low-level group and a high-level group, based on an MSTN level cut-off; the preoperative MSTN cut-off values was 25.55 ng/mL for cognitive dysfunction and 22.29 ng/mL for PPCs. The PPCs and cognitive function of the groups were compared. RESULTS: Preoperative MSTN was confirmed as a risk factor for postoperative cognitive dysfunction and PPCs. After surgery, the proportion of patients with cognitive impairment in the high-level group was significantly higher than in the low-level group (P < 0.001). In the high-level group, the incidence of respiratory tract infections was 17.9% higher (P = 0.021), hypoxaemia was 20.5% higher (P = 0.001) and respiratory failure was 14.4% higher (P = 0.012) than in the low-level group. In addition, a high level of MSTN increased the length of hospital stay (P < 0.001) and decreased the Barthel Index score (P < 0.001). CONCLUSIONS: The study findings suggest that MSTN could be used as an index to predict complications and cognitive impairment after thoracoscopic lobectomy in older patients with sarcopenia and to provide evidence for reducing postoperative cognitive impairment and PPCs.

Machine learning and preoperative risk prediction: the machines are coming.

Preoperative risk prediction is an important component of perioperative medicine. Machine learning is a powerful tool that could lead to increasingly complex risk prediction models with improved predictive performance. Careful consideration is required to guide the machine learning approach to ensure appropriate decisions are made with regard to what we are trying to predict, when we are trying to predict it, and what we seek to do with the results.

Association between driving pressure-guided ventilation and postoperative pulmonary complications in surgical patients: a meta-analysis with trial sequential analysis.

BACKGROUND: Prior studies have reported inconsistent results regarding the association between driving pressure-guided ventilation and postoperative pulmonary complications (PPCs). We aimed to investigate whether driving pressure-guided ventilation is associated with a lower risk of PPCs. METHODS: We systematically searched electronic databases for RCTs comparing driving pressure-guided ventilation with conventional protective ventilation in adult surgical patients. The primary outcome was a composite of PPCs. Secondary outcomes were pneumonia, atelectasis, and acute respiratory distress syndrome (ARDS). Meta-analysis and subgroup analysis were conducted to calculate risk ratios (RRs) with 95% confidence intervals (CI). Trial sequential analysis (TSA) was used to assess the conclusiveness of evidence. RESULTS: Thirteen RCTs with 3401 subjects were included. Driving pressure-guided ventilation was associated with a lower risk of PPCs (RR 0.70, 95% CI 0.56-0.87, P=0.001), as indicated by TSA. Subgroup analysis (P for interaction=0.04) found that the association was observed in non-cardiothoracic surgery (nine RCTs, 1038 subjects, RR 0.61, 95% CI 0.48-0.77, P< 0.0001), with TSA suggesting sufficient evidence and conclusive result; however, it did not reach significance in cardiothoracic surgery (four RCTs, 2363 subjects, RR 0.86, 95% CI 0.67-1.10, P=0.23), with TSA indicating insufficient evidence and inconclusive result. Similarly, a lower risk of pneumonia was found in non-cardiothoracic surgery but not in cardiothoracic surgery (P for interaction=0.046). No significant differences were found in atelectasis and ARDS between the two ventilation strategies. CONCLUSIONS: Driving pressure-guided ventilation was associated with a lower risk of postoperative pulmonary complications in non-cardiothoracic surgery but not in cardiothoracic surgery. SYSTEMATIC REVIEW PROTOCOL: INPLASY 202410068.

Non-pulmonary complications of intrathecal morphine administration: a systematic review and meta-analysis with meta-regression.

BACKGROUND: Intrathecal morphine provides effective analgesia for a range of operations. However, widespread implementation into clinical practice is hampered by concerns for potential side-effects. We undertook a systematic review, meta-analysis, and meta-regression with the primary objective of determining whether a threshold dose for non-pulmonary complications could be defined and whether an association could be established between dose and complication rates when intrathecal morphine is administered for perioperative or obstetric analgesia. METHODS: We systematically searched the literature for randomised controlled trials comparing intrathecal morphine vs control in patients undergoing any type of surgery under general or spinal anaesthesia, or women in labour. Primary outcomes were rates of postoperative nausea and vomiting, pruritus, and urinary retention within the first 24 postoperative hours, analysed according to doses (1-100 µg; 101-200 µg; 201-500 µg; >500 µg), type of surgery, and anaesthetic strategy. Trials were excluded if doses were not specified. RESULTS: Our analysis included 168 trials with 9917 patients. The rates of postoperative nausea and vomiting, pruritus, and urinary retention were significantly increased in the intrathecal morphine group, with an odds ratio (95% confidence interval) of 1.52 (1.29-1.79), P<0.0001; 6.11 (5.25-7.10), P<0.0001; and 1.73 (1.17-2.56), P=0.005, respectively. Meta-regression could not establish an association between dose and rates of non-pulmonary complications. There was no subgroup difference according to surgery for any outcome. The quality of evidence was low (Grading of Recommendations Assessment, Development, and Evaluation [GRADE] system). CONCLUSIONS: Intrathecal morphine significantly increased postoperative nausea and vomiting, pruritus, and urinary retention after surgery or labour in a dose-independent manner. SYSTEMATIC REVIEW PROTOCOL: PROSPERO (CRD42023387838).

Incidence of adverse respiratory events after adjustment of clear fluid fasting recommendations to 1 h: a prospective, observational, multi-institutional cohort study.

BACKGROUND: Preoperative fasting reduces the risk of pulmonary aspiration during anaesthesia, and 2-h fasting for clear fluids has commonly been recommended. Based on recent evidence of shorter fasting times being safe, the Swiss Society of Paediatric Anaesthesia began recommending 1-h fasting for clear fluids in 2018. This prospective, observational, multi-institutional cohort study aimed to investigate the incidence of adverse respiratory events after implementing the new national recommendation. METHODS: Eleven Swiss anaesthesia institutions joined this cohort study and included patients aged 0-15 yr undergoing anaesthesia for elective procedures after implementation of the 1-h fasting instruction. The primary outcome was the perioperative (defined as the time from anaesthesia induction to emergence) incidence of pulmonary aspiration, gastric regurgitation, and vomiting. Data are presented as median (inter-quartile range; minimum-maximum) or count (percentage). RESULTS: From June 2019 to July 2021, 22 766 anaesthetics were recorded with pulmonary aspiration occurring in 25 (0.11%), gastric regurgitation in 34 (0.15%), and vomiting in 85 (0.37%) cases. No major morbidity or mortality was associated with pulmonary aspiration. Subgroup analysis by effective fasting times (<2 h [n=7306] vs ≥2 h [n=14 660]) showed no significant difference for pulmonary aspiration between these two groups (9 [0.12%] vs 16 [0.11%], P=0.678). Median effective fasting time for clear fluids was 157 [104-314; 2-2385] min. CONCLUSIONS: Implementing a national recommendation of 1-h clear fluid fasting was not associated with a higher incidence of pulmonary aspiration compared with previously reported data.

Utilising intraoperative respiratory dynamic features for developing and validating an explainable machine learning model for postoperative pulmonary complications.

BACKGROUND: Timely detection of modifiable risk factors for postoperative pulmonary complications (PPCs) could inform ventilation strategies that attenuate lung injury. We sought to develop, validate, and internally test machine learning models that use intraoperative respiratory features to predict PPCs. METHODS: We analysed perioperative data from a cohort comprising patients aged 65 yr and older at an academic medical centre from 2019 to 2023. Two linear and four nonlinear learning models were developed and compared with the current gold-standard risk assessment tool ARISCAT (Assess Respiratory Risk in Surgical Patients in Catalonia Tool). The Shapley additive explanation of artificial intelligence was utilised to interpret feature importance and interactions. RESULTS: Perioperative data were obtained from 10 284 patients who underwent 10 484 operations (mean age [range] 71 [65-98] yr; 42% female). An optimised XGBoost model that used preoperative variables and intraoperative respiratory variables had area under the receiver operating characteristic curves (AUROCs) of 0.878 (0.866-0.891) and 0.881 (0.879-0.883) in the validation and prospective cohorts, respectively. These models outperformed ARISCAT (AUROC: 0.496-0.533). The intraoperative dynamic features of respiratory dynamic system compliance, mechanical power, and driving pressure were identified as key modifiable contributors to PPCs. A simplified model based on XGBoost including 20 variables generated an AUROC of 0.864 (0.852-0.875) in an internal testing cohort. This has been developed into a web-based tool for further external validation (https://aorm.wchscu.cn/). CONCLUSIONS: These findings suggest that real-time identification of surgical patients' risk of postoperative pulmonary complications could help personalise intraoperative ventilatory strategies and reduce postoperative pulmonary complications.

Weaning from mechanical ventilation in the operating room: a systematic review.

BACKGROUND: Postoperative pulmonary complications (PPCs) are associated with postoperative mortality and prolonged hospital stay. Although intraoperative mechanical ventilation (MV) is a risk factor for PPCs, strategies addressing weaning from MV are understudied. In this systematic review, we evaluated weaning strategies and their effects on postoperative pulmonary outcomes. METHODS: Our protocol was registered on PROSPERO (CRD42022379145). Eligible studies included randomised controlled trials and observational studies of adults weaned from MV in the operating room. Primary outcomes included atelectasis and oxygenation; secondary outcomes included lung volume changes and PPCs. Risk of bias was assessed using the Cochrane Risk of Bias (RoB2) tool, and quality of evidence with the GRADE framework. RESULTS: Screening identified 14 randomised controlled trials including 1719 patients; seven studies were limited to the weaning phase and seven included interventions not restricted to the weaning phase. Strategies combining pressure support ventilation (PSV) with positive end-expiratory pressure (PEEP) and low fraction of inspired oxygen (FiO2) improved atelectasis, oxygenation, and lung volumes. Low FiO2 improved atelectasis and oxygenation but might not improve lung volumes. A fixed-PEEP strategy led to no improvement in oxygenation or atelectasis; however, individualised PEEP with low FiO2 improved oxygenation and might be associated with reduced PPCs. Half of included studies are of moderate or high risk of bias; the overall quality of evidence is low. CONCLUSIONS: There is limited research evaluating weaning from intraoperative MV. Based on low-quality evidence, PSV, individualised PEEP, and low FiO2 may be associated with reduced postoperative pulmonary outcomes. SYSTEMATIC REVIEW PROTOCOL: PROSPERO (CRD42022379145).

Association between inspired oxygen fraction and development of postoperative pulmonary complications in thoracic surgery: a multicentre retrospective cohort study.

BACKGROUND: Limited data exist to guide oxygen administration during one-lung ventilation for thoracic surgery. We hypothesised that high intraoperative inspired oxygen fraction during lung resection surgery requiring one-lung ventilation is independently associated with postoperative pulmonary complications (PPCs). METHODS: We performed this retrospective multicentre study using two integrated perioperative databases (Multicenter Perioperative Outcomes Group and Society of Thoracic Surgeons General Thoracic Surgery Database) to study adult thoracic surgical procedures using one-lung ventilation. The primary outcome was a composite of PPCs (atelectasis, acute respiratory distress syndrome, pneumonia, respiratory failure, reintubation, and prolonged ventilation >48 h). The exposure of interest was high inspired oxygen fraction (FiO2), defined by area under the curve of a FiO2 threshold > 80%. Univariate analysis and logistic regression modelling assessed the association between intraoperative FiO2 and PPCs. RESULTS: Across four US medical centres, 141/2733 (5.2%) procedures conducted in 2716 patients (55% female; mean age 66 yr) resulted in PPCs. FiO2 was univariately associated with PPCs (adjusted OR [aOR]: 1.17, 95% confidence interval [CI]: 1.04-1.33, P=0.012). Logistic regression modelling showed that duration of one-lung ventilation (aOR: 1.20, 95% CI: 1.03-1.41, P=0.022), but not the time-weighted average FiO2 (aOR: 1.01, 95% CI: 1.00-1.02, P=0.165), was associated with PPCs. CONCLUSIONS: Our results do not support limiting the inspired oxygen fraction for the purpose of reducing postoperative pulmonary complications in thoracic surgery involving one-lung ventilation.

A Nomogram for Predicting Postoperative Pulmonary Complications in Critical Patients Transferred to ICU After Abdominal Surgery.

OBJECTIVE: The purpose of this study was to investigate the risk factors associated with postoperative pulmonary complications(PPCs) in critically ill patients transferred to intensive care unit(ICU) after abdominal surgery and develop a predictive model for this disease. METHODS: Data for 3716 patients who were admitted to ICU after abdominal surgery in Peking University People's Hospital between January 2015 and December 2020 were retrospectively collected and analyzed to identify the risk factors and develop a nomogram prediction model. Data for patients admitted to ICU following abdominal surgery at Peking University People's Hospital from March 2021 to December 2022 were prospectively collected as a validation set to validate and assess the model. RESULTS: 10 independent risk factors for PPCs in critically ill patients transferred to ICU after abdominal surgery were identified. A nomogram prediction model was constructed for PPCs in this group patients, the area under ROC curve was 0.771[95%CI: 0.756,0.786] and 0.759[95%CI: 0.726,0.792] in the training set and validation set, respectively. CONCLUSIONS: In this study, independent risk factors for PPCs in critically ill patients transferred to ICU after abdominal surgery were identified. A nomogram prediction model for PPCs in critically ill surgical population was constructed using these factors, demonstrating a good predictive value.

Postoperative pulmonary complications after major abdominal surgery in elderly patients and its association with patient-controlled analgesia.

OBJECTIVES: This study aims to identify the risk factors for postoperative pulmonary complications (PPCs) in elderly patients undergoing major abdominal surgery and to investigate the relationship between patient-controlled analgesia (PCA) and PPCs. DESIGN: A retrospective study. METHOD: Clinical data and demographic information of elderly patients (aged ≥ 60 years) who underwent upper abdominal surgery at the First Affiliated Hospital of Sun Yat-sen University from 2017 to 2019 were retrospectively collected. Patients with PPCs were identified using the Melbourne Group Scale Version 2 scoring system. A directed acyclic graph was used to identify the potential confounders, and multivariable logistic regression analyses were conducted to identify independent risk factors for PPCs. Propensity score matching was utilized to compare PPC rates between patients with and without PCA, as well as between intravenous PCA (PCIA) and epidural PCA (PCEA) groups. RESULTS: A total of 1,467 patients were included, with a PPC rate of 8.7%. Multivariable analysis revealed that PCA was an independent protective factor for PPCs in elderly patients undergoing major abdominal surgery (odds ratio = 0.208, 95% confidence interval = 0.121 to 0.358; P < 0.001). After matching, patients receiving PCA demonstrated a significantly lower overall incidence of PPCs (8.6% vs. 26.3%, P < 0.001), unplanned transfer to the intensive care unit (1.1% vs. 8.4%, P = 0.001), and in-hospital mortality (0.7% vs. 5.3%, P = 0.021) compared to those not receiving PCA. No significant difference in outcomes was observed between patients receiving PCIA or PCEA after matching. CONCLUSION: Patient-controlled analgesia, whether administered intravenously or epidurally, is associated with a reduced risk of PPCs in elderly patients undergoing major upper abdominal surgery.

Prediction models for postoperative pulmonary complications in intensive care unit patients after noncardiac thoracic surgery.

BACKGROUND: Postoperative pulmonary complication (PPC) is a leading cause of mortality and poor outcomes in postoperative patients. No studies have enrolled intensive care unit (ICU) patients after noncardiac thoracic surgery, and effective prediction models for PPC have not been developed. This study aimed to explore the incidence and risk factors and construct prediction models for PPC in these patients. METHODS: This study retrospectively recruited patients admitted to the ICU after noncardiac thoracic surgery at West China Hospital, Sichuan University, from July 2019 to December 2022. The patients were randomly divided into a development cohort and a validation cohort at a 70% versus 30% ratio. The preoperative, intraoperative and postoperative variables during the ICU stay were compared. Univariate and multivariate logistic regression analyses were applied to identify candidate predictors, establish prediction models, and compare the accuracy of the models with that of reported risk models. RESULTS: A total of 475 ICU patients were enrolled after noncardiac thoracic surgery (median age, 58; 72% male). At least one PPC occurred in 171 patients (36.0%), and the most common PPC was pneumonia (153/475, 32.21%). PPC significantly increased the duration of mechanical ventilation (p < 0.001), length of ICU stay (p < 0.001), length of hospital stay (LOS) (p < 0.001), and rate of reintubation (p = 0.047) in ICU patients. Seven risk factors were identified, and then the prediction nomograms for PPC were constructed. At ICU admission, the area under the curve (AUC) was 0.766, with a sensitivity of 0.71 and specificity of 0.60; after extubation, the AUC was 0.841, with a sensitivity of 0.75 and specificity of 0.83. The models showed robust discrimination in both the development cohort and the validation cohort, and they were well calibrated and more accurate than reported risk models. CONCLUSIONS: ICU patients who underwent noncardiac thoracic surgery were at high risk of developing PPCs. Prediction nomograms were constructed and they were more accurate than reported risk models, with excellent sensitivity and specificity. Moreover, these findings could help assess individual PPC risk and enhance postoperative management of patients.

Nomogram for predicting postoperative pulmonary complications in spinal tumor patients.

OBJECTIVES: Although several independent risk factors for postoperative pulmonary complications (PPCs) after spinal tumor surgery have been studied, a simple and valid predictive model for PPC occurrence after spinal tumor surgery has not been developed. PATIENTS AND METHODS: We collected data from patients who underwent elective spine surgery for a spinal tumor between 2013 and 2020 at a tertiary hospital in China. Data on patient characteristics, comorbidities, preoperative examinations, intraoperative variables, and clinical outcomes were collected. We used univariable and multivariable logistic regression models to assess predictors of PPCs and developed and validated a nomogram for PPCs. We evaluated the performance of the nomogram using the area under the receiver operating characteristic curve (ROC), calibration curves, the Brier Score, and the Hosmer-Lemeshow (H-L) goodness-of-fit test. For clinical use, decision curve analysis (DCA) was conducted to identify the model's performance as a tool for supporting decision-making. RESULTS: Among the participants, 61 (12.4%) individuals developed PPCs. Clinically significant variables associated with PPCs after spinal tumor surgery included BMI, tumor location, blood transfusion, and the amount of blood lost. The nomogram incorporating these factors showed a concordance index (C-index) of 0.755 (95% CI: 0.688-0.822). On internal validation, bootstrapping with 1000 resamples yielded a bias-corrected area under the receiver operating characteristic curve of 0.733, indicating the satisfactory performance of the nomogram in predicting PPCs. The calibration curve demonstrated accurate predictions of observed values. The decision curve analysis (DCA) indicated a positive net benefit for the nomogram across most predicted threshold probabilities. CONCLUSIONS: We have developed a new nomogram for predicting PPCs in patients who undergo spinal tumor surgery.

The association of vaping and electronic cigarette use with postoperative hypoxemia and respiratory complications: a retrospective cohort analysis.

PURPOSE: Initially introduced as a safer alternative to smoking, electronic cigarettes (e-cigarettes) and vaping have since been associated with lung injury. Nevertheless, there is limited perioperative data on their potential contribution to the harmful effects of mechanical ventilation on the lungs. We hypothesized that, in adults undergoing noncardiothoracic surgeries, preoperative vaping/e-cigarette use is associated with hypoxemia during the first postoperative hour, and with an increased incidence of intraoperative and postoperative pulmonary complications. METHODS: We conducted a retrospective cohort study in which we included patients reporting as vapers/e-cigarette users within one year before surgery as the exposure group, and nonvapers as the control group. The primary outcome was the time-weighted average (TWA) SpO2/FIO2 ratio in the postanesthesia care unit during the first postoperative hour. The secondary outcome was a composite of intraoperative and postoperative pulmonary complications until discharge. We used entropy balancing to adjust for confounding, and fit weighted linear regression and logistic regression models to estimate treatment effects. RESULTS: A total of 110,940 patients met the inclusion criteria, and 1,941 of these were vapers/e-cigarette users. The average treatment effect on the treated for TWA SpO2/FIO2 ratio (N = 109,217) was estimated to be a mean difference of 4 (95% confidence interval [CI], 1 to 8; P = 0.007). This is equivalent to a 4% change in SpO2 at a 30% FIO2 (or at a fixed FIO2). The difference was statistically significant. The average treatment effect on the treated for experiencing intraoperative and postoperative pulmonary complications (N = 110,940) was an odds ratio of 1.04 (95% CI, 0.71 to 1.54; P = 0.84). CONCLUSION: Vaping/e-cigarette use was neither associated with clinically significant hypoxemia during the first hour in the postanesthesia care unit nor with an increase in pulmonary complications. Nevertheless, our findings cannot definitively exclude the deleterious effects of vaping and e-cigarette use on the lungs, and anesthesiologists should consider potential perioperative complications.

RéSUMé: OBJECTIF: Initialement introduites comme une alternative plus sécuritaire au tabagisme, les cigarettes électroniques et le vapotage ont depuis été associés à des lésions pulmonaires. Néanmoins, il existe peu de données périopératoires concernant leur contribution potentielle aux effets nocifs de la ventilation mécanique sur les poumons. Nous avons émis l'hypothèse que, chez les adultes bénéficiant de chirurgies non cardiothoraciques, l'utilisation préopératoire de vapotage/de cigarette électronique était associée à une hypoxémie au cours de la première heure postopératoire et à une incidence accrue de complications pulmonaires peropératoires et postopératoires. MéTHODE: Nous avons mené une étude de cohorte rétrospective dans laquelle nous avons inclus les patient·es déclarant avoir vapoté ou utilisé des cigarettes électroniques dans l'année précédant la chirurgie comme groupe d'exposition, et les personnes ne vapotant pas comme groupe témoin. Le critère d'évaluation principal était le rapport de SpO2/FIO2 moyen pondéré dans le temps en salle de réveil pendant la première heure postopératoire. Le critère d'évaluation secondaire était un mélange de complications pulmonaires peropératoires et postopératoires jusqu'au congé de l'hôpital. Nous avons utilisé l'équilibrage d'entropie pour ajuster les facteurs de confusion et ajusté les modèles de régression linéaire pondérée et de régression logistique pour estimer les effets du traitement. RéSULTATS: Au total, 110 940 patient·es répondaient aux critères d'inclusion, dont 1941 étaient des vapoteurs ou vapoteuses/utilisaient des cigarettes électroniques. L'effet moyen du traitement sur le rapport de SpO2/FIO2 moyen pondéré dans le temps des personnes traitées (N = 109 217) a été estimé à une différence moyenne de 4 (intervalle de confiance [IC] à 95 %, 1 à 8; P = 0,007). Cela équivaut à une variation de 4 % de la SpO2 à 30% FIO2 (ou à une FIO2 fixe). La différence était statistiquement significative. L'effet moyen du traitement sur les personnes traitées pour des complications pulmonaires peropératoires et postopératoires (N = 110 940) était un rapport de cotes de 1,04 (IC 95 %, 0,71 à 1,54; P = 0,84). CONCLUSION: L'utilisation du vapotage et de la cigarette électronique n'était associée ni à une hypoxémie cliniquement significative au cours de la première heure en salle de réveil, ni à une augmentation des complications pulmonaires. Néanmoins, nos résultats ne peuvent exclure de manière définitive les effets délétères du vapotage et de l'utilisation de la cigarette électronique sur les poumons, et les anesthésiologistes devraient tenir compte des complications périopératoires potentielles.

Intraoperative mechanical power and postoperative pulmonary complications in low-risk surgical patients: a prospective observational cohort study.

BACKGROUND: Inadequate intraoperative mechanical ventilation (MV) can lead to ventilator-induced lung injury and increased risk for postoperative pulmonary complications (PPCs). Mechanical power (MP) was shown to be a valuable indicator for MV outcomes in critical care patients. The aim of this study is to assess the association between intraoperative MP in low-risk surgical patients undergoing general anesthesia and PPCs. METHODS: Two-hundred eighteen low-risk surgical patients undergoing general anesthesia for elective surgery were included in the study. Intraoperative mechanical ventilatory support parameters were collected for all patients. Postoperatively, patients were followed throughout their hospital stay and up to seven days post discharge for the occurrence of any PPCs. RESULTS: Out of 218 patients, 35% exhibited PPCs. The average body mass index, tidal volume per ideal body weight, peak inspiratory pressure, and MP were significantly higher in the patients with PPCs than in the patients without PPCs (30.3 ± 8.1 kg/m2 vs. 26.8 ± 4.9 kg.m2, p < 0.001; 9.1 ± 1.9 ml/kg vs. 8.6 ± 1.4 ml/kg, p = 0.02; 20 ± 4.9 cmH2O vs. 18 ± 3.7 cmH2O, p = 0.001; 12.9 ± 4.5 J/min vs. 11.1 ± 3.7 J/min, p = 0.002). A multivariable regression analysis revealed MP as the sole significant predictor for the risk of postoperative pulmonary complications [OR 1.1 (95% CI 1.0-1.2, p = 0.036]. CONCLUSIONS: High intraoperative mechanical power is a risk factor for developing postoperative pulmonary complications. Furthermore, intraoperative mechanical power is superior to other traditional mechanical ventilation variables in identifying surgical patients who are at risk for developing postoperative pulmonary complications. CLINICAL TRIAL REGISTRATION: NCT03551899; 24/02/2017.

Association between mechanical power during one-lung ventilation and pulmonary complications after thoracoscopic lung resection surgery: a prospective observational study.

BACKGROUND: The role of mechanical power on pulmonary outcomes after thoracic surgery with one-lung ventilation was unclear. We investigated the association between mechanical power and postoperative pulmonary complications in patients undergoing thoracoscopic lung resection surgery. METHODS: In this single-center, prospective observational study, 622 patients scheduled for thoracoscopic lung resection surgery were included. Volume control mode with lung protective ventilation strategies were implemented in all participants. The primary endpoint was a composite of postoperative pulmonary complications during hospital stay. Multivariable logistic regression models were used to evaluate the association between mechanical power and outcomes. RESULTS: The incidence of pulmonary complications after surgery during hospital stay was 24.6% (150 of 609 patients). The multivariable analysis showed that there was no link between mechanical power and postoperative pulmonary complications. CONCLUSIONS: In patients undergoing thoracoscopic lung resection with standardized lung-protective ventilation, no association was found between mechanical power and postoperative pulmonary complications. TRIAL REGISTRATION: Trial registration number: ChiCTR2200058528, date of registration: April 10, 2022.

Positive end-expiratory pressure and postoperative pulmonary complications in laparoscopic bariatric surgery: systematic review and meta-analysis.

BACKGROUND: This study compares the effect of positive end-expiratory pressure (PEEP) on postoperative pulmonary complications (PPCs) in patients with obesity undergoing laparoscopic bariatric surgery (LBS) under general anesthesia with mechanical ventilation. METHODS: A comprehensive search was conducted in PubMed, Embase, Web of Science, Cochrane Central Register of Controlled Trials, China National Knowledge Internet, Wanfang database, and Google Scholar for studies published up to July 29, 2023, without time or language restrictions. The search terms included "PEEP," "laparoscopic," and "bariatric surgery." Randomized controlled trials comparing different levels of PEEP or PEEP with zero-PEEP (ZEEP) in patients with obesity undergoing LBS were included. The primary outcome was a composite of PPCs, and the secondary outcomes were intraoperative oxygenation, respiratory compliance, and mean arterial pressure (MAP). A fixed-effect or random-effect model was selected for meta-analysis based on the heterogeneity of the included studies. RESULTS: Thirteen randomized controlled trials with a total of 708 participants were included for analysis. No statistically significant difference in PPCs was found between the PEEP and ZEEP groups (risk ratio = 0.27, 95% CI: 0.05-1.60; p = 0.15). However, high PEEP ≥ 10 cm H2O significantly decreased PPCs compared with low PEEP < 10 cm H2O (risk ratio = 0.20, 95% CI: 0.05-0.89; p = 0.03). The included studies showed no significant heterogeneity (I2 = 20% & 0%). Compared with ZEEP, PEEP significantly increased intraoperative oxygenation and respiratory compliance (WMD = 74.97 mm Hg, 95% CI: 41.74-108.21; p < 0.001 & WMD = 9.40 ml cm H2O- 1, 95% CI: 0.65-18.16; p = 0.04). High PEEP significantly improved intraoperative oxygenation and respiratory compliance during pneumoperitoneum compared with low PEEP (WMD = 66.81 mm Hg, 95% CI: 25.85-107.78; p = 0.001 & WMD = 8.03 ml cm H2O- 1, 95% CI: 4.70-11.36; p < 0.001). Importantly, PEEP did not impair hemodynamic status in LBS. CONCLUSIONS: In patients with obesity undergoing LBS, high PEEP ≥ 10 cm H2O could decrease PPCs compared with low PEEP < 10 cm H2O, while there was a similar incidence of PPCs between PEEP (8-10 cm H2O) and the ZEEP group. The application of PEEP in ventilation strategies increased intraoperative oxygenation and respiratory compliance without affecting intraoperative MAP. A PEEP of at least 10 cm H2O is recommended to reduce PPCs in patients with obesity undergoing LBS. REGISTRATION NUMBER: CRD42023391178 in PROSPERO.

Impact of staged goal-directed fluid therapy on postoperative pulmonary complications in patients undergoing McKeown esophagectomy: a randomized controlled trial.

BACKGROUND: Our aim was to evaluate the influence of staged goal directed therapy (GDT) on postoperative pulmonary complications (PPCs), intraoperative hemodynamics and oxygenation in patients undergoing Mckeown esophagectomy. METHODS: Patients were randomly divided into three groups, staged GDT group (group A, n = 56): stroke volume variation (SVV) was set at 8-10% during the one lung ventilation (OLV) stage and 8-12% during the two lung ventilation (TLV) stage, GDT group (group B, n = 56): received GDT with a target SVV of 8-12% During the entire surgical procedure, and control group (group C, n = 56): conventional fluid therapy was administered by mean arterial pressure (MAP), central venous pressure (CVP), and urine volume. The primary outcome was the incidence of postoperative pulmonary complications within Postoperative days (POD) 7. The secondary outcomes were postoperative lung ultrasound (LUS) B-lines artefacts (BLA) scoring, incidence of other complications, the length of hospital stay, intraoperative hemodynamic and oxygenation indicators included mean arterial pressure (MAP), heart rate (HR), cardiac index (CI), cardiac output (CO), oxygenation index (OI), respiratory indices (RI), alveolar-arterial oxygen difference (Aa-DO2). RESULTS: Patients in group A and group B had a lower incidence of PPCs (7/56 vs. 17/56 and 9/56 vs. 17/56, p < 0.05), and a fewer B-lines score on postoperative ultrasound (4.61 ± 0.51 vs. 6.15 ± 0.74 and 4.75 ± 0.62 vs. 6.15 ± 0.74, p < 0.05) compared to group C. The CI, CO, MAP, and OI were higher in group A compared to group B and group C in the stage of thoracic operation. During the abdominal operation stage, patients in group A and group B had a better hemodynamic and oxygenation indicators than group C. CONCLUSIONS: In comparison to conventional fluid therapy, intraoperative staged GDT can significantly reduce the incidence of postoperative pulmonary complications in patients undergoing McKeown esophagectomy, facilitating patient recovery. Compared to GDT, it can improve intraoperative oxygenation and stabilize intraoperative hemodynamics in patients. TRIAL REGISTRATION: This study was registered in the Chinese Clinical Trial Registry on 24/11/2021 (ChiCTR2100053598).