Do we have the 'power' to 'drive' down the incidence of pulmonary complications after thoracic surgery

Intraoperative Factors Associated With Mechanical Ventilation Duration Following Aortic Surgery

OBJECTIVES

Prolonged postoperative mechanical ventilation is a common complication after major aortic surgery. The relationship between prolonged ventilation and intraoperative variables influenced by anesthesiologists, such as ventilation practices, fluid administration, and blood pressure control during major aortic surgery is unknown. We sought to identify perioperative factors, including intraoperative physiologic and anesthesia-related variables, which are associated with ventilation duration following aortic surgery.

DESIGN

Single-center retrospective observational study.

SETTING

A tertiary, high-volume cardiac surgery referral center.

PARTICIPANTS

Adult patients undergoing major aortic surgery requiring cardiopulmonary bypass (CPB).

INTERVENTIONS

None (retrospective observational study).

MEASUREMENTS AND MAIN RESULTS

The primary outcome was the duration of postoperative ventilation (hours). Mixed-effects regression was performed to identify factors associated with the primary outcome. Among the 647 patients included in this study, the median of postoperative mechanical ventilation duration was 9.0 (IQR 6.0, 14.4) hours, with 73 (11.3%) of patients receiving mechanical ventilation for more than 24 hours. Variables significantly associated with the outcome were increases in pre- to post-CPB driving pressure (β = 4.23; 95% CI [0.08, 8.39]; p = 0.04), reduction in pre- to post-CPB end-tidal carbon dioxide partial pressure (β = -5.12; 95% CI [-8.85, -1.39]; p < 0.001), and normalized transfusion volumes (β = 11.14; 95% CI [4.36, 17.91]; p < 0.001). Mechanical power was not associated with postoperative ventilation duration (β = -2.29; 95% CI [-6.48, 1.90]; p = 0.52).

CONCLUSIONS

Patients undergoing major aortic surgery are at risk for prolonged mechanical ventilation. Transfusion volume and pre- to post-CPB changes in driving pressures and end-tidal carbon dioxide are significantly associated with postoperative ventilation duration. Intraoperative mechanical ventilator power is not a significant predictor of mechanical ventilation duration after major aortic surgery. These variables are potentially modifiable by anesthesiologists and may be future therapeutic targets.

Analysis of risk factors for hypoxemia in PACU for patients undergoing thoracoscopic lung cancer resection based on logistic regression model

OBJECTIVE

This study aims to identify risk factors of hypoxemia in patients undergoin thoracoscopic lung surgery during their stay in the post-anesthesia care unit (PACU). Hypoxemia was defined as any instance of SpO₂ ≤90% lasting for more than one minute during the PACU stay.

METHODS

We conducted a prospective research involving 398 patients who underwent elective thoracoscopic lung surgery in West China Hospital, Sichuan University, from April to July 2024. Patients were classified into hypoxemia and non-hypoxemia groups based on the presence of hypoxemia in the PACU. We compared clinical data between the two groups to identify factors influencing hypoxemia. Variables with statistical significance (P < 0.05) in univariate analysis were included in logistic regression to identify independent risk factors for hypoxemia.

RESULTS

Among the 398 patients studied, 149 (37.4%) experienced hypoxemia. Univariate analysis indicated significant differences in age, BMI, height, ASA classification, hypertension, diabetes, lung function test with Forced Expiratory Volume at 1 s / Forced Vital Capacity (FEV1/FVC), and awakening time between the groups. Logistic regression revealed that age, BMI, ASA classification, hypertension, diabetes, and awakening time were independent risk factors for hypoxemia during anesthesia recovery, while preoperative SpO2 upon entering operating room (OR = 0.882, 95% CI: 0.783-0.993, P = 0.038) was identified as a protective factor.

CONCLUSION

Age, BMI, ASA classification, and preoperative conditions such as hypertension and diabetes are found to contribute to an increased incidence of hypoxemia in PACU following thoracoscopic lung surgery. Emphasizing preoperative lung function assessments and enhanced monitoring may also facilitate timely interventions, thereby improving post-anesthesia recovery and patient outcomes.

Development and validation of a nomogram for predicting postoperative pulmonary complications in older patients undergoing noncardiac thoracic surgery: a prospective, bicentric cohort study

BACKGROUND

The ARISCAT score, a prospectively developed generic classification for postoperative pulmonary complications (PPCs), has shown excellent predictive performance in general surgery. However, there is no reliable classification instrument for PPCs prediciton in thoracic surgery.

OBJECTIVE

This study aimed to develop and validate a novel nomogram for estimating the risk of pulmonary complications in older patients (≥ 65 years) within 30 days after NCTS.

METHODS

A nomogram was developed using predefined candidate predictors of 30-day PPCs. It was fitted with least absolute shrinkage and selection operator and logistic regression methods. Internal validation was performed using a bootstrap-resampling approach, while external validation used an independent, temporally separated cohort. The model's performance was assessed based on its discriminative potential (area under the receiver operating characteristic curve [AUC]), predictive ability (calibration plots), and clinical utility (net benefit).

RESULTS

In the development (n = 1449) and validation (n = 449) cohorts, 34.9% and 31.4% of patients, respectively, developed pulmonary complications 30 days post-surgery. The final nomogram incorporated eight predictors (age, surgical approach, desaturation of < 92% for more than 2 min, duration of surgery, smoking status, FEV1/FVC%, respiratory infection in the last 30 days, and neoadjuvant chemotherapy). The nomogram showed excellent discrimination (AUC = 0.866, 95% confidence interval [CI], 0.846-0.885), calibration (Hosmer- Lemeshow test, P = 0.97) and overall performance (Brier score = 0.014) in the development cohort. Similar results were observed in the external validation cohort (AUC = 0.825, 95% CI, 0.786-0.864). A decision curve analysis indicated that the nomogram offers a positive net benefit compared with the ARISCAT and LAS VEGAS scores.

CONCLUSIONS

This novel nomogram can reliably identify older patients with a high risk for pulmonary complications within 30 days after NCTS.

TRIAL REGISTRATION

ChiCTR2100051170.

Protective mechanical ventilation in critically ill patients after surgery

PURPOSE OF REVIEW

This review aims to provide an updated overview of lung protective strategies in critically ill patients after surgery, focusing on the utility of postoperative open-lung ventilation during the transition from the operating room to the intensive care unit.

RECENT FINDINGS

Mechanically ventilated patients after surgery represent a challenge in the intensive care unit. Different protective strategies have been proposed to minimize the risk of ventilator-induced lung injury (VILI) and facilitate adequate weaning from mechanical ventilation. Fast-track extubation protocols, increasingly standard in the care of critically ill patients postsurgery, have demonstrated improvements in recovery and reductions in acute lung injury, primarily based on retrospective studies. Open-lung ventilation strategies, such as individualization of positive-end expiratory pressure based on driving pressure and postoperative noninvasive ventilation support with high-flow nasal cannula, are becoming standard of care in high-risk surgical patients after major abdominal or thoracic surgeries.

SUMMARY

Mechanical ventilation in surgical patients should adhere to lung protective strategies (i.e., individualizing positive end expiratory pressure and prioritize alveolar recruitment) during the transition from the operating room to the intensive care unit.

Unveiling the protective role of sevoflurane in video-assisted thoracoscopic surgery associated-acute lung injury: Inhibition of ferroptosis

Acute lung injury (ALI) frequently occurs after video-assisted thoracoscopic surgery (VATS). Ferroptosis is implicated in several lung diseases. Therefore, the disparate effects and underlying mechanisms of the two commonly used anesthetics (sevoflurane (Sev) and propofol) on VATS-induced ALI need to be clarified. In the present study, enrolled patients were randomly allocated to receive Sev (group S) or propofol anesthesia (group P). Intraoperative oxygenation, morphology of the lung tissue, expression of ZO-1, tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), superoxide dismutase (SOD), glutathione (GSH), Fe2+, glutathione peroxidase 4 (GPX4), and phosphoinositide 3-kinase (PI3K)/protein kinase B (AKT)/nuclear factor erythroid-2-related factor 2 (Nrf2)/heme oxygenase-1 (HO-1) pathway in the lung tissue as well as the expression of TNF-α and IL-6 in plasma were measured. Postoperative complications were recorded. Of the 85 initially screened patients scheduled for VATS, 62 were enrolled in either group S (n = 32) or P (n = 30). Compared with propofol, Sev substantially (1) improved intraoperative oxygenation; (2) relieved histopathological lung injury; (3) increased ZO-1 protein expression; (4) decreased the levels of TNF-α and IL-6 in both the lung tissue and plasma; (5) increased the contents of GSH and SOD but decreased Fe2+ concentration; (6) upregulated the protein expression of p-AKT, Nrf2, HO-1, and GPX4. No significant differences in the occurrence of postoperative outcomes were observed between both groups. In summary, Sev treatment, in comparison to propofol anesthesia, may suppress local lung and systemic inflammatory responses by activating the PI3K/Akt/Nrf2/HO-1 pathway and inhibiting ferroptosis. This cascade of effects contributes to the maintenance of pulmonary epithelial barrier permeability, alleviation of pulmonary injury, and enhancement of intraoperative oxygenation in patients undergoing VATS.

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.

Effect of lung isolation with different airway devices on postoperative pneumonia in patients undergoing video-assisted thoracoscopic surgery: a propensity score-matched study

BACKGROUND

Postoperative pneumonia is one of the common complications after video-assisted thoracoscopic surgery. There is no related study on the effect of lung isolation with different airway devices on postoperative pneumonia. Therefore, in this study, the propensity score matching method was used to retrospectively explore the effects of different lung isolation methods on postoperative pneumonia in patients undergoing video-assisted thoracoscopic surgery.

METHODS

This is A single-center, retrospective, propensity score-matched study. The information of patients who underwent VATS in Weifang People 's Hospital from January 2020 to January 2021 was retrospectively included. The patients were divided into three groups according to the airway device used in thoracoscopic surgery: laryngeal mask combined with bronchial blocker group (LM + BB group), tracheal tube combined with bronchial blocker group (TT + BB group) and double-lumen endobronchial tube group (DLT group). The main outcome was the incidence of pneumonia within 7 days after surgery; the secondary outcome were hospitalization time and hospitalization expenses. Patients in the three groups were matched using propensity score matching (PSM) analysis.

RESULTS

After propensity score matching analysis, there was no significant difference in the incidence of postoperative pneumonia and hospitalization time among the three groups (P > 0.05), but there was significant difference in hospitalization expenses among the three groups (P < 0.05).

CONCLUSIONS

There was no significant difference in the effect of different intubation lung isolation methods on postoperative pneumonia in patients undergoing thoracoscopic surgery.

Impact of Lower Tidal Volumes During One-Lung Ventilation: A 2022 Update of the Meta-analysis of Randomized Controlled Trials

OBJECTIVES

To clarify the influence of lower tidal volume (4-7 mL/kg) compared with higher tidal volume (8-15 mL/kg) during one-lung ventilation (OLV) on gas exchange and postoperative clinical outcome.

DESIGN

Meta-analysis of randomized trials.

SETTING

Thoracic surgery.

PARTICIPANTS

Patients receiving OLV.

INTERVENTIONS

Lower tidal volume during OLV.

MEASUREMENTS AND MAIN RESULTS

Primary outcome was PaO2-to-the oxygen fraction (PaO2/FIO2) ratio at the end of the surgery, after the reinstitution of two-lung ventilation. Secondary endpoints included perioperative changes in PaO2/FIO2 ratio and carbon dioxide (PaCO2) tension, airway pressure, the incidence of postoperative pulmonary complications, arrhythmia, and length of hospital stay. Seventeen randomized controlled trials (1,463 patients) were selected. Overall analysis showed that the use of low tidal volume during OLV was associated with a significantly higher PaO2/FIO2 ratio 15 minutes after the start of OLV and at the end of surgery (mean difference 33.7 mmHg [p = 0.02] and mean difference 18.59 mmHg [p < 0.001], respectively). The low tidal volume also was associated with higher PaCO2 values 15 minutes and 60 minutes after the start of OLV and with lower airway pressure, which was maintained during two-lung ventilation after surgery. Moreover, the application of lower tidal volume was associated with fewer postoperative pulmonary complications (odds ratio 0.50; p < 0.001) and arrhythmias (odds ratio 0.58; p = 0.009), with no difference in length of hospital stay.

CONCLUSIONS

The use of lower tidal volume, a component of protective OLV, increases the PaO2/FIO2 ratio, reduces the incidence of postoperative pulmonary complications, and should be considered strongly in daily practice.