Exercise testing and postoperative complications after minimally invasive lung resection: A cohort study

Ventilatory efficiency as a prognostic factor for postoperative complications in patients undergoing elective major surgery: a systematic review

BACKGROUND

Major surgery is associated with high complication rates. Several risk scores exist to assess individual patient risk before surgery but have limited precision. Novel prognostic factors can be included as additional building blocks in existing prediction models. A candidate prognostic factor, measured by cardiopulmonary exercise testing, is ventilatory efficiency (VE/VCO2). The aim of this systematic review was to summarise evidence regarding VE/VCO2 as a prognostic factor for postoperative complications in patients undergoing major surgery.

METHODS

A medical library specialist developed the search strategy. No database-provided limits, considering study types, languages, publication years, or any other formal criteria were applied to any of the sources. Two reviewers assessed eligibility of each record and rated risk of bias in included studies.

RESULTS

From 10,082 screened records, 65 studies were identified as eligible. We extracted adjusted associations from 32 studies and unadjusted from 33 studies. Risk of bias was a concern in the domains 'study confounding' and 'statistical analysis'. VE/VCO2 was reported as a prognostic factor for short-term complications after thoracic and abdominal surgery. VE/VCO2 was also reported as a prognostic factor for mid- to long-term mortality. Data-driven covariable selection was applied in 31 studies. Eighteen studies excluded VE/VCO2 from the final multivariable regression owing to data-driven model-building approaches.

CONCLUSIONS

This systematic review identifies VE/VCO2 as a predictor for short-term complications after thoracic and abdominal surgery. However, the available data do not allow conclusions about clinical decision-making. Future studies should select covariables for adjustment a priori based on external knowledge.

SYSTEMATIC REVIEW PROTOCOL

PROSPERO (CRD42022369944).

Multimodal Prehabilitation for Patients with Crohn's Disease Scheduled for Major Surgery: A Narrative Review

Approximately 15-50% of patients with Crohn's disease (CD) will require surgery within ten years following the diagnosis. The management of modifiable risk factors before surgery is essential to reduce postoperative complications and to promote a better postoperative recovery. Preoperative malnutrition reduced functional capacity, sarcopenia, immunosuppressive medications, anemia, and psychological distress are frequently present in CD patients. Multimodal prehabilitation consists of nutritional, functional, medical, and psychological interventions implemented before surgery, aiming at optimizing preoperative status and improve postoperative recovery. Currently, studies evaluating the effect of multimodal prehabilitation on postoperative outcomes specifically in CD are lacking. Some studies have investigated the effect of a single prehabilitation intervention, of which nutritional optimization is the most investigated. The aim of this narrative review is to present the physiologic rationale supporting multimodal surgical prehabilitation in CD patients waiting for surgery, and to describe its main components to facilitate their adoption in the preoperative standard of care.

Percent predicted peak oxygen uptake is superior to weight-indexed peak oxygen uptake in risk stratification before lung cancer lobectomy

OBJECTIVE

To improve preoperative risk stratification in lung cancer lobectomy by identifying and comparing optimal thresholds for peak oxygen uptake (VO2peak) presented as weight-indexed and percent of predicted values, respectively.

METHODS

This was a longitudinal cohort study including national registry data on patients scheduled for cancer lobectomy that used available data from preoperative cardiopulmonary exercise testing. The measured VO2peak was indexed by body mass (mL/kg/min) and also compared with 2 established reference equations (Wasserman-Hansen and Study of Health in Pomerania, respectively). By receiver operating characteristic analysis, a lower 90% specificity and an upper 90% sensitivity threshold were determined for each measure, in relation to the outcome of any major complication or death. For each measure and based on these thresholds, patients were categorized as low risk, intermediate risk, or high risk. The frequency of complications was compared between groups using χ2.

RESULTS

The frequency of complications differed significantly between the proposed low-, intermediate-, and high-risk groups when using % predicted Study of Health in Pomerania (5%, 21%, 35%, P = .007) or % predicted Wasserman-Hansen (5%, 25%, 35%, P = .002) but not when using the weight-indexed VO2peak groups (7%, 23%, 15%, P = .08). Nonsignificant differences were found using the threshold <15 mL/kg/min (P = .34).

CONCLUSIONS

This study showed that weight-indexed VO2peak was of less use as a marker of risk at the lower range of exercise capacity, whereas % predicted VO2peak was associated with a continuously increasing risk of major complications, also at the lower end of exercise capacity. As identifying subjects at high risk of complications is important, % predicted VO2peak is therefore preferable.

The association between cardiopulmonary exercise testing and postoperative outcomes in patients with lung cancer undergoing lung resection surgery: A systematic review and meta-analysis

BACKGROUND

Exercise capacity should be determined in all patients undergoing lung resection for lung cancer surgery and cardiopulmonary exercise testing (CPET) remains the gold standard. The purpose of this study was to investigate associations between preoperative CPET and postoperative outcomes in patients undergoing lung resection surgery for lung cancer through a review of the existing literature.

METHODS

A search was conducted on PubMed, Scopus, Cochrane Library and CINAHL from inception until December 2022. Studies investigating associations between preoperative CPET and postoperative outcomes were included. Risk of bias was assessed using the QUIPS tool. A random effect model meta-analysis was performed. I2 > 40% indicated a high level of heterogeneity.

RESULTS

Thirty-seven studies were included with 6450 patients. Twenty-eight studies had low risk of bias. [Formula: see text] peak is the oxygen consumption at peak exercise and serves as a marker of cardiopulmonary fitness. Higher estimates of [Formula: see text] peak, measured and as a percentagege of predicted, showed significant associations with a lower risk of mortality [MD: 3.66, 95% CI: 0.88; 6.43 and MD: 16.49, 95% CI: 6.92; 26.07] and fewer complications [MD: 2.06, 95% CI: 1.12; 3.00 and MD: 9.82, 95% CI: 5.88; 13.76]. Using a previously defined cutoff value of > 15mL/kg/min for [Formula: see text] peak, showed evidence of decreased odds of mortality [OR: 0.55, 95% CI: 0.28-0.81] and but not decreased odds of postoperative morbidity [OR: 0.82, 95% CI: 0.64-1.00]. There was no relationship between [Formula: see text] slope, which depicts ventilatory efficiency, with mortality [MD: -9.60, 95% CI: -27.74; 8.54] however, patients without postoperative complications had a lower preoperative [Formula: see text] [MD: -2.36, 95% CI: -3.01; -1.71]. Exercise load and anaerobic threshold did not correlate with morbidity or mortality. There was significant heterogeneity between studies.

CONCLUSIONS

Estimates of cardiopulmonary fitness as evidenced by higher [Formula: see text] peak, measured and as a percentage of predicted, were associated with decreased morbidity and mortality. A cutoff value of [Formula: see text] peak > 15mL/kg/min was consistent with improved survival but not with fewer complications. Ventilatory efficiency was associated with decreased postoperative morbidity but not with improved survival. The heterogeneity in literature could be remedied with large scale, prospective, blinded, standardised research to improve preoperative risk stratification in patients with lung cancer scheduled for lung resection surgery.

Exercise Physiology and Cardiopulmonary Exercise Testing

Aerobic, or endurance, exercise is an energy requiring process supported primarily by energy from oxidative adenosine triphosphate synthesis. The consumption of oxygen and production of carbon dioxide in muscle cells are dynamically linked to oxygen uptake (V̇O2) and carbon dioxide output (V̇CO2) at the lung by integrated functions of cardiovascular, pulmonary, hematologic, and neurohumoral systems. Maximum oxygen uptake (V̇O2max) is the standard expression of aerobic capacity and a predictor of outcomes in diverse populations. While commonly limited in young fit individuals by the capacity to deliver oxygen to exercising muscle, (V̇O2max) may become limited by impairment within any of the multiple systems supporting cellular or atmospheric gas exchange. In the range of available power outputs, endurance exercise can be partitioned into different intensity domains representing distinct metabolic profiles and tolerances for sustained activity. Estimates of both V̇O2max and the lactate threshold, which marks the upper limit of moderate-intensity exercise, can be determined from measures of gas exchange from respired breath during whole-body exercise. Cardiopulmonary exercise testing (CPET) includes measurement of V̇O2 and V̇CO2 along with heart rate and other variables reflecting cardiac and pulmonary responses to exercise. Clinical CPET is conducted for persons with known medical conditions to quantify impairment, contribute to prognostic assessments, and help discriminate among proximal causes of symptoms or limitations for an individual. CPET is also conducted in persons without known disease as part of the diagnostic evaluation of unexplained symptoms. Although CPET quantifies a limited sample of the complex functions and interactions underlying exercise performance, both its specific and global findings are uniquely valuable. Some specific findings can aid in individualized diagnosis and treatment decisions. At the same time, CPET provides a holistic summary of an individual's exercise function, including effects not only of the primary diagnosis, but also of secondary and coexisting conditions.

Interpretable prediction of cardiopulmonary complications after non-small cell lung cancer surgery based on machine learning and SHapley additive exPlanations

Introduction

Lung cancer is a prevalent malignancy globally, with approximately 20% of patients developing cardiopulmonary complications after lobectomy. In order to prevent complications, an accurate and personalized method based on machine learning (ML) is required.

Methods

During the period of 2017-2021, a retrospective analysis was conducted on the medical records of patients who had undergone lobectomy for non-small cell lung cancer (NSCLC). We performed logical regression, decision tree (DT), random forest (RF), gradient boost DT, and eXtreme gradient boosting analyses to establish an ML model. The ten-fold cross-validation was used to evaluate the performance of multiple ML models based on various evaluation metrics, including accuracy, precision, recall, F1 score, and area under the receiver operating (AUC). Additionally, we also calculated the Kappa value of these model. Each model used grid search to optimize hyper-parameters and then used the interpretability method to provide explanations for the model's Decisions.

Results

The study included 718 eligible patients, among whom the incidence of postoperative cardiopulmonary complications was 20.89%. The RF model showed the best comprehensive performance among all models, and its ten-fold cross-validation accuracy, precision, recall, F1 score, and AUC were (OR and 95% confidence interval [CI]) 0.786 (0.738-0.834), 0.803 (0.735-0.872), 0.738 (0.678-0.797), 0.766 (0.714-0.818), 0.856 (0.815-0.898), respectively. The kappa value of the RF model was 0.696 (0.617-0.768). The SHAP method showed that gender, age, and intraoperative blood loss were closely associated with postoperative cardiopulmonary complications.

Conclusion

The application of ML methods for predicting postoperative cardiopulmonary complications based on clinical data of patients with NSCLC showed a good performance. The results indicate that ML combined with the SHAP individualized interpretation method has practical clinical value.

Early outcomes of “low-risk” patients undergoing lung resection assessed by cardiopulmonary exercise testing: Single-institution experience

Objective

Cardiopulmonary exercise testing (CPET) is currently recommended for all patients undergoing lung resection with either respiratory comorbidities or functional limitations. The main parameter evaluated is oxygen consumption at peak (VO2peak). Patients with VO2peak above 20 ml/kg/min are classified as low risk surgical candidates. The aims of this study were to evaluate postoperative outcomes of low-risk patients, and to compare their outcomes with those of patients without pulmonary impairment at respiratory function testing.

Methods

Retrospective monocentric observational study was designed, evaluating outcomes of patients undergoing lung resection at San Paolo University Hospital, Milan, Italy, between January 2016 and November 2021, preoperatively assessed by CPET, according to 2009 ERS/ESTS guidelines. All low-risk patients undergoing any extent surgical lung resection for pulmonary nodules were enrolled. Postoperative major cardiopulmonary complications or death, occurring within 30 days from surgery, were assessed. A case-control study was nested, matching 1:1 for type of surgery the cohort population with control patients without functional respiratory impairment consecutively undergoing surgery at the same centre in the study period.

Results

A total of 80 patients were enrolled: 40 subjects were preoperatively assessed by CPET and deemed at low risk, whereas 40 subjects represented the control group. Among the first, 4 patients (10%) developed major cardiopulmonary complications, and 1 patient (2.5%) died within 30 days from surgery. In the control group, 2 patients (5%) developed complications and none of the patients (0%) died. The differences in morbidity and mortality rates did not reach statistically significance. Instead, age, weight, BMI, smoking history, COPD incidence, surgical approach, FEV1, Tiffenau, DLCO and length of hospital stay resulted significantly different between the two groups. At a case-by-case analysis, CPET revealed a pathological pattern in each complicated patient, in spite of VO2peak above target for safe surgery.

Conclusions

Postoperative outcomes of low-risk patients undergoing lung resections are comparable to those of patients without any pulmonary functional impairment; nonetheless the formers represent a dramatically different category of individuals from the latter and may harbour few patients with worse outcomes. CPET variables overall interpretation may add to the VO2peak in identifying higher risk patients, even in this subgroup.