The ventilatory efficiency slope (VE/VCO₂ slope) as a predictor of postoperative cardiopulmonary complications post lung segmentectomy in high-risk patients?

The ventilatory efficiency slope (VE/VCO₂ slope) as a predictor of postoperative cardiopulmonary complications post lung segmentectomy in high-risk patients? | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article The ventilatory efficiency slope (VE/VCO₂ slope) as a predictor of postoperative cardiopulmonary complications post lung segmentectomy in high-risk patients? Gabriel PLISSONNEAU, Quentin Rudondy, Tayeb Benkiran, Benoit Gerard, and 3 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-8502647/v1 This work is licensed under a CC BY 4.0 License Status: Under Revision Version 1 posted 7 You are reading this latest preprint version Abstract Background The ventilatory efficiency slope (VE/VCO₂) is an established prognostic marker for heart failure and pulmonary hypertension. It has been associated with postoperative risk after major lung resections. However, its predictive value in lung segmentectomy remains unclear. This study aims to assess the relationship between VE/VCO₂ slope and cardiopulmonary complications after segmentectomy, and to determine an optimal predictive threshold. Methods We conducted a retrospective, single-center study including patients over 18 years old, who underwent preoperative CPET before segmentectomy, between 2021 and 2025 in Nice. The primary endpoint was the association between VE/VCO₂ slope and cardiopulmonary complications occurring within 90 days. A subgroup analysis on grade II complications or more was conducted. Results Among 380 segmentectomy candidates, 27 patients with CPET were included (median age 68 years, 52% male, median FEV1 75% predicted). The median peak VO₂ was 16.4 ml/kg/min and median VE/VCO₂ slope was 33.5. Postoperative cardiopulmonary complications occurred in 8 patients (29%). Overall, VE/VCO₂ slope was not significantly different between patients with or without complications (38.0 vs. 33.9; p = 0.26). In subgroup analysis, VE/VCO₂ slope was significantly higher in patients with ≥ grade II complications (38.6 vs. 33.1; p = 0.046). A threshold of VE/VCO₂ ≥38 provided the best predictive performance (sensitivity 80%, specificity 81%, p = 0.02). Conclusion In high-risk patients undergoing segmentectomy, the VE/VCO₂ slope appears sensitive in predicting ≥ grade II complications. A threshold of 38 may be more appropriate. Larger prospective multicentred studies would be required to confirm these results. Trial registration : The Nice University Hospital and the ethical committee approved this retrospective, monocentric study (2025-EI-704, 2025-093, in May 2025) ventilatory slope lung segmentectomy predictor post-operative complications Figures Figure 1 Figure 2 Background Non-small cell lung cancer (NSCLC) is the most common lung cancer in industrialised countries( 1 ), and surgery is the gold standard treatment for localised tumour ( 2 ). Lobectomy is usually the preferred procedure, as recommended by the Lung Cancer Study Group in 1995 ( 3 ). Anatomical segmentectomy is the validated option for localised peripheral NSCLC (< 2 cm and without lymph node invasion)( 4 , 5 ). However, the rate of postoperative complications is estimated at 17.8% after pulmonary segmentectomy( 6 ). Several risk factors for postoperative complications have been identified, including: advanced age, male gender, preoperative forced expiratory volume in one second (FEV1) 30kg/m2, and chronic obstructive pulmonary disease (COPD) ( 7 ). In preoperative assessments, the pulmonary function test (PFT) to measure FEV1 and carbon monoxide diffusion capacity (DLCO) are recommended. Following American recommendations, in cases of PPO FEV1 or DLCO < 60%, a walking test or a stair climbing test may be performed. When the walking test result is < 400m or the stair climbing test is < 22 m of altitude, a cardiopulmonary exercise testing (CPET) to measure maximal oxygen consumption (VO2max) is recommended( 8 ). Furthermore, following European recommendations, CPET could also be performed in cases of preoperative FEV1 or DLCO < 80%( 2 ). According to international recommendations, patients with a VO2max 20 mL/kg/min have a low risk for postoperative complications or even death ( 9 ). In high-risk surgical patient, a lobectomy or pneumonectomy are not recommended. If the indicators demonstrate a low risk, all resection types can be performed. Regarding intermediate risks, other parameters need to be studied, such as the measurement of ventilatory efficiency by the slope of minute ventilation (VE) on carbon dioxide production (VCO2) (VE/VCO2 slope) ( 10 – 18 ). An elevated VE/VCO2 slope > 35 is associated with an increased risk of postoperative cardiorespiratory complications (22% versus 7.6%, p = 0.004) ( 11 ), and an increased 30-day postoperative mortality rate (7.2% vs. 0.6%, p = 0.01) in patients with heart failure and COPD ( 10 , 11 ). In 2016, an algorithm defined patients with a VO2max between 10 and 20 ml/kg/min as a low risk if the VE/VCO2 slope is ≤ 35, or as high risk if the VE/VCO2 slope is > 35 ( 19 ). However, this algorithm is only valid for lobectomy and pneumonectomy. Post-segmentectomy mortality is similar to lobectomy, which is approximately 2% at 3 months ( 20 ). Postoperative complications within 90 days following surgery are circa 34% ( 21 ). The identified risk factors are FEV1 < 60% PPO, male gender, and thoracotomy ( 21 ). Postoperative risk stratification based on VO2max, established for lobectomy, is extended and applied to segmentectomy ( 2 ). Regarding studies on the VE/VCO2 slope, only four articles included segmentectomy ( 13 , 14 , 17 , 18 ), which limits the generalizability of the results. The role of the VE/VCO2 slope remains unclear for infra-lobar resection surgeries such as segmentectomy. Therefore, the aim of this study is to define the role of the VE/VCO2 slope and to validate an appropriate threshold for predicting the risks of post-operative complications after a segmentectomy. Methods 2.1) Patient population : The Nice University Hospital and the ethical committee approved this retrospective, monocentric study (2025-EI-704, 2025-093, in May 2025). We included all adult patients who had performed a CPET before a lung segmentectomy between January 2021 and April 2025. The following patients were excluded: 1) absence of CPET before segmentectomy, 2) unfit for surgery (VO2 max < 10mL/kg/min or pulmonary hypertension), 3) absence of informed consent. 2.2) Variables and outcomes : Anthropometric data (age, height, weight), smoking status, medical and surgical history, calculation of left ventricular ejection fraction (LVEF), FEV1, and DLCO were collected preoperatively. The calculation of PPO lung capacity values is based on the ERS/ESTS recommendations for lobectomy ( 2 ). CPET data such as maximality, VE/VCO2 slope, peak VO2 and work rate were recorded. CPET was performed according to international recommendations ( 22 ). Maximality in CPET is defined by the presence of at least three of the following criteria: 1) Heart rate > 90% of theoretical maximum heart rate, 2) Change in VO2 of 1.10, 4) Borg scale rated 10/10 for dyspnoea or muscle, 5) pedalling frequency < 60 rpm. In case of a non-maximal test, the value used was peak VO2: maximum VO2 reached at peak effort. The VE/VCO2 slope was measured, by a single operator, in the MEDISOFT® software, plotting a linear relationship between the start of the exercise and the Ventilation threshold 1 (VT1). A multidisciplinary consultation meeting involving pulmonologists, thoracic surgeons, oncologists, pathologists, and radiation therapists, decided to perform segmentectomies on eligible patients. The surgical procedures were performed according to international guidelines ( 2 ). Intraoperative data such as the type of surgery, operating time, length of stay, and complications was recorded. In accordance with international recommendations ( 23 ), cardiopulmonary complications included: 1) atelectasis requiring bronchoscopy, 2) pneumonia requiring antibiotic therapy, 3) prolonged leakage > 5 days, 4) Occurrence of pneumothorax post-drain removal necessitating subsequent chest tube reinsertion, 5)pulmonary embolism, 6) acute respiratory distress syndrome, 7) prolonged intubation > 48 hours, 8) reintubation, 9) atrial or ventricular fibrillation requiring drug or electrical reduction, 10) acute pulmonary oedema, 11) myocardial infarction, 12) empyema, or 13) death. Our primary endpoint was a correlation between an increased VE/VCO2 slope and postoperative complications within 90 days. Our secondary endpoint was to define a predictive threshold for postoperative complications following segmentectomy. 2.3) Statistical analysis : Quantitative variables are presented as median and quartiles. Categorical variables are presented as percentages with their frequencies. A Mann-Whitney test was used to compare quantitative variables. A Fisher test was used to compare qualitative variables. For every descriptive analysis, differences were considered significant when the p-value was < 0.05. Subgroup analyses were performed based on the type of complication: the severity of postoperative complications (those requiring therapeutic intervention (grade II or higher according to the Dindo et al. classification) ( 24 )). For our secondary endpoint, calculations of sensitivity, specificity, positive and negative predictive values were also performed. Results Between January 2021 and April 2025, 380 patients have had an indication of a segmentectomy. Among them, only 35 (9%) performed a CPET before surgery. A total of 27 patients were included in the study (Fig. 1). Our population consisted of 52% men with a median age of 68 [63; 72.5] years and a median BMI of 24.6 [21.9; 26.9] kg/m2 (Table 1 ). Thirty-seven percent of patients were active smokers, and 55% were former smokers. The most common comorbidities were COPD (62%), hypertension (40%), and peripheral arterial disease (PAD, 31%). The median FEV1 was 1.94 [1.69; 2.59] L, or 75 [66.2; 87.8]% of predicted, and the median PPO FEV1 was 68.5 [61.3; 81.7]% of predicted. The median DLCO was 58.5 [52.8; 73.0]% of predicted, with a median PPO DLCO of 53.2 [48.8; 62.5]% of predicted. The median VO2 peak was 16.4 [14.1; 18.0] ml/kg/min, or 68.1 [58.8; 79.2]% of predicted, and the median VE/VCO2 slope was 33.5 [30.2; 38.4] (Tables 1 & 2 ). Table 1 Preoperative characteristics of our study population All patients (n = 27) Without complication (n = 19) With complication (n = 8) p value Preoperative clinical data Male gender, n (%) 14 (52%) 10 (52%) 4 (50%) 0.68 Age, years 68.0 [63.0 ; 72.5] 67.6 [61.8; 70.6] 70.7 [67.6; 73.9] 0.12 BMI, kg/m2 24.6 [21.9; 26.9] 23.7 [21.0; 26.0] 26.8 [25.2; 27.4] 0.039 Current smokers, n (%) 10 (37%) 8 (42%) 2 (25%) 0.4 Former smokers, n (%) 15 (55%) 10 (52%) 5 (62%) 0.68 Pack-years 45.0 [30.0; 50.0] 45.0 [30.0; 50.0] 50.0 [40.0; 52.5] 0.23 Non smokers, n (%) 2 (7%) 1 (5%) 1 (12%) 0.53 COPD, n (%) 18 (63%) 13 (68%) 5 (62%) 0.67 Hypertension, n (%) 10 (37%) 3 (15%) 7 (88%) < 0.01 Atrial fibrillation, n (%) 3 (11%) 1 (5%) 2 (25%) 0.22 Ischemic heart disease, n (%) 3 (11%) 3 (15%) 0 (0%) 0.53 Venous thromboembolism, n (%) 1 (3.5%) 1 (5%) 0 (0%) 1 Peripheral arterial disease, n (%) 8 (29%) 4 (19%) 4 (50%) 0.2 Diabetes, n (%) 2 (7%) 1 (5%) 1 (12%) 0.53 History of thoracic surgery, n (%) 9 (33%) 7 (36%) 2 (25%) 0.67 Spirometric and echocardiographic data FEV1 (L) 1.94 [1.69; 2.59] 1.92 [1.60; 2.31] 2.27 [1.83; 2.68] 0.41 FEV1 (%) 79.0 [66.5; 87.8] 71.0 [63.5; 93.0] 83.5 [68.5; 90.7] 0.49 ppoFEV1 (%) 68.5 [61.3 ; 81.7] 64.7 [54.4; 81.7] 78.7 [62.1; 84.6] 0.42 DLCO (%) 58.5 [52.8; 73.0] 56.0 [50.0; 64.0] 63.0 [58.0; 78.0] 0.14 ppoDLCO (%) 53.2 [48.8 ; 62.5] 50.1 [47.4; 58.7] 59.7 [49.2; 73.9] 0.23 FEV1/FVC (%) 62.5 [54.1 ; 70.9] 64.6 [50.3; 70.8] 59.4 [57.5; 71.1] 0.81 LVEF (%) 65.5 [61.5 ; 70.2] 65.0 [61.0; 68.5] 70.0 [65.0; 70.0] 0.73 CPET data peakVO2 (ml/kg/min) 16.4 [14.1; 18.0] 17 [14.5; 18.4] 13.8 [11.3; 17.7] 0.12 Peak VO2 between (n,%) Peak VO2 between 10–12 (ml/Kg/min) 4 (14%) 1 (5 .3%) 3 (38%) 0.065 12–15 (ml/Kg/min) 9 (28%) 6 (32%) 2 (25%) 1 15–18 (ml/Kg/min) 7 (26%) 5 (26%) 2 (25%) 1 18–20 (ml/Kg/min) 5 (18%) 4 (21%) 1(12%) 1 > 20 (ml/kg/min) 3 (11%) 3 (16%) 0 (0%) 0.53 peakVO2 (%predicted) 68.1 [58.8 ; 79.2] 66.1 [58.8; 83.0] 75.0 [61.3; 76.2] 0.98 Peak workrate (Watts) 80.0 [60.0; 97.5] 80.0 [70.0; 97.5] 60.0 [57.5; 93.8] 0.23 Peak workrate (%predicted) 64.7 [54.5 ; 77.6] 64.7 [56.7; 77.2] 65.6 [49.6; 80.6] 0.74 VE/VCO2 slope 34.1 [30.4; 38.0] 33.9 [30.7; 35.8] 38.0 [29.9; 41.3] 0.26 Maximality, n (%) 13 (48%) 11 (58%) 2 (25%) 0.21 Data are presented as total numbers and percentages (in parentheses), median and quartiles (in parentheses). BMI: body mass index, COPD: chronic obstructive pulmonary disease, DLCO: carbon monoxide diffusion capacity, FEV1: forced expiratory volume in one second, FVC: forced vital capacity, LVEF: left ventricular ejection fraction, peakVO2: peak oxygen uptake, VCO2: carbon dioxide elimination, VE: minute ventilation Table 2 Surgical and postoperative characteristics of our study population All patients (n = 27) Without complication (n = 19) With complication (n = 8) p value Surgery Robot, n (%) 2 (7%) 2 (11%) 0 (0%) 1 Video assisted, n (%) 17 (63%) 14 (78%) 3 (38%) 0.07 Thoracotomy, n (%) 8 (29%) 3 (17%) 5 (62%) 0.06 Time (min) 164 [101; 188] 160 [99.2; 178] 190 [160; 228] 0.07 Length of stay Time (days) 6.0 [4.0 ; 10.5] 4.5 [3.2; 6.5] 12.0 [11.8; 13.8] 5 days, n (%) 4 (14%) - 4 (50%) - Pneumonia, n (%) 2 (7%) - 2 (22%) - Atelectasis, n (%) 1 (3.5%) - 1 (11%) - Pulmonary embolism, n (%) 1 (3.5%) - 1 (11%) - Atrial fibrillation, n (%) 2 (7%) - 2 (22%) - Postoperative cardiopulmonary complications occurred in 8 patients (29%) (Tables 1 & 2 ), among who 4 patients (50%) had a prolonged leakage. There were no deaths reported among patients throughout the study period. Patients with complications had significantly more hypertension than those without (88% versus 17%, p < 0.01) and a significantly higher BMI (26.8 [25.2; 27.4] versus 23.7 [21.0; 26.0], p = 0.039). Patients with complications had a significantly longer median length of hospital stay than patients without complications (12.0 [11.8; 13.8] days versus 4.5 [3.2; 6.5] days, p < 0.001). The median peak VO2 of the complicated group was not significantly different from the uncomplicated group (13.8 [11.3; 17.7] ml/kg/min versus 17 [14.5; 18.4] ml/kg/min, p = 0.12), as was the median VE/VCO2 slope (38.0 [29.9; 41.3] versus 33.9 [30.7; 35.8], p = 0.26). With ≥ grade II cardiopulmonary complications (without leakage), median peak VO2 was not significantly different in uncomplicated patients compared to complicated patients (16.9 [14.2; 18.4] ml/kg/min versus 14.5 [11.5; 17.6] ml/kg/min, p = 0.34). However, the VE/VCO2 slope was significantly higher in complicated patients (33.1 [30.0; 35.8] versus 38.6 [38.0; 49.5], p = 0.046) (Table 3 ). Table 3 Subgroup analysis on ≥ grade II cardiopulmonary complications. Without complication (n = 22) ≥ grade II cardiopulmonary complication (n = 5) n p Age, years 68.6 [62.6; 71.9] 67.9 [66.7; 74.2] 27 0.41 VE/VCO2 slope 33.1 [30.0; 35.8] 38.6 [38.0; 49.5] 27 0.046 peakVO2, ml/kg/min 16.9 [14.2; 18.4] 14.5 [11.5; 17.6] 27 0.34 FEV1, %predicted 79.5[66.2 ; 95.5] 69.0 [67.0; 83.0] 27 0.85 COPD, n (%) 15 (68%) 4 (80%) 19 1 Male gender, n (%) 11 (52%) 3 (60%) 14 1 BMI, (kg/m²) 24.0 [21.3; 26.9] 26.7 [25.6; 26.8] 27 0.21 BMI: body mass index, COPD: chronic obstructive pulmonary disease, FEV1: forced expiratory volume in one second, peakVO2: peak oxygen uptake, VCO2: carbon dioxide elimination, VE: minute ventilation Three VE/VCO2 slope thresholds were used for sensitivity and specificity analyses: ≥35, ≥ 38, and ≥ 40. The incidence of cardiopulmonary complications (≥ grade II) in the VE/VCO2 slope ≥ 38 versus < 38 group was 50% versus 5.6% (relative risk RR = 9, odds ratio OR = 17, 95% confidence interval: 1.47–137, p = 0.02) (Table 4 & Fig. 2). Table 4 Prognostic values of different VE/VCO2 slope thresholds VE/VCO2 slope threshold Sensibility Specificity PPV NPV RR OR 95% CI AUC p ≥ 35 0.80 0.62 0.33 0.92 4.67 6.50 0.61–68.90 0.71 0.06 ≥ 38 0.80 0.81 0.50 0.94 9 17 1.47–137 0.80 0.02 ≥ 40 0.40 0.85 0.40 0.85 2.80 4 0.46–34.92 0.67 0.15 CI: confidence interval, NPV: negative predictive value, OR: odds ratio, PPV: positive predictive value, RR: relative risk, VCO2: carbon dioxide elimination, VE: minute ventilation Discussion The aim of our study was to determine whether there was an association between the VE/VCO2 slope and postoperative complications. We did not observe any significant difference in the VE/VCO2 slope between the two groups (median for the group with complications at 38.0 versus 33.9, p = 0.26) for the total of cardiopulmonary complications. In all previous studies ( 10 – 18 ), the predictive value of the VE/VCO2 slope for postoperative complications was observed only in complications of grade II or higher according to the Dindo classification scheme (24) (excluding prolonged leakage > 5 days). Risk factors for prolonged postoperative leakage in lobectomy are known to be FEV1 < 80%, BMI 65 years, or the presence of pleural adhesions( 9 ). Subgroup analysis including only cardiopulmonary complications ≥ grade II showed a significant increase in the VE/VCO2 slope in the group with complications (median 38.6 versus 33.1, p = 0.046). In patients experiencing complications, peak VO2 was not significantly decreased, which is consistent with findings from previous studies on lobectomy and pneumonectomy ( 10 – 18 ). In our study, the rate of postoperative complications is 29%, which is consistent with data reported in the scientific literature ( 21 ). An interesting finding is that 88% of patients who experienced complications had hypertension, compared with 17% in the group without complications. The data on this subject is inconsistent, as hypertension was not initially described as a risk factor for postoperative pulmonary complications ( 7 ). However, Two 2022 publications present similar results to ours, with a higher proportion of hypertension in the group with vascular complications ( 14 , 15 ). Other risk factors have been described in the literature, such as BMI, prolonged operating time (> 180 min), thoracotomy surgery, COPD, or FEV1 < 60% ( 8 , 21 ). Our results are consistent with these findings, as there is a significant difference between the groups for BMI (23.7 vs. 28.6, p = 0.039). A significant association exists between overweight status and the incidence of general cardiorespiratory complications. However, this association was not observed in the subgroup analysis, potentially indicating a link between leaks and weight. Regarding COPD and FEV1, the absence of significant difference in our study could be explained by the fact that all patients included had a CPET indication: either a FEV1 or DLCO < 80%, and a probably higher rate of COPD. Operation time and thoracotomy would seem to be resulting in more complications (160 versus 180 minutes, p = 0.07 and 3 versus 6 thoracotomy, p = 0.06). It is coherent with literature ( 8 , 21 ) but our study related a higher prevalence of thoracotomy because our cohort was more fragile than general population. The secondary objective was to define a prediction threshold for the VE/VCO2 slope in segmentectomy. Historically, the VE/VCO2 slope was used by cardiologists to assess patients with heart failure ( 25 ). Based on these data, early studies on lobectomy used a slope threshold of 35 to identify patients at high risk of complications ( 10 – 13 , 18 ). Miyazaki & al. in 2018, as well as Rushwan & al. in 2024, concluded that the VE/VCO2 slope with a threshold of 40 is an independent prognostic factor for predicting 90-day postoperative mortality, including pneumonectomy, lobectomy, segmentectomy, and wedges ( 16 , 17 ). In 2024, Krinstenson & al. concluded that the use of two VE/VCO2 slope thresholds ( 41) to define three groups of preoperative patients (low, intermediate, and high risk) provides a better prognostic value than the use of a single threshold. This study did not include segmentectomy ( 26 ). In our study, contingency analyses show that the best prognostic values for grade II or more cardiopulmonary complications are obtained for a threshold of 38, with a complication rate of 50% when VE/VCO2 ≥ 38 (AUC = 0.80, 95% CI: 1.47–137, p = 0.02). The commonly accepted threshold of 35 for lobectomies is less effective in our study, with a complication rate of 33% when VE/VCO2 ≥ 35 (AUC = 0.71, 95% CI: 0.61–68.90, p = 0.06). With segmentectomies, due to less parenchymal resection compared to lobectomies, it does seem consistent to use a higher VE/VCO2 slope threshold to classify patients at risk of complications ( 27 ). On the other hand, only 13 patients (48%) achieved maximal CPET, implying that 52% of peakVO2 was underestimated. As these limitations to exercise are common in patients with chronic respiratory or cardiac failure, it does seem important to have a tool available that could overcome the limitations of CPET, such as the VE/VCO2 slope, in order to better characteri s e preoperative risks. The 8 excluded patients (peak VO2 < 10ml/kg/min) had a non-maximal CPET (shown in supplemental material). Four patients out of 8 had a VE/VCO2 slope < 38, which could indicate a discussion on patient’s surgery eligibility. Our study has several limitations: it is a single-center, retrospective study conducted on a small sample size. Results cannot be generalised to all centres, although the indications for CPET and segmentectomies are in line with international guidelines ( 2 , 4 , 5 ). Furthermore, CPET was not routinely performed in all the patients undergoing segmentectomy, only in those with impaired lung function ( 2 , 8 ). Therefore, the patients included in our study represent a population with greater perioperative and postoperative risks than general population, as they represent 10% of segmentectomies with the highest risk of complications. Finally, ERS recommendations advise against surgery for patients with a peakVO2 < 10ml/kg/min ( 2 ), so these patients could not be included in our study, which could reduce the predictive value of peakVO2. Conclusions The VE/VCO2 slope appears to be a valuable tool, for predicting grade II or more postoperative complications following segmentectomies. A more restrictive threshold of 38 would be more appropriate for segmentectomies. However, the role of the VE/VCO2 slope in the preoperative assessment of patients eligible for segmentectomy remains to be clearly defined, particularly through larger-scale, ideally prospective and multicentred studies. The relevance of preoperative CPET in segmentectomy planning remains open to discussion. Abbreviations BMI: body mass index COPD: chronic obstructive pulmonary disease CPET :cardiopulmonary exercise testing DLCO: carbon monoxide diffusion capacity FEV1 : forced expiratory volume in one second LVEF: left ventricular ejection fraction NSCLC : Non-small cell lung cancer PAD: peripheral arterial disease PFT: pulmonary function test PPO : predicted postoperative VE/VCO2 slope : ventilatory efficiency slope VO2max: maximal oxygen consumption VT1: Ventilation threshold 1 Declarations Ethics approval: 2025-EI-704, 2025-093, in May 2025 Consent for publications: all participants give a non-opposition for publications. No competing interest. Funding: This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors. Authors’ contributions: conceptualization (MD), design (MD,GP,BG,SL, JPB), data collection (GP,QR, TB, MD, BG, SL, JPB), analysis (GP, MD), decision to publish (MD, SL, JPB), preparation of manuscript (GP, MD), validation of manuscript (GP, QR, TB, BG, SL, JPB, MD). Acknowledgments : to the Thoracic Surgery unit and the Day Hospital unit of pneumology and to Miss Margaux Bruyere for translating. References Sung H, Ferlay J, Siegel RL, Laversanne M, Soerjomataram I, Jemal A et al. Global Cancer Statistics 2020: GLOBOCAN Estimates of Incidence and Mortality Worldwide for 36 Cancers in 185 Countries. CA Cancer J Clin [Internet]. 2021 May [cited 2025 Oct 27];71(3):209–49. Available from: https://pubmed.ncbi.nlm.nih.gov/33538338/ Brunelli A, Charloux A, Bolliger CT, Rocco G, Sculier JP, Varela G et al. ERS/ESTS clinical guidelines on fitness for radical therapy in lung cancer patients (surgery and chemo-radiotherapy). Eur Respir J [Internet]. 2009 [cited 2025 Oct 27];34(1):17–41. 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Front Physiol [Internet]. 2022 Sep 23 [cited 2025 Oct 27];13. Available from: https://pubmed.ncbi.nlm.nih.gov/36213231/ Mazur A, Brat K, Homolka P, Merta Z, Svoboda M, Bratova M et al. Ventilatory efficiency is superior to peak oxygen uptake for prediction of lung resection cardiovascular complications. PLoS One [Internet]. 2022 Aug 1 [cited 2025 Oct 27];17(8). Available from: https://pubmed.ncbi.nlm.nih.gov/35960723/ Miyazaki T, Callister MEJ, Franks K, Dinesh P, Nagayasu T, Brunelli A. Minute ventilation-to-carbon dioxide slope is associated with postoperative survival after anatomical lung resection. Lung Cancer [Internet]. 2018 Nov 1 [cited 2025 Oct 27];125:218–22. Available from: https://pubmed.ncbi.nlm.nih.gov/30429023/ Rushwan A, Stefanou D, Tariq J, Drosos P, Chaudhuri N, Milton R et al. Increased minute ventilation-to-carbon dioxide slope during cardiopulmonary exercise test is associated with poor postoperative outcome following lung cancer resection. Eur J Cardiothorac Surg [Internet]. 2024 Mar 1 [cited 2025 Oct 27];65(3). Available from: https://pubmed.ncbi.nlm.nih.gov/37812232/ Kristenson K, Hylander J, Boros M, Fyrenius A, Hedman K. Ventilatory efficiency in combination with peak oxygen uptake improves risk stratification in patients undergoing lobectomy. JTCVS Open [Internet]. 2022 Sep 1 [cited 2025 Oct 27];11:317–26. Available from: https://pubmed.ncbi.nlm.nih.gov/36172418/ Salati M, Brunelli A. Risk Stratification in Lung Resection. Curr Surg reports [Internet]. 2016 Nov 1 [cited 2025 Oct 27];4(11). Available from: https://pubmed.ncbi.nlm.nih.gov/27730011/ Kidane B, Bott M, Spicer J, Backhus L, Chaft J, Chudgar N et al. The American Association for Thoracic Surgery (AATS) 2023 Expert Consensus Document: Staging and multidisciplinary management of patients with early-stage non–small cell lung cancer. J Thorac Cardiovasc Surg [Internet]. 2023 Sep 1 [cited 2025 Oct 27];166(3):637–54. Available from: https://pubmed.ncbi.nlm.nih.gov/37306641/ Traibi A, Grigoroiu M, Boulitrop C, Urena A, Masuet-Aumatell C, Brian E et al. Predictive factors for complications of anatomical pulmonary segmentectomies. Interact Cardiovasc Thorac Surg [Internet]. 2013 Nov 1 [cited 2025 Oct 27];17(5):838–44. Available from: https://pubmed.ncbi.nlm.nih.gov/23864580/ Radtke T, Crook S, Kaltsakas G, Louvaris Z, Berton D, Urquhart DS et al. ERS statement on standardisation of cardiopulmonary exercise testing in chronic lung diseases. Eur Respir Rev [Internet]. 2019 Dec 1 [cited 2025 Oct 27];28(154). Available from: https://pubmed.ncbi.nlm.nih.gov/31852745/ Fernandez FG, Falcoz PE, Kozower BD, Salati M, Wright CD, Brunelli A. The society of thoracic surgeons and the european society of thoracic surgeons general thoracic surgery databases: Joint standardization of variable definitions and terminology. Ann Thorac Surg [Internet]. 2015 Jan 1 [cited 2025 Oct 27];99(1):368–76. Available from: https://pubmed.ncbi.nlm.nih.gov/25555970/ Dindo D, Demartines N, Clavien PA. Classification of surgical complications: a new proposal with evaluation in a cohort of 6336 patients and results of a survey. Ann Surg [Internet]. 2004 Aug [cited 2025 Oct 27];240(2):205–13. Available from: https://pubmed.ncbi.nlm.nih.gov/15273542/ Chua TP, Ponikowski P, Harrington D, Anker SD, Webb-Peploe K, Clark AL et al. Clinical correlates and prognostic significance of the ventilatory response to exercise in chronic heart failure. J Am Coll Cardiol [Internet]. 1997 Jun [cited 2025 Oct 27];29(7):1585–90. Available from: https://pubmed.ncbi.nlm.nih.gov/9180123/ Kristenson K, Hylander J, Boros M, Hedman K. VE/VCO2 slope threshold optimization for preoperative evaluation in lung cancer surgery: identifying true high- and low-risk groups. J Thorac Dis [Internet]. 2024 Jan 30 [cited 2025 Oct 27];16(1):123–32. Available from: https://pubmed.ncbi.nlm.nih.gov/38410536/ Bédat B, Abdelnour-Berchtold E, Perneger T, Licker MJ, Stefani A, Krull M et al. Comparison of postoperative complications between segmentectomy and lobectomy by video-assisted thoracic surgery: a multicenter study. J Cardiothorac Surg [Internet]. 2019 Nov 7 [cited 2025 Oct 27];14(1). Available from: https://pubmed.ncbi.nlm.nih.gov/31699121/ Additional Declarations No competing interests reported. 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Nice","correspondingAuthor":false,"prefix":"","firstName":"Quentin","middleName":"","lastName":"Rudondy","suffix":""},{"id":586587887,"identity":"fb25d4f1-942a-47b7-a62a-16da13069437","order_by":2,"name":"Tayeb Benkiran","email":"","orcid":"","institution":"Centre Hospitalier Universitaire de Nice","correspondingAuthor":false,"prefix":"","firstName":"Tayeb","middleName":"","lastName":"Benkiran","suffix":""},{"id":586587888,"identity":"5adac4bd-b540-4913-a61a-118914679129","order_by":3,"name":"Benoit Gerard","email":"","orcid":"","institution":"Centre Hospitalier Universitaire de Nice","correspondingAuthor":false,"prefix":"","firstName":"Benoit","middleName":"","lastName":"Gerard","suffix":""},{"id":586587889,"identity":"a3af668e-5aaf-49df-a9c4-7e1886055a37","order_by":4,"name":"Jean-Philippe Berthet","email":"","orcid":"","institution":"Centre Hospitalier Universitaire de 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this version\u003c/p\u003e","description":"","filename":"2.png","url":"https://assets-eu.researchsquare.com/files/rs-8502647/v1/be9cf37aa0d8af46ea5396b9.png"},{"id":104834901,"identity":"ed6ed9a2-5aeb-4592-809b-83d7bd02d6c0","added_by":"auto","created_at":"2026-03-17 17:35:43","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":836595,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-8502647/v1/bb883c01-7c27-4114-bd82-778ceaea7f5e.pdf"},{"id":102379830,"identity":"35830423-1108-4b35-ac1d-ea18ea13f9e3","added_by":"auto","created_at":"2026-02-11 06:26:47","extension":"docx","order_by":0,"title":"","display":"","copyAsset":false,"role":"supplement","size":13564,"visible":true,"origin":"","legend":"","description":"","filename":"Supplementaldata.docx","url":"https://assets-eu.researchsquare.com/files/rs-8502647/v1/e13a165d2141a34cfc113733.docx"}],"financialInterests":"No competing interests reported.","formattedTitle":"The ventilatory efficiency slope (VE/VCO₂ slope) as a predictor of postoperative cardiopulmonary complications post lung segmentectomy in high-risk patients?","fulltext":[{"header":"Background","content":"\u003cp\u003eNon-small cell lung cancer (NSCLC) is the most common lung cancer in industrialised countries(\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e), and surgery is the gold standard treatment for localised tumour (\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e). Lobectomy is usually the preferred procedure, as recommended by the Lung Cancer Study Group in 1995 (\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e). Anatomical segmentectomy is the validated option for localised peripheral NSCLC (\u0026lt;\u0026thinsp;2 cm and without lymph node invasion)(\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e, \u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e). However, the rate of postoperative complications is estimated at 17.8% after pulmonary segmentectomy(\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eSeveral risk factors for postoperative complications have been identified, including: advanced age, male gender, preoperative forced expiratory volume in one second (FEV1)\u0026thinsp;\u0026lt;\u0026thinsp;60% of predicted postoperative (PPO), surgery duration, body mass index (BMI)\u0026thinsp;\u0026gt;\u0026thinsp;30kg/m2, and chronic obstructive pulmonary disease (COPD) (\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eIn preoperative assessments, the pulmonary function test (PFT) to measure FEV1 and carbon monoxide diffusion capacity (DLCO) are recommended. Following American recommendations, in cases of PPO FEV1 or DLCO\u0026thinsp;\u0026lt;\u0026thinsp;60%, a walking test or a stair climbing test may be performed. When the walking test result is \u0026lt;\u0026thinsp;400m or the stair climbing test is \u0026lt;\u0026thinsp;22 m of altitude, a cardiopulmonary exercise testing (CPET) to measure maximal oxygen consumption (VO2max) is recommended(\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e). Furthermore, following European recommendations, CPET could also be performed in cases of preoperative FEV1 or DLCO\u0026thinsp;\u0026lt;\u0026thinsp;80%(\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eAccording to international recommendations, patients with a VO2max\u0026thinsp;\u0026lt;\u0026thinsp;10 mL/kg/min have a high surgical risk. Patients with a VO2max between 10 and 20 mL/kg/min have a moderate risk, and those with a VO2max\u0026thinsp;\u0026gt;\u0026thinsp;20 mL/kg/min have a low risk for postoperative complications or even death (\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e). In high-risk surgical patient, a lobectomy or pneumonectomy are not recommended. If the indicators demonstrate a low risk, all resection types can be performed. Regarding intermediate risks, other parameters need to be studied, such as the measurement of ventilatory efficiency by the slope of minute ventilation (VE) on carbon dioxide production (VCO2) (VE/VCO2 slope) (\u003cspan additionalcitationids=\"CR11 CR12 CR13 CR14 CR15 CR16 CR17\" citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eAn elevated VE/VCO2 slope\u0026thinsp;\u0026gt;\u0026thinsp;35 is associated with an increased risk of postoperative cardiorespiratory complications (22% versus 7.6%, p\u0026thinsp;=\u0026thinsp;0.004) (\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e), and an increased 30-day postoperative mortality rate (7.2% vs. 0.6%, p\u0026thinsp;=\u0026thinsp;0.01) in patients with heart failure and COPD (\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e, \u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e). In 2016, an algorithm defined patients with a VO2max between 10 and 20 ml/kg/min as a low risk if the VE/VCO2 slope is \u0026le;\u0026thinsp;35, or as high risk if the VE/VCO2 slope is \u0026gt;\u0026thinsp;35 (\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e). However, this algorithm is only valid for lobectomy and pneumonectomy.\u003c/p\u003e \u003cp\u003ePost-segmentectomy mortality is similar to lobectomy, which is approximately 2% at 3 months (\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e). Postoperative complications within 90 days following surgery are circa 34% (\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e). The identified risk factors are FEV1\u0026thinsp;\u0026lt;\u0026thinsp;60% PPO, male gender, and thoracotomy (\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e). Postoperative risk stratification based on VO2max, established for lobectomy, is extended and applied to segmentectomy (\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eRegarding studies on the VE/VCO2 slope, only four articles included segmentectomy (\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e, \u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e, \u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e, \u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e), which limits the generalizability of the results. The role of the VE/VCO2 slope remains unclear for infra-lobar resection surgeries such as segmentectomy.\u003c/p\u003e \u003cp\u003eTherefore, the aim of this study is to define the role of the VE/VCO2 slope and to validate an appropriate threshold for predicting the risks of post-operative complications after a segmentectomy.\u003c/p\u003e"},{"header":"Methods","content":"\u003cp\u003e\u003cspan\u003e\u003cstrong\u003e2.1) Patient population\u003c/strong\u003e: The Nice University Hospital and the ethical committee approved this retrospective, monocentric study (2025-EI-704, 2025-093, in May 2025). We included all adult patients who had performed a CPET before a lung segmentectomy between January 2021 and April 2025. The following patients were excluded: 1) absence of CPET before segmentectomy, 2) unfit for surgery (VO2 max\u0026thinsp;\u0026lt;\u0026thinsp;10mL/kg/min or pulmonary hypertension), 3) absence of informed consent.\u003cbr\u003e\u003c/span\u003e\u003cspan\u003e\u003cstrong\u003e2.2) Variables and outcomes\u003c/strong\u003e: Anthropometric data (age, height, weight), smoking status, medical and surgical history, calculation of left ventricular ejection fraction (LVEF), FEV1, and DLCO were collected preoperatively. The calculation of PPO lung capacity values is based on the ERS/ESTS recommendations for lobectomy (\u003cspan class=\"CitationRef\"\u003e2\u003c/span\u003e).\u003cbr\u003e\u003c/span\u003e\u003c/p\u003e \u003cp\u003eCPET data such as maximality, VE/VCO2 slope, peak VO2 and work rate were recorded. CPET was performed according to international recommendations (\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e). Maximality in CPET is defined by the presence of at least three of the following criteria: 1) Heart rate\u0026thinsp;\u0026gt;\u0026thinsp;90% of theoretical maximum heart rate, 2) Change in VO2 of \u0026lt;\u0026thinsp;2.1 mL\u0026middot;min\u0026thinsp;\u0026minus;\u0026thinsp;1\u0026middot;kg\u0026thinsp;\u0026minus;\u0026thinsp;1 between consecutive stage, 3) Respiratory exchange ratio\u0026thinsp;\u0026gt;\u0026thinsp;1.10, 4) Borg scale rated 10/10 for dyspnoea or muscle, 5) pedalling frequency\u0026thinsp;\u0026lt;\u0026thinsp;60 rpm. In case of a non-maximal test, the value used was peak VO2: maximum VO2 reached at peak effort. The VE/VCO2 slope was measured, by a single operator, in the MEDISOFT\u0026reg; software, plotting a linear relationship between the start of the exercise and the Ventilation threshold 1 (VT1).\u003c/p\u003e \u003cp\u003eA multidisciplinary consultation meeting involving pulmonologists, thoracic surgeons, oncologists, pathologists, and radiation therapists, decided to perform segmentectomies on eligible patients. The surgical procedures were performed according to international guidelines (\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eIntraoperative data such as the type of surgery, operating time, length of stay, and complications was recorded. In accordance with international recommendations (\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e), cardiopulmonary complications included: 1) atelectasis requiring bronchoscopy, 2) pneumonia requiring antibiotic therapy, 3) prolonged leakage\u0026thinsp;\u0026gt;\u0026thinsp;5 days, 4) Occurrence of pneumothorax post-drain removal necessitating subsequent chest tube reinsertion, 5)pulmonary embolism, 6) acute respiratory distress syndrome, 7) prolonged intubation\u0026thinsp;\u0026gt;\u0026thinsp;48 hours, 8) reintubation, 9) atrial or ventricular fibrillation requiring drug or electrical reduction, 10) acute pulmonary oedema, 11) myocardial infarction, 12) empyema, or 13) death.\u003c/p\u003e \u003cp\u003eOur primary endpoint was a correlation between an increased VE/VCO2 slope and postoperative complications within 90 days. Our secondary endpoint was to define a predictive threshold for postoperative complications following segmentectomy.\u003c/p\u003e \u003cp\u003e \u003cb\u003e2.3) Statistical analysis\u003c/b\u003e: Quantitative variables are presented as median and quartiles. Categorical variables are presented as percentages with their frequencies. A Mann-Whitney test was used to compare quantitative variables. A Fisher test was used to compare qualitative variables. For every descriptive analysis, differences were considered significant when the p-value was \u0026lt;\u0026thinsp;0.05.\u003c/p\u003e \u003cp\u003eSubgroup analyses were performed based on the type of complication: the severity of postoperative complications (those requiring therapeutic intervention (grade II or higher according to the Dindo et al. classification) (\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e)). For our secondary endpoint, calculations of sensitivity, specificity, positive and negative predictive values were also performed.\u003c/p\u003e"},{"header":"Results","content":"\u003cp\u003eBetween January 2021 and April 2025, 380 patients have had an indication of a segmentectomy. Among them, only 35 (9%) performed a CPET before surgery. A total of 27 patients were included in the study (Fig.\u0026nbsp;1).\u003c/p\u003e \u003cp\u003eOur population consisted of 52% men with a median age of 68 [63; 72.5] years and a median BMI of 24.6 [21.9; 26.9] kg/m2 (Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e). Thirty-seven percent of patients were active smokers, and 55% were former smokers. The most common comorbidities were COPD (62%), hypertension (40%), and peripheral arterial disease (PAD, 31%). The median FEV1 was 1.94 [1.69; 2.59] L, or 75 [66.2; 87.8]% of predicted, and the median PPO FEV1 was 68.5 [61.3; 81.7]% of predicted. The median DLCO was 58.5 [52.8; 73.0]% of predicted, with a median PPO DLCO of 53.2 [48.8; 62.5]% of predicted. The median VO2 peak was 16.4 [14.1; 18.0] ml/kg/min, or 68.1 [58.8; 79.2]% of predicted, and the median VE/VCO2 slope was 33.5 [30.2; 38.4] (Tables\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e \u0026amp; \u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e).\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab1\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003ePreoperative characteristics of our study population\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"5\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eAll patients\u003c/p\u003e \u003cp\u003e(n\u0026thinsp;=\u0026thinsp;27)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eWithout complication\u003c/p\u003e \u003cp\u003e(n\u0026thinsp;=\u0026thinsp;19)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eWith complication\u003c/p\u003e \u003cp\u003e(n\u0026thinsp;=\u0026thinsp;8)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003ep value\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colspan=\"5\" nameend=\"c5\" namest=\"c1\"\u003e \u003cp\u003ePreoperative clinical data\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eMale gender, n (%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e14 (52%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e10\u0026nbsp;(52%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e4\u0026nbsp;(50%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.68\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eAge, years\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e68.0 [63.0\u0026nbsp;; 72.5]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e67.6 [61.8; 70.6]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e70.7\u0026nbsp;[67.6;\u0026nbsp;73.9]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.12\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eBMI, kg/m2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e24.6 [21.9; 26.9]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e23.7 [21.0; 26.0]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e26.8 [25.2; 27.4]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e\u003cb\u003e0.039\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCurrent smokers, n (%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e10 (37%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e8\u0026nbsp;(42%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e2\u0026nbsp;(25%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.4\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eFormer smokers, n (%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e15 (55%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e10\u0026nbsp;(52%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e5\u0026nbsp;(62%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.68\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePack-years\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e45.0\u0026nbsp;[30.0;\u0026nbsp;50.0]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e45.0\u0026nbsp;[30.0;\u0026nbsp;50.0]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e50.0\u0026nbsp;[40.0;\u0026nbsp;52.5]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.23\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eNon smokers, n (%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e2 (7%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e1\u0026nbsp;(5%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e1\u0026nbsp;(12%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.53\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCOPD, n (%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e18 (63%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e13\u0026nbsp;(68%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e5\u0026nbsp;(62%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.67\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eHypertension, n (%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e10 (37%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e3\u0026nbsp;(15%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e7\u0026nbsp;(88%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e\u003cb\u003e\u0026lt;\u0026thinsp;0.01\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eAtrial fibrillation,\u003c/p\u003e \u003cp\u003en (%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e3 (11%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e1\u0026nbsp;(5%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e2\u0026nbsp;(25%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.22\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eIschemic heart disease, n (%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e3 (11%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e3\u0026nbsp;(15%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0\u0026nbsp;(0%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.53\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eVenous thromboembolism,\u003c/p\u003e \u003cp\u003en (%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e1 (3.5%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e1\u0026nbsp;(5%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0\u0026nbsp;(0%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePeripheral arterial disease, n (%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e8 (29%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e4\u0026nbsp;(19%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e4\u0026nbsp;(50%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.2\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eDiabetes, n (%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e2 (7%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e1\u0026nbsp;(5%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e1\u0026nbsp;(12%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.53\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eHistory of thoracic surgery, n (%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e9 (33%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e7\u0026nbsp;(36%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e2\u0026nbsp;(25%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.67\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colspan=\"5\" nameend=\"c5\" namest=\"c1\"\u003e \u003cp\u003eSpirometric and echocardiographic data\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eFEV1 (L)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e1.94\u0026nbsp;[1.69;\u0026nbsp;2.59]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e1.92\u0026nbsp;[1.60;\u0026nbsp;2.31]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e2.27\u0026nbsp;[1.83;\u0026nbsp;2.68]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.41\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eFEV1 (%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e79.0\u0026nbsp;[66.5;\u0026nbsp;87.8]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e71.0\u0026nbsp;[63.5;\u0026nbsp;93.0]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e83.5\u0026nbsp;[68.5;\u0026nbsp;90.7]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.49\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eppoFEV1 (%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e68.5 [61.3\u0026nbsp;; 81.7]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e64.7\u0026nbsp;[54.4;\u0026nbsp;81.7]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e78.7\u0026nbsp;[62.1;\u0026nbsp;84.6]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.42\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eDLCO (%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e58.5\u0026nbsp;[52.8;\u0026nbsp;73.0]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e56.0\u0026nbsp;[50.0;\u0026nbsp;64.0]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e63.0\u0026nbsp;[58.0;\u0026nbsp;78.0]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.14\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eppoDLCO (%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e53.2 [48.8\u0026nbsp;; 62.5]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e50.1\u0026nbsp;[47.4;\u0026nbsp;58.7]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e59.7\u0026nbsp;[49.2;\u0026nbsp;73.9]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.23\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eFEV1/FVC (%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e62.5 [54.1\u0026nbsp;; 70.9]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e64.6\u0026nbsp;[50.3;\u0026nbsp;70.8]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e59.4\u0026nbsp;[57.5;\u0026nbsp;71.1]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.81\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eLVEF (%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e65.5 [61.5\u0026nbsp;; 70.2]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e65.0\u0026nbsp;[61.0;\u0026nbsp;68.5]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e70.0\u0026nbsp;[65.0;\u0026nbsp;70.0]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.73\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colspan=\"5\" nameend=\"c5\" namest=\"c1\"\u003e \u003cp\u003eCPET data\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003epeakVO2 (ml/kg/min)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e16.4\u0026nbsp;[14.1;\u0026nbsp;18.0]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e17\u0026nbsp;[14.5;\u0026nbsp;18.4]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e13.8\u0026nbsp;[11.3;\u0026nbsp;17.7]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.12\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePeak VO2 between (n,%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePeak VO2 between 10\u0026ndash;12 (ml/Kg/min)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e4 (14%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e1 (5\u0026nbsp;.3%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e3 (38%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.065\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e12\u0026ndash;15 (ml/Kg/min)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e9 (28%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e6 (32%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e2 (25%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e15\u0026ndash;18 (ml/Kg/min)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e7 (26%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e5 (26%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e2 (25%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e18\u0026ndash;20 (ml/Kg/min)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e5 (18%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e4 (21%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e1(12%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u0026gt;\u0026thinsp;20 (ml/kg/min)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e3 (11%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e3 (16%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0 (0%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.53\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003epeakVO2 (%predicted)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e68.1 [58.8\u0026nbsp;; 79.2]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e66.1\u0026nbsp;[58.8;\u0026nbsp;83.0]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e75.0\u0026nbsp;[61.3;\u0026nbsp;76.2]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.98\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePeak workrate (Watts)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e80.0\u0026nbsp;[60.0;\u0026nbsp;97.5]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e80.0\u0026nbsp;[70.0;\u0026nbsp;97.5]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e60.0\u0026nbsp;[57.5;\u0026nbsp;93.8]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.23\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePeak workrate (%predicted)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e64.7 [54.5\u0026nbsp;; 77.6]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e64.7\u0026nbsp;[56.7;\u0026nbsp;77.2]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e65.6\u0026nbsp;[49.6;\u0026nbsp;80.6]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.74\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eVE/VCO2 slope\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e34.1 [30.4; 38.0]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e33.9 [30.7; 35.8]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e38.0 [29.9; 41.3]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.26\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eMaximality, n (%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e13 (48%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e11 (58%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e2 (25%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.21\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003ctfoot\u003e \u003ctr\u003e\u003ctd colspan=\"5\"\u003e\u003cem\u003eData are presented as total numbers and percentages (in parentheses), median and quartiles (in parentheses). BMI: body mass index, COPD: chronic obstructive pulmonary disease, DLCO: carbon monoxide diffusion capacity, FEV1: forced expiratory volume in one second, FVC: forced vital capacity, LVEF: left ventricular ejection fraction, peakVO2: peak oxygen uptake, VCO2: carbon dioxide elimination, VE: minute ventilation\u003c/em\u003e\u003c/td\u003e\u003c/tr\u003e \u003c/tfoot\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab2\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 2\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eSurgical and postoperative characteristics of our study population\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"7\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c7\" colnum=\"7\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colspan=\"2\" nameend=\"c2\" namest=\"c1\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eAll patients\u003c/p\u003e \u003cp\u003e(n\u0026thinsp;=\u0026thinsp;27)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colspan=\"2\" nameend=\"c5\" namest=\"c4\"\u003e \u003cp\u003eWithout complication\u003c/p\u003e \u003cp\u003e(n\u0026thinsp;=\u0026thinsp;19)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c6\"\u003e \u003cp\u003eWith complication\u003c/p\u003e \u003cp\u003e(n\u0026thinsp;=\u0026thinsp;8)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c7\"\u003e \u003cp\u003ep value\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colspan=\"7\" nameend=\"c7\" namest=\"c1\"\u003e \u003cp\u003eSurgery\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eRobot, n (%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"3\" nameend=\"c4\" namest=\"c2\"\u003e \u003cp\u003e2 (7%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e2\u0026nbsp;(11%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e0\u0026nbsp;(0%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eVideo assisted,\u003c/p\u003e \u003cp\u003en (%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"3\" nameend=\"c4\" namest=\"c2\"\u003e \u003cp\u003e17 (63%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e14\u0026nbsp;(78%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e3\u0026nbsp;(38%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e0.07\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eThoracotomy, n (%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"3\" nameend=\"c4\" namest=\"c2\"\u003e \u003cp\u003e8 (29%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e3\u0026nbsp;(17%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e5\u0026nbsp;(62%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e0.06\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eTime (min)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"3\" nameend=\"c4\" namest=\"c2\"\u003e \u003cp\u003e164\u0026nbsp;[101;\u0026nbsp;188]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e160\u0026nbsp;[99.2;\u0026nbsp;178]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e190\u0026nbsp;[160;\u0026nbsp;228]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e0.07\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colspan=\"7\" nameend=\"c7\" namest=\"c1\"\u003e \u003cp\u003eLength of stay\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eTime (days)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"3\" nameend=\"c4\" namest=\"c2\"\u003e \u003cp\u003e6.0 [4.0\u0026nbsp;; 10.5]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e4.5\u0026nbsp;[3.2;\u0026nbsp;6.5]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e12.0\u0026nbsp;[11.8;\u0026nbsp;13.8]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e\u003cb\u003e\u0026lt;\u0026thinsp;0.001\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eDrain removal (days)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"3\" nameend=\"c4\" namest=\"c2\"\u003e \u003cp\u003e2.0 [2.0\u0026nbsp;; 4.8]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e2.0\u0026nbsp;[2.0;\u0026nbsp;3.5]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e5.0\u0026nbsp;[2.7;\u0026nbsp;8.0]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e\u003cb\u003e0.01\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eComplications\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"3\" nameend=\"c4\" namest=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePneumothorax,\u003c/p\u003e \u003cp\u003en (%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"3\" nameend=\"c4\" namest=\"c2\"\u003e \u003cp\u003e1 (3.5%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e1 (11%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eAir leak\u0026thinsp;\u0026gt;\u0026thinsp;5 days,\u003c/p\u003e \u003cp\u003en (%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"3\" nameend=\"c4\" namest=\"c2\"\u003e \u003cp\u003e4 (14%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e4 (50%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePneumonia, n (%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"3\" nameend=\"c4\" namest=\"c2\"\u003e \u003cp\u003e2 (7%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e2 (22%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eAtelectasis, n (%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"3\" nameend=\"c4\" namest=\"c2\"\u003e \u003cp\u003e1 (3.5%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e1 (11%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePulmonary embolism, n (%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"3\" nameend=\"c4\" namest=\"c2\"\u003e \u003cp\u003e1 (3.5%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e1 (11%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eAtrial fibrillation,\u003c/p\u003e \u003cp\u003en (%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"3\" nameend=\"c4\" namest=\"c2\"\u003e \u003cp\u003e2 (7%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e2 (22%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003ePostoperative cardiopulmonary complications occurred in 8 patients (29%) (Tables\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e \u0026amp; \u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e), among who 4 patients (50%) had a prolonged leakage. There were no deaths reported among patients throughout the study period. Patients with complications had significantly more hypertension than those without (88% versus 17%, p\u0026thinsp;\u0026lt;\u0026thinsp;0.01) and a significantly higher BMI (26.8 [25.2; 27.4] versus 23.7 [21.0; 26.0], p\u0026thinsp;=\u0026thinsp;0.039). Patients with complications had a significantly longer median length of hospital stay than patients without complications (12.0 [11.8; 13.8] days versus 4.5 [3.2; 6.5] days, p\u0026thinsp;\u0026lt;\u0026thinsp;0.001). The median peak VO2 of the complicated group was not significantly different from the uncomplicated group (13.8 [11.3; 17.7] ml/kg/min versus 17 [14.5; 18.4] ml/kg/min, p\u0026thinsp;=\u0026thinsp;0.12), as was the median VE/VCO2 slope (38.0 [29.9; 41.3] versus 33.9 [30.7; 35.8], p\u0026thinsp;=\u0026thinsp;0.26).\u003c/p\u003e \u003cp\u003eWith \u0026ge;\u0026thinsp;grade II cardiopulmonary complications (without leakage), median peak VO2 was not significantly different in uncomplicated patients compared to complicated patients (16.9 [14.2; 18.4] ml/kg/min versus 14.5 [11.5; 17.6] ml/kg/min, p\u0026thinsp;=\u0026thinsp;0.34). However, the VE/VCO2 slope was significantly higher in complicated patients (33.1 [30.0; 35.8] versus 38.6 [38.0; 49.5], p\u0026thinsp;=\u0026thinsp;0.046) (Table\u0026nbsp;\u003cspan refid=\"Tab3\" class=\"InternalRef\"\u003e3\u003c/span\u003e).\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab3\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 3\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eSubgroup analysis on \u0026ge;\u0026thinsp;grade II cardiopulmonary complications.\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"5\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eWithout complication (n\u0026nbsp;=\u0026nbsp;22)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003e\u0026ge; grade II cardiopulmonary complication (n\u0026nbsp;=\u0026nbsp;5)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003en\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003ep\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eAge,\u0026nbsp;years\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e68.6 [62.6; 71.9]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e67.9 [66.7; 74.2]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e27\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.41\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eVE/VCO2 slope\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u003cb\u003e33.1 [30.0; 35.8]\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e\u003cb\u003e38.6 [38.0; 49.5]\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u003cb\u003e27\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e\u003cb\u003e0.046\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003epeakVO2, ml/kg/min\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e16.9\u0026nbsp;[14.2;\u0026nbsp;18.4]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e14.5 [11.5; 17.6]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e27\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.34\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eFEV1, %predicted\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e79.5[66.2 ;\u0026nbsp;95.5]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e69.0\u0026nbsp;[67.0;\u0026nbsp;83.0]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e27\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.85\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCOPD,\u0026nbsp;n (%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e15\u0026nbsp;(68%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e4\u0026nbsp;(80%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e19\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eMale gender,\u0026nbsp;n (%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e11\u0026nbsp;(52%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e3 (60%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e14\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eBMI, (kg/m\u0026sup2;)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e24.0 [21.3; 26.9]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e26.7 [25.6; 26.8]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e27\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.21\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003ctfoot\u003e \u003ctr\u003e\u003ctd colspan=\"5\"\u003e\u003cem\u003eBMI: body mass index, COPD: chronic obstructive pulmonary disease, FEV1: forced expiratory volume in one second, peakVO2: peak oxygen uptake, VCO2: carbon dioxide elimination, VE: minute ventilation\u003c/em\u003e\u003c/td\u003e\u003c/tr\u003e \u003c/tfoot\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003eThree VE/VCO2 slope thresholds were used for sensitivity and specificity analyses: \u0026ge;35, \u0026ge;\u0026thinsp;38, and \u0026ge;\u0026thinsp;40. The incidence of cardiopulmonary complications (\u0026ge;\u0026thinsp;grade II) in the VE/VCO2 slope\u0026thinsp;\u0026ge;\u0026thinsp;38 versus \u0026lt;\u0026thinsp;38 group was 50% versus 5.6% (relative risk RR\u0026thinsp;=\u0026thinsp;9, odds ratio OR\u0026thinsp;=\u0026thinsp;17, 95% confidence interval: 1.47\u0026ndash;137, p\u0026thinsp;=\u0026thinsp;0.02) (Table\u0026nbsp;\u003cspan refid=\"Tab4\" class=\"InternalRef\"\u003e4\u003c/span\u003e \u0026amp; Fig.\u0026nbsp;2).\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab4\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 4\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003ePrognostic values of different VE/VCO2 slope thresholds\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"11\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c7\" colnum=\"7\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c8\" colnum=\"8\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c9\" colnum=\"9\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c10\" colnum=\"10\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c11\" colnum=\"11\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eVE/VCO2 slope threshold\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eSensibility\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eSpecificity\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003ePPV\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003eNPV\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c6\"\u003e \u003cp\u003eRR\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c7\"\u003e \u003cp\u003eOR\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c8\"\u003e \u003cp\u003e95% CI\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c9\"\u003e \u003cp\u003eAUC\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c10\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colname=\"c11\"\u003e \u003cp\u003ep\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u0026ge;\u0026thinsp;35\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.80\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.62\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.33\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.92\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e4.67\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e6.50\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e0.61\u0026ndash;68.90\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e0.71\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c11\"\u003e \u003cp\u003e0.06\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u0026ge;\u0026thinsp;38\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.80\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.81\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.50\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.94\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e17\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e1.47\u0026ndash;137\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e0.80\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c11\"\u003e \u003cp\u003e\u003cb\u003e0.02\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u0026ge;\u0026thinsp;40\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.40\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.85\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.40\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.85\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e2.80\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e0.46\u0026ndash;34.92\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e0.67\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c11\"\u003e \u003cp\u003e0.15\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003ctfoot\u003e \u003ctr\u003e\u003ctd colspan=\"11\"\u003e\u003cem\u003eCI: confidence interval, NPV: negative predictive value, OR: odds ratio, PPV: positive predictive value, RR: relative risk, VCO2: carbon dioxide elimination, VE: minute ventilation\u003c/em\u003e\u003c/td\u003e\u003c/tr\u003e \u003c/tfoot\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e"},{"header":"Discussion","content":"\u003cp\u003eThe aim of our study was to determine whether there was an association between the VE/VCO2 slope and postoperative complications. We did not observe any significant difference in the VE/VCO2 slope between the two groups (median for the group with complications at 38.0 versus 33.9, p\u0026thinsp;=\u0026thinsp;0.26) for the total of cardiopulmonary complications. In all previous studies (\u003cspan additionalcitationids=\"CR11 CR12 CR13 CR14 CR15 CR16 CR17\" citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e), the predictive value of the VE/VCO2 slope for postoperative complications was observed only in complications of grade II or higher according to the Dindo classification scheme (24) (excluding prolonged leakage\u0026thinsp;\u0026gt;\u0026thinsp;5 days). Risk factors for prolonged postoperative leakage in lobectomy are known to be FEV1\u0026thinsp;\u0026lt;\u0026thinsp;80%, BMI\u0026thinsp;\u0026lt;\u0026thinsp;25.5 kg/m2, age\u0026thinsp;\u0026gt;\u0026thinsp;65 years, or the presence of pleural adhesions(\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eSubgroup analysis including only cardiopulmonary complications\u0026thinsp;\u0026ge;\u0026thinsp;grade II showed a significant increase in the VE/VCO2 slope in the group with complications (median 38.6 versus 33.1, p\u0026thinsp;=\u0026thinsp;0.046).\u003c/p\u003e \u003cp\u003eIn patients experiencing complications, peak VO2 was not significantly decreased, which is consistent with findings from previous studies on lobectomy and pneumonectomy (\u003cspan additionalcitationids=\"CR11 CR12 CR13 CR14 CR15 CR16 CR17\" citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eIn our study, the rate of postoperative complications is 29%, which is consistent with data reported in the scientific literature (\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e). An interesting finding is that 88% of patients who experienced complications had hypertension, compared with 17% in the group without complications. The data on this subject is inconsistent, as hypertension was not initially described as a risk factor for postoperative pulmonary complications (\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e). However, Two 2022 publications present similar results to ours, with a higher proportion of hypertension in the group with vascular complications (\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e, \u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eOther risk factors have been described in the literature, such as BMI, prolonged operating time (\u0026gt;\u0026thinsp;180 min), thoracotomy surgery, COPD, or FEV1\u0026thinsp;\u0026lt;\u0026thinsp;60% (\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e, \u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e). Our results are consistent with these findings, as there is a significant difference between the groups for BMI (23.7 vs. 28.6, p\u0026thinsp;=\u0026thinsp;0.039). A significant association exists between overweight status and the incidence of general cardiorespiratory complications. However, this association was not observed in the subgroup analysis, potentially indicating a link between leaks and weight.\u003c/p\u003e \u003cp\u003eRegarding COPD and FEV1, the absence of significant difference in our study could be explained by the fact that all patients included had a CPET indication: either a FEV1 or DLCO\u0026thinsp;\u0026lt;\u0026thinsp;80%, and a probably higher rate of COPD.\u003c/p\u003e \u003cp\u003eOperation time and thoracotomy would seem to be resulting in more complications (160 versus 180 minutes, p\u0026thinsp;=\u0026thinsp;0.07 and 3 versus 6 thoracotomy, p\u0026thinsp;=\u0026thinsp;0.06). It is coherent with literature (\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e, \u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e) but our study related a higher prevalence of thoracotomy because our cohort was more fragile than general population.\u003c/p\u003e \u003cp\u003eThe secondary objective was to define a prediction threshold for the VE/VCO2 slope in segmentectomy. Historically, the VE/VCO2 slope was used by cardiologists to assess patients with heart failure (\u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e). Based on these data, early studies on lobectomy used a slope threshold of 35 to identify patients at high risk of complications (\u003cspan additionalcitationids=\"CR11 CR12\" citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e, \u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e). Miyazaki \u0026amp; al. in 2018, as well as Rushwan \u0026amp; al. in 2024, concluded that the VE/VCO2 slope with a threshold of 40 is an independent prognostic factor for predicting 90-day postoperative mortality, including pneumonectomy, lobectomy, segmentectomy, and wedges (\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e, \u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e). In 2024, Krinstenson \u0026amp; al. concluded that the use of two VE/VCO2 slope thresholds (\u0026lt;\u0026thinsp;30 and \u0026gt;\u0026thinsp;41) to define three groups of preoperative patients (low, intermediate, and high risk) provides a better prognostic value than the use of a single threshold. This study did not include segmentectomy (\u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e). In our study, contingency analyses show that the best prognostic values for grade II or more cardiopulmonary complications are obtained for a threshold of 38, with a complication rate of 50% when VE/VCO2\u0026thinsp;\u0026ge;\u0026thinsp;38 (AUC\u0026thinsp;=\u0026thinsp;0.80, 95% CI: 1.47\u0026ndash;137, p\u0026thinsp;=\u0026thinsp;0.02). The commonly accepted threshold of 35 for lobectomies is less effective in our study, with a complication rate of 33% when VE/VCO2\u0026thinsp;\u0026ge;\u0026thinsp;35 (AUC\u0026thinsp;=\u0026thinsp;0.71, 95% CI: 0.61\u0026ndash;68.90, p\u0026thinsp;=\u0026thinsp;0.06). With segmentectomies, due to less parenchymal resection compared to lobectomies, it does seem consistent to use a higher VE/VCO2 slope threshold to classify patients at risk of complications (\u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eOn the other hand, only 13 patients (48%) achieved maximal CPET, implying that 52% of peakVO2 was underestimated. As these limitations to exercise are common in patients with chronic respiratory or cardiac failure, it does seem important to have a tool available that could overcome the limitations of CPET, such as the VE/VCO2 slope, in order to better characteri\u003cb\u003es\u003c/b\u003ee preoperative risks. The 8 excluded patients (peak VO2\u0026thinsp;\u0026lt;\u0026thinsp;10ml/kg/min) had a non-maximal CPET (shown in supplemental material). Four patients out of 8 had a VE/VCO2 slope\u0026thinsp;\u0026lt;\u0026thinsp;38, which could indicate a discussion on patient\u0026rsquo;s surgery eligibility.\u003c/p\u003e \u003cp\u003eOur study has several limitations: it is a single-center, retrospective study conducted on a small sample size. Results cannot be generalised to all centres, although the indications for CPET and segmentectomies are in line with international guidelines (\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e, \u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e, \u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e). Furthermore, CPET was not routinely performed in all the patients undergoing segmentectomy, only in those with impaired lung function (\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e, \u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e). Therefore, the patients included in our study represent a population with greater perioperative and postoperative risks than general population, as they represent 10% of segmentectomies with the highest risk of complications. Finally, ERS recommendations advise against surgery for patients with a peakVO2\u0026thinsp;\u0026lt;\u0026thinsp;10ml/kg/min (\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e), so these patients could not be included in our study, which could reduce the predictive value of peakVO2.\u003c/p\u003e"},{"header":"Conclusions","content":"\u003cp\u003eThe VE/VCO2 slope appears to be a valuable tool, for predicting grade II or more postoperative complications following segmentectomies. A more restrictive threshold of 38 would be more appropriate for segmentectomies. However, the role of the VE/VCO2 slope in the preoperative assessment of patients eligible for segmentectomy remains to be clearly defined, particularly through larger-scale, ideally prospective and multicentred studies. The relevance of preoperative CPET in segmentectomy planning remains open to discussion.\u003c/p\u003e"},{"header":"Abbreviations","content":"\u003cp\u003eBMI: body mass index\u003c/p\u003e\n\u003cp\u003eCOPD: chronic obstructive pulmonary disease\u003c/p\u003e\n\u003cp\u003eCPET\u0026nbsp;:cardiopulmonary exercise testing\u003c/p\u003e\n\u003cp\u003eDLCO: carbon monoxide diffusion capacity\u003c/p\u003e\n\u003cp\u003eFEV1\u0026nbsp;: forced expiratory volume in one second\u003c/p\u003e\n\u003cp\u003eLVEF: left ventricular ejection fraction\u003c/p\u003e\n\u003cp\u003eNSCLC\u0026nbsp;: Non-small cell lung cancer\u003c/p\u003e\n\u003cp\u003ePAD: peripheral arterial disease\u003c/p\u003e\n\u003cp\u003ePFT: pulmonary function test\u003c/p\u003e\n\u003cp\u003ePPO\u0026nbsp;: predicted postoperative\u003c/p\u003e\n\u003cp\u003eVE/VCO2 slope : ventilatory efficiency slope\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eVO2max: maximal oxygen consumption\u003c/p\u003e\n\u003cp\u003eVT1: Ventilation threshold 1\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003eEthics approval: 2025-EI-704, 2025-093, in May 2025\u003c/p\u003e\n\u003cp\u003eConsent for publications: all participants give a non-opposition for publications.\u003c/p\u003e\n\u003cp\u003eNo competing interest.\u003c/p\u003e\n\u003cp\u003eFunding: This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.\u003c/p\u003e\n\u003cp\u003eAuthors\u0026rsquo; contributions: conceptualization (MD), design (MD,GP,BG,SL, JPB), data collection (GP,QR, TB, MD, BG, SL, JPB), analysis (GP, MD), decision to publish (MD, SL, JPB), preparation of manuscript (GP, MD), validation of manuscript (GP, QR, TB, BG, SL, JPB, MD). \u0026nbsp;\u003c/p\u003e\n\u003cp\u003eAcknowledgments : to the Thoracic Surgery unit and the Day Hospital unit of pneumology and \u0026nbsp;to Miss Margaux Bruyere for translating.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eSung H, Ferlay J, Siegel RL, Laversanne M, Soerjomataram I, Jemal A et al. 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Available from: \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://pubmed.ncbi.nlm.nih.gov/31699121/\u003c/span\u003e\u003cspan address=\"https://pubmed.ncbi.nlm.nih.gov/31699121/\" targettype=\"URL\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"journal-of-cardiothoracic-surgery","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"jcts","sideBox":"Learn more about [Journal of Cardiothoracic Surgery](http://cardiothoracicsurgery.biomedcentral.com)","snPcode":"13019","submissionUrl":"https://submission.nature.com/new-submission/13019/3","title":"Journal of Cardiothoracic Surgery","twitterHandle":"@BioMedCentral","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"BMC/SO AJ","inReviewEnabled":true,"inReviewRevisionsEnabled":true},"keywords":"ventilatory slope, lung segmentectomy, predictor, post-operative complications","lastPublishedDoi":"10.21203/rs.3.rs-8502647/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-8502647/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003ch2\u003eBackground\u003c/h2\u003e \u003cp\u003eThe ventilatory efficiency slope (VE/VCO₂) is an established prognostic marker for heart failure and pulmonary hypertension. It has been associated with postoperative risk after major lung resections. However, its predictive value in lung segmentectomy remains unclear. This study aims to assess the relationship between VE/VCO₂ slope and cardiopulmonary complications after segmentectomy, and to determine an optimal predictive threshold.\u003c/p\u003e\u003ch2\u003eMethods\u003c/h2\u003e \u003cp\u003eWe conducted a retrospective, single-center study including patients over 18 years old, who underwent preoperative CPET before segmentectomy, between 2021 and 2025 in Nice. The primary endpoint was the association between VE/VCO₂ slope and cardiopulmonary complications occurring within 90 days. A subgroup analysis on grade II complications or more was conducted.\u003c/p\u003e\u003ch2\u003eResults\u003c/h2\u003e \u003cp\u003eAmong 380 segmentectomy candidates, 27 patients with CPET were included (median age 68 years, 52% male, median FEV1 75% predicted). The median peak VO₂ was 16.4 ml/kg/min and median VE/VCO₂ slope was 33.5. Postoperative cardiopulmonary complications occurred in 8 patients (29%). Overall, VE/VCO₂ slope was not significantly different between patients with or without complications (38.0 vs. 33.9; p\u0026thinsp;=\u0026thinsp;0.26). In subgroup analysis, VE/VCO₂ slope was significantly higher in patients with \u0026ge;\u0026thinsp;grade II complications (38.6 vs. 33.1; p\u0026thinsp;=\u0026thinsp;0.046). A threshold of VE/VCO₂ \u0026ge;38 provided the best predictive performance (sensitivity 80%, specificity 81%, p\u0026thinsp;=\u0026thinsp;0.02).\u003c/p\u003e\u003ch2\u003eConclusion\u003c/h2\u003e \u003cp\u003eIn high-risk patients undergoing segmentectomy, the VE/VCO₂ slope appears sensitive in predicting\u0026thinsp;\u0026ge;\u0026thinsp;grade II complications. A threshold of 38 may be more appropriate. Larger prospective multicentred studies would be required to confirm these results.\u003c/p\u003e\u003ch2\u003eTrial registration :\u003c/h2\u003e \u003cp\u003e The Nice University Hospital and the ethical committee approved this retrospective, monocentric study (2025-EI-704, 2025-093, in May 2025)\u003c/p\u003e","manuscriptTitle":"The ventilatory efficiency slope (VE/VCO₂ slope) as a predictor of postoperative cardiopulmonary complications post lung segmentectomy in high-risk patients?","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2026-02-11 06:26:42","doi":"10.21203/rs.3.rs-8502647/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Revision requested","date":"2026-04-05T10:11:03+00:00","index":"","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2026-02-12T19:56:26+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"30961212756741313366370331075947377722","date":"2026-02-04T19:33:37+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2026-02-04T12:45:25+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2026-01-06T06:44:31+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2026-01-06T06:43:46+00:00","index":"","fulltext":""},{"type":"submitted","content":"Journal of Cardiothoracic Surgery","date":"2026-01-02T17:31:28+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"journal-of-cardiothoracic-surgery","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"jcts","sideBox":"Learn more about [Journal of Cardiothoracic Surgery](http://cardiothoracicsurgery.biomedcentral.com)","snPcode":"13019","submissionUrl":"https://submission.nature.com/new-submission/13019/3","title":"Journal of Cardiothoracic Surgery","twitterHandle":"@BioMedCentral","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"BMC/SO AJ","inReviewEnabled":true,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"32350a79-dea8-4edb-97ef-08bf70c274fc","owner":[],"postedDate":"February 11th, 2026","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"in-revision","subjectAreas":[],"tags":[],"updatedAt":"2026-04-05T10:24:32+00:00","versionOfRecord":[],"versionCreatedAt":"2026-02-11 06:26:42","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-8502647","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-8502647","identity":"rs-8502647","version":["v1"]},"buildId":"XKTyCvWXoU3ODBz1xrDgd","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}