INTRODUCTION: Ventilatory efficiency (V'E/V'CO2 ) has been shown to predict postoperative pulmonary complications (PPCs) in lung resection candidates. V'E/V'CO2 is determined by arterial partial pressure of carbon dioxide (P aCO2 ) and by dead space to tidal volume ratio (V D/V T). We hypothesised P aCO2 and V D/V T contribute equally to the increase in V'E/V'CO2 in lung resection patients. METHODS: Consecutive lung resection candidates from two prior prospective studies were included in this post hoc analysis. All subjects underwent preoperative spirometry, cardiopulmonary exercise testing and arterial blood gas analysis at rest and peak exercise. PPCs were prospectively assessed during the first 30 postoperative days, or hospital stay. A t-test, Mann-Whitney U-test and two-tailed Fisher's exact test were used to compare patients with and without PPCs. p-values <0.05 were considered statistically significant. RESULTS: Of 398 patients, PPC developed in 64 (16%). Patients with PPCs more frequently underwent lobectomy by open thoracotomy, had longer hospital and ICU length of stay and higher 30- and 90-day mortality. Moreover, patients with PPCs exhibited a higher V'E/V'CO2 ratio both at rest and peak exercise. Both ratios were independently associated with PPCs. At rest, the contribution of P aCO2 and V D/V T to the increase in V'E/V'CO2 ratio in patients with PPCs was 45% and 55%, respectively. At peak exercise, the contribution of P aCO2 and V D/V T to the increase in V'E/V'CO2 ratio was 16% and 84%, respectively. CONCLUSIONS: V D/V T (V'/Q' mismatch and/or rapid shallow breathing pattern) is the dominant contributor to the increase in V'E/V'CO2 in lung resection candidates who develop PPCs.

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• Journal Article MeSH

INTRODUCTION: In recent years, ventilatory efficiency (minute ventilation (V'E)/carbon dioxide production (V'CO2 ) slope) and partial pressure of end-tidal carbon dioxide (P ETCO2 ) have emerged as independent predictors of postoperative pulmonary complications (PPC). Single parameters may give only partial information regarding periprocedural hazards. Accordingly, our aim was to create prediction models with improved ability to stratify PPC risk in patients scheduled for elective lung resection surgery. METHODS: This post hoc analysis was comprised of consecutive lung resection candidates from two prior prospective trials. All individuals completed pulmonary function tests and cardiopulmonary exercise testing (CPET). Logistic regression analyses were used for identification of risk factors for PPC that were entered into the final risk prediction models. Two risk models were developed; the first used rest P ETCO2 (for patients with no available CPET data), the second used V'E/ V'CO2 slope (for patients with available CPET data). Receiver operating characteristic analysis with the De-Long test and area under the curve (AUC) were used for comparison of models. RESULTS: The dataset from 423 patients was randomly split into the derivation (n=310) and validation (n=113) cohorts. Two final models were developed, both including sex, thoracotomy, "atypical" resection and forced expiratory volume in 1 s/forced vital capacity ratio as risk factors. In addition, the first model also included rest P ETCO2 , while the second model used V'E/V'CO2 slope from CPET. AUCs of risk scores were 0.795 (95% CI: 0.739-0.851) and 0.793 (95% CI: 0.737-0.849); both p<0.001. No differences in AUCs were found between the derivation and validation cohorts. CONCLUSIONS: We created two multicomponental models for PPC risk prediction, both having excellent predictive properties.

• Publication type
• Journal Article MeSH

INTRODUCTION: Post-operative oxygen therapy is used to prevent hypoxemia and surgical site infection. However, with improvements of anesthesia techniques, post-operative hypoxemia incidence is declining and the benefits of oxygen on surgical site infection have been questioned. Moreover, hyperoxemia might have adverse effects on the pulmonary and cardiovascular systems. We hypothesized hyperoxemia post thoracic surgery is associated with post-operative pulmonary and cardiovascular complications. METHODS: Consecutive lung resection patients were included in this post-hoc analysis. Post-operative pulmonary and cardiovascular complications were prospectively assessed during the first 30 post-operative days, or hospital stay. Arterial blood gases were analyzed at 1, 6 and 12 h after surgery. Hyperoxemia was defined as arterial partial pressure of oxygen (PaO2)>100 mmHg. Patients with hyperoxemia duration in at least two adjacent time points were considered as hyperoxemic. Student t-test, Mann-Whitney U test and two-tailed Fisher exact test were used for group comparison. P values < 0.05 were considered statistically significant. RESULTS: Three hundred sixty-three consecutive patients were included in this post-hoc analysis. Two hundred five patients (57%), were considered hyperoxemic and included in the hyperoxemia group. Patients in the hyperoxemia group had significantly higher PaO2 at 1, 6 and 12 h after surgery (p < 0.05). Otherwise, there was no significant difference in age, sex, comorbidities, pulmonary function tests parameters, lung surgery procedure, incidence of post-operative pulmonary and cardiovascular complications, intensive care unit and hospital length of stay and 30-day mortality. CONCLUSION: Hyperoxemia after lung resection surgery is common and not associated with post-operative complications or 30-day mortality.

• Keywords
• Hyperoxemia, Lung resection surgery, Post-operative complications,
• Publication type
• Journal Article MeSH

INTRODUCTION: According to the guidelines for preoperative assessment of lung resection candidates, patients with normal forced expiratory volume in 1 s (FEV1) and diffusing capacity of the lung for carbon monoxide (D LCO) are at low risk for post-operative pulmonary complications (PPC). However, PPC affect hospital length of stay and related healthcare costs. We aimed to assess risk of PPC for lung resection candidates with normal FEV1 and D LCO (>80% predicted) and identify factors associated with PPC. METHODS: 398 patients were prospectively studied at two centres between 2017 and 2021. PPC were recorded from the first 30 post-operative days. Subgroups of patients with and without PPC were compared and factors with significant difference were analysed by uni- and multivariate logistic regression. RESULTS: 188 subjects had normal FEV1 and D LCO. Of these, 17 patients (9%) developed PPC. Patients with PPC had significantly lower pressure of end-tidal carbon dioxide (P ETCO2 ) at rest (27.7 versus 29.9; p=0.033) and higher ventilatory efficiency (V'E/V'CO2 ) slope (31.1 versus 28; p=0.016) compared to those without PPC. Multivariate models showed association between resting P ETCO2 (OR 0.872; p=0.035) and V'E/V'CO2 slope (OR 1.116; p=0.03) and PPC. In both models, thoracotomy was strongly associated with PPC (OR 6.419; p=0.005 and OR 5.884; p=0.007, respectively). Peak oxygen consumption failed to predict PPC (p=0.917). CONCLUSIONS: Resting P ETCO2 adds incremental information for risk prediction of PPC in patients with normal FEV1 and D LCO. We propose resting P ETCO2 be an additional parameter to FEV1 and D LCO for preoperative risk stratification.

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• Journal Article MeSH

INTRODUCTION: Ventilatory efficiency (VE/VCO2 slope) has been shown superior to peak oxygen consumption (VO2) for prediction of post-operative pulmonary complications in patients undergoing thoracotomy. VE/VCO2 slope is determined by ventilatory drive and ventilation/perfusion mismatch whereas VO2 is related to cardiac output and arteriovenous oxygen difference. We hypothesized pre-operative VO2 predicts post-operative cardiovascular complications in patients undergoing lung resection. METHODS: Lung resection candidates from a published study were evaluated by post-hoc analysis. All of the patients underwent preoperative cardiopulmonary exercise testing. Post-operative cardiovascular complications were assessed during the first 30 post-operative days or hospital stay. One-way analysis of variance or the Kruskal-Wallis test, and multivariate logistic regression were used for statistical analysis and data summarized as median (IQR). RESULTS: Of 353 subjects, 30 (9%) developed pulmonary complications only (excluded from further analysis), while 78 subjects (22%) developed cardiovascular complications and were divided into two groups for analysis: cardiovascular only (n = 49) and cardiovascular with pulmonary complications (n = 29). Compared to patients without complications (n = 245), peak VO2 was significantly lower in the cardiovascular with pulmonary complications group [19.9 ml/kg/min (16.5-25) vs. 16.3 ml/kg/min (15-20.3); P<0.01] but not in the cardiovascular only complications group [19.9 ml/kg/min (16.5-25) vs 19.0 ml/kg/min (16-23.1); P = 0.18]. In contrast, VE/VCO2 slope was significantly higher in both cardiovascular only [29 (25-33) vs. 31 (27-37); P = 0.05] and cardiovascular with pulmonary complication groups [29 (25-33) vs. 37 (34-42); P<0.01)]. Logistic regression analysis showed VE/VCO2 slope [OR = 1.06; 95%CI (1.01-1.11); P = 0.01; AUC = 0.74], but not peak VO2 to be independently associated with post-operative cardiovascular complications. CONCLUSION: VE/VCO2 slope is superior to peak VO2 for prediction of post-operative cardiovascular complications in lung resection candidates.

• MeSH
• Oxygen MeSH
• Humans MeSH
• Lung surgery   MeSH
• Prognosis MeSH
• Oxygen Consumption * MeSH
• Heart Failure * MeSH
• Exercise Test MeSH
• Check Tag
• Humans MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Names of Substances
• Oxygen MeSH