Causes of ventilatory inefficiency in lung resection candidates

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.

Different measures of ventilatory efficiency in preoperative cardiopulmonary exercise testing are useful for predicting postoperative complications in abdominal cancer surgery

BACKGROUND

Ventilation as a function of elimination of CO2 during incremental exercise (VE/VCO2 slope) has been shown to be a valuable predictor of complications and death after major non-cardiac surgery. VE/VCO2 slope and partial pressure of end-tidal carbon dioxide (PetCO2) are both affected by ventilation/perfusion mismatch, but research on the utility of PetCO2 for risk stratification in major abdominal surgery is limited.

AIM

We aimed to determine the correlation between VE/VCO2 slope and PetCO2 measured during preoperative cardiopulmonary exercise testing (CPET) and its association with major cardiopulmonary complications (MCPCs) or death following oesophageal and other major abdominal cancer surgeries.

METHOD

In a retrospective cohort of 116 patients undergoing preoperative CPET 2008-2023, VE/VCO2 slope and PetCO2 (kPa) were recorded. The main outcome was MCPC during hospitalisation or death ≤90 days of surgery. We determined threshold values for each measure, corresponding to 90% specificity, using receiver operating characteristics analysis.

RESULTS

A strong negative correlation was found between PetCO2 after a 5-minute warm-up and VE/VCO2 slope (Pearson r = -.88). In oesophagus cancer, VE/VCO2 slope >38 and PetCO2 < 4.1 kPa (30.8 mmHg) were both significant thresholds for the main outcome. For other major abdominal surgery patients, threshold analyses were non-significant. The area under the curve to predict outcome was similar using VE/VCO2 slope (0.70, 95% confidence interval 0.51-0.89) as compared to PetCO2 (0.71, 0.53-0-90).

CONCLUSION

Both preoperative VE/VCO2 slope and PetCO2 could identify subjects with a very high risk of complications following oesophageal resection, with similar prognostic utility. PetCO2 can be measured with simpler equipment and could therefore be useful when CPET is not available.

Based on Cardiopulmonary Exercise Testing to Construct and Validate Nomogram of Long-Term Prognosis Within 12 Months for NSCLC

OBJECTIVE

Construction nomogram was to effectively predict long-term prognosis in patients with non-small cell lung cancer (NSCLC).

MATERIALS AND METHODS

The nomogram is developed by a retrospective study of 347 patients with NSCLC who underwent cardiopulmonary exercise testing (CPET) before surgery from May 2019 to February 2022. Cross-validation divided the data into a training cohort and validation cohort. The discrimination and accuracy ability of the nomogram were proofed by concordance index (C-index), calibration curve, receiver operating characteristic (ROC) curve, the area under the curve (AUC), and time-dependent ROC in validation cohort.

RESULTS

Age, intraoperative blood loss, VO2 peak, and VE/VCO2 slope were included in the model of nomogram. The model demonstrated good discrimination and accuracy with C-index of 0.770 (95% CI: 0.712-0.822). AUC of 6 (AUC: 0.789, 95% CI: 0.726-0.851) and 12 months (AUC: 0.787, 95% CI: 0.724-0.850) were shown in ROC. Time-independent ROC maintains a good effect within 12 months.

CONCLUSION

We developed a nomogram based on CPET. This model has a good ability of discrimination and accuracy. It could help clinicians to make treatment decision in clinical decision.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

SYSTEMATIC REVIEW PROTOCOL

PROSPERO (CRD42022369944).

Increased minute ventilation-to-carbon dioxide slope during cardiopulmonary exercise test is associated with poor postoperative outcome following lung cancer resection

OBJECTIVES

Ventilatory efficiency [minute ventilation-to-carbon dioxide output slope (VE/VCO2 slope)] can be measured at sub-maximal workload during cardiopulmonary exercise test. The aim of this study is to assess the association between VE/VCO2 slope and outcome after lung cancer resections.

METHODS

Retrospective, single-centre analysis on all patients undergoing lung resection for cancer (April 2014-August 2022) and with a preoperative cardiopulmonary exercise test. VE/VCO2 slope >40 was chosen as high-risk threshold. Logistic regression analysis was used to test the association of VE/VCO2 slope and several patient- and surgery-related factors with 90-day mortality.

RESULTS

A total of 552 patients were included (374 lobectomies, 81 segmentectomies, 55 pneumonectomies and 42 wedge resections). Seventy-four percent were minimally invasive procedures. Cardiopulmonary morbidity was 32%, in-hospital/30-day mortality 6.9% and 90-day mortality 8.9%. A total of 137 patients (25%) had a slope of >40. These patients were older (72 vs 70 years, P = 0.012), had more frequently coronary artery disease (17% vs 10%, P = 0.028), lower carbon monoxide lung diffusion capacity (57% vs 68%, P < 0.001), lower body mass index (25.4 vs 27.0 kg/m2, P = 0.001) and lower peak VO2 (14.9 vs 17.0 ml/kg/min, P < 0.001) than those with a lower slope. The cardiopulmonary morbidity among patients with a slope of >40 was 40% vs 29% in those with lower slope (P = 0.019). Ninety-day mortality was 15% vs 6.7% (P = 0.002). The 90-day mortality of elderly patients with slope >40 was 21% vs 7.8% (P = 0.001). After adjusting for peak VO2 value, extent of operation and other patient-related variables in a logistic regression analysis, VE/VCO2 slope retained a significant association with 90-day mortality.

CONCLUSIONS

VE/VCO2 slope was strongly associated with morbidity and mortality following lung resection and should be included in the functional algorithm to assess fitness for surgery.

Peak oxygen uptake in combination with ventilatory efficiency improve risk stratification in major abdominal surgery

This pilot study aimed to evaluate if peak VO2 and ventilatory efficiency in combination would improve preoperative risk stratification beyond only relying on peak VO2 . This was a single-center retrospective cohort study including all patients who underwent cardiopulmonary exercise testing (CPET) as part of preoperative risk evaluation before major upper abdominal surgery during years 2008-2021. The primary outcome was any major cardiopulmonary complication during hospitalization. Forty-nine patients had a preoperative CPET before decision to pursue to surgery (cancer in esophagus [n = 18], stomach [6], pancreas [16], or liver [9]). Twenty-five were selected for operation. Patients who suffered any major cardiopulmonary complication had lower ventilatory efficiency (i.e., higher VE/VCO2 slope, 37.3 vs. 29.7, p = 0.031) compared to those without complications. In patients with a low aerobic capacity (i.e., peak VO2  < 20 mL/kg/min) and a VE/VCO2 slope ≥ 39, 80% developed a major cardiopulmonary complication. In this pilot study of patients with preoperative CPET before major upper abdominal surgery, patients who experienced a major cardiopulmonary complication had significantly lower ventilatory efficiency compared to those who did not. A low aerobic capacity in combination with low ventilatory efficiency was associated with a very high risk (80%) of having a major cardiopulmonary complication.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Performance Comparison of Pulmonary Risk Scoring Systems in Lung Resection

OBJECTIVE

To validate and compare the performance of different pulmonary risk scoring systems to predict postoperative pulmonary complications (PPCs) in lung resection surgery.

DESIGN

Retrospective cohort study SETTING: A historic single-center cohort of lung resection surgeries PARTICIPANTS: Adult patients undergoing lung resection surgery under 1-lung ventilation.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

The accuracy of the following pulmonary risk scoring systems were used to predict pulmonary complications: the ARISCAT (Assess respiratory RIsk in Surgical patients in CATalonia), the LAS VEGAS (Local Assessment of VEntilatory management during General Anesthesia for Surgery), the SPORC (Score for Prediction of Postoperative Respiratory Complications), and a recent thoracic-specific risk score, named CARDOT. Discrimination and calibration were assessed using the concordance (c) index and the intercept of LOESS (locally estimated scatterplot)-smoothed curves, respectively. Additional models were constructed that incorporated predicted postoperative forced expiratory volume (ppoFEV1) into each scoring system. Of the 2,104 patients undergoing lung surgery, 123 developed postoperative pulmonary complications (PPCs; 5.9%). All scoring systems had poor discriminatory power to predict PPCs (ARISCAT c-index 0.60, 95% confidence interval [CI] 0.55-0.65; LAS VEGAS c-index 0.68, 95% CI 0.63-0.73; SPORC c-index 0.63, 95% CI 0.59-0.68; CARDOT c-index 0.64, 95% CI 0.58-0.70), but the inclusion of ppoFEV1 slightly improved the performance of LAS VEGAS (c-index 0.70, 95% CI 0.66-0.75) and CARDOT (c-index 0.68, 95% CI 0.62-0.73). Analysis of calibration showed a slight overestimation when using ARISCAT (intercept -0.28) and LAS VEGAS (intercept -0.27).

CONCLUSIONS

None of the scoring systems appeared to have adequate discriminatory power to predict PPCs among patients undergoing lung resection. An alternative risk score is necessary to better predict patients at risk of PPCs after thoracic surgery.

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

Objective

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

Methods

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

Results

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

Conclusions

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

Perioperative cardiovascular pathophysiology in patients undergoing lung resection surgery: a narrative review

Although thoracic surgery is understood to confer a high risk of postoperative respiratory complications, the substantial haemodynamic challenges posed are less well appreciated. This review highlights the influence of cardiovascular comorbidity on outcome, reviews the complex pathophysiological changes inherent in one-lung ventilation and lung resection, and examines their influence on cardiovascular complications and postoperative functional limitation. There is now good evidence for the presence of right ventricular dysfunction postoperatively, a finding that persists to at least 3 months. This dysfunction results from increased right ventricular afterload occurring both intraoperatively and persisting postoperatively. Although many patients adapt well, those with reduced right ventricular contractile reserve and reduced pulmonary vascular flow reserve might struggle. Postoperative right ventricular dysfunction has been implicated in the aetiology of postoperative atrial fibrillation and perioperative myocardial injury, both common cardiovascular complications which are increasingly being appreciated to have impact long into the postoperative period. In response to the physiological demands of critical illness or exercise, contractile reserve, flow reserve, or both can be overwhelmed resulting in acute decompensation or impaired long-term functional capacity. Aiding adaptation to the unique perioperative physiology seen in patients undergoing thoracic surgery could provide a novel therapeutic avenue to prevent cardiovascular complications and improve long-term functional capacity after surgery.

Ventilatory efficiency in combination with peak oxygen uptake improves risk stratification in patients undergoing lobectomy

Objective

We aimed to evaluate whether or not using the slope of the increase in minute ventilation in relation to carbon dioxide (VE/VCo₂-slope), with a cutoff value of 35, could improve risk stratification for major pulmonary complications or death following lobectomy in lung cancer patients at moderate risk (Vo_2peak = 10-20 mL/kg/min).

Methods

Single center, retrospective analysis of 146 patients with lung cancer who underwent lobectomy and preoperative cardiopulmonary exercise testing in 2008-2020. The main outcome was any major pulmonary complication or death within 30 days of surgery. Patients were categorized based on their preoperative cardiopulmonary exercise testing as: low-risk group, peak oxygen uptake >20 mL/kg/min; low-moderate risk, peak oxygen uptake 10 to 20 mL/kg/min and VE/VCo₂-slope <35; and moderate-high risk, peak oxygen uptake 10 to 20 mL/kg/min and VE/VCo₂-slope ≥35. The frequency of complications between groups was compared using χ² test. Logistic regression was used to calculate the odds ratio with 95% CI for the main outcome based on the cardiopulmonary exercise testing group.

Results

Overall, 25 patients (17%) experienced a major pulmonary complication or died (2 deaths). The frequency of complications differed between the cardiopulmonary exercise testing groups: 29%, 13%, and 8% in the moderate-high, low-moderate, and low-risk group, respectively (P = .023). Using the low-risk group as reference, the adjusted odds ratio for the low-moderate risk group was 3.44 (95% CI, 0.66-17.90), whereas the odds ratio for the moderate-high risk group was 8.87 (95% CI, 1.86-42.39).

Conclusions

Using the VE/VCo₂-slope with a cutoff value of 35 improved risk stratification for major pulmonary complications following lobectomy in lung cancer patients with moderate risk based on a peak oxygen uptake of 10 to 20 mL/kg/min. This suggests that the VE/VCo₂-slope can be used for preoperative risk evaluation in lung cancer lobectomy.

Ventilatory efficiency is superior to peak oxygen uptake for prediction of lung resection cardiovascular complications

Introduction

Ventilatory efficiency (V_E/VCO₂ slope) has been shown superior to peak oxygen consumption (VO₂) for prediction of post-operative pulmonary complications in patients undergoing thoracotomy. V_E/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, V_E/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 V_E/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

V_E/VCO₂ slope is superior to peak VO₂ for prediction of post-operative cardiovascular complications in lung resection candidates.

Prediction of Postoperative Complications: Ventilatory Efficiency and Rest End-tidal Carbon Dioxide

BACKGROUND

Cardiopulmonary exercise testing parameters including ventilatory efficiency (V_E/VCO₂ slope) are used for risk assessment of lung resection candidates. However, many patients are unable or unwilling to undergo exercise. V_E/VCO₂ slope is closely related to the partial pressure of end-tidal carbon dioxide (P_ETCO₂). We hypothesized P_ETCO₂ at rest predicts postoperative pulmonary complications.

METHODS

Consecutive lung resection candidates were included in this prospective multicenter study. Postoperative respiratory complications were assessed from the first 30 postoperative days or from the hospital stay. Student t test or Mann-Whitney U test was used for comparison. Multivariate stepwise logistic regression analysis was used to analyze association with the development of postoperative pulmonary complications. The De Long test was used to compare area under the curve (AUC). Data are summarized as median (interquartile range).

RESULTS

Three hundred fifty-three patients were analyzed, of which 59 (17%) developed postoperative pulmonary complications. P_ETCO₂ at rest was significantly lower (27 [24-30] vs 29 [26-32] mm Hg; P < .01) and V_E/VCO₂ slope during exercise significantly higher (35 [30-40] vs 29 [25-33]; P < .01) in patients who developed postoperative pulmonary complications. Both rest P_ETCO₂ with odds ratio 0.90 (95% confidence interval [CI] 0.83-0.97); P = .01 and V_E/VCO₂ slope with odds ratio 1.10 (95% CI 1.05-1.16); P < .01 were independently associated with postoperative pulmonary complications by multivariate stepwise logistic regression analysis. There was no significant difference between AUC of both models (rest P_ETCO₂: AUC = 0.79 (95% CI 0.74-0.85); V_E/VCO₂ slope: AUC = 0.81 (95% CI 0.75-0.86); P = .48).

CONCLUSIONS

P_ETCO₂ at rest has similar prognostic utility as V_E/VCO₂ slope, suggesting rest P_ETCO₂ may be used for postoperative pulmonary complications prediction in lung resection candidates.

Exertional ventilation/carbon dioxide output relationship in COPD: from physiological mechanisms to clinical applications

There is well established evidence that the minute ventilation (V′_E)/carbon dioxide output (V′_CO2) relationship is relevant to a number of patient-related outcomes in COPD. In most circumstances, an increased V′_E/V′_CO2 reflects an enlarged physiological dead space (“wasted” ventilation), although alveolar hyperventilation (largely due to increased chemosensitivity) may play an adjunct role, particularly in patients with coexistent cardiovascular disease. The V′_E/V′_CO2 nadir, in particular, has been found to be an important predictor of dyspnoea and poor exercise tolerance, even in patients with largely preserved forced expiratory volume in 1 s. As the disease progresses, a high nadir might help to unravel the cause of disproportionate breathlessness. When analysed in association with measurements of dynamic inspiratory constraints, a high V′_E/V′_CO2 is valuable to ascertain a role for the “lungs” in limiting dyspnoeic patients. Regardless of disease severity, cardiocirculatory (heart failure and pulmonary hypertension) and respiratory (lung fibrosis) comorbidities can further increase V′_E/V′_CO2. A high V′_E/V′_CO2 is a predictor of poor outcome in lung resection surgery, adding value to resting lung hyperinflation in predicting all-cause and respiratory mortality across the spectrum of disease severity. Considering its potential usefulness, the V′_E/V′_CO2 should be valued in the clinical management of patients with COPD.

The minute ventilation/carbon dioxide production relationship is relevant to a number of patient-related outcomes in COPD. Minute ventilation/carbon dioxide production, therefore, should be valued in the clinical management of these patients.https://bit.ly/3df2upH

The Year in Thoracic Anesthesia: Selected Highlights From 2020

Selected highlights in thoracic anesthesia in 2020 include updates in the preoperative assessment and prehabilitation of patients undergoing thoracic surgery; updates in one-lung ventilation (OLV) pertaining to the devices used for OLV; the use of dexmedetomidine for lung protection during OLV and protective ventilation, recommendations for the care of thoracic surgical patients with coronavirus disease 2019; a review of recent meta-analyses comparing truncal blocks with paravertebral and thoracic epidural blocks; and a review of outcomes after initiating the enhanced recovery after surgery guidelines for lung and esophageal surgery.

Associations between pretreatment physical performance tests and treatment complications in patients with non-small cell lung cancer: A systematic review

This systematic review evaluated which outcome variables and cut-off values of pretreatment exercise tests are associated with treatment complications in patients with stage I-III non-small cell lung cancer (NSCLC). PRISMA and Cochrane guidelines were followed. A total of 38 studies with adult patients undergoing treatment for stage I-III NSCLC who completed pretreatment exercise tests, and of whom treatment-related complications were recorded were included. A lower oxygen uptake at peak exercise amongst several other variables on the cardiopulmonary exercise test and a lower performance on field tests, such as the incremental shuttle walk test, stair-climb test, and 6-minute walk test, were associated with a higher risk for postoperative complications and/or postoperative mortality. Cut-off values were reported in a limited number of studies and were inconsistent. Due to the variety in outcomes, further research is needed to evaluate which outcomes and cut-off values of physical exercise tests are most clinically relevant.

Evaluation of Risk for Thoracic Surgery

Modern surgical practice places increased emphasis on treatment outcomes. There has been a paradigm shift from paternalistic ways of practicing medicine to patients having a major involvement in decision making and treatment planning. The combination of these two factors undoubtedly leaves the surgeon open to greater scrutiny in respect of results and outcomes. In dealing with this it is important that the surgeon, wider multidisciplinary team, and patient appreciate the idea of surgical risk. This article reviews the latest evidence relating to risk assessment in thoracic surgery and suggests how this should be incorporated into clinical practice.

Cardiopulmonary exercise testing in chronic obstructive pulmonary disease: An update on its clinical value and applications

Chronic obstructive pulmonary disease is a debilitating disorder, characterized by airflow limitation, exercise impairment, reduced functional capacity and significant systemic comorbidity, which complicates the course of the disease. The critical inspiratory constraint to tidal volume expansion during exercise (that may be further complicated by the presence of dynamic hyperinflation), abnormalities in oxygen transportation and gas exchange abnormalities are the major pathophysiological mechanisms of exercise intolerance in COPD patients, and thus, exercise testing has been traditionally used for the functional evaluation of these patients. Compared to various laboratory and field exercise tests, cardiopulmonary exercise testing (CPET) provides a thorough assessment of exercise physiology, involving the integrative respiratory, cardiovascular, muscle and metabolic responses to exercise. This review highlights the clinical utility of CPET in COPD patients, as it provides important information for the determination of the major factors that limit exercise among patients with several comorbidities, allows the assessment of the severity of dynamic hyperinflation, provides valuable prognostic information and can be used to evaluate the response to several therapeutic interventions.

Incorporating Lung Diffusing Capacity for Carbon Monoxide in Clinical Decision Making in Chest Medicine

Lung diffusing capacity for carbon monoxide (Dlco) remains the only noninvasive pulmonary function test to provide an integrated picture of gas exchange efficiency in human lungs. Due to its critical dependence on the accessible "alveolar" volume (Va), there remains substantial misunderstanding on the interpretation of Dlco and the diffusion coefficient (Dlco/Va ratio, Kco). This article presents the physiologic and methodologic foundations of Dlco measurement. A clinically friendly approach for Dlco interpretation that takes those caveats into consideration is outlined. The clinical scenarios in which Dlco can effectively assist the chest physician are discussed and illustrative clinical cases are presented.

Effects of a high-intensity pulmonary rehabilitation program on the minute ventilation/carbon dioxide output slope during exercise in a cohort of patients with COPD undergoing lung resection for non-small cell lung cancer

OBJECTIVE

Preoperative functional evaluation is central to optimizing the identification of patients with non-small cell lung cancer (NSCLC) who are candidates for surgery. The minute ventilation/carbon dioxide output (VE/VCO2) slope has proven to be a predictor of surgical complications and mortality. Pulmonary rehabilitation programs (PRPs) could influence short-term outcomes in patients with COPD undergoing lung resection. Our objective was to evaluate the effects of a PRP on the VE/VCO2 slope in a cohort of patients with COPD undergoing lung resection for NSCLC.

METHODS

We retrospectively evaluated 25 consecutive patients with COPD participating in a three-week high-intensity PRP prior to undergoing lung surgery for NSCLC, between December of 2015 and January of 2017. Patients underwent complete functional assessment, including spirometry, DLCO measurement, and cardiopulmonary exercise testing.

RESULTS

There were no significant differences between the mean pre- and post-PRP values (% of predicted) for FEV1 (61.5 ± 22.0% vs. 62.0 ± 21.1%) and DLCO (67.2 ± 18.1% vs. 67.5 ± 13.2%). Conversely, there were significant improvements in the mean peak oxygen uptake (from 14.7 ± 2.5 to 18.2 ± 2.7 mL/kg per min; p < 0.001) and VE/VCO2 slope (from 32.0 ± 2.8 to 30.1 ± 4.0; p < 0.01).

CONCLUSIONS

Our results indicate that a high-intensity PRP can improve ventilatory efficiency in patients with COPD undergoing lung resection for NSCLC. Further comprehensive prospective studies are required to corroborate these preliminary results.

Relationship of ventilatory inefficiency and low cardiorespiratory fitness in the elderly: a retrospective observational study

Abstract Objectives : To check if ventilatory inefficiency is related to low cardiorespiratory fitness in the elderly and to identify the variable(s) of the cardiopulmonary exercise test (CPET) best suited to determining this relationship. Methods : A retrospective analysis of 1357 CPETs was performed. Sixty-one subjects over 60 years old with a ventilatory efficiency slope (VE/VCO2) index >35 were selected and divided into two groups: low cardiorespiratory fitness (VO2<80% predicted) (n=22) and normal cardiorespiratory fitness (VO2>80% predicted) (n=39) and were compared with a control group of healthy elderly persons with normal cardiorespiratory fitness and VE/VCO2 slope index <35 (n=16), matched by gender, weight, height, and age. Results : Oxygen consumption had a low correlation with VE/VCO2 slope (r= -0.35, p<0.01), a moderate correlation with the cardiorespiratory optimal point (COP) (r= -0.59, p<0.001) and a strong correlation with oxygen uptake efficiency Slope (OUES) =0.92, p<0.0001). In relation to the ROC curve, the VE/VCO2 slope presented an area under the curve of 0.65, but without statistical significance (p> 0.05); the COP showed an area under the curve of 0.84 (p <0.0001) and the OUES presented an area under the curve of 0.81 (p<0.0001). Conclusion : Ventilatory inefficiency is related to poor cardiorespiratory fitness in the elderly. The COP and OUES were more accurate at predicting low cardiorespiratory fitness.

Patient and procedural features predicting early and mid-term outcome after radical surgery for non-small cell lung cancer

Background

Postoperative cardiovascular and pulmonary complications (PCVCs and PPCs) are frequent and result in prolonged hospital stay. The aim of this study was to update the risk factors associated with major complications and survival after lung cancer surgery.

Methods

This is a post-hoc analysis of a randomized controlled trial that was designed to assess the benefits of preoperative physical training. After enrollment, clinical, biological and functional data as well as intraoperative details were collected. In-hospital PCVCs and PPCs were recorded and survival data were adjudicated up to 4 years after surgery.

Results

Data from 151 patients were analyzed. Thirty-day mortality rate was 2.6% and the incidence of PCVCs and PPCs was 15% and 33%, respectively. Stepwise logistic regression analysis showed that, PCVCs were mainly related to elevated plasma levels of brain natriuretic peptides [odds ratios (ORs) =6.0; 95% confidence interval (CI), 1.3-27.3] and performance of a pneumonectomy (OR =9.6; 95% CI, 2.9-31.5) whereas PPCs were associated with the presence of COPD (OR =5.9; 95% CI, 2.4-14.8), current smoking (OR =2.6; 95% CI, 1.1-6.5) and the need for blood transfusion (OR =5.2; 95% CI, 1.2-23.3). Preoperative physical training was a protective factor regarding PPCs (OR =0.13; 95% CI, 0.05-0.34). Cox proportional hazards regression analysis showed that ventilatory inefficiency during exercise (expressed by a ratio >40 of ventilation to carbon dioxide elimination), coronary artery disease, elevated plasma levels of brain natriuretic peptides and the occurrence of PPCs were all predictive of poor survival after surgery.

Conclusions

Besides smoking and the extent of lung resection, preexisting cardiopulmonary disease as evidence by elevated levels of brain natriuretic peptides and inefficient ventilation are associated with poor clinical outcome after lung cancer surgery.

Minute ventilation-to-carbon dioxide slope is associated with postoperative survival after anatomical lung resection

OBJECTIVES

The aim of the study was to identify whether ventilation-to-carbon dioxide output (V_E/V _CO2) slope obtained from cardiopulmonary exercise test (CPET) as part of the preoperative functional workup was an independent prognostic factor for short and long-term survival after major lung resection.

PATIENTS AND METHODS

974 consecutive patients undergoing lobectomy (n = 887) or segmentectomy (n = 87) between April 2014 to March 2018 were included. 209 (22%) underwent CPET, and pulmonary function tests and several clinical factors including age, sex, performance status and comorbidities were retrospectively investigated to identify the prognostic factors with a multivariable Cox regression analysis.

RESULTS

Among the patients with measured V_E/V _CO2, the incidence of cardiopulmonary complications in patients with high V_E/V _CO2 slope (>40) was 37% (19 of 51) vs. 27% (33 of 121) in those with lower slope values (p = 0.19). The 90-day mortality in patients with high V_E/V _CO2 slope (n = 8) was 16% vs. 5% (n = 6) in those with lower slope values (p = 0.03). No overall difference in 2-year mortality was identified between the two groups (VE/VCO2 > 40: 70% (54-80) vs. VE/VCO2 ≤ 40: 72% (63-80), log-rank test, p = 0.39). In a Cox regression analysis V_E/V_CO2 values were associated with poorer 2-year survival (HR 1.05, 95% CI 1.01-1.10, p = 0.030).

CONCLUSIONS

We found that V_E/V _CO2 slope was an independent prognostic factor for the 90-day mortality and 2-year survival after anatomic pulmonary resection. This finding may assist during the multidisciplinary treatment decision-making process in high-risk patients with lung cancer.

Cardiopulmonary Exercise Testing and Surgery

The surgical patient population is increasingly elderly and comorbid and poses challenges to perioperative physicians. Accurate preoperative risk stratification is important to direct perioperative care. Reduced aerobic fitness is associated with increased postoperative morbidity and mortality. Cardiopulmonary exercise testing is an integrated and dynamic test that gives an objective measure of aerobic fitness or functional capacity and identifies the cause of exercise intolerance. Cardiopulmonary exercise testing provides an individualized estimate of patient risk that can be used to predict postoperative morbidity and mortality. This technology can therefore be used to inform collaborative decision-making and patient consent, to triage the patient to an appropriate perioperative care environment, to diagnose unexpected comorbidity, to optimize medical comorbidities preoperatively, and to direct individualized preoperative exercise programs. Functional capacity, evaluated as the anaerobic threshold and peak oxygen uptake ([Formula: see text]o₂peak) predicts postoperative morbidity and mortality in the majority of surgical cohort studies. The ventilatory equivalents for carbon dioxide (an index of gas exchange efficiency), is predictive of surgical outcome in some cohorts. Prospective cohort studies are needed to improve the precision of risk estimates for different patient groups and to clarify the best combination of variables to predict outcome. Early data suggest that preoperative exercise training improves fitness, reduces the debilitating effects of neoadjuvant chemotherapy, and may improve clinical outcomes. Further research is required to identify the most effective type of training and the minimum duration required for a positive effect.

Physiological and clinical relevance of exercise ventilatory efficiency in COPD

Exercise ventilation (V'_E) relative to carbon dioxide output (V'_CO2 ) is particularly relevant to patients limited by the respiratory system, e.g. those with chronic obstructive pulmonary disease (COPD). High V'_E-V'_CO2 (poor ventilatory efficiency) has been found to be a key physiological abnormality in symptomatic patients with largely preserved forced expiratory volume in 1 s (FEV₁). Establishing an association between high V'_E-V'_CO2 and exertional dyspnoea in mild COPD provides evidence that exercise intolerance is not a mere consequence of detraining. As the disease evolves, poor ventilatory efficiency might help explaining "out-of-proportion" breathlessness (to FEV₁ impairment). Regardless, disease severity, cardiocirculatory co-morbidities such as heart failure and pulmonary hypertension have been found to increase V'_E-V'_CO2 In fact, a high V'_E-V'_CO2 has been found to be a powerful predictor of poor outcome in lung resection surgery. Moreover, a high V'_E-V'_CO2 has added value to resting lung hyperinflation in predicting all-cause and respiratory mortality across the spectrum of COPD severity. Documenting improved ventilatory efficiency after lung transplantation and lung volume reduction surgery provides objective evidence of treatment efficacy. Considering the usefulness of exercise ventilatory efficiency in different clinical scenarios, the V'_E-V'_CO2 relationship should be valued in the interpretation of cardiopulmonary exercise tests in patients with mild-to-end-stage COPD.

Navigation bronchoscopy for diagnosis and small nodule location

Lung cancer continues to be the most common cause of cancer death. Screening programs for high risk patients with the use of low-dose computed tomography (CT) has led to the identification of small lung lesions that were difficult to identify using previous imaging modalities. Electromagnetic navigational bronchoscopy (ENB) is a novel technique that has shown to be of great utility during the evaluation of small, peripheral lesions, that would otherwise be challenging to evaluate with conventional bronchoscopy. The diagnostic yield of navigational bronchoscopy however is highly variable, with reports ranging from 59% to 94%. This variability suggests that well-defined selection criteria and standardized protocols for the use of ENB are lacking. Despite this variability, we believe that this technique is a useful tool evaluating small peripheral lung lesions when patients are properly selected.