The prognostic value of cardiopulmonary exercise testing in interstitial lung disease: a systematic review

Body composition, maximal fitness, and submaximal exercise function in people with interstitial lung disease

BACKGROUND

Cardiopulmonary exercise testing (CPET) is feasible, valid, reliable, and clinically useful in interstitial lung disease (ILD). However, maximal CPET values are often presented relative to body mass, whereas fat-free mass (FFM) may better reflect metabolically active muscle during exercise. Moreover, despite the value of maximal parameters, people with ILD do not always exercise maximally and therefore clinically relevant submaximal parameters must be identified. Therefore, this study assessed peak oxygen uptake (VO2peak) relative to FFM, identifying the validity of common scaling techniques; as well as characterising the oxygen uptake efficiency slope (OUES) and plateau (OUEP) as possible submaximal parameters.

METHODS

Participants with ILD underwent assessment of body composition and CPET via cycle ergometry during a single study visit. To determined effectiveness of scaling for body size, both body mass and FFM were scaled using ratio-standard (X/Y) and allometric (X/Yb) techniques. Pearsons's correlations determined agreement between OUES, OUEP, and parameters of lung function. Cohens kappa (κ) assessed agreement between OUES, OUEP and VO2peak.

RESULTS

A total of 24 participants (7 female; 69.8 ± 7.5 years; 17 with idiopathic pulmonary fibrosis) with ILD completed the study. Maximal exercise parameters did not require allometric scaling, and when scaled to FFM, it was shown that women have a significantly higher VO2peak than men (p = 0.044). Results also indicated that OUEP was significantly and positively correlated with DLCO (r = 0.719, p < 0.001), and held moderate agreement with VO2peak (κ = 0.50, p < 0.01).

CONCLUSION

This study identified that ratio-standard scaling is sufficient in removing residual effects of body size from VO2peak, and that VO2peak is higher in women when FFM is considered. Encouragingly, this study also identified OUEP as a possible alternative submaximal marker in people with ILD, and thus warrants further examination.

A Summed Score From Cardiopulmonary Exercise Test Parameters Predicts 1-Year Mortality in Newly Diagnosed Interstitial Lung Disease

BACKGROUND

Cardiopulmonary exercise testing (CPET) is a unique diagnostic tool that assesses the functional capacity of the heart, lungs, and peripheral oxidative system in an integrated manner. However, the clinical utility of CPET for evaluating interstitial lung disease (ILD) remains uncertain. The objective of this study was to determine the predictive value of CPET for mortality in subjects with ILD.

METHODS

We prospectively enrolled subjects with ILD who underwent CPET at a tertiary medical center in Taiwan and followed up their survival status for 12 months. Mortality prediction was based on comparing CPET parameters between subjects who survived and those who died. We further analyzed CPET parameters that showed significant differences using receiver operating characteristic curves to identify their optimal cutoff values.

RESULTS

A total of 106 newly diagnosed subjects with ILD underwent CPET, and the 1-y mortality rate was 7.5%. Six CPET variables were found to be significant predictors of mortality: peak oxygen consumption, oxygen pulse, end-tidal partial pressure of carbon dioxide, heart rate recovery 1 min after CPET, minute ventilation to carbon dioxide output slope, and functional aerobic impairment. We calculated a summed score by adding the number of CPET variables that exceeded their cutoff values. Subjects with a summed score of 6 had a 1-y survival rate of only 25%, whereas subjects with scores of 0-5 had a survival rate of 98%.

CONCLUSIONS

In conclusion, the summed score represents a useful tool for screening patients with ILD who can undergo a CPET to determine their prognosis.

Abnormal Heart Rate Recovery and Chronotropic Incompetence With Exercise in Patients With Interstitial Lung Disease With and Without Pulmonary Hypertension

Introduction Chronotropic incompetence (CI) and heart rate (HR) recovery at one minute post-exercise (HRR1) have been proposed as indicators of autonomic imbalance. We retrospectively studied the presence of CI and HRR1 attained on cardiopulmonary exercise testing (CPET) in patients with interstitial lung disease (ILD) and those with interstitial lung disease with pulmonary hypertension (ILD-PHTN). Methods A total of 32 patients (21 had ILD alone; 11 had ILD-PHTN) underwent CPET performed per American Thoracic Society protocol on a manually-braked bicycle. HRR1 was defined as the difference between peak HR and HR after one minute post-exercise. The utilization of HR reserve recovery at peak exercise was expressed as Chronotropic Response Index (CRI) and was calculated as (peak HR-resting HR)/(220-age-resting HR). CI was defined by failure to reach 85% of the age-predicted maximum heart rate (APMHR = 200-Age) and CRI<0.80 (80%). Results VO2max was lower in patients with ILD-PHTN compared to ILD alone (14.15± 5.00 vs. 18.11± 4.48, p<0.05). Mean CRI (0.468± 0.179 versus 0.691± 0.210, p<0.05) and HRR1 (10± 7 versus 18± 9, p<0.05) were lower in patients with ILD-PHTN compared to ILD alone. Twenty out of a total of 32 patients (62.5%) met the criteria for CI. In the ILD group, 10 out of 21 patients (47.62%) and in the ILD-PHTN group 10 of 11 patients (90.90%) had CI. Conclusion Chronotropic Incompetence and abnormal heart rate recovery at one minute post-exercise are notable in patients with ILD and are more severe in patients with ILD-PHTN. These findings may contribute to our understanding of dyspnea due to these conditions.

[Comprehensive approach to rehabilitation of patients with COVID-19. (A literature review)]

The COVID-19 epidemic has made significant changes in the organization of treatment process both at the inpatient and outpatient stages.

OBJECTIVE

To analyze the work results of the rehabilitation units dealing with patients who have suffered from COVID-19, in order to summarize the used approaches to medical rehabilitation and improve the effectiveness of care delivery in the recovery phase.

RESULTS AND CONCLUSION

Currently, the rehabilitation system has been effectively rebuilt to meet new challenges of the COVID-19 pandemic. Recovery of patients with pronounced neurotic disorders has become a showing good results direction in rehabilitation. It is necessary to implement a tight integration of physical exercises and telerehabilitation facilities in order to effectively settle the main issues directly related to the treatment and recovery of patients with COVID-19 and other pathologies. The control, prevention, treatment and rehabilitation of other infectious diseases will have great prospects regarding the possibility of remote follow-up of patients and correction of their functional state of the body in the nearest future.

Cardiopulmonary exercise testing criteria for advanced therapies in patients with heart failure

Many cardiology associations endorse the role of the cardiopulmonary exercise test (CPET) to define the severity of impairment of functional capacity in individuals with heart failure with reduced ejection fraction (HFrEF) and when evaluating the need for advanced therapies for these patients. The focus of the CPET within the cardiology community has been on peak volume of oxygen uptake (VO2). However, several CPET variables are associated with outcomes in individuals with and without chronic disease and can inform clinical decisions in individuals with HFrEF. In this manuscript, we will review the normal cardiopulmonary response to a graded exercise test and review current guideline recommendations relative to CPET in patients with HFrEF.

Validity and repeatability of cardiopulmonary exercise testing in interstitial lung disease

BACKGROUND

Cardiopulmonary exercise testing (CPET), and its primary outcome of peak oxygen uptake (VO_2peak), are acknowledged as biomarkers in the diagnostic and prognostic management of interstitial lung disease (ILD). However, the validity and repeatability of CPET in those with ILD has yet to be fully characterised, and this study fills this evidence gap.

METHODS

Twenty-six people with ILD were recruited, and 21 successfully completed three CPETs. Of these, 17 completed two valid CPETs within a 3-month window, and 11 completed two valid CPETs within a 6-month window. Technical standards from the European Respiratory Society established validity, and repeatability was determined using mean change, intraclass correlation coefficient and typical error.

RESULTS

Every participant (100%) who successfully exercised to volitional exhaustion produced a maximal, and therefore valid, CPET. Approximately 20% of participants presented with a plateau in VO₂, the primary criteria for establishing a maximal effort. The majority of participants otherwise presented with secondary criteria of respiratory exchange ratios in excess of 1.05, and maximal heart rates in excess of their predicted values. Repeatability analyses identified that the typical error (expressed as percent of coefficient of variation) was 20% over 3-months in those reaching volitional exhaustion.

CONCLUSION

This work has, for the first time, fully characterised how patients with ILD respond to CPET in terms of primary and secondary verification criteria, and generated novel repeatability data that will prove useful in the assessment of disease progression, and future evaluation of therapeutic regimens where VO_2peak is used as an outcome measure.

Value of Cardiopulmonary Exercise Testing in Prognostic Assessment of Patients with Interstitial Lung Diseases

BACKGROUND

Interstitial lung disease (ILD) is associated with high rates of comorbidities and non-infectious lung disease mortality. Against this background, we aimed to evaluate the prognostic capacity of lung function and cardiopulmonary exercise testing (CPET) in patients with ILD.

MATERIALS AND METHODS

A total of 183 patients with diverse ILD entities were included in this monocentric analysis. Prediction models were determined using Cox regression models with age, sex, body mass index (BMI), and all parameters from pulmonary function testing and CPET. Kaplan-Meier curves were plotted for selected variables.

RESULTS

The median follow-up period was 3.0 ± 2.5 years. Arterial hypertension (57%) and pulmonary hypertension (38%) were the leading comorbidities. The Charlson comorbidity index score was 2 ± 2 points. The 3-year and 5-year survival rates were 68% and 50%, respectively. VO₂peak (mL/kg/min or %pred.) was identified as a significant prognostic parameter in patients with ILD. The cut-off value for discriminating mortality was 61%.

CONCLUSION

The present analyses consistently revealed the high prognostic power of VO₂peak %pred. and other parameters evaluating breathing efficacy (VÉ/VCO₂ @AT und VÉ/VCO₂ slope) in ILD patients. VO₂peak %pred., in contrast to the established prognostic values FVC %pred., DLCO/KCO %pred., and GAP, showed an even higher prognostic ability in all statistical models.

Cardiopulmonary exercise testing in interstitial lung diseases and the value of ventilatory efficiency

Interstitial lung diseases (ILDs) are diverse parenchymal pulmonary disorders, primarily characterised by alveolar and interstitial inflammation and/or fibrosis, and sharing pathophysiological similarities. Thus, patients generally harbour common respiratory symptoms, lung function abnormalities and modified exercise adaptation. The most usual and disabling complaint is exertional dyspnoea, frequently responsible for premature exercise interruption. Cardiopulmonary exercise testing (CPET) is increasingly used for the clinical assessment of patients with ILD. This is because exercise performance or dyspnoea on exertion cannot reliably be predicted by resting pulmonary function tests. CPET, therefore, provides an accurate evaluation of functional capacity on an individual basis. CPET can unmask anomalies in the integrated functions of the respiratory, cardiovascular, metabolic, peripheral muscle and neurosensory systems in ILDs. CPET uniquely provides an evaluation of all above aspects and can help clinicians shape ILD patient management. Preliminary evidence suggests that CPET may also generate valuable prognostic information in ILDs and can be used to shed light on the presence of associated pulmonary hypertension. This review aims to provide comprehensive and updated evidence concerning the clinical utility of CPET in ILD patients, with particular focus on the physiological and clinical value of ventilatory efficiency (V˙_E/V˙_CO2 ).

Effect of induced acute metabolic alkalosis on the V̇E/V̇CO2 response to exercise in healthy adults

We tested the hypothesis that increasing the respiratory control systems' arterial PCO₂ equilibrium point via induced acute metabolic alkalosis by ingestion of sodium bicarbonate (NaHCO₃, 0.3 g/kg) would decrease the ventilatory equivalent for CO₂ (V̇_E/V̇CO₂) at its lowest point ("nadir") during constant-load cycle exercise testing performed at 80 % of peak power output in 18 healthy young adults. Compared to the sodium chloride (4 g) control condition, ingestion of NaHCO₃: increased arterialized venous pH, HCO₃- and PCO₂ at rest by 0.05 ± 0.01 units (mean ± SE), 6.4 ± 0.4 mEq/L and 4.3 ± 0.7 mmHg, respectively (all p < 0.0001); and decreased the V̇_E/V̇CO₂ nadir during exercise by 9.4 % (p < 0.0001) secondary to a 4.7 ± 1.8 L/min decrease in V̇_E (p = 0.019). In conclusion, induced acute metabolic alkalosis by ingestion of NaHCO₃ decreased the V̇_E/V̇CO₂ response to strenuous exercise in healthy adults.

Prognostic value of cardiopulmonary exercise test after heart transplantation

BACKGROUND

The clinical utility of cardiopulmonary exercise testing (CPET) has not been extensively studied yet in heart transplantation (HTX) patients.

OBJECTIVE

To analyze the predictive value of the CPET on hospitalizations and mortality in HTX recipients.

METHODS

A retrospective cohort was performed from a secondary database. Patients > 18 years with HTX who underwent a CPET between 3 and 12 months after transplantation were included. Time to the first primary endpoint (HTX-related hospitalization) was analyzed and adjusted using Cox proportional hazards regression model.

RESULTS

A total of 122 patients (mean age 50.1 years, 77.0% men) were included. Fifty-seven patients (46.7%) had the primary endpoint. Peak VO₂ (HR .95; CI 95% .90-.99, P = .03), oxygen pulse (HR .57; CI 95% .34-.96, P = .03) and predicted VO₂ (HR .97; CI 95% .96-.99, P = .002) were associated with the endpoint. We did not find a significant association between the other variables and the outcome.

CONCLUSION

In HTX recipients, peak VO₂ , oxygen pulse, and predicted VO₂ were independently associated with hospitalizations at follow up.

A role for cardiopulmonary exercise testing in detecting physiological changes underlying health status in Idiopathic pulmonary fibrosis: a feasibility study

Introduction

There is limited data available on the use of CPET as a predictive tool for disease outcomes in the setting of IPF. We investigated the feasibility of undertaking CPET and the relationship between CPET and quality of life measurements in a well-defined population of mild and moderate IPF patients.

Methods

A prospective, single-centre observational study.

Results

Thirty-two IPF patients (mild n = 23, moderate n = 9) participated in the study, n = 13 mild patients attended for repeat CPET testing at 12 months. At baseline, total K-BILD scores and total IPF-PROM scores significantly correlated with 6MWT distance, but not with baseline FVC % predicted, TLco % predicted, baseline or minimum SpO₂. VO₂ peak/kg at AT positively correlated with total scores, breathlessness/activity and chest domains of the K-BILD questionnaire (p < 0.05). VO₂ peak significantly correlated with total IPF PROM scores and wellbeing domains (p < 0.05), with a trend towards statistical significance for total IPF-PROM and VO₂ peak/kg at anaerobic threshold (p = 0.06).

There was a statistically significant reduction in FVC% predicted at 12 months follow up, although the mean absolute decline was < 10% (p < 0.05). During this period VO₂ peak significantly reduced (21.6 ml/kg/min ± 2.9 vs 19.1 ± 2.8; p = 0.017), with corresponding reductions in total K-BILD and breathlessness/activity domains that exceeded the MCID for responsiveness. Lower baseline VO₂ peak/kg at anaerobic threshold correlated with greater declines in total K-BILD scores (r =  − 0.62, 0.024) at 12 months. Whilst baseline FVC% predicted or TLco % predicted did not predict change in health status,

Conclusion

We have shown that it is feasible to undertake CPET in patients with mild to moderate IPF.

CPET measures of VO₂ peak correlated with both baseline and change in K-BILD measurements at 1 year, despite relatively stable standard lung function (declines of < 10% in FVC), suggesting its potential sensitivity to detect physiological changes underlying health status.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12890-021-01520-8.