Accuracy of pulmonary function tests in predicted exercise capacity in COPD patients

A new maximal bicycle test using a prediction algorithm developed from four large COPD studies

Background: Maximum exercise workload (W_MAX) is today assessed as the first part of Cardiopulmonary Exercise testing. The W_MAX test exposes patients with COPD, often having cardiovascular comorbidity, to risks. Our research project was initiated with the final aim to eliminate the W_MAX test and replace this test with a predicted value of W_MAX, based on a prediction algorithm of W_MAX derived from multicentre studies.

Methods: Baseline data (W_MAX, demography, lung function parameters) from 850 COPD patients from four multicentre studies were collected and standardized. A prediction algorithm was prepared using Random Forest modelling. Predicted values of W_MAX were used in a new W_MAX test, which used a linear increase in order to reach the predicted W_MAX within 8 min. The new W_MAX test was compared with the standard stepwise W_MAX test in a pilot study including 15 patients with mild/moderate COPD.

Results: The best prediction algorithm of W_MAX included age, sex, height, weight, and six lung function parameters. FEV₁ and DLCO were the most important predictors. The new W_MAX test had a better correlation (R² = 0.84) between predicted and measured W_MAX than the standard W_MAX test (R² = 0.66), with slopes of 0.50 and 0.46, respectively. The results from the new W_MAX test and the standard W_MAX test correlated well.

Conclusion: A prediction algorithm based on data from four large multicentre studies was used in a new W_MAX test. The prediction algorithm provided reliable values of predicted W_MAX. In comparison with the standard W_MAX test, the new W_MAX test provided similar overall results.

Comparison of cardiopulmonary exercise testing variables in COPD patients with and without coronary artery disease

BACKGROUND

Coronary artery disease (CAD) is a common concomitant condition and an important cause of morbidity and mortality in patients with chronic obstructive pulmonary disease (COPD). Since COPD and CAD can both independently cause reduced exercise capacity, it is reasonable to hypothesize that the combination of these diseases may compound the abnormalities observed during cardiopulmonary exercise testing (CPET). However, little is known about the impact of CAD on the CPET response in COPD patients. The aim of this study is to compare exercise capacity and gas exchange variables in COPD patients with and without CAD.

METHODS

Fifty-four COPD subjects without CAD (COPDnoCAD) were matched to 54 COPD subjects diagnosed with CAD (COPD/CAD) according to age, gender, body mass index and severity of COPD. All subjects underwent resting pulmonary function and symptom-limited CPET.

RESULTS

Comparing COPDnoCAD patients with COPD/CAD patients revealed that exercise capacity, as measured by % peak oxygen consumption (42 ± 16% vs 53 ± 19%, p = 0.002) and % peak wattage (23 ± 13% vs 32 ± 16%, p = 0.001), was significantly lower in COPD/CAD. Ventilatory response, as measured by VE/VCO2 nadir (36 ± 9 vs 32 ± 5, p = 0.001), was significantly higher in COPD/CAD, with % peak VO2 and VE/VCO2 nadir correlating to % FEV1 and inversely correlating with %DLCO.

CONCLUSION

COPD patients with CAD have significantly impaired CPET responses with lower exercise capacity and impaired gas exchange compared to COPD patients without CAD. These findings may affect the clinical interpretation of CPET data in COPD patients who have concomitant CAD.

Cardiopulmonary exercise testing characteristics in heart failure patients with and without concomitant chronic obstructive pulmonary disease

BACKGROUND

The assessment of aerobic exercise capacity is an important component in the clinical management of patients with heart failure (HF). Although a significant percentage of patients diagnosed with HF also present with chronic obstructive pulmonary disease (COPD) comorbidity, the combined impact of these chronic conditions on the aerobic exercise response is unknown and is therefore the purpose of the present investigation.

METHODS

Sixty-nine subjects with HF and COPD were matched to 69 subjects solely diagnosed with HF according to age, sex, and HF etiology. All subjects underwent resting pulmonary function and diffusion capacity testing, echocardiography with tissue Doppler imaging, and cardiopulmonary exercise testing (CPX).

RESULTS

Subjects with COPD comorbidity had significantly lower pulmonary function testing and diffusion capacity values versus HF alone (P < .05). In addition, subjects with both HF and COPD had significantly higher pulmonary artery systolic pressures (51.9 ± 9.0 vs 37.0 ± 7.8 mm Hg, P < .001) as assessed by pulsed Doppler echocardiography. Cardiopulmonary exercise testing revealed a significantly poorer response in subjects with HF and COPD by all variables that were analyzed, including peak oxygen consumption (12.1 ± 4.3 vs 16.3 ± 4.3 mL kg⁻¹ min⁻¹, P < .001), minute ventilation/carbon dioxide production slope (42.7 ± 7.4 vs 33.3 ± 6.6, P < .001) and heart rate recovery at 1 minute (12.1 ± 2.5 vs 14.2 ± 2.9 beats, P < .001).

CONCLUSIONS

Patients with HF and the comorbidity of COPD have significantly impaired CPX responses. This novel finding may impact the clinical interpretation of CPX data in patients with HF who also present with this chronic pulmonary condition.

The future of aerobic exercise testing in clinical practice: is it the ultimate vital sign?

The four traditional vital signs: resting heart rate, blood pressure, respiratory rate and body temperature, serve as the cornerstone of a physical examination. Other assessments such as pain have been proposed as additional vital signs. To this point however, there has been limited consideration for aerobic exercise assessment as a vital sign. A wealth of literature demonstrating the prognostic, diagnostic and interventional value of the aerobic exercise assessment now exists, supporting its use in numerous clinical scenarios. Moreover, the assessment of the aerobic exercise response allows for the manifestation of physiologic abnormalities that are not readily apparent during the collection of resting data. This review will provide evidence supporting the assertion that the aerobic exercise assessment may be afforded vital sign status in future clinical practice.

Clinical findings of the patients with legal pulmonary disability--short-term follow-up at a tertiary university hospital in Korea

BACKGROUND/AIMS

Legal pulmonary disability in Korea is decided for chronic respiratory patients who have been diagnosed for a year or more, and the patients haven't gotten better after more than 2 months of sufficient treatment and they have shown no change in their pulmonary function within the two years after their original diagnosis. The purpose of this study was to investigate the clinical features and progress of those patients who have been diagnosed as having pulmonary disability.

METHODS

We reviewed retrospectively the medical records of the patients who had been decided as having pulmonary disability at a tertiary university hospital from 2003 to 2004, and these patients could be followed up for more than 6 months.

RESULTS

The number of enrolled patients was 118 (male : female = 95 : 23) and their mean age was 60+/-10 years. Their major underlying diseases were chronic obstructive pulmonary disease (n=45, 38%), tuberculous destroyed lung (n=29, 25%), and bronchial asthma (n=27, 23%). Of them, the number of patients with a class 1 pulmonary disability were 24 (20%), there were 28 class 2 patients (24%) and 66 class 3 patients (56%). The FEV1 could be followed up for 42 of these patients, of whom 20 patients showed no change or a decrease in their FEV1 but 22 showed an increased FEV1. Especially, some of them showed the increase of their FEV1 of 10% or more, and the 50% of them were patients with bronchial asthma. During the follow-up period, 6 patients died; 3 were class 1, 1 was class 2 and 2 were class 3. Five of these patients died of their underlying pulmonary diseases or combined pneumonia.

CONCLUSIONS

It is necessary to decide the pulmonary disability after sufficient treatment and to perform periodic follow-up testing even after the disability decision for confirming that the disability is stable and also to adjust the class of the disability. Further studies are needed to observe the clinical progress and prognosis of patients with pulmonary disability by performing long-term follow-up for a large number of patients.