Impact of pulmonary emphysema on exercise capacity and its physiological determinants in chronic obstructive pulmonary disease

Abstract

Exercise limitation is common in chronic obstructive pulmonary disease (COPD). We determined the impact of pulmonary emphysema on the physiological response to exercise independent of contemporary measures of COPD severity. Smokers 40–79 years old with COPD underwent computed tomography, pulmonary function tesing, and symptom-limited incremental exercise testing. COPD severity was quantified according to the Global Initiative for Chronic Obstructive Lung Disease (GOLD) by spirometry (GOLD 1–4); and symptom burden and exacerbation risk (GOLD A-D). Emphysema severity was quantified as the percent lung volume <−950 Hounsfield units. Regression models adjusted for age, gender, body size, smoking status, airflow limitation, symptom burden and exacerbation risk. Among 67 COPD subjects (age 67 ± 8 years; 75% male; GOLD 1–4: 11%, 43%, 30%, 16%), median percent emphysema was 11%, and peak power output (PPO) was 61 ± 32 W. Higher percent emphysema independently predicted lower PPO (−24 W per 10% increment in emphysema; 95%CI −41 to −7 W). Throughout exercise, higher percent emphysema predicted 1) higher minute ventilation, ventilatory equivalent for CO2, and heart rate; and 2) lower oxy-hemoglobin saturation, and end-tidal PCO2. Independent of contemporary measures of COPD severity, the extent of pulmonary emphysema predicts lower exercise capacity, ventilatory inefficiency, impaired gas-exchange and increased heart rate response to exercise.

Animal Models Reflecting Chronic Obstructive Pulmonary Disease and Related Respiratory Disorders: Translating Pre-Clinical Data into Clinical Relevance

“…Minimizing exposure to both smoking and indoor air pollution decreases the rate of disease progression and is positively correlated with a decrease in mortality [67,68]. Physical activity is exceptionally important in reducing exacerbation frequency and mortality rates in patients with COPD [69][70][71][72]. Other interventions include vaccinations against influenza and pneumococcal infections, as these may reduce the risk of exacerbation events and hospital admission [73,74].…”

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

“…Several studies have shown that an increased V D /V Tphys , partially due to emphysema [21,23,25,28,96,97], constitutes an important correlate of a high V′ E /V′ CO 2 . As discussed later, this is particularly true in patients who are not severely compromised from the mechanical standpoint, i.e.…”

Correlation of the Radiological Emphysema Score of Chronic Obstructive Pulmonary Disease Patients with Clinic Parameters

“…3 Emphysema is a major determinant to predict lung function decline and mortality in COPD patients independent of airflow limitation. 6 Also, CTquantified emphysema in COPD patients is associated with exercise intolerance, impaired gas-exchange independent of airflow limitation, symptom scale and exacerbation risk was shown by Smith et al 7 Computed tomography (CT) is a well-validated technique to visually and quantitatively assess the presence, pattern and extent of emphysema, and a standardised characterisation of COPD on CT is crucial. 8 Determining COPD phenotypes related to emphysema severity can be important in properly managing the treatment and subtyping of the disease, and emphysema severity can be used as a predictor of COPD and functional impairment of the patients.…”