Utility of Cardiopulmonary Exercise Testing in Chronic Obstructive Pulmonary Disease: A Review

Abstract

Chronic obstructive pulmonary disease (COPD) is a disease defined by airflow obstruction with a high morbidity and mortality and significant economic burden. Although pulmonary function testing is the cornerstone in diagnosis of COPD, it cannot fully characterize disease severity or cause of dyspnea because of disease heterogeneity and variable related and comorbid conditions affecting cardiac, vascular, and musculoskeletal systems. Cardiopulmonary exercise testing (CPET) is a valuable tool for assessing physical function in a wide range of clinical conditions, including COPD. Familiarity with measurements made during CPET and its potential to aid in clinical decision-making related to COPD can thus be useful to clinicians caring for this population. This review highlights pulmonary and extrapulmonary impairments that can contribute to exercise limitation in COPD. Key elements of CPET are identified with an emphasis on measurements most relevant to COPD. Finally, clinical applications of CPET demonstrated to be of value in the COPD setting are identified. These include quantifying functional capacity, differentiating among potential causes of symptoms and limitation, prognostication and risk assessment for operative procedures, and guiding exercise prescription

Keywords:

• dyspnea
• obstructive lung disease
• exercise intolerance
• exercise limitation

Abbreviations

AT, anaerobic threshold; BP, blood pressure; BR, breathing reserve; C(a-v)O₂, arteriovenous oxygen content difference; CO, cardiac output; DH, dynamic hyperinflation; DLCO, diffusion capacity for carbon monoxide; EELV, end expiratory lung volume; EILV, end inspiratory lung volume; FEV₁, forced expiratory volume at 1 second; FRC, functional residual capacity; FVC, forced vital capacity; fb, breathing frequency; GOLD, Global Initiative for Chronic Obstructive Lung Disease; HCO₃, serum bicarbonate; HR, heart rate; IC, inspiratory capacity; IRV, inspiratory reserve volume; LT, lactate threshold; OUES, oxygen uptake efficiency slope; P_AO2, alveolar oxygen pressure; P_aCO2, arterial CO₂ pressure; P_aO2, arterial oxygen pressure; PEEP, positive end expiratory pressure; P_ECO2, mixed expired CO₂ pressure; P_ETCO2, end tidal CO₂ pressure; P_ETO2, end tidal oxygen pressure; PFT, pulmonary function test; RER, respiratory exchange ratio; S_pO2, arterial oxygen saturation; SV, stroke volume; TLC, total lung capacity; _CO2, Carbon dioxide output; V_D /V_T, dead space to tidal volume ratio; _E, minute ventilation; _E/ _CO2, ventilatory equivalent for CO₂; _O2, Oxygen uptake; V_T, tidal volume; V/Q, ventilation-perfusion; WR, work rate; 6MWT, 6-minute walk test.

Disclosure

Dr Kathy E Sietsema reports royalties for “Wasserman & Whipp’s Princilpes of Exercise Testing and Interpretation; 6th ed.” from Wolters Kluwer. The authors report no other conflicts of interest in this work.