Chest wall volumes during constant compared to incremental cycle ergometer tests in chronic obstructive pulmonary disease (COPD) patients: A systematic review and meta-analysis

Aim: to compare acute effects of a constant load or incremental cycle ergometer tests on dyspnea and chest wall volumes in COPD hyperinflators by optoelectronic plethysmography. Methods: electronic searches were performed on Medline, EMBASE, Cumulative Index to Nursing and Allied Health, Cochrane Central Register of Controlled Trials and Web of Science. Electronic search identified 6,374 studies. Results: Six studies met inclusion criteria. End inspiratory volume (EIV) increased to hyperinflators and euvolumics during constant load, and decreased during incremental protocol in abdominal compartment. For chest wall and abdominal, end expiratory volume (EEV) increased for hyperinflators and decreased for euvolumics during both tests (p=0.0002) . Five studies evaluated dyspnea using the modified Borg scale at the peak of test, constant load testshowed higher dyspnea scores than incremental protocols(6.9±3, 8.2±1.7 versus, 3.9±0.5, 4.2±0.4, 3.2±0.9, respectively, p=0.008). Conclusion: Fewer symptoms of dyspnea arise in COPD patients who are hyperinflators during incremental load compared with constant load. Euvolumic COPD patients respond more favourable with less dyspnea to both types of exercise tests which are likely due to a decrease of abdominal EEV, a more normal physiologic response to increased ventilatory demands.