A recent study explored the role of peak oxygen pulse (O2P) in patients with chronic obstructive pulmonary disease (COPD).
The authors explained that O2P acts as a surrogate for stroke volume; however, there is a lack of studies evaluating O2P, HRQL, and exercise capacity in patients with COPD. This study involved 79 patients with COPD who underwent lung function testing, a cardiopulmonary exercise test (CPET), Borg Dyspnea Scale evaluation, completion of the St. George’s Respiratory Questionnaire, and echocardiography. Two groups of patients were used in order to compare cardiovascular comorbidities, COPD-related hospitalizations, and emergency room visits—one group of patients with normal peak O2P and one group with impaired peak O2P.
“With respect to pathophysiology, there is a close interaction between COPD and cardiac function. The principal pathophysiological changes of COPD include airway inflammation, lung emphysema, and pulmonary vascular changes,” explained the authors. “The obstruction and inflammation of COPD cause expiratory flow limitation, air-trapping, and hyperinflation. Airway obstruction and hyperinflation are further associated with impaired left heart diastolic filling.”
The results reported that patients with normal peak O2P had higher exercise capacity, better HRQL, lower dyspnea score, lower COPD-related hospitalizations and higher circulatory and ventilator parameters than those with impaired peak O2P. In addition, following a simple linear regression analysis, anaerobic threshold (AT) and forced expiratory volume in 1 second (FEV1) demonstrated an association with peak O2P.
The study demonstrated 3 main impacts of peak O2P:
- Lung function is correlated with peak O2P, and therefore O2P is inversely associated with lung hyperinflation.
- Ventilation (VE) is associated with peak O2P with patients with impaired peak O2P. demonstrating lower VE at peak exercise
- Ventilatory equivalent (VEQ) is associated with peak O2P since patients with impaired peak O2P had more severe hyperinflation and poor cardiac function and in turn, higher VEQ.
“To the best of our knowledge, this is the first study that comprehensively demonstrated the impact of peak O2P on patients with COPD,” concluded the authors. “peak O2P is an important parameter in COPD, and could be an indicative parameter of the overall condition of lung hyperinflation, pulmonary hypertension, and heart failure comorbidity.”
Wu C, Hsieh P, Yang M, et al. Impact Of Peak Oxygen Pulse On Patients With Chronic Obstructive Pulmonary Disease [published online November 20, 2019]. Int J Chron Obstruct Pulmon Dis. doi: 10.2147/COPD.S224735