Study Investigates the Role of Peak Oxygen Pulse in Patients With COPD

Peak oxygen pulse (O₂P) plays a significant role in patients with chronic obstructive pulmonary disease (COPD) by impacting exercise capacity, health-related quality of life (HRQL), dyspnea, COPD-related hospitalization, and circulatory and ventilatory functions, according to research published in the International Journal of Chronic Obstructive Pulmonary Disease.

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.”

Reference

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