Unraveling the Role of Oxygen Pulse Variability in Endurance Exercise Training in Individuals with COPD: A Novel Approach to Response of Oxygen Pulse and Quality of Life in Pulmonary Rehabilitation.

Background: Chronic obstructive pulmonary disease (COPD) is characterized by airway inflammation, airflow limitation, reduced health-related quality of life (HRQL), and exercise intolerance. Pulmonary rehabilitation (PR) is essential for COPD management, but outcomes may be influenced by individual physiological factors. Cardiopulmonary exercise testing (CPET) measures oxygen pulse (O2P), an indicator of stroke volume, yet the impact of baseline O2P on PR effectiveness remains unclear.

Methods: This retrospective study included 97 participants with COPD who had received PR, of whom 48 were classified as Group 1 (normal O2P) and 49 as Group 2 (low O2P). PR involved 12 weeks of hospital-based endurance training on a bike, performed twice a week. Participants were assessed before and after PR using spirometry, respiratory muscle strength measurements, CPET, and HRQL evaluation with the St. George's Respiratory Questionnaire (SGRQ).

Results: PR significantly improved exercise capacity (peak work rate and oxygen consumption), dyspnea score, and all domains of the SGRQ, maximum expiratory pressure, ventilatory equivalent, respiratory rate, and mean blood pressure at rest in both groups (p < 0.05). However, improvements in O2P, maximal inspiratory pressure, and tidal volume at rest were observed only in Group 2 but not in Group 1.

Conclusion: PR improves exercise capacity, HRQL and specific respiratory function in participants with COPD, regardless of baseline O2P levels. Individuals with lower baseline O2P experience more benefits from PR, including a significant increase in O2P.