Introduction: Exertional oscillatory ventilation (EOV) occurs in many patients with chronic heart failure (CHF) and is a predictor of adverse outcomes in this population. Many CHF patients (20-40%) have also chronic obstructive pulmonary disease (COPD) which frequently delays diagnosis of CHF and complicates assessment of prognosis. The pathogenetic mechanism of EOV is still not clear; however, the breathing pattern of EOV is similar to central sleep apnoea. It is hypothesized that EOV is primarily related to impaired ability to augment cardiac index during exercise with secondary circulatory delay causing instability in the feedback loop of ventilatory control.
Aim: We aimed to estimate prevalence of EOV and its clinical significance in patients with CHF and comorbid COPD.
Material and Methods: It is a prospective analysis of 69 CHF patients (47 with CHF alone and 22 with both CHF and COPD). These patients underwent a symptom-limited treadmill exercise test with metabolic gas exchange measurements using RAMP protocol. EOV was defined by Corrá criteria as cyclic fluctuations in ventilation during over 60% of exercise, and with amplitude over 15% of the average amplitude at rest.
Results: Twenty-two patients with both CHF and COPD presented with similar age and NYHA class, and higher ejection fraction (EF) in comparison with those with CHF only. Cardiopulmonary exercise tests showed significantly lower breathing reserve (BR) and higher PETCO2 in the group with COPD. EOV occurred in 23.2 % of all the patients. Prevalence of EOV in both groups did not differ significantly (p = 0.807). A 3-month follow-up showed no significant differences in mortality and hospitalization rates between the patients with CHF only and those with comorbid COPD.
Conclusion: COPD does not influence occurrence of EOV in patients with CHF. Further studies are required to evaluate if EOV has the same prognostic value in patients with CHF regardless of pulmonary diseases.