Relation Between Oscillatory Breathing and Cardiopulmonary Function During Exercise in Cardiac Patients

Background: Oscillatory breathing, alternating between hyperpnea and hypopnea, has been recognized in cardiac patients, especially in those with heart failure. We evaluated whether the cycle length and amplitude of oscillatory breathing correlate with impaired cardiopulmonary function during exercise. Methods and Results: We analyzed respiratory gas data during cardiopulmonary exercise testing (CPX) in 17 cardiac patients (68 +/- 12 years) who showed clear oscillatory ventilation during CPX. The cycle length (time from peak to peak) and the amplitude (difference between peak and nadir) for both oscillating ventilation ((V) over dotE) and oscillating O2 uptake ((V) over dotO2) were calculated from several consecutive oscillations noted at rest, and compared with indices of CPX. Oscillating (V) over dotO2 preceded oscillating (V) over dotE in 16 of the 17 patients. Peak (V) over dotO2 (10.3 +/- 3.1 ml.min(-1).kg(-1)) correlated significantly negatively with the cycle length of the (V) over dotE oscillation (r=-0.60, P=0.010), and of the (V) over dotO2 oscillation (r=-0.61, P=0.008), and the difference in time between the peak of oscillating (V) over dotE and the corresponding peak of (V) over dotO2 (r=-0.58, P=0.012). Similarly, the slope of the increase in (V) over dotE to the increase in CO2 output (45.6 +/- 11.5) correlated significantly positively with the cycle length of the (V) over dotE and (V) over dotO2 oscillations (r=0.68, P=0.002; r=0.67, P=0.003, respectively). Conclusions: The cycle length of oscillatory breathing is closely related to impaired cardiac reserve during exercise in cardiac patients. (Circ J 2013; 77: 661-666)