Obstructive sleep apnoea: longer respiratory event lengths in patients with heart failure

This study investigated the effect of heart failure on respiratory patterns in patients with obstructive sleep apnoea (OSA). 39 patients with established OSA (apnoea/hypopnoea index (AHI) >10 events·h(-1)) and either with heart failure (New York Heart Association (NYHA) class II and III, left ventricular-ejection fraction (LVEF) ≤40%; n=26, age mean ± SD 67 ± 9 years) or without heart failure (LVEF ≥50%, N-terminal pro-brain naturic peptide <400 pg·mL(-1); n=13, age 73 ± 6 years) underwent simultaneous right- and left-heart catheterisation within 12 h of cardiorespiratory polygraphy recording. Respiratory patterns of OSA were significantly longer in OSA patients with heart failure versus without heart failure, including mean ± SD cycle length (46.0 ± 10.0 versus 37.8 ± 10.6 s; p=0.024), ventilation length (25.4 ± 6.3 versus 21.3 ± 7.1 s; p=0.044), apnoea length (20.5 ± 4.9 versus 16.5 ± 3.9 s; p=0.013), time-to-peak ventilation (10.6 ± 3.0 versus 8.3 ± 2.5 sc; p=0.021) and circulatory delay (28.5 ± 7.5 versus 22.6 ± 3.7 s; p=0.005). Positive and robust correlations were found between some of these parameters and the degree of congestion in heart failure: cycle length (r=0.53; p=0.006), ventilation length (r=0.55; p=0.004) and time-to-peak ventilation (r=0.47; p=0.015) all increased with a rise in pulmonary capillary wedge pressure. Respiratory patterns in OSA appear to be dependent on cardiac function, with an increase in event lengths as cardiac function decreases. In patients with heart failure, some of these events correlate with the degree of pulmonary congestion.