Periodic respiration in patients with heart failure.

Patients with heart failure are known to demonstrate periodic respiration (PR) during sleep. The factors causing PR are not well known. We therefore studied 20 patients (aged 18-66 years) with idiopathic dilated cardiomyopathy. Full-night polysomnography and evaluation of respiration and transcutaneous oxygen saturation were performed. Hypercapnic ventilatory response (HCVR) was evaluated during daytime. The patients showed PR for 25 +/- 26% (mean +/- standard deviation) of total sleep time. During PR, oxygen desaturated 7.1 +/- 4.6%. Sleep was impaired. HCVR was normal. Oxygen desaturation during PR was predicted by HCVR (r = 0.47, P < 0.05) and left atrial diameter (r = 0.60, P < 0.05). The time period of PR expressed as a fraction of total sleep time was correlated with HCVR (r = 0.45, P < 0.05) and left atrial diameter (r = 0.51, P < 0.05). In conclusion, PR with oxygen desaturation, arousals, and impaired sleep was observed in stable heart failure. HCVR and left heart dimensions were related to PR. These findings confirm the concept of a feedback loop describing respiratory control in PR.