Methods: Five adult patients with congestive heart failure due to dilated cardiomyopathy complicated by CSA were enrolled. They were treated with continuous positive airways pressure (CPAP) at individualised pressures ranging between 10 and 16cm H2O. 5 subjects were restudied after 3 months and 4 subjects after 12 months of treatment. CPAP compliance was objectively documented.
Results: Central apnea hypopnea index (AHI) fell from 51±14/hr to 3±5/hr over 12 months (p<0.01). Surprisingly the obstructive AHI increased from 4±5/hr to 31±15/hr over the same period (NS). Stage 1 sleep fell from 44±18% to 13±5% (p<0.05), Stage 2 increased from 36±16% to 59±8% (p=0.01), and REM sleep from 10±5% to 18±4% (p=0.01)]. Cardiac index increased, vascular
resistances fell and six minute walk distance increased from 344±51m to 459±81m (p=0.05). PaCO2 awake increased from 38±5 to 41±5mmHg. Lung water fell from 10.6±2.1 to 8±2.3ml/kg (both NS). Night time plasma noradrenaline levels fell from 5.8±2.4 to 1.9±1.6 nmo/l (p<0.01). There were no confounding changes in body mass index or medications.

Conclusion: The clinical importance of these findings is that in patients with severe cardiac failure complicated by CSA, CPAP therapy is likely to improve cardiac function with resolution of the CSA, and development of OSA. This may require revision of our approach to CPAP therapy.