Effects of nasal O2 on sleep-related disordered breathing in ambulatory patients with stable heart failure

Objective: The purpose of this study was 1) to determine the effects of nasal O-2 on periodic breathing, arterial oxyhemoglobin desaturation and nocturnal ventricular arrhythmias in patients with heart failure and 2) determine the characteristics of patients whose periodic breathing will be reversed by O-2 administration; our hypothesis was that patients with more severe periodic breathing and desaturation, will respond more favorably to oxygen. Design: Prospective study Setting: Referral sleep laboratory of a Department of Veterans Affairs Medical Center. Participants: 36 ambulatory male patients with heart failure whose initial polysomnograms showed periodic breathing with fifteen or more episodes of apnea (A) and hypopnea (H) per hour (AM index, AHI) were treated with nasal O-2 during the subsequent full night polysomnography. Interventions: Oxygen Measurements and Results: Arterial blood gases and hydrogen ion concentrations were measured, and cardiac radionuclide ventriculography, Holter monitoring, and polysomnography were done. The studies were scored blindly. Treatment with O-2 resulted in a significant reduction in AHI (49+/-19 vs 29+/-29, means+/-SD), central apnea index (28+/-23 vs 13+/-18 per hour), and the percent of total sleep time below an arterial oxyhemoglobin saturation of 90% (23+/-21% vs 0.8+/-2.3%). In spite of virtual normalization of saturation with O-2 therapy, the number of ventricular arrhythmias during sleep did not change significantly. In 39% of the patients (14 out of 36), O-2 therapy resulted in reversal of central sleep apnea (defined by a reduction in AHI to less than 15/hr). In this group, the AHI decreased by 78% which was significantly (p=0.0001) more than improved (22%) in AHI of the remaining patients (n=22). The main differences between baseline characteristics of the two groups was a significantly higher mean PaCO2 in patients who did respond fully to O-2 (39.3+/-5.4 VS 36.1+/-4.2 mm Hg, p=0.03). In both groups, however, O-2 administration resulted in significant and similar improvement in arterial oxyhemoglobin saturation (saturation (90%, percent total sleep time 0.1+/-0.3% vs 1+/-3%). Conclusion: In patients with stable heart failure, administration of nasal O-2 significantly improves periodic breathing and virtually eliminates clinically significant arterial oxyhemoglobin desaturation. The beneficial effects of O-2, however, may be modulated by the level of arterial PCO2. Acute O-2 therapy has important benefits on sleep apnea and nocturnal arterial oxyhemoglobin desaturation in heart failure patients. Long term benefits of O-2 therapy in heart failure and sleep apnea need to be determined.