Short- and long-term effects of nocturnal oxygen therapy on sleep apnea in chronic heart failure.

Purpose: This paper studies the short- and long-term effects of nocturnal oxygen therapy (NOT) on sleep apnea in chronic heart failure (CHF).

Methods: We enrolled 51 adults in New York Heart Association (NYHA) heart failure functional classes II or III, ≤45 % left ventricular ejection fraction (LVEF), in a randomized, open, single-center study. Nocturnal cardiorespiratory polygraphy showed sleep apnea [apnea-hypopnea index (AHI) ≥15 events/h] in 33 patients, of whom 19 were randomly assigned to NOT, 3.0 l/min, and 14 to no NOT. The NOT group underwent follow-up polygraphy at 24 h and 6 months, and the no NOT group a single follow-up polygraphy at 6 months.

Results: No significant difference was observed between baseline and 6 months in the no NOT group. In the NOT group, AHI decreased from 36.8 ± 2.6 events/h at baseline to 20.8 ± 3.0 at 24 h and to 18.3 ± 2.4 at 6 months (both P < 0.0001 vs. baseline), due to central AHI changes from 23.3 ± 2.8 events/h at baseline to 8.3 ± 1.6 at 24 h and to 6.1 ± 1.4 at 6 months (both P < 0.0001 vs. baseline). Oxygen desaturation index (ODI) decreased from 33.0 ± 5.2 events/h at baseline to 7.5 ± 0.5 at 24 h and 9.3 ± 2.6 at 6 months (both P < 0.0001 vs. baseline). NOT had no significant effect on obstructive and mixed AHI, quality of life (QOL), NYHA class, and LVEF up to 6 months of follow-up.

Conclusions: NOT decreased central AHI and ODI significantly within 24 h and up to 6 months in CHF patients with sleep apnea, without significantly modifying obstructive and mixed AHI, QOL, and ventricular function.