Effects of captopril and oxygen on sleep apnoea in patients with mild to moderate congestive cardiac failure.

OBJECTIVES To determine the effects of captopril and oxygen on sleep quality in patients with mild to moderate cardiac failure. DESIGN An open observational study. PATIENTS 12 patients with New York Heart Association class II-III heart failure were studied at baseline. 9 of these patients were then examined at the end of 1 month of treatment with captopril; 9 of the patients were separately assessed during a single night of supplementary oxygen. MAIN OUTCOME MEASURES Sleep patterns by polysomnography, overnight oximetry, and subjective sleep assessment using visual analogue scores. RESULTS Abnormal sleep was present in all baseline studies. Complete polysomnograms after treatment with captopril were obtained in 8 patients. Light sleep (stages 1 and 2) was reduced (mean (SEM) 61%(8)% to 48%(6)% actual sleep time, P < 0.05) but slow wave (stages 3 and 4) and REM (rapid eye movement) sleep increased (25%(6)% to 31%(5)%, 14%(2)% to 21%(5)% actual sleep time, P < 0.05). Apnoeic episodes (242(59) to 118(30), P < 0.05), desaturation events (171(60) to 73(37), P < 0.05), and arousals (33(5) to 18(3) P < 0.01) were reduced. Visual analogue scores of sleep quality increased 49(5) to 69(5), P < 0.01). Complete polysomnograms were obtained in 7 patients treated with oxygen. Light sleep duration was reduced (55% (7)% to 42%(5)% actual sleep time, P < 0.05) and slow wave sleep increased (30%(5)% to 38%(6)% actual sleep time, P < 0.05). REM sleep duration was not significantly different. Total arousals (33(6)% to 20(2) P < 0.05), desaturation events (140(33) to 38(10), P < 0.01), and apnoeic episodes (212(53) to 157(33), P < 0.05) were reduced. Visual analogue scores of sleep quality were unchanged. CONCLUSIONS Captopril and oxygen may improve sleep quality and reduce nocturnal desaturation in patients with mild to moderate cardiac failure. Improved sleep quality could explain the reduction in daytime symptoms seen after treatment in patients with chronic heart failure.