Study Objective: To determine the effect of supplemental oxygen on Cheyne-Stokes respiration, nocturnal oxygen saturation (SaO2), and sleep in male patients with severe, stable congestive heart failure.
Design: Randomized, single-blind, placebo-controlled crossover study.
Setting: Patients referred from outpatient cardiology clinics of two teaching hospitals.
Patients: Sequential sample of nine outpatients with severe, stable congestive heart failure.
Interventions: For each patient, sleep studies (after an adaptation night) from two consecutive randomized nights were compared; one study was done while the patient breathed compressed air and the other while the patient breathed oxygen (O2). Compressed air and oxygen were both administered through nasal cannulae at 2 to 3 L/min.
Measurements and Main Results: Cheyne-Stokes respiration, defined as periodic breathing with apnea or hypopnea, was found in all patients. Low-flow oxygen significantly reduced the duration of Cheyne-Stokes respiration (50.7% ± 12.0% to 24.2% ± 5.4% total sleep time), mainly during stage 1 NREM (non-rapid eye movement) sleep (21.3% ± 7.1% to 6.7% ± 2.3% total sleep time) with no significant change during stage 2 sleep, slow-wave sleep, or REM (rapid eye movement) sleep. Although patients had normal SaO2 (96.0% ± 1.7%) while awake, severe sleep hypoxemia was common; breathing oxygen reduced the amount of time that SaO2 was less than 90% from 22.3% ± 8.0% to 2.41% ± 1.93% of total sleep time. Sleep, disrupted to a variable extent in all patients, improved with oxygen therapy: There was an increase in total sleep time from 275.3 min ± 36.6 to 324.6 min ± 23.3; a reduction in the proportion of stage 1 sleep (27.6% ± 5.8% total sleep time to 15.2% ± 2.6% total sleep time); and a reduction in the number of arousals (30.4/h ± 8.0 to 13.8/h ± 1.9). The apnea-hypopnea index was reduced from 30.0 ± 4.7 to 18.9 ± 2.4 with oxygen breathing.
Conclusions: In severe, stable congestive heart failure, nocturnal oxygen therapy reduces Cheyne-Stokes respiration, corrects hypoxemia, and consolidates sleep by reducing arousals caused by the hyperpneic phase of Cheyne-Stokes respiration. Correction of nocturnal hypoxemia and sleep disruption may improve the clinical status of these patients.