Central sleep apnea treated by a constant low-dose CO₂ supplied by a novel device

CO ₂ inhalation has been previously reported as a treatment for central sleep apnea both when associated with heart failure or where the cause is unknown. Here, we evaluated a novel CO ₂ supply system using a novel open mask capable of comfortably delivering a constantly inspired fraction of CO ₂ (FI _CO2) during sleep. We recruited 18 patients with central sleep apnea (13 patients with cardiac disease, and 5 patients idiopathic) diagnosed by diaphragm electromyogram (EMG) recordings made during overnight full polysomnography (PSG) (night 1). In each case, the optimal FI _CO2 was determined by an overnight manual titration with PSG (night 2). Titration commenced at 1% CO ₂ and increased by 0.2% increments until central sleep apnea (CSA) disappeared. Patients were then treated on the third night (night 3) with the lowest therapeutically effective concentration of CO ₂ derived from night 2. Comparing night 1 and night 3, both apnea-hypopnea index (AHI; 31±14 vs. 6±3 events/h, P < 0.01) and arousal index (22±8 vs. 15±8 events/h, P < 0.01) were significantly improved during CO ₂ treatment. Sleep efficiency improved from 71±18 to 80±11%, P < 0.05, and sleep latency was shorter (23±18 vs. 10±10 min, P < 0.01). Heart rate was not different between night 1 and night 3. Our data confirm the feasibility of our CO ₂ delivery system and indicate that individually titrated CO ₂ supplementation with a novel device including a special open mask can reduce sleep disordered breathing severity and improve sleep quality. Randomized controlled studies should now be undertaken to assess therapeutic benefit for patients with CSA.