Real-time dynamic carbon dioxide administration: a novel treatment strategy for stabilization of periodic breathing with potential application to central sleep apnea

Objectives: This study targeted carbon dioxide (CO(2)) oscillations seen in oscillatory ventilation with dynamic pre-emptive CO(2) administration.

Background: Oscillations in end-tidal CO(2) (et-CO(2)) drive the ventilatory oscillations of periodic breathing (PB) and central sleep apnea in heart failure (HF).

Methods: Seven healthy volunteers simulated PB, while undergoing dynamic CO(2) administration delivered by an automated algorithm at different concentrations and phases within the PB cycle. The algorithm was then tested in 7 patients with HF and PB.

Results: In voluntary PB, the greatest reduction (74%, p < 0.0001) in et-CO(2) oscillations was achieved when dynamic CO(2) was delivered at hyperventilation; when delivered at the opposite phase, the amplitude of et-CO(2) oscillations increased (35%, p = 0.001). In HF patients, oscillations in et-CO(2) were reduced by 43% and ventilatory oscillations by 68% (both p < 0.05). During dynamic CO(2) administration, mean et-CO(2) and ventilation levels remained unchanged. Static CO(2) (2%, constant flow) administration also attenuated spontaneous PB in HF patients (p = 0.02) but increased mean et-CO(2) (p = 0.03) and ventilation (by 45%, p = 0.03).

Conclusions: Dynamic CO(2) administration, delivered at an appropriate time during PB, can almost eliminate oscillations in et-CO(2) and ventilation. This dynamic approach might be developed to treat central sleep apnea, as well as minimizing undesirable increases in et-CO(2) and ventilation.