Mixed apnea metrics during diagnostic polysomnographies in obstructive sleep apnea patients with/without treatment-emergent central sleep apnea

Mixed apneas (MA) are characterized by absent respiratory effort and airflow in the first section of the event and respiratory effort without airflow in the last section. The pathophysiology is based on coexisting ventilatory control instability and upper airway collapsibility. Diagnostic polysomnographies (PSG) from 17 male OSA patients with/without treatment-emergent central sleep apnea (TE-CSA) were retrospectively analyzed to determine breathing pattern metrics (figure 1). TE-CSA was defined as central apnea-hypopnea index ≥10/h during positive airway pressure therapy initiation. Duty ratio (DR), a surrogate for the loop gain, was calculated as ventilatory duration/cycle duration. Conclusion: MA metrics in diagnostic PSGs differ significantly between patients with/without TE-CSA. TE-CSA patients show longer apneic durations, more frequent arousals, shorter VD and smaller DR, consistent with higher ventilatory control instability.