Overnight deep inspiration patterns in obstructive sleep apnea patients with and without asthma

Asthma and obstructive sleep apnea (OSA) often co-occur, exacerbating respiratory difficulties and altering airway physiology during sleep. Respiratory obstructions in OSA usually terminate with deep inspiration, and in asthma, deep inspiration may function as a bronchodilator or induce bronchoconstriction. This study investigated deep inspiration patterns using polysomnography data from 202 OSA patients (Apnea-Hypopnea Index (AHI) > 5) in the Sleep Heart Health Study, including asthma patients and matched controls. Airflow signals were used to calculate the average amplitude of three post-event deep breaths (PEDB), as overshoots usually peak within these breaths. PEDB curves were compared within and between groups, each including 68 mild, 19 moderate, and 14 severe OSA cases (AHI > 30). In severe OSA, mean PEDB increased from the first to last sleep quartile in controls (p < 0.05) but showed no change in those with asthma (p > 0.05). PEDB values were higher in controls than in asthma patients with moderate and severe OSA. Reduced PEDB intensity in severe OSA with asthma suggests impaired bronchodilator effects of deep inspirations, possibly from chronic inflammation and fluid shifts. These findings enhance understanding of asthma-OSA interactions and the potential role of deep inspirations in mitigating overnight narrowing in lower airways.