Cough reflex sensitivity is decreased in female obese patients with obstructive sleep apnea

Obstructive sleep apnea (OSA) is associated with impaired airway reflexes. Cough is the main airway defense mechanism but the effect of OSA on cough is unknown. Thirty-two female obese patients scheduled to undergo bariatric surgery were studied. They were classified as presenting OSA (20 patients) when the apnea-hypopnea index (AHI) was greater than 5h. Cough sensitivity was measured with citric acid. Increasing concentrations of nebulized citric acid were delivered until cough was elicited. The concentrations eliciting one (C1) and two coughs (C2) were recorded and log transformed (log C1 and log C2). log C1 and log C2 (median (interquartile)) were 1.90 mg/mL (0.90) and 2.2mg/mL (0.30) in OSA patients and 1.60 mg/mL (0.45) and 1.60 mg/mL (0.45) in non-OSA patients, respectively (comparison between groups: p=0.0372 for log C1 and p=0.0227 for log C2). A significant relationship was observed between AHI and log C1 and log C2. Cough sensitivity is therefore, decreased in female obese OSA patients and this decreased sensitivity is positively correlated with disease severity.