Polysomnographic Markers in Children With Cystic Fibrosis Lung Disease

BACKGROUND AND OBJECTIVES: Children with cystic fibrosis (CF) often report poor sleep, increased daytime sleepiness, and fatigue. The purpose of this study was to identify respiratory patterns over the spectrum of disease severity in children with CF. The overall hypothesis for the current study is that children with CF compared with snoring control subjects demonstrate gas exchange abnormalities and increased respiratory loads during sleep that are not reported or recognized by conventional polysomnography (PSG). METHODS: Analysis of breathing patterns and gas exchange on PSG was performed in children with CF and healthy controls matched by age and BMI. For all CF and control subjects, the indication for PSG was evaluation for obstructive sleep apnea based on a history of snoring. RESULTS: Children with CF, compared with age-and BMI-matched snoring controls, demonstrated lower oxyhemoglobin saturation (95% +/- 1.6% vs 98% +/- 0.6%, P = .005), higher respiratory rate (19.5 +/- 4.9 vs 16.5 +/- 1.2 breaths per minute, P = .03), and a higher proportion of inspiratory flow limitation (44.1% +/- 24.7% vs 12.1% +/- 13.5%, P = .007) during non-rapid eye movement sleep. The respiratory disturbance index did not differ between CF and snoring control groups (1.5 +/- 2.7 vs 0.6 +/- 0.6 events per hour, P = .11). CONCLUSIONS: Children with CF exhibited abnormalities in gas exchange and increased respiratory load during sleep compared with normal age-and BMI-matched snoring controls. Because these abnormalities were independent of weight and lung function, sleep state may serve as an opportunity for early detection of breathing abnormalities and possibly CF lung disease progression.