Objectives: The aim of the study was to evaluate sleep quality and nocturnal gas exchange in patients with cystic fibrosis (CF) and to assess if sleep quality and daytime lung function could predict nocturnal hypoxaemia or hypercapnia.
Study design: Daytime sleepiness and objective sleep quality were evaluated by the Pittsburgh Sleep Quality Index (PSQI) and actigraphy in 25 children and 55 young adults (mean age 24±10 years, forced expiratory volume in 1 s (FEV(1)) 41±11% predicted). Nocturnal gas exchange was assessed by pulse oximetry (SpO(2)) and transcutaneous carbon dioxide (PtcCO(2)) recordings. Eleven patients underwent simultaneous polysomnography (PSG).
Results: PSQI was 6.3±3.4 with 51% of the patients having a score >5 corresponding to significant sleep complaints. On actigraphy, sleep efficiency was impaired at 79±11% with a fragmentation index at 41±18. Mean nocturnal SpO(2) was 93±3% with 18% of the patients exhibiting >10% of night time spent with a value below 90%. Mean PtcCO(2) was 44±6 mm Hg with 47% of the patients exhibiting >10% of night time with a value >45 mm Hg. Daytime arterial blood gases correlated with nocturnal gas exchange. FEV(1) was the only lung function parameter that correlated with nocturnal SpO(2) (p<0.01). Compared with PSG, SpO(2) and PtcCO(2) accurately identified rapid eye movement sleep hypoventilation.
Conclusions: Patients with CF exhibit poor sleep quality that does not predict nocturnal gas exchange. Nocturnal hypoxaemia and hypercapnia can be identified by simple tools.