Study objectives: To examine predictors of
sleep-disordered breathing in patients with cystic fibrosis (CF) and
moderate-to-severe lung disease using a comprehensive evaluation of
both sleep and daytime function.
Cross-sectional analysis of sleep studies, lung function, respiratory
muscle strength, and evening and morning arterial blood gas
measurements in patients with stable CF. A questionnaire addressing
sleep quality was administered. Forward stepwise regression analysis
was used to identify the parameters that best predict sleep-related
desaturation, hypercapnia, and respiratory disturbance.
Setting: Sleep investigation unit and lung function
Patients: Thirty-two patients with CF and
FEV1 < 65% predicted, in stable clinical condition.
Patients were aged 27 ± 8 years (mean ± 1 SD) with
FEV1 of 36 ± 10% predicted, evening
Pao2 of 68 ± 8 mm Hg, and
Paco2 of 43 ± 5 mm Hg.
Results: Evening Pao2
(p < 0.0001) and morning Paco2 (p < 0.01)
were predictive of the average minimum oxyhemoglobin saturation per
30-s epoch of sleep (r2 = 0.74;
p < 0.0001). Evening Pao2 (p < 0.001) was
predictive of the rise in transcutaneous carbon dioxide
(Tcco2) seen from non-rapid eye movement (NREM)
to rapid eye movement (REM) sleep
(r2 = 0.37; p < 0.001). In addition,
there was some relationship between expiratory respiratory muscle
strength and the REM respiratory disturbance index
(r2 = 0.22; p < 0.01).
Conclusion: Evening Pao2 was found
to contribute significantly to the ability to predict both
sleep-related desaturation and the rise in
Tcco2 from NREM sleep to REM sleep in this
subgroup of patients with CF.