Z.S. Uyan (1) , N. Ozdemir (2) , R. Ersu (1) , E. Cakir (1) , B. Karadag (1) , F Karakoc (1) , E. Dagli (1) .
(1) Pediatric Pulmonology, Marmara University, Istanbul, Turkey; (2) Pediatrics, Marmara University, Istanbul, Turkey

Objective: Cystic fibrosis (CF) patients may develop hypoxemia during sleep. Limited information is available on nocturnal oxygen saturation in CF children with less severe lung disease. The aim of this study was to investigate the degree of nocturnal oxygen desaturation and predictive factors in CF children with normal pulmonary function tests (PFT) or mild to moderate lung disease.

Method: Awake resting and post-exercise SpO₂ were measured by pulse oximetry. Each patient had overnight oximetry  monitorization at home. Six minute walk test 6MWT), Shwachman-Kulczycki (S-K), Brasfield and computed tomography (CT)
scores, blood gas analysis and nutritional status of patients were evaluated.

Results: Twenty-four patients (75% female) with a median age of 9,5 years were included. Nocturnal mean SpO₂ did not differ according to the severity of lung disease based on PFT. However, lowest SpO₂ obtained was lower in children with both mild and moderate lung disease compared to normal (87.4% vs.91.7%, respectively, p= 0.009). Nocturnal mean SpO₂ correlated with S-K (r =0.80, p < 0.0001), Brasfield (r =0.56, p= 0.007) and CT scores (r = –0.82, p <0.0001) as well as PaO₂ (r=0.53, p = 0.021), SaO₂ (r = 53, p = 0.023), z-score of weight (r 0.48, p =0.20) and height (r = 0.45, p =0.30), there was no correlation with 6MWT. Multiple linear regression analysis with Backward elimination showed that nocturnal mean SpO₂ was predicted by S-K scores (B= 0.085, p <0.0001) and CT scores (B = –0.22, p <0.0001) while lowest SpO₂ was predicted by FEV₁ (B=0.12
p=0.012).

Conclusions: CF children with normal PFT or mild-to-moderate lung disease may develop sleep hypoxemia and S-K and CT scores are the best predictive factors.