Predictors of sleep hypoxemia in children with cystic fibrosis.

Abstract

To identify the determinants of nocturnal hypoxemia in children with CF using clinical parameters, polysomnography (PSG), and lung function. Sleep hypoxemia in children with CF is predicted by both apnea hypopnea index (AHI) and percent predicted forced expiratory volume in one second (pFEV1). Retrospective case series. Children aged 5-18 years were included based on (i) a diagnosis of CF; and (ii) availability of concurrent PSG and pFEV1 data. The impact of (i) demographic and clinical parameters; and (ii) PSG and pFEV1, on the total sleep time spent with arterial oxygen saturation below 90% (TSpO2 < 90) was measured using regression analysis. P-value <0.05 was considered significant. The mean age was 11.6 years (95% confidence interval: 9.5, 13.1). Twenty of 35 (57%) were boys and the mean body mass index percentile was 42.1 (31.5, 52.6). The most common ethnicity was white (66%). OSA was diagnosed in 50%. Neither demographic predictors nor clinical variables predicted the severity of hypoxemia (R2 = 0.23, P = 0.09). While pFEV1 and PSG variables accounted for significant proportion of the overall variance in TSpO2 < 90 (R2 = 0.53, P < 0.001), pFEV1 was identified as the single best predictor of sleep hypoxemia. A pFEV1 cut-off of 53% indicated a sensitivity of 0.80 and a specificity of 0.87 in predicting sleep hypoxemia. pFEV1 is the best predictor of sleep hypoxemia in children with CF and referred for PSG. No demographic or clinical predictors of hypoxemia were identified in this population.