Association between the activity of salivary alpha-amylase and the severity of pediatric sleep disordered breathing (SDB)

Abstract

SDB has its common features, that is, abnormal breathing patterns shown in children with SDB during sleep, ranging from reduced airflow (flow limitation, hypopnea) with increased respiratory efforts with to repetitive cessation of airflow (apnea). Considering autonomic nervous system (ANS), parasympathetic tone is elevated during apneas and hypopneas and sympathetic tone is elevated after respiratory events. Therefore, children with SDB may have unstable status of ANS during sleep and show irregular pattern of sympathetic and parasympathetic nervous system (ANS and PNS, respectively). We hypothesized that children with SDB would have altered autonomic balance and changes of sAA level caused by SDB would be predictive of severity during sleep. Therefore, the aim of this study was to evaluate the change of sAA during sleep and its correlation with PSG parameters in pediatric subjects with SDB. Seventy-three children who attended our clinic during 1 year were enrolled prospectively and underwent full-night polysomnography. Their saliva was collected for quantitative analysis of alpha-amylase before and after polysomnography. The level of salivary alpha-amylase were measured and analyzed with polysomnography parameters. The subjects ( n = 73) were divided into control ( n = 32, AHI <1) and OSAS ( n = 41, AHI ≥ 1) groups. The ratio and substrate of the sAA after PSG to sAA before PSG in the severe subgroup were significantly larger than those in the control and mild-moderate subgroup. Receiver operating characteristic curves were constructed to determine the optimal sAA measurements for predicting severe OSAS. The area under the curve in the sAA measurements was approximately 0.82 and a value approximately yielded a sensitivity of 80% and a specificity of 55%. Sampling for salivary cortisol is an easy, safe, and non-invasive method that is especially appropriate for multiple sampling in children. Our data suggest the ratio of post- to pre-sleep cortisol to be a consistent index that is well-correlated with AHI. Measurement of salivary cortisol in children with OSAS may represent a useful screening tool for identification of those with OSAS and high AHI and management of follow-up care.