Salivary Amylase Level in Bronchoalveolar Fluid as a Marker of Chronic Pulmonary Aspiration in Children.

Chronic pulmonary aspiration is a common cause of chronic respiratory symptoms in children. However, there is no gold standard diagnostic test for aspiration. In this study, we explore the diagnostic value of measuring salivary amylase in bronchoalveolar lavage (BAL) fluid as a marker of chronic aspiration in children with different chronic respiratory illnesses. Measurements of salivary amylase in BAL fluid were routinely done in patients undergoing flexible bronchoscopy. Patients' demographic and clinical data were extracted from records and reviewed by one of the investigators. Patients were classified into three different groups based on the reviewer's assessment of risk for aspiration. BAL amylase measurements were masked from the reviewer. Multiple regression analysis was used to determine the effect of the patients' clinical variables on BAL amylase. Sixty-four patients (median age 2 years; range 0-14 years) were included. Indications for bronchoscopy included chronic cough (=20), chronic wheezing (=27), Cystic Fibrosis (=6), recurrent pneumonia (=5), and lung infiltrate in immunocompromised patients (=6). Young age, history of excessive drooling, and wet cough were predictive of high BAL amylase. Thirteen patients were considered at no risk of aspiration, 41 patients were at low risk, and 10 patients were at high risk based on clinical symptoms and other diagnostic tests. No significant differences in BAL amylase levels were found between the three groups. However, when high and low risk groups were combined and compared to the no risk group, there was a significantly higher BAL amylase level in the combined at risk groups (1,722 vs. 307 U/L; =0.03). Receiver operator curve analysis demonstrated that amylase cutoff value of 250 U/L differentiates between the two risk groups with sensitivity of 66.7% and specificity of 69.2%. Salivary amylase level in BAL can help identify children at risk for chronic pulmonary aspiration.