Recurrent aspiration of refluxed material is a risk factor for developing serious lung disease. Accurate diagnosis of gastroesophageal reflux-related aspiration is a clinical challenge due to the lack of sensitive and specific tests. We hypothesized that detection of pepsin in bronchoalveolar lavage fluid (BAL) would serve as a surrogate marker for aspiration.
Anesthetized BALB/c mice were exposed to a single aspiration of 25 μl of human gastric juice and control animals received the same amount of normal saline. Lung lavage was performed with 3 aliquots of 0.5 ml of saline 2, 4, 6, 24, 48, and 72 hours following aspiration. Lavage fluid was centrifuged and the supernatant was studied for pepsin concentration using an indirect ELISA technique. To evaluate the sensitivity of the ELISA test, a separate group of mice was exposed to a single aspiration of 25 μl of human gastric juice diluted with normal saline (1:5, 1:10, 1:20, 1:40 and 1:80 dilutions) and lavaged 4 hours after the aspiration.
At 2, 4, 6, 24, 48 and 72 hours after a single aspiration of undiluted gastric juice mean pepsin concentration±SD in the lavage fluid was 14.3±6.2, 8.0±2.8, 2.8±1.2, 0.7±0.2, 0.2±0.1 and 0.17±0.02 μg/ml, respectively, (n=4, at each time point). Mean control value was 0.13±0.04 μg/ml (n=6). Differences between the controls and values detected up to 24 hours after aspiration were statistically significant (p<0.005). Mean pepsin concentration±SD of the lavage fluid 4 hours after aspiration of undiluted and 1:5, 1:10, 1:20, 1:40 and 1:80 diluted gastric juice was 3.05±1.0, 0.63±0.28, 0.31±0.14, 0.21±0.11, 0.09±0.02, and 0.1±0.02 μg/ml, respectively, (n=4, at each dilution). Mean control value was 0.08±0.02 μg/ml (n=6). Values up to 1:20 dilution were statistically significantly different from control value (p<0.005).
These findings demonstrate that pepsin can be detected and quantified in the BAL fluid after aspiration of gastric contents.
If confirmed in clinical studies, this method has the potential to become a simple, routine test to detect accurately reflux-related aspiration in children and adults.
Okan Elidemir, None.