Pepsin in bronchoalveolar lavage fluid: a specific and sensitive method of diagnosing gastro-oesophageal reflux-related pulmonary aspiration.

OBJECTIVES Gastro-oesophageal reflux (GOR)-related aspiration is associated with respiratory disease, but the current "gold standard" investigation, the lipid-laden macrophage index (LLMI), is flawed. A specific marker of GOR-related aspiration should originate in the stomach, but not the lung. An assay to detect gastric pepsin in the bronchoalveolar lavage (BAL) of children was developed and validated. METHODS Gastro-oesophageal reflux was diagnosed in 33 children using intra-oesophageal pH monitoring. Thirteen asymptomatic negative controls requiring endotracheal intubation for elective surgery and 5 positive control patients with observed aspiration were recruited. All subjects received a BAL; the fluid obtained was analysed for the pepsin content and the LLMI. RESULTS All subjects in the negative control group were negative for pepsin. The positive control group had a significantly greater median pepsin level (P < .01) compared with negative controls. Patients with proximal oesophageal GOR and chronic cough also had significantly elevated pepsin levels (P = .04). The LLMI was not significantly elevated by the presence of cough or GOR. CONCLUSIONS This study suggests that GOR-related aspiration plays a role in chronic cough in children with known GOR. Detecting pepsin in BAL fluid may therefore become an important adjunct in patient selection for antireflux surgery.