Bronchoalveolar lavage pepsin in acute exacerbation of idiopathic pulmonary fibrosis

Abstract

Some patients with idiopathic pulmonary fibrosis experience acute exacerbations in their respiratory status leading to substantial morbidity and mortality. Occult aspiration of gastric contents has been proposed as one possible mechanism leading to these acute exacerbations. We sought to determine whether pepsin, a marker of gastric aspiration, is elevated in bronchoalveolar lavage fluid obtained from patients during acute exacerbation of idiopathic pulmonary fibrosis, compared with that obtained in stable disease. Lavage samples were obtained in a case-control study of well-characterised patients. Acute exacerbation was defined using standard criteria. Levels of lavage pepsin were compared in cases and controls, and were correlated with clinical features and disease course. 24 cases with acute exacerbations and 30 stable controls were identified. There were no significant differences in baseline demographics between the two groups. Pepsin level was an indicator of acute exacerbation status (p=0.04). On average, pepsin appeared higher in patients with acute exacerbations compared with stable controls. This difference was driven by a subgroup of eight patients (33%) with pepsin levels ≥70 ng·mL(-1). Pepsin level was not an independent predictor of survival time. These results suggest occult aspiration may play a role in some cases of acute exacerbation of idiopathic pulmonary fibrosis.

Figures

FIGURE 1

Bronchoalveolar lavage (BAL) pepsin levels in patients with stable idiopathic pulmonary fibrosis (IPF) compared with acute exacerbation of IPF. Horizontal lines represent median, 25th percentile and 75th percentile.

FIGURE 2

Bronchoalveolar lavage (BAL) pepsin levels in seven patients with matched stable and acute exacerbation of idiopathic pulmonary fibrosis BAL samples. Each line represents one study subject. The closed circles and solid line represent the subject who had a high BAL pepsin level during the acute exacerbation. The open circles and dashed lines represent those subjects who had low BAL pepsin levels during their acute exacerbations.

FIGURE 3

Correlation between bronchoalveolar lavage (BAL) pepsin levels and % predicted total lung capacity (TLC).