Lipid-laden macrophages in induced sputum are a marker of oropharyngeal reflux and possible gastric aspiration.

The diagnostic properties of a "lipid index" of macrophages in induced sputum as a noninvasive marker of aspiration of acidic gastric contents were evaluated. In a cross-sectional study, 33 subjects (17 with symptoms suggestive of gastrooesophageal reflux) with normal chest radiographs and no symptoms of aspiration or sinus disease, underwent dual-channel 24-h ambulatory oesophageal pH recording and sputum induction. Oropharyngeal reflux, defined as at least one episode of a fall in pH to