OBJECTIVETo explore the role of gastro-pulmonary infection route in the development of ventilator-associated pneumonia (VAP), so as to improve the management of VAP.

METHODSForty-three patients who received mechanical ventilation (MV) were enrolled in the study. Intra-gastric contents were labeled with (99)mTc-DTPA. Randomized two-period crossover trial was employed to determine the radioactive level in the oropharyngeal and bronchial secretion when patients were in supine or semi-reclining position. Gastric juice, oropharyngeal secretion and tracheal lavage fluid were collected for bacterial culture every other day. Bronchoalveolar lavage fluid (BALF) was harvested from those suspected of VAP for quantitative bacterial culture. Infrequent-restriction site amplification (IRS-PCR) was employed in the identification of the identity of the bacteria from intra-gastric colonization with those causing VAP. The sIgA content in the BALF was determined.

RESULTSThe gastroesophageal regurgitation rate was higher (89.7%) with lower aspiration rate (28.5%) in patients receiving MV. Moreover, the aspiration rate and the radioactivity of deep tracheal aspirates in patients in supine position were significantly higher than those in semi-reclining position (P < 0.01). There was high homology of the bacteria isolated from intra-gastric colonization with that causing VAP (55.8%). The sIgA content in BALF in VAP patients was evidently lower than that in non-VAP patients (P < 0.01).

CONCLUSIONRegurgitation and aspiration of stomach contents are very common in patients receiving MV. Intra-gastric colonized bacteria might be one of the important origins causing VAP. The lowering of sIgA in BALF in patients with MV could be a risk factor for VAP.