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Updated: Aug 25, 2026
Murine Oropharyngeal Aspiration Model of Ventilator-associated and Hospital-acquired Bacterial Pneumonia
Published on: June 28, 2018
[Prospective study on the gastro-pulmonary infection route of ventilator-associated pneumonia]
Qing-ling Zhang1, Ming-hua Liu, Yu-fu Liu
1Nursing Department, Xinqiao Hospital, The Third Military Medical University, Chongqing 400037, P.R. China.
Objective:
To explore the role of gastro-pulmonary infection route in the development of ventilator-associated pneumonia (VAP), so as to improve the management of VAP.
Methods:
Forty-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.
Results:
The 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).
Conclusion:
Regurgitation 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.
Insights
Stomach content regurgitation is common in mechanically ventilated patients, potentially leading to ventilator-associated pneumonia (VAP). Lowering of sIgA in bronchoalveolar lavage fluid may increase VAP risk.
Area of Science:
- Critical Care Medicine
- Infectious Diseases
- Pulmonary Medicine
Background:
- Ventilator-associated pneumonia (VAP) is a significant concern in mechanically ventilated patients.
- The gastro-pulmonary route is a suspected pathway for VAP development.
Purpose of the Study:
- To investigate the role of the gastro-pulmonary infection route in VAP development.
- To identify potential risk factors for VAP in mechanically ventilated patients.
Main Methods:
- A crossover study involving 43 mechanically ventilated patients.
- Tracking gastric content movement using (99m)Tc-DTPA and measuring radioactivity in respiratory secretions.
- Bacterial cultures of gastric, oropharyngeal, and tracheal samples, with molecular typing (IRS-PCR) to link gastric colonization to VAP pathogens.
- Quantification of sIgA levels in bronchoalveolar lavage fluid (BALF).
Main Results:
- High rates of gastroesophageal regurgitation (89.7%) and aspiration (28.5%) were observed.
- Supine positioning increased aspiration rates and radioactivity in tracheal aspirates compared to semi-reclining.
- Significant bacterial homology (55.8%) was found between gastric colonization and VAP pathogens.
- Lower sIgA levels in BALF were associated with VAP development.
Conclusions:
- Gastric content regurgitation and aspiration are frequent in mechanically ventilated patients.
- Bacteria from gastric colonization are a potential source of VAP.
- Reduced sIgA levels in BALF may be a risk factor for VAP.
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