Published in:
01-04-2004 | Experimental
Infectious and inflammatory dissemination are affected by ventilation strategy in rats with unilateral pneumonia
Authors:
Frédérique Schortgen, Lila Bouadma, Marie-Laure Joly-Guillou, Jean-Damien Ricard, Didier Dreyfuss, Georges Saumon
Published in:
Intensive Care Medicine
|
Issue 4/2004
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Abstract
Objective
To evaluate the effect of VT reduction and alveolar recruitment on systemic and contralateral dissemination of bacteria and inflammation during right-side pneumonia.
Design
Interventional animal study.
Setting
University hospital research laboratory.
Subjects
A total of 54 male Wistar rats.
Interventions
One day after right lung instillation of 1.4×107
Pseudomonas aeruginosa, rats were left unventilated or ventilated for 2 h at low VT (6 ml/kg) with different strategies of alveolar recruitment: no PEEP, 8 cm H2O PEEP, 8 cm H2O PEEP in a left lateral position, 3 cm H2O PEEP with partial liquid ventilation, or high VT (set such as end-inspiratory pressure was 30 cm H2O) without PEEP (ZEEP). After ventilation the lungs, spleen and liver were cultivated for bacterial counts. Global bacterial dissemination was scored considering the percentage of positive spleen, liver and left lung cultures. TNF-α was assayed in plasma before and after mechanical ventilation.
Measurements and results
All rats had right-side pneumonia with similar bacterial counts. All mechanical ventilation strategies, with the exception of low VT-PEEP 8, promoted contralateral lung dissemination. Overall bacterial dissemination was less in non-ventilated controls (22%) and low VT-PEEP 8 (22%) than in high VT-ZEEP (67%), low VT-PEEP 8 in left lateral position (59%) and low VT-ZEEP (56%) (p<0.05). Partial liquid ventilation prevented systemic bacterial translocation, but at the expense of contralateral bacterial seeding. Plasma TNF-α concentration increased significantly after mechanical ventilation with no PEEP at both high and low VT.
Conclusions
Our results suggest that PEEP might reduce the risk of ventilation-induced bacterial and inflammatory mediator dissemination during pneumonia.