Abstract
Objective: To study the impact of high VT ventilation on top of elevated positive end-expiratory pressure (PEEP) in an infant rat pneumonia model.
Methods: Two week old rats received lipopolysaccharide (LPS) via trachea. After 24 hours rats were allocated to 4 hours of ventilation with a VT of 6 or 12 mL/kg at PEEP 6 cmH2O or a VT of 6 or 12 mL/kg at PEEP 10. Also, lung injury was assessed in non-ventilated LPS and saline groups. Pressure-volume curves were constructed and airway resistance (Raw) and the coefficient of tissue elastance (H) were obtained from low-frequency forced oscillatory impedance. Cytokine and protein concentrations were measured in bronchoalveolar lavage fluid (BALF).
Results: At lower PEEP high VT ventilation produced insignificant changes of lung mechanics whereas low VT ventilation resulted in a linear rise in Raw and H by 13 and 41%, respectively. Though Raw and H significantly decreased with both strategies at higher PEEP, lung function improvement was more pronounced in combination with high VT ventilation. Quasi-static lung compliance improved the most with high VT and high PEEP. Macrophage inflammatory protein-2 and interleukin-6 concentrations in BALF were higher in all ventilated animals when compared to non-ventilated animals. Increased BALF protein concentration was related to previous LPS exposure and independent of applied ventilation strategy.
Conclusion: Short-term mechanical ventilation with high VT and high PEEP is not injurious in infant rats with pre-injured lungs. Absence of augmented ALI might be explained by maximum lung volume recruitment and minimal atelectasis-induced shear stress.
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Cannizzaro, V., Nicholls, P., Berry, L. et al. 25 Ventilation with High Tidal Volume and High Peep is Not Injurious in An Infant Rat Pneumonia Model. Pediatr Res 68 (Suppl 1), 16 (2010). https://doi.org/10.1203/00006450-201011001-00025
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DOI: https://doi.org/10.1203/00006450-201011001-00025