High tidal volume ventilation is not deleterious in infant rats exposed to severe hemorrhage

Publication URL: http://researchrepository.murdoch.edu.au/2083/1/high_tidal_volume_ventilation.pdf

Date: January 1, 2010

Authors: Background: Both high tidal volume (VT) ventilation and hemorrhage induce acute lung injury in adult rodents. It is not known whether injurious ventilation augments lung injury in infant rats exposed to severe hemorrhage. Methods: Two week old rats were allocated to ventilation with VT 7 mL/kg and PEEP 5 cmH2O (low VT) or VT 21 mL/kg and PEEP 1 (high VT) for 4 h. Additional rats were subjected to volume-controlled hemorrhage and delayed saline resuscitation, followed by low VT or high VT ventilation for 4 h. Non-ventilated control groups were also included. Airway resistance and the coefficient of tissue elastance (H) were derived from respiratory input impedance measurements using the low-frequency forced oscillation technique. Pressure-volume curves were obtained at baseline and at the end of the study. Interleukin-6 (IL-6), macrophage inflammatory protein-2 (MIP-2), and tumor necrosis factor alpha (TNF-α) were determined in bronchoalveolar lavage fluid (BALF) and serum. Results: In both healthy and hemorrhage-exposed animals high VT resulted in reduced H (better lung compliance), and increased transcutaneous oxygen saturation. IL-6 in BALF was greater in ventilated animals when compared to non-ventilated controls, but not different between ventilated groups. No significant differences were found for all other inflammatory mediators, total protein concentration in BALF, and histology. Conclusion: High VT ventilation with low PEEP improves respiratory system mechanics without causing additional damage to healthy and hemorrhage-exposed infant rats after 4 3h of ventilation. This study highlights the tolerance to high VT ventilation in infant rats and underscores the need for age-specific animal models.

Product: MouseOX Publications

Study Category: Lung Injury & Mechanical Ventilation