Effects of increasing tidal volume on the mechanics of the respiratory system of healthy rats

Mechanical ventilation is an advanced life support that has as one of its objectives to promote gas exchange. The use of protocols that vary the tidal volume is a practice that aims at maintaining the most stable minute volume, where this mode is cycled upon reaching the predetermined inspiratory tidal volume. In the midst of this context, the question is raised: What are the effects of increased tidal volume on parenchyma and pulmonary mechanics in healthy rats submitted to mechanical ventilation? Therefore, the present study aimed to analyze the effects of tidal volume increase on the mechanics of the respiratory system of healthy rats submitted to mechanical ventilation.18 Wistar rats were randomly divided into two groups:GCTRL, ventilated during the 4 hour with tidal volume of 10 mL/kg, and GTV, ventilated during the 4 hour with tidal volume of 20 mL/kg. Our results demonstrate significant differences between the GTV and GCTRL groups, for tissue resistance (G), tissue elastance (H), static compliance (C_ST), inspiratory capacity (IC) and PV loop area. Regarding the histological data, we observed alterations in the percentage of normal and hyperinflamed alveoli, in the mean alveolar diameter and number of polymorphonuclear cells in the GTV group in relation to the GCTRL group. In conclusion, the use of mechanical ventilation with high tidal volumes is associated with destruction of the alveolar wall, increased respiratory work and presence of inflammatory processes in the pulmonary parenchyma.