Different Tidal Volumes May Jeopardize Pulmonary Redox and Inflammatory Status in Healthy Rats Undergoing Mechanical...

Area of Science:

• Physiology
• Pathology
• Biochemistry

Background:

• Mechanical ventilation (MV) is critical for gas exchange in critically ill patients.
• However, MV can induce ventilator-associated lung injury (VALI).
• The link between redox imbalance and pulmonary inflammation in MV-induced lung injury is not fully understood.

Purpose of the Study:

• To investigate the effects of different tidal volumes during controlled mechanical ventilation on lung injury.
• To determine if redox imbalance mechanisms are associated with pulmonary inflammation in healthy lungs undergoing MV.

Main Methods:

• Healthy Wistar rats were subjected to controlled mechanical ventilation with varying tidal volumes (4, 8, 12 mL/kg) or spontaneous breathing for 1 hour.
• Arterial blood, bronchoalveolar lavage fluid (BALF), and lung tissue were analyzed.
• Parameters assessed included blood gases, neutrophil influx, MPO activity, inflammatory cytokine levels, and markers of lipid and protein oxidation.

Main Results:

• High tidal volume (12 mL/kg) led to significant changes in blood gases (lower PaCO2, bicarbonate).
• Increased neutrophil influx and MPO activity were observed in the high tidal volume group.
• Elevated levels of inflammatory cytokines (CCL5, TNF-α, IL-1, IL-6) and markers of lipid and protein peroxidation were found in lungs subjected to high tidal volumes.

Conclusions:

• Controlled mechanical ventilation with high tidal volumes, without PEEP and in normoxia, impairs lung histoarchitecture in healthy rats.
• This MV strategy triggers significant redox imbalance and pulmonary inflammation.
• Findings suggest that MV settings can induce lung injury even in the absence of pre-existing lung disease.