Injurious mechanical ventilation affects neuronal activation in ventilated rats

Area of Science:

• Neuroscience
• Critical Care Medicine
• Pulmonary Medicine

Background:

• Survivors of critical illness frequently experience long-term brain dysfunction.
• Mechanical ventilation (MV), a common procedure, may negatively influence brain outcomes.

Purpose of the Study:

• To investigate the impact of increased tidal volume (Vt) on brain activation in a rat model.
• To explore the relationship between lung function and brain response during mechanical ventilation.

Main Methods:

• Rats were randomized into basal (unventilated), low Vt (8 ml/kg), and high Vt (30 ml/kg) MV groups for three hours.
• Lung mechanics, hemodynamics, blood gases, and cytokine levels were measured.
• Immunohistochemistry assessed c-fos expression as a marker of neuronal activation in the brain.

Main Results:

• High Vt MV led to increased PaCO2 and systemic/pulmonary inflammation compared to low Vt and basal groups.
• Plasma TNFα levels were significantly elevated in the high Vt group.
• Neuronal activation, indicated by c-fos, significantly increased in the retrosplenial cortex and thalamus of high Vt rats.

Conclusions:

• Mechanical ventilation promotes brain activation, with higher intensity observed at high tidal volumes.
• This suggests a potential iatrogenic effect of MV on the brain.
• Further research into this lung-brain crosstalk mechanism in ventilated patients is warranted.