Phrenic nerve stimulation mitigates hippocampal and brainstem inflammation in an ARDS model

Area of Science:

• Neuroscience
• Critical Care Medicine
• Pulmonary Medicine

Background:

• Mechanical ventilation (MV) in acute respiratory distress syndrome (ARDS) can lead to neuroinflammation.
• Phrenic nerve stimulation (PNS) has shown potential in reducing neuroinflammation in ARDS models.

Purpose of the Study:

• To investigate the effects of PNS combined with MV on hippocampal and brainstem inflammatory and synaptic markers in an ARDS porcine model.
• To compare the impact of PNS applied every other breath versus every breath during MV.

Main Methods:

• A moderate ARDS porcine model was created using oleic acid infusion.
• Three groups were studied: MV alone, MV + PNS every other breath, and MV + PNS every breath for 12 hours.
• Tissue concentrations of inflammatory markers (e.g., IL-1β, IL-8, IFN-γ) and synaptic markers (e.g., synaptophysin, N-methyl-D-aspartate receptors) in the hippocampus and brainstem were measured.

Main Results:

• The MV + PNS every breath group showed increased hippocampal concentrations of GM-CSF, N-methyl-D-aspartate receptor 2B, and synaptophysin compared to MV alone.
• The MV + PNS every breath group exhibited lower brainstem concentrations of IL-1β and IL-8, but higher concentrations of IFN-γ and N-methyl-D-aspartate receptor 2A compared to MV alone.

Conclusions:

• Mechanical ventilation in ARDS is associated with hippocampal and brainstem inflammation.
• Phrenic nerve stimulation applied with every breath during MV can mitigate this inflammation in a moderate ARDS porcine model.