Restoring brain connectivity by phrenic nerve stimulation in sedated and mechanically ventilated patients

Background In critically ill patients, deep sedation and mechanical ventilation suppress the brain-diaphragm-lung axis and are associated with cognitive issues in survivors. Methods This exploratory crossover design study investigates whether phrenic nerve stimulation can enhance brain activity and connectivity in six deeply sedated, mechanically ventilated patients with acute respiratory distress syndrome. Results Our findings indicate that adding phrenic stimulation on top of invasive mechanical ventilation in deeply sedated, critically ill, moderate acute respiratory distress syndrome patients increases cortical activity, connectivity, and synchronization in the frontal-temporal-parietal cortices. Conclusions Adding phrenic stimulation on top of invasive mechanical ventilation in deeply sedated, critically ill, moderate acute respiratory distress syndrome patients increases cortical activity, connectivity, and synchronization. The observed changes resemble those during diaphragmatic breathing in awake humans. These results suggest that phrenic nerve stimulation has the potential to restore the brain-diaphragm-lung crosstalk when it has been shut down or impaired by mechanical ventilation and sedation. Further research should evaluate the clinical significance of these results. Plain language summary Critically ill patients receive sedation and mechanical ventilation as life support measures. Sedation and mechanical ventilation impact the ability of the brain, lungs and diaphragm to communicate as normal. We studied whether stimulating a nerve involved in breathing, called the phrenic nerve, would lead to brain activity in deeply sedated and mechanically ventilated patients. Stimulating the phrenic nerve increased the amount of communication within the brain and the communication seen was similar to that seen in studies in healthy participants. These data suggest that stimulating the phrenic nerve could restore the brain-diaphragm-lung crosstalk when it has been shut down or impaired by mechanical ventilation and sedation which could prevent cognitive impairment in critically ill patients. Bassi et al investigate the impact of phrenic nerve stimulation on deeply sedated, mechanically ventilated patients with acute respiratory distress syndrome. Cortical activity, connectivity, and synchronization are increased when phrenic stimulation is included in addition to invasive mechanical ventilation.