Lung–brain cross talk in the critically ill

Excerpt

Severe acute brain injury predisposes to other organ dysfunctions, especially lung impairment. Neurological patients, despite being younger and having fewer comorbidities than other patients, develop intensive care unit (ICU)-acquired sepsis and respiratory failure more frequently [1]. Patients with traumatic brain injury and subarachnoid hemorrhage develop acute respiratory distress syndrome (ARDS) at rates similar to patients with sepsis, trauma, or aspiration [2]. Among several risk factors for ARDS in these patients including hypoxemia, acidosis, or vasopressor dependency, the single greatest risk factor for ARDS is high tidal volume, which is also an independent risk factor for mortality [2]. Using a lung-protective strategy in potential organ donors results in a higher number of eligible lung donors and harvested lungs compared with a conventional strategy, but had no effect on the number of harvested hearts, livers, and kidneys [3]. Brain injury increases pulmonary vascular hydrostatic pressure and endothelial permeability and triggers biological mechanisms that either directly render the lung more susceptible to mechanical injury (mechanical ventilation) or act to prime the lung so that additional non-mechanical insults could be relatively more deleterious [1]. …