First Breath Matters: Out-of-Hospital Mechanical Ventilation in Patients with Traumatic Brain Injury.

Invasive mechanical ventilation (MV) is often a lifesaving intervention in patients with traumatic brain injury (TBI) to optimize gas exchange and prevent secondary brain injury, thereby avoiding the deleterious effects of both hypoxia and hyperoxia, as well as hypocapnia and hypercapnia. However, MV in these patients represents a unique clinical challenge, as it must take into account multiple parameters, including cerebral autoregulation and autoregulatory reserves, brain compliance, cerebral dynamics such as intracranial pressure (ICP), cerebral perfusion pressure (CPP), and cerebral blood flow (CBF), as well as systemic hemodynamics and respiratory system mechanics. Moreover, the detrimental effects of MV on extracranial organs and systems are well established, with the lungs being the most vulnerable, particularly when non-protective ventilation strategies involving high tidal volumes (TV) and inspiratory pressures are applied. Currently, the optimal ventilation approach in patients with TBI, with or without LI, remains incompletely defined. While protective ventilation practices are recommended for a large number of critically ill patients, their application in individuals with acute brain injury (ABI) may adversely affect cerebral and systemic hemodynamics, as well as brain physiology, potentially leading to secondary damage and poor clinical outcomes. Because the consequences of TBI, such as secondary brain damage and lung complications, begin shortly after the primary event, the role of prehospital MV in these patients is crucial. However, existing data from the out-of-hospital setting are scarce. Thus, in the present review, we aim to summarize the available evidence on MV in patients with TBI, with an emphasis on the prehospital setting.