Update on traumatic brain injury

Abstract

Traumatic brain injury (TBI) is an alteration in brain function, or other evidence of brain pathology, caused by an external force. Clinically, TBI is described by severity as per the well-recognised Glasgow Coma Scale (GCS). Traditionally, according to the GCS, a mild TBI is defined by a GCS of 13–15; a moderate TBI by a GCS of 9–12, and a severe TBI by a GCS of less than 8. Primary TBI occurs at the time of the traumatic incident. Regardless of the cause, external mechanical forces transfer energy to intracranial contents, resulting in the pathological pattern of injury. Secondary TBI occurs at a molecular level, is initiated at the time of initial trauma and can lead to nerve cell death and cerebral oedema, which culminate in an exacerbation of the initial injury. Secondary TBI presents a host of factors which the anaesthesiologist can mitigate to potentially improve patient outcome, but at the very least, to prevent deterioration. These are aimed at managing mean arterial pressure, ventilation and therefore PaCO2, glucose, temperature, intracranial pressure, seizures and coagulation. The Brain Trauma Foundation publish evidence-based guidelines on this subject that are freely accessible in order to standardise the treatment of this condition. The most recent publication is the fourth edition from 2016. The outcomes from the RESCUEicp and DECRA trials affect the decompressive craniectomy recommendations, and have been added after this, as part of the ‘living guidelines’ initiative.