Assessment of impaired cerebral autoregulation in patients with traumatic brain injury and its correlation with neurological outcomes: A prospective observational study

Cerebral autoregulation (CA) is an integral autoregulatory mechanism of our body by which blood flow to the brain is maintained in spite of fluctuations in blood pressure. Autoregulation can be assessed by observing changes in cerebral blood flow or its equivalents in response to differences in cerebral perfusion pressure or mean arterial pressure. TBI is one of the largest medical burdens worldwide. TBI survivors suffer from several post injury sequalae months or years after the event. Research indicates that post Traumatic Brain Injury (TBI) cerebral autoregulatory mechanisms are lost and this can result in secondary brain injury. TBI has been known to increase the incidence of several neurological dysfunctions like stroke, seizure disorder and incidence of all-cause mortality. There is a lacuna in available literature regarding the assessment of impaired cerebral autoregulation (ICA) in patients of TBI using TCD along with Transient Hyperaemic Response Test (THRT) and its correlation with neurological outcome. We hypothesize that impaired cerebral autoregulation during initial 48 hours following TBI can compromise cerebral perfusion which can lead to poorer neurological outcome.

Cerebral autoregulation monitoring in TBI is essential for guiding clinical decision-making and treatment protocols. On receiving patients in the Trauma and Neuro Intensive Care Unit, patients will be stabilised as per ICU protocol. Thereafter, patients will be screened for eligibility which includes bilateral carotid ultrasound to rule out carotid plaque or atheroma to avoid the disruption and dislodgement of the plaque during THRR test. Once the patients fulfil the eligibility criteria they will be enrolled for the study. Baseline demographics shall be recorded. TCD will be done at baseline, during Transient Hyperaemic Response Test and after THRT. Dynamic autoregulation will be assessed via THR. Mean flow velocity, peak flow velocity, diastolic flow velocity and pulsatality index (PI) will be noted.  THR test will be repeated at 48 hours. The outcomes, as mentioned above shall be assessed.