To evaluate the effect of decompressive craniectomy on cerebral venous oxygen saturation (SjVO2) in traumatic brain injury patients

Traumatic brain injury (TBI) is one of the leading causes of morbidity and mortality worldwide.After the primary insult, secondary insult plays a major role in the pathophysiology of TBI. Factors leading to secondary insult include, hypotension, hypoxia, hypercarbia, decreased cerebral blood flow (CBF), decreased cerebral perfusion pressure (CPP), increased intracranial pressure (ICP), etc. Many protocols are followed by neuro-intensivists to minimize secondary insult and to maintain adequate CBF by decreasing ICP to <22 mm Hg and maintaining an optimum CPP between 60 to 70 mm Hg for adults (as per Brain Trauma Foundation (BTF) guidelines 2016).

Increased ICP is a common occurrence after TBI and decompressive craniectomy is required to reduce ICP and improve CPP if medical measures fail. However, CPP may not always improve despite a decrease in ICP in TBI patients and thus may lead to cerebral ischemia and infarction. The DECRA (Decompressive Craniectomy in Diffuse Traumatic Brain Injury) trial, in patients with severe TBI and refractory intracranial hypertension, showed that an early bifronto-temporo-parietal decompressive craniectomy led to a decrease in ICP and length of ICU stay but did not result into a better outcome. Cerebral ischemia and cerebral oxygenation are important factors for clinical outcome in TBI patients. Cerebral jugular venous oximetry (SjVO2) is a marker of global cerebral blood flow and brain metabolism that indicates the delivery and utilization of oxygen by brain cells. Along with SjVO2,cerebral arteriovenous oxygen difference (AVDO2), arterial-venous differences of glucose (AVDG), and venous-arterial difference of lactate (VADL) have also been used as surrogate markers of cerebral perfusion and metabolism.

Decompressive  craniectomy  has  an  established  role in decreasing ICP but has never been evaluated for its effect on jugular venous oximetry. Thus, there is no concrete evidence to state whether the decrease in ICP after decompressive craniectomy leads to improvement in cerebral blood flow and/or cerebral oxygenation which may result in improved clinical outcome. Considering these factors, this study is planned to determine whether decompressive craniectomy offers any advantage in terms of improved CBF and improved oxygen delivery to brain in moderate to severe TBI patients