TAILIEUCHUNG - 2013 Trauma intensive care 2
Chapter 12Traumatic brain injury:.assessment, pathophysiology,.and managementTraumatic brain injury (TBI) is the most common cause of death among individuals under 45 years of age in the Western World. Each year, roughly in the United States sustain head injuries, most of which are mild TBI. However, brain trauma has a significant impact in the United States,.as underscored by the approximately 52,000 deaths and 275,000 year, as well as the considerable financial burden placed on the healthcare system in terms of direct medical expenditures, including long-term care to disabilities from TBI, and indirect costs related to loss of Coma Glasgow Coma Scale (GCS) is the most commonly used scheme to determine the neurologic status of a patient following a head injury (Table )The GCS serves as a readily reproducible, objective measure of ascertaining ’s level of consciousness by assessing three factors:.• Eye opening.• Verbal response.• Motor responseSevere TBI is classified by GCS scores of 3 to 8, while moderate and mild classified by GCS scores from 9 to 12 and 13 to 15, respectively. A patient’ GCS score correlates significantly with outcome; however, factors such , pupil reactivity, head computed tomography (CT) scan findings, and trauma-related extracranial injuries also serve as key predictors of following severe and secondary traumatic brain brain brain injury refers to damage suffered as a direct result of the initial traumatic event and may be caused by penetrating, blunt, and blast trauma. Primary133Ramesh Grandhi and David O. brain 12134Table Glasgow Coma Scale (GCS).Eye opening (E).Spontaneous speech pain open response (V).Conversant response (M).To command pain:.Localizing flexion extension response Score = E + V + M (range, 3 or 3T–15).From: Teasdale G, Jennett B. Assessment of coma and impaired consciousness: A practical scale. Lancet1974;2:81– injury can be broadly divided into focal and diffuse injuries. Focal traumatic intracranial hematomas and contusions. Diffuse injuries, a wide range of injury patterns including diffuse axonal injury (DAI),.are more common and constitute upwards of 60% of severe brain brain injury is attributable to local phenomena within the skull factors that cause damage following the initial insult. Preventing secondary brain injury is of fundamental importance in the management of severe head trauma. Research has shown that the reduced over the past 30 years—from 50% to less than 25%—in patients with is a function of avoiding and treating factors known to precipitate injury. The endpoint of these key factors—hypotension, hypoxia, inadequate cerebral perfusion pressure, and intracranial hypertension—is cerebral ischemia, the avoidance of which lies at the very foundation of severe TBI management protocolsUnderstanding the pathophysiology behind cerebral ischemia and intracranial hypertension, the reasons for invasive monitoring of both systemic Blood Flow (ml/100 g/min)Cerebral ischemia occurs when there is insufficient cerebral blood flow (CBF) its metabolic demands. The brain is unique among our organs due to its dependency on blood flow to provide substrates for metabolism. 95% of the brain’s metabolism is oxidative and it lacks a capacity for storage. It also has minimal glucose and glycogen reserves. In turn, cerebrovascular physiology is predicated on pre
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