The Effect of Associated Injuries, Blood Loss, and Oxygen Debt on Death and Disability in Blunt Traumatic Brain Injury: The Need for Early Physiologic Predictors of Severity

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Abstract
Studies of 4590 patients with blunt trauma injuries admitted to a Level I Trauma Center, have shown that 37% had a blunt traumatic brain injury (BTBI). Of these brain injured patients 60% has an associated other injury. Examination of mortality has shown that those with an isolated brain injury had an 11% mortality compared with 21.8% in those with an associated systemic injury. Further investigation demonstrated that the cause of the increased mortality was related to the blood loss associated with the injuries and that when hypovolemic shock resulted, mortality rose from 12.8 to 62%. The severity of the associated injuries effect on the brain injured patient could be estimated by a parameter of oxygen debt, the base deficit and this allowed for a quantitative estimate of the probability of death as an index of severity. A combined linear logistic model using the admission Glasgow Coma Score (GCS) as a measure of brain injury and the base deficit as a measure of physiologic injury provides such a predictive score. The effect of associated injuries in patients with moderate brain injury (AIS 2,3) was to increase the average total cost of medical care in the first year of injury by three-fold ($12,489 to $36,177) and for severe brain injury (AIS 4,5) to increase average cost from $59,000 in isolated BTBI to $90,000 in BTBI with associated injury. The high incidence of brain injuries in motor vehicle crashes (MVC) caused by lateral impacts and their association with other side-impact injuries (lungs, spleen, kidney, and pelvic fractures) in which large blood volume losses are common, focuses attention on the need for side impact protection standards that simultaneously protect brain, thoracoabdominal viscera, and pelvis as a means of reducing the severity and cost of lateral impact MVCs. Key words: traumatic brain injury; secondary insult; hypovolemia; morbidity