Incidence of neurologic death among patients with brain injury: a cohort study in a Canadian health region

Background:

Hospital mortality has decreased over time for critically ill patients with various forms of brain injury. We hypothesized that the proportion of patients who progress to neurologic death may have also decreased.

Methods:

We performed a prospective cohort study involving consecutive adult patients with traumatic brain injury, subarachnoid hemorrhage, intracerebral hemorrhage or anoxic brain injury admitted to regional intensive care units in southern Alberta over a 10.5-year period. We used multivariable logistic regression to adjust for patient age and score on the Glasgow Coma Scale at admission, and to assess whether the proportion of patients who progress to neurologic death has changed over time.

Results:

The cohort consisted of 2788 patients. The proportion of patients who progressed to neurologic death was 8.1% at the start of the study period, and the adjusted odds of progressing to neurologic death decreased over the study period (odds ratio OR] per yr 0.92, 95% confidence interval CI] 0.87–0.98, p = 0.006). This change was most pronounced among patients with traumatic brain injury (OR per yr 0.87, 95% CI 0.78–0.96, p = 0.005); there was no change among patients with anoxic injury (OR per yr 0.96, 95% CI 0.85–1.09, p = 0.6). A review of the medical records suggests that missed cases of neurologic death were rare (≤ 0.5% of deaths).

Interpretation:

The proportion of patients with brain injury who progress to neurologic death has decreased over time, especially among those with head trauma. This finding may reflect positive developments in the prevention and care of brain injury. However, organ donation after neurologic death represents the major source of organs for transplantation. Thus, these findings may help explain the relatively stagnant rates of deceased organ donation in some regions of Canada, which in turn has important implications for the care of patients with end-stage organ failure.Mortality has decreased among critically ill patients with various forms of brain injury in Canada and around the world.^1–10 There have also been changes in the incidence of stroke and the rate of admission to hospital for traumatic brain injury, especially among younger people and those whose injuries are related to motor vehicle or bicycle crashes.^5,6,10–13Some countries have noted a possible decline in the total number of patients with neurologic death.^14,15 Neurologic death (“brain death”) may occur when patients with brain injury experience progressive cerebral edema, complicated by transtentorial herniation. It is defined by the irreversible cessation of cerebral and brainstem functions, including respiration.¹⁶ Circulation and gas exchange persist only because of the use of mechanical ventilation. National guidelines exist for the diagnosis of neurologic death.^17,18 We hypothesized that the proportion of patients with acute brain injury who progress to neurologic death may have decreased over time.