Abstract 35: A Validation of the Association Between a Quantitative CT Scan Measure of Cerebral Edema and Outcomes Post Cardiac Arrest
Introduction: The presence of cerebral edema post cardiac arrest (CA) may indicate widespread neurologic injury. Previous studies have examined the association between a quantitative measure of brain edema on CT scan and outcome. A calculated gray matter to white matter attenuation ratio (GWR) of <1.2 was associated with near 100% non-survivable injury post CA. These findings have yet to be validated in a separate population.
Objective: To validate whether a GWR <1.2 reliably indicates poor survival post arrest. We also sought to determine the inter-relater reliability among reviewers and develop a novel GWR that may be simpler to use in practice.
Methods: We performed a retrospective analysis of post CA patients admitted to a single center from 2008 to 2012. Inclusion criteria were age >18years, non traumatic arrest, and a brain CTscan within 24 hours of ROSC. Three independent physician reviewers measured attenuation in pre-specified areas.
Results: We evaluated 300 patients, of whom 91 met inclusion criteria and 79 had a technically adequate CT for evaluation. Mean age was 64 years (SD +/- 17); 69% were male. In-hospital mortality was 63%. Approximately 59% of patients received therapeutic hypothermia. For the validation measurement, the interclass correlation coefficient was 0.70. Results of GWR <1.2 are shown in Table. Adjusting the cut-off value to <1.1, no survivors were noted by reviewers 2 and 3 (0/19) and 89% did not survive as judged by reviewer 1 (1/8).
Conclusion: A GWR <1.2 on CT imaging within 24 hours post CA was associated with a high degree of mortality and poor neurologic outcome, however this was not invariably true. Similarly, our experimental model did not perform well enough to be used for prognostication. We caution against implementation based on previous investigations until reasons for these disparate findings are elucidated. A threshold <1.1 may be a safer cut-off to identify patients with low chance of neurological survival.
- © 2012 by American Heart Association, Inc.