The association between a quantitative computed tomography (CT) measurement of cerebral edema and outcomes in post-cardiac arrest-a validation study.

AIM: Previous studies have examined the association between quantitative head computed tomography (CT) measures of cerebral edema and patient outcomes reporting that a calculated gray matter to white matter attenuation ratio (GWR) of <1.2 indicates a near 100% non-survivable injury post-cardiac arrest. The objective of the current study was to validate whether a GWR <1.2 reliably indicates poor survival post-cardiac arrest. We also sought to determine the inter-rater variability among reviewers, and examine the utility of a novel GWR measurement to facilitate easier practical use. METHODS: We performed a retrospective analysis of post-cardiac arrest patients admitted to a single center from 2008 to 2012. Inclusion criteria were age ≥18 years, non-traumatic arrest, and available CT imaging within 24h after ROSC. Three independent physician reviewers from different specialties measured CT attenuation of pre-specified gray and white matter areas for GWR calculations. RESULTS: Out of 171 consecutive patients, 90 met the study inclusion criteria. Thirteen patients were excluded for technical reasons and/or significant additional pathology, leaving 77 head CT scans for evaluation. Median age was 66 years and 64% were male. In-hospital mortality was 65% and 70% of patients received therapeutic hypothermia. For the validation measurement, the intra-class correlation coefficient was 0.70. In our dataset, a GWR below 1.2 did not accurately predict mortality or poor neurological outcome (sensitivity 0.56-0.62 and specificity 0.63-0.81). A score below 1.1 predicted a near 100% mortality but was not a sensitive metric (sensitivity 0.14-0.20 and specificity 0.96-1.00). Similar results were found for the exploratory model. CONCLUSION: A GWR <1.2 on CT imaging within 24h after cardiac arrest was moderately specific for poor neurologic outcome and mortality. Based on our data, a threshold GWR <1.1 may be a safer cut-off to identify patients with low chance of survival and good neurological outcome. Intra-class correlation among reviewers was moderately good.

APACHE II scoring to predict outcome in post-cardiac arrest.

INTRODUCTION: Despite advancements in management of cardiac arrest, mortality remains high and few severity of illness scoring systems have been calibrated in this population. The goal of the current investigation was to assess the Acute Physiology and Chronic Health Evaluation II score in post-cardiac arrest. MEASUREMENTS: This is a prospective observational study of adult post-cardiac arrest patients at a tertiary-care center. The primary outcome variable was in-hospital mortality and secondary outcome variable was neurologic outcome. APACHE II scores were used to predict outcomes using logistic modeling. MAIN RESULTS: A total of 228 subjects were included in the analysis. The median age of the cohort was 70 (IQR: 64-71) and 32% (72/228) of the patients were female. The median downtime was 15 min (IQR: 7-27) and initial lactate 5.9 mmol/L (IQR: 3.5-8.4). 71 (57%) of deaths occurred prior to the 72-h follow-up and overall in-hospital mortality was 55% (125/228). Discrimination of APACHE II score in all cardiac arrest patients increased in stepwise fashion from 0-h to 72-h follow-up (AUC: 0-h: 0.62; 24-h: 0.75; 48-h: 0.82; 72-h: 0.86). CONCLUSIONS: APACHE II score is a poor predictor of outcome at time zero for out-of-hospital cardiac arrest (OHCA) post-arrest patients consistent with the original development of the score in the critically ill. For in-hospital cardiac arrest (IHCA) at time zero and for both IHCA and OHCA at 24h and beyond, the APACHE II score was a modest indicator of illness severity and predictor of mortality/neurologic morbidity.