Abstract 256: Cerebral Oximetry and End Tidal CO2 as Predictors of Futility During Cardiopulmonary Resuscitation

Background: There is currently no validated predictor of futility, defined as the inability to obtain ROSC, (IOR), and therefore no specific guidelines for cessation of resuscitation. Previous literature suggests that ETCO2 values of ?10 are predictive of IOR. Cerebral Oximetry (CerOx) uses near infrared light to non-invasively measure regional O2 saturation in the frontal lobes of the brain. CerOx has been shown in pilot studies to identify ROSC in 85% of arrests. Objective: The study’s objective was to compare ETCO2 and CerOx measurements during CPR to predict futility. Methods: We prospectively enrolled a convenience sample of subjects suffering from OHCA and ED cardiac arrest. Data was analyzed utilizing linear regression with Receiver Operating Characteristic (ROC) curves on the max and last readings of both ETCO2 and CerOx during CPR. Results: We analyzed 169 events with 48 (28%) obtaining ROSC. The average age was 64.5 ± 15.6. The average downtime was 24.6 ± 15.0 minutes, 113 (66.7%) of the events were witnessed, and 95 (56%) of the events had bystander CPR. The initial rhythms were asystole in 48%, PEA 35%, and V-Fib/V-Tach in 17% of cases. ROC curve analysis was used to determine the best discriminating variable in predicting IOR. Area under the curve (AUC) for the last value [CerOx AUC=.856, ETCO2 AUC= .761] and max value [CerOx, AUC=.802, ETCO2 AUC=.630] obtained prior to death showed CerOx to be a better predictor or IOR than ETCO2. All subjects who failed to obtain a max ETCO2 value of 15 had IOR, while five subjects with a max CerOx of 15 had ROSC. Sensitivity/Specificity for select values in Table 1. Conclusion: The max and last CerOx value was overall a better predictor of futility than the max and last value of ETCO2. However at lower ranges ETCO2 proved to be more specific than CerOx.