Abstract 288: Predicting Return of Spontaneous Circulation Using Cerebral Oximetry and End Tidal CO2

Background: Previous literature has identified ETCO2 as a good predictor of ROSC. Cerebral Oximetry (CerOx) utilizes near infrared spectroscopy to non-invasively measure regional O2 saturation of the frontal lobes of the brain. Objectives: The objective of this study is to compare the predictive value of simultaneously measured ETCO2 and CerOx for ROSC during CPR. Methods: We conducted an IRB approved, prospective study on a convenience sample of subjects suffering cardiac arrest. Subjects were monitored with ETCO2 and CerOx simultaneously during CPR performed in the ED. We analyzed the data using logistic regression modeling and ROC curve analysis. Results: We analyzed 135 events. Mean age was 64.5±15.6 years. 90 (66.7%) were witnessed arrests with 78 (57.8%) receiving bystander CPR. Average downtime was 24.9±15.0 minutes. ROSC was achieved in 39 (28.9%) of these subjects. Initial rhythm presented as 58 (43.0%) asystole, 52 (38.5%) PEA and 25 (18.5%) VF/VT. A series of binary logistic regression models were run in which various derivations of ETCO2 and CerOx were simultaneously entered into the model to predict ROSC. CerOx, but not ETCO2, proved to be a significant predictor in determining ROSC for the following variables: regression slope during the full code [CerOx p<0.000, ETCO2 p<0.386], regression slope during the last 5 minutes of the resuscitation [CerOx p<0.000, ETCO2 p<0.749], maximum value recorded during resuscitation [CerOx p<0.000, ETCO2 p<0.858]. Both CerOx and ETCO2 proved to be significant predictors of ROSC for the following variables: last value recorded during resuscitation [CerOx p<0.000, ETCO2 p<0.009], the change from first value recorded to last value recorded [CerOx p<0.000, ETCO2 p<0.000]. CerOx also proved to be a better predictor of ROSC than ETCO2 when utilizing a ROC curve analysis: last values recorded [CerOx, AUC=0.856; ETCO2, AUC=0.761] and maximum values recorded [CerOx, AUC=0.802; ETCO2, AUC=0.630]. Conclusions: CerOx is a better predictor of ROSC than ETCO2 when analyzed by the whole resuscitation effort, the last five minutes, the maximum value, the last value recorded, and the change in values from first to last recordings during CPR. The maximum and last values of CerOx are good diagnostic tests for predicting ROSC.