Background:
Predicting the outcome of a cardiac arrest (CA) is exceedingly difficult. Previous literature has identified end tidal CO
2
(ETCO
2
)
as a reasonable predictor of both return of spontaneous circulation (ROSC) and futility of resuscitation. Cerebral Oximetry (CerOx) measures the regional O
2
saturation of the frontal lobes of the brain utilizing non-invasive near infrared spectroscopy and has been correlated with cerebral oxygenation.
Objectives:
The objective of this study is to compare measurement of ETCO
2
and CerOx to predict ROSC during both out of hospital cardiac arrests (OHCA) and emergency department cardiac arrests (EDCA).
Methods:
We conducted an IRB approved, prospective study on a convenience sample of patients suffering from OHCA and EDCA. Patients were monitored with ETCO
2
and CerOx simultaneously while CPR was being performed in the ED. All patients were evaluated to predict ROSC by six parameters utilizing area under the curve (AUC) values. Data was analyzed using logistic regression modeling. AUCs were compared using the Delong, Delong, and Clarke-Pearson method.
Results:
Overall, we analyzed 176 patients. The mean age was 62.3 ± 14.4 . 116 (66.7%)were witnessed arrest with 93 (53.8%) having received immediate CPR. The average downtime from EMS call to ED arrival was 39 minutes. The initial rhythm in these patients was 56 (31.8%) asystole, 49 (27.8%) PEA, 45 (25.6%) VF/VT, and non-shockable rhythm in 26 (14.8%) . ROSC was achieved in 46 (26.1%) of patients. The analysis of the individual variable prediction of ROSC, revealed: first value [CerOx AUC = 0.554 p = 0.1143 ; ETCO
2
AUC = 0.533, p = 0.3981], maximum value [CerOx AUC = 0.778 p < 0.0001; ETCO
2
AUC = 0.616 p = 0.0849 ], trend over the last 5 minutes [CerOx AUC = 0.821 p < 0.0001 ; ETCO
2
AUC = 0.744 p = 0.7354 ], delta from first to last value [CerOx AUC = 0.859 p < 0.0001 ; ETCO
2
AUC = 0.734 p = < 0.0001 ], average value of the penultimate minute of resuscitation [CerOx AUC = 0.814 p <0.0001 ; ETCO2 AUC = 0.759 p = 0.0003 ], and average value of the final minute of the resuscitation [CerOx AUC = 0.886 p < 0.0001 ; ETCO2 AUC = 0.770 p = 0.0001}.
Conclusion:
Our data shows that both ETCO2 and rSO2 are good predictors of ROSC. We found CerOx superior to ETCO
2
in predicting ROSC.
Can an initial end-tidal CO2 <1.33 kPa predict lack of return of spontaneous circulation during pre-hospital cardiac arrest?