Cerebral oximetry versus end tidal CO₂ in predicting ROSC after cardiac arrest

Area of Science:

• Emergency Medicine
• Critical Care
• Cardiology

Background:

• End tidal CO2 (ETCO2) and cerebral oxygen saturations (rSO2) are vital signs monitored during cardiopulmonary resuscitation (CPR).
• Their effectiveness in predicting return of spontaneous circulation (ROSC) in out-of-hospital cardiac arrest (OHCA) requires further comparative analysis.

Purpose of the Study:

• To compare the accuracy of ETCO2 and rSO2 in predicting ROSC.
• To evaluate the diagnostic characteristics of ETCO2 and rSO2 in OHCA patients presenting to the emergency department (ED).

Main Methods:

• A prospective, observational study was conducted on adult ED patients experiencing cardiac arrest.
• Data collected included demographics, presenting rhythm, rSO2, and ETCO2.
• Receiver operating characteristic (ROC) curves were used to compare the predictive performance of rSO2 and ETCO2 for ROSC.

Main Results:

• Of 225 OHCA patients, 100 had both rSO2 and ETCO2 measurements; 33% achieved ROSC.
• The area under the curve (AUC) for rSO2 was 0.69 and for ETCO2 was 0.77, indicating similar overall predictive ability.
• ETCO2 demonstrated higher sensitivity (100%) at a cutoff of 20 mm Hg, while rSO2 showed higher specificity (85%) at a cutoff of 50%.

Conclusions:

• Despite poor correlation, ETCO2 and rSO2 exhibit comparable diagnostic capabilities for predicting ROSC in OHCA.
• ETCO2 is a more sensitive indicator, whereas rSO2 is a more specific predictor of ROSC in this patient population.