Impact of pre-hospital vital parameters on the neurological outcome of out-of-hospital cardiac arrest: Results from the French National Cardiac Arrest Registry

Abstract

Introduction: The targets for vital parameters following return of spontaneous circulation (ROSC) from an out-of-hospital cardiac arrest (OHCA) are based on studies carried out predominantly in intensive care units. Therefore, we studied the pre-hospital phase.

Method: We included all adult OHCA from the French OHCA Registry. Vital parameters [peripheral oxygen saturation level (SpO₂), end-tidal carbon dioxide (ETCO₂) and systolic blood pressure (SBP)] documented during the pre-hospital phase by mobile medical team, were evaluated with regard to the neurological outcome on day 30 (classified as good for Cerebral Performance Category (CPC) 1 - 2, and poor for CPC 3 - 5 or death).

Results: When compared with a reference range of 94-98%, SpO₂ values less than 94% were associated with a worse outcome on univariate analysis [relative risk (RR) = 1.108(1.069 - 1.147)]. An SpO₂ of 99 - 100% did not appear to be harmful [RR = 0.9851(0.956-1.015)]. ETCO₂ values that deviated from the reference of 30 - 40 mmHg were associated with a worse outcome on univariate analysis [<20, RR = 1.191(1.143 - 1.229); 20 - 29, RR = 1.092(1.061 - 1.123); 41 - 50, RR = 1.075(1.039 - 1.110); >50, RR = 1.136(1.085 - 1.179)]. When compared with a reference range of 100 - 130, higher or lower values of SBP were associated with a worse outcome on univariate analysis [<80, RR = 1.203(1.158 - 1.243); 80 - 99, RR = 1.069(1.033 - 1.105); 131 - 160, RR = 1.076(1.043 - 1.110); >160, RR = 1.168(1.126 - 1.208)]. The multivariate analysis yielded similar results.

Conclusion: In comatose patients who have achieved ROSC after OHCA, vital parameters in the pre-hospital phase appear to have a real impact on the 30-day neurological outcome. We found that an SpO₂ ≥ 94%, an ETCO₂ of 30 - 40 mmHg, and an SBP of 100 - 130 mmHg were associated with a better prognosis.

Keywords: Hemodynamic monitoring; Out of hospital cardiac arrest; Prehospital emergency care; Ventilation; Vital signs.