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The association between arterial-end-tidal carbon dioxide difference and outcomes after out-of-hospital cardiac

Aleksandra A Abrahamowicz1, Catherine R Counts2, Kyle R Danielson3

  • 1University of Washington, Department of Internal Medicine, Seattle, WA, United States.

Resuscitation
|October 2, 2022
PubMed

Insights

The difference between partial arterial carbon dioxide (PaCO2) and end-tidal carbon dioxide (ETCO2) does not predict survival or neurological outcomes in out-of-hospital cardiac arrest (OHCA) patients. These measures may guide ventilation but are not reliable for prognostication after OHCA.

Area of Science:

  • Critical Care Medicine
  • Emergency Medicine
  • Cardiology

Background:

  • Out-of-hospital cardiac arrest (OHCA) poses significant challenges for patient survival and neurological recovery.
  • Monitoring carbon dioxide levels, specifically the difference between partial arterial carbon dioxide (PaCO2) and end-tidal carbon dioxide (ETCO2), is a potential tool in managing these patients.

Purpose of the Study:

  • To investigate the association between the PaCO2-ETCO2 difference and hospital mortality in OHCA survivors.
  • To evaluate the relationship between the PaCO2-ETCO2 difference and neurological outcomes at hospital discharge following OHCA.

Main Methods:

  • Retrospective cohort study including adult OHCA patients who achieved return of spontaneous circulation (ROSC).
  • Primary exposure: PaCO2-ETCO2 difference on hospital arrival.
  • Primary outcome: Survival to hospital discharge; Secondary outcome: Favorable neurological status. Analysis included ROC curves and multivariate logistic regression.

Main Results:

  • A total of 381 OHCA patients with qualifying CO2 values were analyzed; 160 (42%) survived.
  • The mean PaCO2-ETCO2 difference was 6.8 mmHg in survivors versus 9.0 mmHg in non-survivors (p < 0.05).
  • Adjusted analysis revealed no significant association between higher PaCO2-ETCO2 difference and hospital mortality (OR 0.99) or neurological outcome. ROC analysis showed limited predictive value for both PaCO2-ETCO2 and ETCO2.

Conclusions:

  • The PaCO2-ETCO2 difference and ETCO2 alone are not strong predictors of survival or neurological status post-OHCA.
  • While potentially useful for guiding ventilation and resuscitation efforts, these CO2 metrics should not be relied upon for prognostication in OHCA patients.
Abstract

Keywords:
Arterial carbon dioxideCardiac arrestEnd tidal carbon dioxideOHCAOut-of-hospital cardiac arrest

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