Six Vital Signs? Should We Measure ETCO2 in Triage?

March 16, 2023

Written by Clark Strunk

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ETCO2 measured during emergency department triage outperforms standard vital signs in predicting in-hospital mortality, ICU admission, and correlates with markers of metabolic acidosis.

Why does this matter?
As patient volumes continue to rise throughout the country and healthcare resources are constrained, it is important to adequately triage patients in a timely and safe manner. ETCO2 is a readily available, non-invasive, and familiar tool to emergency clinicians and may be able to assist in the initial assessment of disease severity.

End tidal to determine end-hospital mortality and who will end up in the ICU
This was a prospective observational study where investigators measured the ETCO2 of patients during emergency department triage as well as standard vital signs and compared their test characteristics in regard to predicting in-hospital mortality and ICU admission. The average ETCO2 in survivors was 34 versus 22 in the non-survivors (p<0.001). The ETCO2 AUC for in-hospital mortality and ICU admission was 0.82 and 0.75, respectively, which was higher than all other point estimates for standard vital signs. Furthermore, they found a robust statistically significant direct correlation between ETCO2 and bicarbonate, and inverse relationship between ETCO2 with lactate and anion gap.

Ultimately, I believe this study provides additional compelling data to the large body of literature that already exists demonstrating the value of ETCO2 in a variety of clinical scenarios. However, its routine use in triage is not widespread. I think this paper displays promising data that perhaps implementation of ETCO2 in ED triage might be able to augment clinician judgment and aid in identification of patients with increased illness severity.

Source
End-Tidal Carbon Dioxide Measured at Emergency Department Triage Outperforms Standard Triage Vital Signs in Predicting In-Hospital Mortality and ICU admission. Acad Emerg Med. 2023 Feb 21. doi: 10.1111/acem.14703. Epub ahead of print.