End-Tidal Carbon Dioxide Measured at Emergency Department Triage Outperforms Standard Triage Vital Signs in Predicting In-Hospital Mortality and ICU admission

Link to article at PubMed

Acad Emerg Med. 2023 Feb 21. doi: 10.1111/acem.14703. Online ahead of print.


This study assessed the ability of end tidal carbon dioxide (ETCO2) in predicting in-hospital mortality and ICU admission compared to standard vital signs at ED triage as well as comparing to measures of metabolic acidosis.

METHODS: This prospective study enrolled adult patients presenting to the ED of a tertiary care level 1 trauma center over 30 months. Patients had standard vital signs measured along with exhaled ETCO2 at triage. Outcome measures included in-hospital mortality, ICU admission and correlations with lactate, sodium bicarbonate (HCO3) and anion gap.

RESULTS: There were 1136 patients enrolled and 1091 patients with outcome data available. There were 26 (2.4%) patients who did not survive to hospital discharge. Mean ETCO2 levels was 34 (33-34) in survivors and 22 (18-26) non-survivors (p<0.001). The AUC for predicting in-hospital mortality for ETCO2 was 0.82 (0.72-0.91). In comparison the AUC for temp was 0.55 (0.42-0.68); RR 0.59 (0.46-0.73); SBP 0.77 (0.67-0.86); DBP 0.70 (0.59-0.81); HR 0.76 (0.66-0.85); and SpO2 0.53 (0.40-0.67). There were 64 (6%) patients admitted to the ICU and the ETCO2 AUC for predicting ICU admission was 0.75 (0.67-0.80). In comparison the AUC for temp was 0.51; RR 0.56; SBP 0.64; DBP 0.63; HR 0.66; and SpO2 0.53. Correlations between expired ETCO2 and serum lactate, anion gap, and HCO3, were rho=-0.25 (p<0.001), rho=-0.20 (p<0.001), and rho=0.330 (p<0.001) respectively.

CONCLUSION: ETCO2 was a better predictor of in-hospital mortality and ICU admission than the standard vital signs at ED triage. ETCO2 correlated significantly with measures of metabolic acidosis.

PMID:36802204 | DOI:10.1111/acem.14703

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