High total carbon dioxide predicts 1-year readmission and death in patients with acute dyspnea

Patients with acute dyspnea are a large heterogeneous patient group where initial management is important for outcome.

The objective of the study is to investigate if venous blood gas parameters predict 1-year risk of readmission or death in patients admitted to the emergency department due to acute dyspnea.

We studied 283 patients with acute dyspnea and followed them up for 1 year regarding incidence of readmission or death.

In venous blood obtained immediately upon admission levels of total carbon dioxide (TCO2), base excess (BE), potential hydrogen (pH), and partial pressure of carbon dioxide (pCO2) were measured. In Cox proportional hazards models, patients belonging to top and bottom quartiles of TCO2, BE, pH, and pCO2 were compared to patients belonging to the 2 central quartiles and assessed for end point. After adjustment, top (hazard ratio [HR], 1.48; 95% confidence interval [CI], 1.08-2.04; P=.016) and bottom (HR, 1.54; 95% CI, 1.08-2.18; P=.017) quartiles of BE were associated with increased risk of readmission or death. The strongest predictor was top quartile of TCO2 (HR, 1.68; 95% CI, 1.21-2.35; P=.002). In the combined analysis, top quartile of TCO2 remained significantly related to the end point (HR, 1.59; 95% CI, 1.03-2.45; P=.035), whereas BE became nonsignificant. Comorbidities, for example, prevalent chronic obstructive pulmonary disease, did not explain the association. Neither pCO2 nor pH predicted the end point.

A high value of TCO2 appears to be an easily accessible marker for 1-year readmission or death in patients with acute dyspnea and may thus add clinically important information for risk stratification and follow-up strategies.