End-tidal carbon dioxide is associated with mortality and lactate in patients with suspected sepsis

Exhaled end-tidal carbon dioxide (ETCO(2)) concentration is associated with lactate levels in febrile patients. We assessed the association of ETCO(2) with mortality and lactate levels in patients with suspected sepsis.

This was a prospective observational study. We enrolled 201 adult patients presenting with suspected infection and 2 or more systemic inflammatory response syndrome criteria. Lactate and ETCO(2) were measured and analyzed with patient outcomes.

The area under the receiver operator characteristics curve (AUC) was 0.75 (confidence interval [CI], 0.65-0.86) for lactate and mortality and 0.73 (CI, 0.61-0.84) for ETCO(2) and mortality. When analyzed across the different categories of sepsis, the AUCs for lactate and mortality were 0.61 (CI, 0.36-0.87) for sepsis, 0.69 (CI, 0.48-0.89) for severe sepsis, and 0.74 (CI, 0.55-0.93) for septic shock. The AUCs for ETCO(2) and mortality were 0.60 (CI, 0.37-0.83) for sepsis, 0.67 (CI, 0.46-0.88) for severe sepsis, and 0.78 (CI, 0.59-0.96) for septic shock. There was a significant inverse relationship between ETCO(2) and lactate in all categories, with correlation coefficients of -0.421 (P < .001) in the sepsis group, -0.597 (P < .001) in the severe sepsis group, and -0.482 (P = .011), respectively. Adjusted odds ratios were calculated, demonstrating 3 significant predictors of mortality: use of vasopressors 16.4 (95% CI, 1.80-149.2), mechanical ventilation 16.4 (95% CI, 3.13-85.9), and abnormal ETCO(2) levels 6.48 (95% CI, 1.06-39.54).

We observed a significant association between ETCO(2) concentration and in-hospital mortality in emergency department patients with suspected sepsis across a range of disease severity.