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

Abstract Objective Exhaled end-tidal carbon dioxide (E tco2 ) concentration is associated with lactate levels in febrile patients. We assessed the association of E tco2 with mortality and lactate levels in patients with suspected sepsis. Methods 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 E tco2 were measured and analyzed with patient outcomes. Results 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 E tco2 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 E tco2 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 E tco2 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 E tco2 levels 6.48 (95% CI, 1.06-39.54). Conclusions We observed a significant association between E tco2 concentration and in-hospital mortality in emergency department patients with suspected sepsis across a range of disease severity.