Serum total carbon dioxide as a prognostic factor for 28-day mortality in patients with sepsis

Abstract

Objective: Metabolic acidosis is commonly associated with the disease severity in patients with sepsis or septic shock. This study was performed to investigate the association between serum total carbon dioxide (TCO₂₎ concentration and 28-day mortality in patients with sepsis.

Methods: This study was a multicenter retrospective cohort study of patients with sepsis or septic shock. The relationships between serum TCO₂ and 28-day mortality, bicarbonate, pH, lactate, and anion gap were determined with cubic spline curves. The patients were divided into four groups according to their serum TCO₂ concentration: Group I (TCO₂ > 20 mmol/l), Group II (15 < TCO₂ ≤ 20 mg/dl), Group III (10 < TCO₂ ≤ 15 mmol/l), and Group IV (TCO₂ ≤ 10 mmol/l).

Results: A total of 3168 patients were included in the analysis, and the overall mortality rate was 24.1%. Serum TCO₂ concentrations below 20 mmol/l showed an almost linear correlation with mortality as well as with lactate, bicarbonate, and pH. The 28-day mortality rates of Group I, II, III, and IV were 18.3%, 23.6%, 32.6%, and 50.0%, respectively (p < .001). In Multivariable Cox proportional hazard regression analysis, the groups with lower serum TCO₂ concentrations had a higher risk of 28-day mortality compared with Group I: Group II (Hazard ratio (HR), 1.35; 95% confidence interval (CI), 1.11-1.64), Group III (HR, 1.74; 95% CI, 1.37-2.21), and Group IV (HR, 2.72; 95% CI, 2.03-3.64).

Conclusions: Serum TCO₂ concentrations of 20 mmol/l or less were associated with 28-day mortality in patients with sepsis.

Keywords: Acidosis; Carbon dioxide; Mortality; Prognosis; Sepsis.