Prognostic value of combined venoarterial carbon dioxide to arteriovenous oxygen content ratio and lactate measurements in patients with severe trauma: A prospective observational study

Abstract Background Trauma remains a significant global health burden, with complex pathophysiological processes necessitating accurate and timely markers for risk assessment. Objective This study investigated the prognostic value of combining the venoarterial carbon dioxide to arteriovenous oxygen content ratio (Pv‐aCO 2 /Ca‐vO 2 ) with lactate measurements in patients with severe trauma. Methods This single‐center prospective observational study involved 60 adults with an Injury Severity Score of ≥16 from October 2023 to November 2024. Blood gas parameters and clinical data were collected within 3 h of intensive care unit admission. The primary outcome was 28‐day mortality. Results Twenty‐nine patients died during the study period. Nonsurvivors had significantly higher Pv‐aCO 2 /Ca‐vO 2 (median, 2.78 vs. 2.13; p = 0.003) and lactate levels (median, 5.20 vs. 2.70 mmol/L; p = 0.001) than survivors. Multivariate Cox regression analysis identified Pv‐aCO 2 /Ca‐vO 2 as an independent predictor of mortality (hazard ratio: 1.297; 95% confidence interval: 1.021–1.647; and p = 0.033). The combined indicator demonstrated superior prognostic performance (area under the curve [AUC] = 0.768) over individual parameters (Pv‐aCO 2 /Ca‐vO 2 : AUC = 0.713 and lactate: AUC = 0.729). A moderate positive correlation was observed between Pv‐aCO 2 /Ca‐vO 2 and lactate ( r = 0.456 and p = 0.0002). Conclusions The combination of Pv‐aCO 2 /Ca‐vO 2 and the lactate level provides enhanced prognostic value in patients with severe trauma. This approach may improve risk stratification and guide clinical decision‐making in trauma care.