Treatment of Acute Circulatory Failure Based on Carbon Dioxide-Oxygen (CO₂-O₂) Derived Indices: The Lactel Randomized Multicenter Study.

Abstract

Acute circulatory failure is critical in patients in the ICU. Indices derived from oxygen and CO₂ metabolism (CO₂-O₂-derived indices) including the central venous-to-arterial CO₂ difference and central venous-to-arterial CO₂ difference/arteriovenous oxygen content ratio are markers for global metabolic demand and tissue hypoxia. Does a resuscitation strategy using CO₂-O₂-derived indices improve tissular hypoperfusion compared with standard care? We conducted a randomized, prospective, multicenter, single-anonymized study in 3 ICUs. Patients aged ≥ 18 years with acute circulatory failure and arterial blood lactate levels ≥ 3 mM were included. Patients were randomized to receive either a CO₂-O₂-derived algorithm-based treatment or standard clinical practice. The primary outcome was lactate clearance > 10% within 2 hours. Secondary outcomes included Sepsis-Related Organ Failure Assessment score and mortality. Of the 179 patients enrolled (90 control patients and 89 treatment patients), there was no significant difference in achieving a lactate clearance > 10% at 2 hours between the control (50%) and interventional groups (43.8%) (P = .497). At t2 hours, the median change in lactate levels in the control group was -10.53% (-29.27 to 5.68), whereas in the interventional group, it was -2.70% (-22.58 to 19.1; P = .096). Secondary outcomes did not differ between groups in Sepsis-Related Organ Failure Assessment scores (6 [3 to 9] vs 7 [4 to 10]; P = .719), ICU and hospital length of stay (4.5 days [2.0 to 10.8] vs 5.0 days [2.0 to10.0]; P = .963 and 11 days [3.0 to 27.0] vs 10 days [3.0 to 21.0]; P = .493), or 28-day mortality (44.9% vs 33.3%, P = .150). Our results indicate that algorithm-based resuscitation using CO₂-O₂-derived indices did not improve lactate clearance or clinical outcomes compared with standard care. Further research is needed to identify specific patient subgroups who may benefit from this approach. ClinicalTrials.gov; No.: NCT05032521; URL: www. gov.