Treatment of Acute Circulatory Failure Based on CO-O-Derived Indices: the Lactel randomized multicentre study.

Background: Acute circulatory failure is critical in ICU patients. CO-O-derived indices including the central venous-to-arterial CO difference (P(v-a)CO gap) and the P(v-a)CO gap/Ca-vO ratio are markers for global metabolic demand and tissue hypoxia.

Research Question: Does a resuscitation strategy using CO-O-derived indices improve tissular hypoperfusion compared to standard care?

Study Design And Methods: We conducted a randomized, prospective, multicenter, single-blind study in three ICUs. Patients aged 18 years or older with acute circulatory failure and arterial blood lactate levels ≥ 3 mmol/L were included. Patients were randomized to receive either a CO-O-derived algorithm-based treatment or standard clinical practice. The primary outcome was lactate clearance >10% within 2 hours. Secondary outcomes include SOFA, mortality.

Results: Of the 179 patients enrolled (90 control, 89 treatment), there was no significant difference in achieving a lactate clearance over 10% at two hours between the control (50%) and interventional groups (43.8%), p=0.497. At 2 hours, the median change in lactate levels in the control group was -10.53% [-29.27; 5.68] while in the interventional group, it was -2.70% [-22.58; 19.1], p=0.096. Secondary outcomes did not differ between groups in SOFA scores (6 [3;9] vs 7 [4;10], p=0.719), ICU and hospital length of stay (4.5 days [2.0;10.8] vs 5.0 [2.0;10.0], p=0.963 and 11 days [3.0;27.0] vs 10 [3.0;21.0], p=0.493), or 28-day mortality (44.9% vs 33.3%, p=0.150).

Interpretation: Algorithm-based resuscitation using CO-O-derived indices did not improve lactate clearance or clinical outcomes compared to standard care. Further research needed to identify specific patient subgroups who may benefit from this approach.