Standard vs. carbone dioxide adapted kidney replacement therapy in hypercapnic ARDS patients: a randomized controlled pilot trial (BigBIC)

 

by Julius Valentin Kunz, Helena Hansmann, Mareike Fähndrich, Mareen Pigorsch, Nicole Bethke, Harm Peters, Anne Krüger, Tim Schroeder, Florian Marcy, Abakar Magomedov, Holger Müller-Redetzky, Kai-Uwe Eckardt, Dmytro Khadzhynov and Philipp Enghard 

 

Critical Care volume 28, Article number: 198. Published: 11 June 2024

 

Background

Current continuous kidney replacement therapy (CKRT) protocols ignore physiological renal compensation for hypercapnia. This study aimed to explore feasibility, safety, and clinical benefits of pCO2-adapted CKRT for hypercapnic acute respiratory distress syndrome (ARDS) patients with indication for CKRT.

Methods

We enrolled mechanically ventilated hypercapnic ARDS patients (pCO2 > 7.33 kPa) receiving regional citrate anticoagulation (RCA) based CKRT in a prospective, randomized-controlled pilot-study across five intensive care units at the Charité—Universitätsmedizin Berlin, Germany. Patients were randomly assigned 1:1 to the control group with bicarbonate targeted to 24 mmol/l or pCO2-adapted-CKRT with target bicarbonate corresponding to physiological renal compensation. Study duration was six days. Primary outcome was bicarbonate after 72 h. Secondary endpoints included safety and clinical endpoints. Endpoints were assessed in all patients receiving treatment.

Results

From September 2021 to May 2023 40 patients (80% male) were enrolled. 19 patients were randomized to the control group, 21 patients were randomized to pCO2-adapted-CKRT. Five patients were excluded before receiving treatment: three in the control group (consent withdrawal, lack of inclusion criteria fulfillment (n = 2)) and two in the intervention group (lack of inclusion criteria fulfillment, sudden unexpected death) and were therefore not included in the analysis. Median plasma bicarbonate 72 h after randomization was significantly higher in the intervention group (30.70 mmol/l (IQR 29.48; 31.93)) than in the control group (26.40 mmol/l (IQR 25.63; 26.88); p < 0.0001). More patients in the intervention group received lung protective ventilation defined as tidal volume < 8 ml/kg predicted body weight. Thirty-day mortality was 10/16 (63%) in the control group vs. 8/19 (42%) in the intervention group (p = 0.26).

Conclusion

Tailoring CKRT to physiological renal compensation of respiratory acidosis appears feasible and safe with the potential to improve patient care in hypercapnic ARDS.