First clinical experience with citrate-anticoagulated CVVHD-based low-flow ECCO₂R in severe hypercapnic respiratory...

Hypercapnic respiratory failure is a frequent and life-threatening condition in intensive care. While lung-protective ventilation is essential to limit ventilator-induced lung injury, it may aggravate hypercapnia, particularly in severely ill patients. Low-flow extracorporeal CO₂ removal (ECCO₂R) has therefore been proposed as an adjunct to facilitate CO₂ clearance and support protective ventilation. When integrated into continuous renal replacement therapy (CRRT) platforms, ECCO₂R offers a less invasive alternative to high-flow extracorporeal support. However, the effectiveness of CRRT-based ECCO₂R operated at very low blood flows, particularly under regional citrate anticoagulation, remains insufficiently characterized.

We conducted a retrospective analysis of invasively ventilated ICU patients with severe hypercapnic respiratory failure treated with low-flow ECCO₂R integrated into a citrate-anticoagulated CRRT system. Arterial blood gas parameters and ventilatory settings were retrospectively extracted at baseline and 2, 12, and 48 h after ECCO₂R initiation.

In 11 patients, median PaCO₂ decreased from 83.1 to 52.9 mmHg at 48 h, with a corresponding rise in pH from 7.21 to 7.33 (both p = 0.008). Tidal volume showed early pairwise changes, whereas overall ventilator settings and oxygenation remained unchanged. The system was feasible, required no systemic anticoagulation, and caused no coagulation-related complications.

In invasively ventilated patients with severe hypercapnic respiratory failure, low-flow ECCO₂R integrated into citrate-anticoagulated CRRT reduced PaCO₂ and improved acidosis, without significant overall changes in ventilator settings. This first report of exclusive regional citrate anticoagulation in CRRT-based ECCO₂R demonstrated feasibility and safety without coagulation complications. Despite a blood-flow limit of 200 ml/min, a statistically significant and clinically detectable reduction in PaCO₂ was achieved.