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

BACKGROUND

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.

METHODS

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.

RESULTS

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.

CONCLUSIONS

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.