Citrate anticoagulation in continuous venovenous hemodiafiltration: a metabolic challenge

Feasibility and safety evaluation of regional citrate anticoagulation (RCA) versus systemic heparinization for continuous venovenous hemodiafiltration.

Combined retrospective and prospective observational study performed in a secondary multidisciplinary intensive care unit of the Ospedale Civico Lugano Switzerland.

Twelve hemodynamically unstable patients (median APACHE II score 26, interquartile range 22-29) in whom heparin was judged to be at least temporarily contraindicated. A switch from RCA (predilution setting; same iso-osmotic replacement and dialysis fluid) to heparinization or vice versa was recommended for the final evaluation; 56 dialyzers were used for RCA (1,400 h) and 39 for heparinization (1,271 h).

Median dialyzer life span was 24.2 h (interquartile range 17.4-42.3) for RCA and 42.5 h (20.6-69.1) for heparinization. Fluid control and dialysis quality were similar in the two groups and required no additional intervention. The risk of significant hypocalcemia and metabolic alkalosis was higher at the beginning of the RCA program and decreased with the further training of the staff. Seven bleeding episodes occurred with heparinization vs. three in RCA.

RCA may be a safe and useful form of anticoagulation which is more expensive than heparinization but helps to minimize bleeding risk. The risk of metabolic complications is higher at the beginning of a new RCA program. For centers lacking experienced staff we suggest reserving this technique for patients with rapid clotting of the extracorporeal circuit if treated without anticoagulation.