Impact of post-filter ionized calcium target range on circuit survival and citrate-related complications in pediatric continuous kidney replacement therapy.

BACKGROUND

Regional citrate anticoagulation (RCA) is the preferred strategy for continuous kidney replacement therapy in children; however, the optimal post-filter ionized calcium target remains uncertain. Lower targets may increase anticoagulation but raise citrate exposure and metabolic complications. We aimed to compare anticoagulation efficacy and metabolic safety between a low-target (0.25-0.35 mmol/L) and a high-target (0.30-0.40 mmol/L) post-filter ionized calcium protocol in critically ill children.

METHODS

This retrospective cohort study included critically ill children receiving continuous veno-venous hemodiafiltration with citrate as the pre-filter anticoagulation solution at a tertiary pediatric intensive care unit over a 4-year period. A total of 87 patients (42 low-target, 45 high-target) and 154 circuits (71 versus 83) were analyzed. The primary outcome was circuit survival (CS). Secondary outcomes included citrate dose, citrate load, and RCA-related complications. Continuous variables were analyzed using the Mann-Whitney U test, and CS was assessed with Cox regression. Linear mixed models evaluated citrate changes, and generalized estimating equations analyzed metabolic outcomes.

RESULTS

Median CS was comparable between groups (49 versus 48 h, p = 0.76) as was the survival of clotted circuits (41 versus 40 h, p = 0.70) and circuit clotting rates were similar (21.1% versus 24.1%, p = 0.70). The low-target group had higher median citrate dose (2.9 versus 2.6 mmol/L, p < 0.001), citrate load (0.76 versus 0.72 mmol/kg/h, p = 0.03), and more frequent hypocalcemia (17.5% versus 12.9%, p = 0.01), metabolic alkalosis (31.9% versus 22.8%, p < 0.001), and citrate accumulation (24.5% versus 15.4%, p < 0.001). Linear mixed models showed a persistently higher citrate dose and citrate load in the low-target group (all p < 0.001). Generalized estimating equations demonstrated increased odds of hypocalcemia (odds ratio 1.47, p = 0.01) and citrate accumulation (odds ratio 1.93, p < 0.001) in the low-target group.

CONCLUSIONS

Raising the target of post-filter ionized calcium from 0.25-0.35 to 0.30-0.40 mmol/L reduced citrate exposure and metabolic complications without compromising CS.

TRIAL REGISTRATION: Retrospectively registered.