Antithrombin Dose Optimization in Extracorporeal Membrane Oxygenation in Infants

Area of Science:

• Pediatric Critical Care Medicine
• Hematology
• Pharmacology

Background:

• Anticoagulation is critical during extracorporeal membrane oxygenation (ECMO) but challenging due to thrombotic risks.
• Unfractionated heparin (UFH) relies on antithrombin (AT) for anticoagulation.
• AT deficiency is prevalent in infants on ECMO, necessitating AT concentrate replacement, yet dosing guidelines are scarce.

Purpose of the Study:

• To evaluate the efficacy of commonly used dosing equations for recombinant AT (ATryn) in infants (<1 year) on ECMO.
• To determine the correlation between predicted and actual postdose AT levels.
• To identify optimal dosing strategies for AT replacement in this vulnerable population.

Main Methods:

• Retrospective review of 41 infants (<1 year) receiving ATryn during UFH-anticoagulated ECMO (2010-2017).
• Analysis of 102 ATryn doses to assess correlation between predicted and postdose AT levels.
• Comparison of various dosing equations, including weight-based and modified formulas.

Main Results:

• Baseline mean AT level was 43%, with a median increase of 8% post-ATryn administration.
• Weight-based dosing showed poor correlation (r²=0.082) with postdose AT levels.
• An equation incorporating desired AT change, patient weight, and ECMO circuit volume best predicted postdose AT levels (r²=0.427).

Conclusions:

• Existing weight-based dosing equations are inadequate for predicting AT levels in infants on ECMO.
• A more complex dosing formula, accounting for baseline AT, weight, and circuit volume, offers better prediction.
• Prospective studies are essential to establish optimal AT dosing, safety, and efficacy in pediatric ECMO patients.