title: Assessing heparin dosing in neonates on venoarterial extracorporeal membrane oxygenation.
abstract: We studied 12 consecutive neonates placed on venoarterial extracorporeal membrane oxygenation (ECMO) in 2004-2005. Activated clotting times (ACT) and anti-factor Xa levels were measured, and the corresponding heparin drip rate was noted. The mean heparin drip rate was 42.2 +/- 10.9 (SD) U/kg/hour (range 20.0-69.5 U/kg/hour). There were 55 simultaneous ACT and anti-factor Xa samples drawn. The mean ACT was 167 +/- 20 seconds (range 128-227 seconds). There was no correlation between ACT levels and heparin dose (r = 0.21; p = 0.12). The mean anti-factor Xa activities were 0.73 +/- 0.19 U/ml (range 0.1-1.0 U/ml). There was a correlation (r = 0.75; p < 0.0001) between anti-factor Xa and heparin dose. We also examined the effect of day on ECMO on heparin drip rate, ACT, and anti-factor Xa. There was no correlation between day on ECMO and either heparin drip rate (r = 0.21, p = 0.12) or ACT (r = 0.002, p = 0.99). However, there was a positive correlation (r = 0.46, p < 0.0005) between day on ECMO and anti-factor Xa activities. In these neonatal patients on venoarterial ECMO, ACT was not a reliable indicator of heparin effect. Furthermore, the increase in anti-factor Xa levels with time on ECMO suggests that heparin accumulates and/or that anti-thrombin III levels decrease with time on ECMO.
authors.affiliation: Neonatal ECMO Program, Columbus Children's Hospital, Columbus, Ohio, USA.
authors.forename: Craig A
authors.initials: CA
authors.lastname: Nankervis
authors.forename: Thomas J
authors.initials: TJ
authors.lastname: Preston
authors.forename: Kevin C
authors.initials: KC
authors.lastname: Dysart
authors.forename: Whitney D
authors.initials: WD
authors.lastname: Wilkinson
authors.forename: Louis G
authors.initials: LG
authors.lastname: Chicoine
authors.forename: Stephen E
authors.initials: SE
authors.lastname: Welty
authors.forename: Leif D
authors.initials: LD
authors.lastname: Nelin
mesh_terms: D000925:Anticoagulants / Q000008:administration & dosage*; D000990:Antithrombin III / Q000032:analysis; D015199:Extracorporeal Membrane Oxygenation; D006493:Heparin / Q000008:administration & dosage*; D006801:Humans; D007231:Infant, Newborn; D016014:Linear Models; D014914:Whole Blood Coagulation Time
chemical_list: D000925:Anticoagulants; D000990:Antithrombin III; D006493:Heparin