Related Experiment Video
Updated: May 19, 2026
In Vitro Thrombosis Test for Ventricular Assist Devices
Published on: March 21, 2025
Activated partial thromboplastin time is a better trending tool in pediatric extracorporeal membrane oxygenation
Timothy M Maul1, Erin L Wolff, Bradley A Kuch
1Department of Cardiothoracic Surgery, Children's Hospital of Pittsburgh of University of Pittsburgh Medical Center, Pittsburgh, PA, USA.
Insights
Activated clotting time is inaccurate for heparin management in pediatric extracorporeal membrane oxygenation (ECMO). Clinical laboratory activated partial thromboplastin time is superior, reducing bleeding complications and mortality risk in ECMO patients.
Area of Science:
- Pediatric Critical Care Medicine
- Cardiovascular Surgery
- Hematology
Background:
- Heparin anticoagulation is crucial for pediatric extracorporeal membrane oxygenation (ECMO).
- Accurate monitoring of anticoagulation is essential to prevent thrombotic and hemorrhagic complications.
- Activated clotting time (ACT) and activated partial thromboplastin time (aPTT) are commonly used but their efficacy in pediatric ECMO is debated.
Purpose of the Study:
- To compare the efficacy of activated clotting time (ACT) versus activated partial thromboplastin time (aPTT) for heparin management in pediatric ECMO.
- To determine if clinical laboratory aPTT or point-of-care aPTT is a more reliable indicator of heparinization.
- To assess the impact of different coagulation monitoring strategies on patient outcomes.
Main Methods:
- Single-center retrospective analysis of pediatric patients (<21 years) on ECMO.
- Collected data included point-of-care and clinical laboratory ACT and aPTT values, heparin dosage, and patient outcomes.
- Statistical analyses included Spearman's correlations and hazard analysis to compare monitoring methods and outcomes.
Main Results:
- Clinical laboratory aPTT correlated with heparin dosage (ρ = 0.40), while ACT did not (ρ = -0.04).
- Point-of-care aPTT correlated well with clinical laboratory aPTT (ρ = 0.76) but were not interchangeable.
- Management with clinical laboratory aPTT significantly reduced bleeding complications (associated with increased mortality) and circuit clotting.
Conclusions:
- Activated clotting time is not a reliable tool for heparin management in pediatric ECMO.
- Clinical laboratory activated partial thromboplastin time is a more effective monitoring method, reducing bleeding complications and associated mortality.
- Point-of-care aPTT is a reliable correlate of laboratory aPTT but not a substitute for it.
Objectives:
To determine whether activated partial thromboplastin times are a better heparin management tool than activated clotting times in pediatric extracorporeal membrane oxygenation.
Design:
A single-center retrospective analysis of perfusion and patient records.
Setting:
Academic pediatric tertiary care center.
Patients:
Pediatric patients (<21 yrs old) requiring extracorporeal membrane oxygenation support initiated at Children's Hospital of Pittsburgh.
Interventions:
None.
Measurements And Main Results:
Point-of-care activated clotting time and activated partial thromboplastin time values, clinical laboratory activated partial thromboplastin time values, weight-normalized heparin administration (units/kg/hr), and reported outcomes were collected for pediatric patients treated for cardiac and/or respiratory failure with extracorporeal membrane oxygenation. Spearman's ranked correlations were performed for each coagulation test compared to heparin dosage. The Bland-Altman test was used to determine the validity of the point-of-care activated partial thromboplastin time. Hazard analysis was conducted for outcomes and complications for patients whose heparin management was based on the clinical laboratory activated partial thromboplastin time or the activated clotting time. Only the clinical laboratory activated partial thromboplastin time showed a correlation (ρ = 0.40 vs. ρ = -0.04 for activated clotting time) with the heparin administration (units/kg/hr). Point-of-care activated partial thromboplastin time and activated partial thromboplastin time values correlated well (ρ = 0.76), with <5% of samples showing a difference outside 2 SDs, but differences in their absolute values (Δactivated partial thromboplastin time = 100 secs) preclude them from being interchangeable measures. Furthermore, despite no effective change in the mean activated clotting time, cardiac patients showed a significantly improved correlation to heparin dose for all coagulation tests (e.g., point-of-care activated partial thromboplastin time ρ = 0.60). Management of patients with the clinical laboratory activated partial thromboplastin time did not significantly affect patient survival rates but did significantly reduce bleeding complications and significantly increased clotting in the extracorporeal membrane oxygenation circuit. A hazard analysis demonstrated that bleeding complications were associated with an increased risk of mortality, whereas clotting complications in the extracorporeal membrane oxygenation circuit were not.
Conclusions:
The activated clotting time is not an accurate monitoring tool for heparin management in pediatricextracorporeal membrane oxygenation. The point-of-care activated partial thromboplastin time correlates well with the clinical laboratory activated partial thromboplastin time but cannot be substituted for the clinical laboratory activated partial thromboplastin time values. Management of pediatric extracorporeal membrane oxygenation patients with the clinical laboratory activated partial thromboplastin time reduced bleeding complications which are associated with increases in mortality.
