PB0659 - Filtration of heparin during preparation of a cardiopulmonary bypass circuit priming solution for infants.

Monday, June 24, 2024

13:45 – 14:45 ICT

Room: Exhibition Hall

Presenting Author(s)

PD

Paul G. Davies, BM FANZCA FCICM

Consultant Anaesthetist
The Royal Children's Hospital, Melbourne
Parkville, Victoria, Australia

Co-Author(s)

NL

Natasha Letunica

Research Associate
Haematology Research, Murdoch Children's Research Institute
Melbourne, Victoria, Australia
SV

Suelyn Van Den Helm

PhD Student
Department of Paediatrics, The University of Melbourne
Melbourne, Victoria, Australia
SM

Shannon Morrison

Consultant Anaesthetist
Queensland Children's Hospital, Brisbane
Brisbane, Queensland, Australia
BD

Ben Davies

Cardiac Surgeon
The Royal Children's Hospital, Melbourne
Melbourne, Victoria, Australia
IK

Igor Konstantinov

Cardiac Surgeon
The Royal Children's Hospital, Melbourne
Melbourne, Victoria, Australia
SH

Stephen Horton

Director of Perfusion
The Royal Children's Hospital, Melbourne
Melbourne, Victoria, Australia
SB

Stephen Bottrell

Perfusionist
The Royal Children's Hospital
Melbourne, Victoria, Australia
GB

Georgia Brown

Intensive Care Physician
The Royal Children's Hospital
Melbourne, Victoria, Australia
AD

Andrew Davidson

Consultant Anaesthetist
The Royal Children's Hospital, Melbourne
Melbourne, Victoria, Australia
PM

Paul Monagle

Head of Haematology Research
Murdoch Children's Research Institute
Melbourne, Victoria, Australia
CA

Chantal Attard

Senior Research Officer, Haematology Research
Murdoch Children's Research Institute
Melbourne, Victoria, Australia

Background: Cardiopulmonary bypass (CPB) in infants can be associated with bleeding, leading to increased exposure to blood products. Excessive heparinisation can contribute to bleeding in these patients.

CPB circuits for infants at The Royal Children’s Hospital, Melbourne, are primed with 1000 ml fluid containing packed red cells, albumin and 3000 IU heparin, haemofiltered to 550 ml final volume. For patients under 3 kg, the prime includes FFP and 4000 IU heparin.

Heparin, with molecular weight 3000 – 30000 Daltons (Da), is assumed to be freely filtered by a 60000 Da haemofilter, so heparin concentration in both prime and filtrate is assumed to be equal.

Aims: To investigate whether heparin is freely filtered during preparation of an infant CPB priming solution.

Methods: The study was approved by the RCH Ethics Committee (HREC74533). Written informed consent was obtained from parents/guardians. Funding was from the National Blood Authority and the McDonald Family.

Seventeen (81%) circuits prepared as above contained 3000 IU heparin (3 IU/ml). Four (19%) contained FFP and 4000 IU heparin (4 IU/ml).

After filtration of the prime, filtrate samples were stored at –80oC for batch testing.

Filtrate samples were spiked with Pool Norm plasma (Diagnostica Stago, France) at ratio 1:3 to ensure sufficient antithrombin for maximal heparin detection.

Heparin was measured using STA- Liquid Anti Xa on a STA-R Max ® analyser (Diagnostica Stago, France).

Results: Average heparin in the filtrate of standard prime was 0.98 IU/ml (SD 0.31 IU/ml). With FFP it was 0.44 IU/ml (SD 0.23 IU/ml).

Conclusion(s): Filtering the prime removed less heparin than expected. FFP in the prime led to even less heparin removal. This may reflect increasing degrees of heparin binding to plasma proteins.

Therefore, heparin concentrations when commencing CPB are likely higher than previously assumed.

Impacts of continuous and modified ultrafiltration on heparin concentrations should be investigated.