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Clinical evaluation of measuring the ACT during elective cardiac surgery with two different devices

Clinical evaluation of measuring the ACT during elective cardiac surgery with two different devices
Clinical evaluation of measuring the ACT during elective cardiac surgery with two different devices

Unfractionated heparin is the mainstay of anticoagulation during cardiac surgery on cardiopulmonary bypass (CPB) due to its low cost, quick onset, and ease of reversal. Since over 30 years, the activated clotting time (ACT) has been used to assess the level of heparin activity both before and after CPB. We compared two different methods of measuring the ACT: i-STAT, which uses amperometric detection of thrombin cleavage, and Hemochron Jr, which is based on detecting viscoelastic changes in blood. We included 402 patients from three institutions (Papworth Hospital, Cambridge, UK; Groote Schuur, Cape Town, South Africa; University Hospital Basel, Basel, Switzerland) undergoing elective cardiac surgery on CPB in our study. We analyzed duplicate samples on both devices at all standard measuring points during the procedure. The correlation coefficient between two Hemochron and two i-STAT devices was .9165 and .9857, respectively. The within-subject coefficient of variation (WSCV) ranged from 8.2 to 13.6% for the Hemochron and from 4.1 to 9.1% for the i-STAT. We found that the number of occasions where one of the duplicate readings was >1,000 seconds while the other was below or close to the clinically significant threshold of 400 seconds were higher for the Hemochron. We found the i-STAT to systematically return higher measurements. We conclude that the i-STAT provides a more reliable test for heparin activity and assesses safe anticoagulation during cardiac surgery on pump. The fact the that the i-STAT reads higher than the Hemochron leads to the recommendation to validate the methods against each other before changing devices.

activated clotting time (ACT), anticoagulation, cardiopulmonary bypass, method comparison
0022-1058
38-43
Falter, Florian
6a80b563-e2e7-4649-b195-e181c5c3c450
Razzaq, Nabeel
a150b4b5-f1d8-478f-8bf6-b2ee773ad44f
John, Martin
03096ee3-dc3c-45f9-82a4-3dc6fb3eef55
Fassl, Jens
7c1c977c-1122-4ee9-b593-7b04ffddd579
Maurer, Markus
718c4204-4e06-41d3-a7fb-0c66adc6bf4c
Ewing, Sean
326656df-c0f0-44a1-b64f-8fe9578ca18a
Hofmeyr, Ross
bd24ef69-f0e4-4f8e-bafb-27f21ce60392
Falter, Florian
6a80b563-e2e7-4649-b195-e181c5c3c450
Razzaq, Nabeel
a150b4b5-f1d8-478f-8bf6-b2ee773ad44f
John, Martin
03096ee3-dc3c-45f9-82a4-3dc6fb3eef55
Fassl, Jens
7c1c977c-1122-4ee9-b593-7b04ffddd579
Maurer, Markus
718c4204-4e06-41d3-a7fb-0c66adc6bf4c
Ewing, Sean
326656df-c0f0-44a1-b64f-8fe9578ca18a
Hofmeyr, Ross
bd24ef69-f0e4-4f8e-bafb-27f21ce60392

Falter, Florian, Razzaq, Nabeel, John, Martin, Fassl, Jens, Maurer, Markus, Ewing, Sean and Hofmeyr, Ross (2018) Clinical evaluation of measuring the ACT during elective cardiac surgery with two different devices. The Journal of ExtraCorporeal Technology, 50 (1), 38-43.

Record type: Article

Abstract

Unfractionated heparin is the mainstay of anticoagulation during cardiac surgery on cardiopulmonary bypass (CPB) due to its low cost, quick onset, and ease of reversal. Since over 30 years, the activated clotting time (ACT) has been used to assess the level of heparin activity both before and after CPB. We compared two different methods of measuring the ACT: i-STAT, which uses amperometric detection of thrombin cleavage, and Hemochron Jr, which is based on detecting viscoelastic changes in blood. We included 402 patients from three institutions (Papworth Hospital, Cambridge, UK; Groote Schuur, Cape Town, South Africa; University Hospital Basel, Basel, Switzerland) undergoing elective cardiac surgery on CPB in our study. We analyzed duplicate samples on both devices at all standard measuring points during the procedure. The correlation coefficient between two Hemochron and two i-STAT devices was .9165 and .9857, respectively. The within-subject coefficient of variation (WSCV) ranged from 8.2 to 13.6% for the Hemochron and from 4.1 to 9.1% for the i-STAT. We found that the number of occasions where one of the duplicate readings was >1,000 seconds while the other was below or close to the clinically significant threshold of 400 seconds were higher for the Hemochron. We found the i-STAT to systematically return higher measurements. We conclude that the i-STAT provides a more reliable test for heparin activity and assesses safe anticoagulation during cardiac surgery on pump. The fact the that the i-STAT reads higher than the Hemochron leads to the recommendation to validate the methods against each other before changing devices.

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More information

Accepted/In Press date: 23 October 2017
e-pub ahead of print date: 26 June 2018
Keywords: activated clotting time (ACT), anticoagulation, cardiopulmonary bypass, method comparison

Identifiers

Local EPrints ID: 424947
URI: https://eprints.soton.ac.uk/id/eprint/424947
ISSN: 0022-1058
PURE UUID: 811c7f6a-cbfb-42b3-bdb4-caed9ecd80cc
ORCID for Sean Ewing: ORCID iD orcid.org/0000-0001-7214-4917

Catalogue record

Date deposited: 05 Oct 2018 16:30
Last modified: 14 Mar 2019 01:38

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