Intraoperative Monitoring of Heparin: Comparison of Activated Coagulation Time and Whole Blood Heparin Measurements by Different Point-of-Care Devices with Heparin Concentration by Laboratory-Performed Plasma Anti-Xa Assay

Abstract

Background Cardiac surgical interventions, extracorporeal membrane oxygenation, transcutaneous coronary-artery angioplasty, and stenting are carried out while patients are being treated with the anticoagulation drug heparin. Monitoring the level and reversal of heparinization during and at the conclusion of medical and surgical procedures is a critical issue in patient care. Methods We performed parallel testing of the ACCRIVA Hemochron Signature Elite ACT+ and Hemochron Response analyzer, iSTAT platform, and 2 Hepcon Hemostasis Management System (HMS) Plus analyzers for monitoring intraoperative heparin treatment. Laboratory anti-Xa assay was used as the criterion standard for heparin measurement. Results Poor correlation between the 2 Hemochron analyzers was identified at 0.78. Correlation between the analyzers on the i-STAT platform was 0.97. Regression analysis revealed that i-STAT values were generally lower, by 43 seconds, than Hemochron values. The correlation between Hepcon and i-STAT activated clotting time (ACT) results was 0.94. The i-STAT ACT results were generally 23 seconds lower than the Hepcon ACT values. Correlation coefficients on comparing Hepcon ACT and i-STAT ACT using laboratory anti-Xa assay were 0.83 and 0.87, respectively. The correlation between Hepcon heparin concentration and anti-Xa results was 0.85. Conclusions ACT monitoring with iSTAT offers good correlation between instruments and with the Hepcon ACT. Hepcon occupies a specific niche in cardiac operating departments because of its ability to provide additional information regarding heparin concentration; however, lack of suitable proficiency testing may impair its use. The iSTAT is a more reliable platform for broader, hospital-wide application.

Anticoagulation Monitoring for Perioperative Physicians

“…Reported correlation coefficients of heparinized samples between different devices generally range between 0.7 and 0.9, with differences up to 70 s as the level of anticoagulation increases. [29][30][31] It is therefore not surprising that target activated clotting time values for initiating cardiopulmonary bypass (CPB) can vary from fewer than 350 s to more than 500 s among cardiac surgical centers. 32 Nevertheless, since other coagulation tests such as the PTT become unclottable with high levels of systemic heparinization, the activated clotting time is the de facto anticoagulation monitor during the conduct of CPB.…”

Hemostatic Testing in Critically Ill Infants and Children

“…This practice does not account for the primarily anti-IIa action of UFH potentially introducing a degree of uncertainty regarding the extrapolated therapeutic threshold (132,133). ACT is the preferred monitoring test for UFH given during cardiopulmonary bypass surgery with "therapeutic" (i.e., desired) values being surgeon and device specific (134,135).…”

Reference interval, longitudinal variability and reliability of activated clotting time in healthy dogs using a point‐of‐care analyser

“…ACT assays were initially performed by manually mixing fresh noncoagulated whole blood in a test tube with a contact activator such as diatomaceous earth or kaolin at 37 • C. ACT was defined as the time duration in seconds between contact activation and visual clot formation (Byars et al, 1976;Middleton & Watson, 1978). Contemporary point-of-care (POC) analysers automate the detection of fibrin formation using mechanical or photo-optical sensors, which has improved practicality and measurement accuracy (Thompson et al, 2019). One of the latest ACT assays available on the market as POC analyser, the i-STAT 1 (Abbott Point-of-Care, Wavre, Belgium), uses an amperometric sensor to detect an alternative test endpoint, namely an electrochemical change that occurs during thrombin cleavage in the sample.…”