Kaolin-Based Activated Coagulation Time Measured by Sonoclot in Patients Undergoing Cardiopulmonary Bypass

Ganter, Michael T.; Monn, Antoinette; Tavakoli, Reza; Klaghofer, Richard; Zollinger, Andreas; Hofer, Christoph K.

doi:10.1053/j.jvca.2006.12.012

« Previous Next »Journal of Cardiothoracic and Vascular Anesthesia
Volume 21, Issue 4 , Pages 524-528, August 2007

Kaolin-Based Activated Coagulation Time Measured by Sonoclot in Patients Undergoing Cardiopulmonary Bypass

Presented in part at the annual meeting of the Swiss Society of Anesthesiologists, Fribourg, Switzerland, November 5-6, 2004.

Michael T. Ganter, MD, DEAA
- Department of Anesthesia and Perioperative Care, University of California San Francisco, San Francisco, CA
- Address reprint requests to Michael T. Ganter, MD, DEAA, Department of Anesthesia and Perioperative Care, San Francisco General Hospital, UCSF, 1001 Potrero Avenue, Room 3C-38, San Francisco, CA 94110.
Antoinette Monn, BS
- Institute of Hematology and Oncology, Triemli City Hospital, Zurich, Switzerland
Reza Tavakoli, MD
- Division of Cardiac Surgery, Triemli City Hospital, Zurich, Switzerland
Richard Klaghofer, PhD
- Department of Psychosocial Medicine, University Hospital, Zurich, Switzerland.
Andreas Zollinger, MD
- Institute of Anesthesiology and Intensive Care Medicine, Triemli City Hospital, Zurich, Switzerland
Christoph K. Hofer, MD, DEAA
- Institute of Anesthesiology and Intensive Care Medicine, Triemli City Hospital, Zurich, Switzerland

published online 15 March 2007.

Objectives: In vivo data for the kaolin-based ACT test from the Sonoclot Analyzer (SkACT, Sienco Inc, Arvada, CO) are lacking. The aim of this study was to compare SkACT with an established kaolin-based ACT from Hemochron (HkACT) and anti-Xa activity in patients undergoing cardiopulmonary bypass (CPB).

Design: Prospective observational study.

Setting: Community hospital.

Participants: Fifty patients scheduled for elective cardiac surgery.

Interventions: Blood samples were taken before CPB at baseline (T0) and after heparinization (T1 and T2), on CPB after administration of aprotinin (5, 15, 30, 60 minutes; T3-T6), and at the end after protamine infusion (T7).

Measurements and Main Results: A total of 375 blood samples were analyzed. ACT measurements were comparable for SkACT and HkACT at each measurement time point. Overall bias ± standard deviation between SkACT and HkACT was −19 ± 75 seconds (−2.4% ± 11.7%). Mean bias between SkACT and HkACT at each time point ranged from −35 to 3 seconds (−4.5% to 2.6%) and showed no statistical significance over time. Heparin sensitivity of SkACT and HkACT, defined as (ACT_Tx-ACT_T0)/(anti-Xa_Tx-anti-Xa_T0), significantly increased for measurements during CPB (p < 0.001) but without significant difference between the 2 methods. Test variability was comparable for both ACT measurement techniques. Overall test variability was 7.5% ± 7.4% for SkACT and 7.8% ± 11% for HkACT.

Conclusions: Accuracy and performance of SkACT and HkACT were comparable for heparin monitoring in patients undergoing CPB for elective cardiac surgery. However, both tests were affected significantly after initiating CPB and aprotinin infusion.

Key Words: activated coagulation time, kaolin, anticoagulation, heparin, blood coagulation, Sonoclot analysis, cardiopulmonary bypass