The activated clotting time in cardiac surgery: should Celite or kaolin be used?
Adrianus J De Vries1, Annemieke Oude Lansink-Hartgring2, Freek-Jan Fernhout3
1Department of Anesthesiology, University Medical Center Groningen, University of Groningen, Groningen, Netherlands.
Insights
Kaolin and Celite activated clotting times (ACT) guide anticoagulation during cardiopulmonary bypass. While clinically similar, these ACT methods are not interchangeable due to significant differences in precision and bias.
Area of Science:
- Cardiovascular Surgery
- Hematology
- Anesthesiology
Background:
- Activated clotting time (ACT) tests, using kaolin or Celite activators, are crucial for monitoring anticoagulation during cardiopulmonary bypass.
- The interchangeability of kaolin- and Celite-based ACT methods in clinical practice remains unclear, particularly regarding their impact on anticoagulation management.
- Understanding potential biases, precision, and variability between these ACT methods is essential for ensuring patient safety and optimal anticoagulation.
Purpose of the Study:
- To compare the clinical management of anticoagulation guided by kaolin- versus Celite-activated clotting times (ACT) during cardiopulmonary bypass.
- To evaluate the bias, precision, and variability between kaolin and Celite ACT methods in guiding heparin administration.
- To determine if kaolin and Celite ACT methods are interchangeable for anticoagulation management in patients undergoing cardiac surgery.
Main Methods:
- A randomized trial involving 97 patients undergoing coronary artery bypass grafting or aortic valve replacement.
- Patients were assigned to either kaolin- or Celite-guided anticoagulation, with simultaneous ACT measurements using both methods.
- Heparin was administered based on ACT values, with a predefined protocol for initial dosing and supplemental doses.
Main Results:
- No significant differences were observed in total heparin dose or number of supplements between kaolin- and Celite-guided groups.
- Postoperative outcomes, including thrombin generation, fibrinolytic response, blood loss, and transfusion requirements, were similar between groups.
- Significant differences were found in individual patient supplemental heparin needs (P = 0.002), baseline bias (+10.3% Celite higher), and coefficient of variation (2.6 times larger for kaolin, P < 0.001).
Conclusions:
- Clinical management of anticoagulation guided by kaolin and Celite ACT methods is comparable during cardiopulmonary bypass.
- Despite similar clinical outcomes, the kaolin and Celite ACT methods are not interchangeable due to significant differences in precision and bias.
- The choice of ACT method can influence individual heparin dosing adjustments, highlighting the need for careful interpretation of results.
Objectives:
Both kaolin- and Celite-activated clotting times (ACT) are used to guide anticoagulation during cardiopulmonary bypass. It is unknown whether these methods lead to similar management procedures for anticoagulation in patients and are thus interchangeable in terms of bias, precision and variability.
Methods:
We randomized 97 patients undergoing coronary artery bypass grafting or aortic valve replacement to either kaolin- or Celite-guided anticoagulation. The ACT was measured simultaneously with the other method. We administered 300 IU/kg heparin to obtain initial ACT values greater than 400 s and additional heparin in each group using the minimum value of duplicate measurements according to a predefined protocol. The primary end point was the total heparin dose and the number of heparin supplements.
Results:
The total heparin dose per patient in the 48 Celite-guided patients was 35 271 ± 12 406 IU with 51 supplements and in the 49 kaolin-guided patients, 35 997 ± 11 540 IU ( P = 0.77) with 56 supplements ( P = 0.53). Postoperative thrombin generation time, fibrinolytic response time, chest tube loss and transfusion requirements were not different between the two groups. However, the methods differed in individual patients with regard to supplemental heparin ( P = 0.002). Bias between methods at baseline was +10.3%, Celite being higher, and changed to a value of -12.9% at 2 h bypass. The coefficient of variation at baseline for individual patients was 2.6 times larger with kaolin than with Celite ( P < 0.001). Correlation between ACT values at baseline was only 45%.
Conclusions:
Kaolin- and Celite-guided management of anticoagulation is clinically not different, but the methods are not interchangeable.
Clinical Registration Number:
www.trialregister.nl identifier 1738.
