Effects of heparin, haemodilution and aprotinin on kaolin-based activated clotting time: in vitro comparison of two different point of care devices.
BACKGROUND
During cardiopulmonary bypass (CPB), measurement of kaolin-based activated clotting time (kACT) is a standard practice in monitoring heparin-induced anticoagulation. Despite the fact that the kACT test from the Sonoclot Analyzer (SkACT) has been commercially available for several years, no published data on the performance of SkACT are available. Thus, the aim of this in vitro study was to compare SkACT with an established kACT from Hemochron (HkACT).


METHODS
Blood was withdrawn from 25 patients before elective cardiac surgery. SkACT and HkACT were measured in duplicate after in vitro administration of heparin (0, 1, 2 and 3 U/ml), calcium-free lactated Ringer's solution (25% and 50% haemodilution) and aprotinin (200 kIU/ml).


RESULTS
A total of 600 duplicate kACT measurements were obtained from 25 cardiac surgery patients. Overall, mean bias +/- SD between SkACT and HkACT was 7 +/- 70 s (1.3% +/- 14.1%). Administration of heparin, haemodilution and aprotinin induced a comparable effect on both activated clotting time (ACT) tests. Mean bias ranged from -4 +/- 39 s (-1.7% +/- 12.9%) to 4 +/- 78 s (3.2% +/- 15.6%) for heparinzed blood samples after haemodilution or aprotinin application and increased after combined aprotinin administration and haemodilution. After haemodilution and administration of aprotinin, both ACT tests were less reliable for values >480 s in heparinized blood samples.


CONCLUSIONS
Accuracy and performance of SkACT and HkACT were comparable after in vitro administration of heparin, aprotinin and haemodilution. Both ACT tests were considerably affected by aprotinin and haemodilution.
Institute of Anaesthesiology and Intensive Care Medicine, Triemli City Hospital Zurich, Zurich, Switzerland.
S
S
Dalbert
M T
MT
Ganter
L
L
Furrer
R
R
Klaghofer
A
A
Zollinger
C K
CK
Hofer
D000925:Anticoagulants / Q000494:pharmacology*; D007611:Aprotinin / Q000494:pharmacology*; D001780:Blood Coagulation Tests / Q000295:instrumentation*; D006348:Cardiac Surgical Procedures; D006438:Hemodilution; D006490:Hemostatics / Q000494:pharmacology*; D006493:Heparin / Q000494:pharmacology*; D006801:Humans; D066298:In Vitro Techniques; D007552:Isotonic Solutions / Q000008:administration & dosage; D007616:Kaolin / Q000494:pharmacology*; D019095:Point-of-Care Systems; D000077325:Ringer's Lactate; D014914:Whole Blood Coagulation Time
D000925:Anticoagulants; D006490:Hemostatics; D007552:Isotonic Solutions; D000077325:Ringer's Lactate; D007616:Kaolin; D006493:Heparin; D007611:Aprotinin