In this observational study a comparison is made between two different monitors for measurement of the activated clotting time (ACT): mechanical versus biochemical techniques

The ACT is a functional test influenced by multiple factors, such as platelet function, coagulation factors, temperature and contact activation inhibitors. Results produced by different monitors are also prone to vary influenced by the specific method employed to perform the test.

The present clinical study aims to compare two types of ACT monitors: the Hemostatic Management System Plus (Medtronic) and i-STAT (Abbott) in 20 cardiac surgical patients by performing five intraoperative consecutive measurements using anti factor Xa as a reference for the actual heparin concentration.

Inclusion criteria comprised patients aged 20-80 years, scheduled for coronary bypass surgery.

Measurements: 1) before induction of anaesthesia 2 ) after heparin bolus 3) rewarming of the patient 4) weaning from cardiopulmonary bypass 5) after protamine administration.

The Hemostatic System Plus ACT monitor served as reference for dosing of heparin in all patients. The study protocol did not intervene with the standard protocol used for anticoagulation. No patient interventions were made.

It is hypothesised that the i-STAT ACT monitor has a better correlation with the actual heparin concentration than the Hemostatic Management System Plus

Inclusion Criteria: Patients listed for coronary bypass surgery, -

Exclusion Criteria: Primary coagulation disorder, diabetes mellitus, ongoing anti-coagulation therapy, emergency, reduced kidney function, allergy for fish, sea food and protamine

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Patients admitted for routine coronary bypass surgery with the use of cardiopulmonary bypass