Een vergelijking van twee meetmethoden voor de mate van ontstolling gedurende cardiopulmonale bypass tijdens hartchirurgie.

Rationale:

During cardiac surgery a sufficient anticoagulation is necessary for the period of cardiopulmonary bypass (CPB). Heparin is used for this purpose. Anticoagulation is point of care monitored using the activated clotting time (ACT) as described by Bull [1]. As activator for this measurement either celite or kaolin is used. Both activators are used routinely in clinical practice. In this hospital both measurements are also used. However, there is doubt about the consequences of heparin management using these measurements. Moreover, a review of patient charts suggests that kaolin ACT has less variability than celite ACT.

Objective:

In this study we will therefore measure total heparin use and the concentration of fibrinopeptide A at the end of CPB, using either celite ACT or kaolin ACT guided heparin management. In addidtion clinical parameters as chest tube loss, blood use, and length of stay in the intensive care unit will be measured. We propose this study also to compare duplicate measurements of celite ACT with duplicate measurements of kaolin ACT in patients undergoing cardiac surgery.

Study design:
Prospective randomized clinical trial.

Study population:
Patients presenting for cabg and/or valve reair/replacement. Excluded are patients with heredetary coagulopathies, patients pre-operatively treated with unfractionated heparin, patients less than 18 years old.

Intervention:
Group one: heparin management for CPB is guided by celite ACT.

Group two: heparin management for CPB is guided by kaolinACT.

Main study parameters/endpoints:
Primary: the total amount of heparin given in each group.
Secondary: Fibrinopeptide A concentration; postoperative chest tube loss, use of blood and blood products, and length of stay in the intensive care unit.

We recently found that the longterm use of aspirin resulted in lower celite-ACT during cardiopulmonary bypass (CPB). The ACT is routinely measured in duplicate. A review of patient charts suggests that kaolin-ACT has less variability than celite ACT. We hypothesize that kaolin guided ACT management results in less heparin use.

After induction of anesthesia baseline ACT is measured. Heparin is given before CPB as usual (300IU/kg). After 3 min ACT is measured as usual. If ACT<400s addiitonal heparin (100IU/kg) is given. 5 min after start CPB and then after every 30 min ACT is measured as usual. If ACT<400s addiitonal heparin (100IU/kg) is given according to our clinical practice. After CPB the heparin is neutralized with protamine in a 1:1 ratio as usual.

Group one: heparin management is guided by celite-ACT.

Group two: heparin management is guided by kaolin-ACT.


To measure the actual heparin concentration a duplicate HiTT (high dose thrombin time) measurement will also be perfomed (3mL).

Additional measurements:

1. Preoperative and postoperative antithrombin-3 (3mL);

2. End cpb fibrinopeptide a (3mL);

3. Postoperative chest tube loss;

4. Use of blood and bloodproducts;

5. Length of stay in the ICU.