Heparin Levels and Activated Clotting Time (ACT) during Open Heart Surgery

Abstract

Heparin levels were followed by an amidolytic method during open heart surgery in 10 adult patients and correlated to the activated clotting time (ACT) (Haemochron®). There was a good correlation between the 2 parameters when the ACT was below 600 s. Based on the present and previous studies of the ACT the authors conclude that the ACT is a useful tool in control of heparinization during open heart surgery.

Pharmacokinetic/pharmacodynamic model for unfractionated heparin dosing during cardiopulmonary bypass

“…However, in some clinical situations (such as heparin resistance, haemodilution, and hypothermia) ACT is of more limited value, and discrepancies between heparin dose, heparin effect, and heparin concentration have been observed. [6][7][8][9] Although many other devices are available to assess individual heparin sensitivity, ACT remains the most commonly used functional test.…”

Evaluation of the Hemochron 8000 Rx/Dx System for Heparin Management

“…In addition, other variable factors have been implicated as well, such as the platelet count ( 11 ), hypothermia (12,13) and hemodilution (12)(13)(14)(15). Stenbjerg and associates however, did not see any changes with hemodilution in their study (16). The ACT machine itself has been shown to have variations ranging from 10% (17,18) to 25% (19,20), indicating that there may be a need for two samples to be drawn each time.…”

“…The ACT machine itself has been shown to have variations ranging from 10% (17,18) to 25% (19,20), indicating that there may be a need for two samples to be drawn each time. The technique used by the perfusionist may cause the results to vary as well, which would include the time of the sampling (pre vs. post skin incision) (21 ), the amount of time the heparin is allowed to circulate (22), manual vs. automated (I 0), the site where the sample is drawn from (13,14,16), and the technique used to shake the tube (20). All of these factors indicate the need for a standardized technique during each case.…”