480 seconds

The Cardiopulmonary Bypass begins with values greater than 450 seconds. it is always advisable to maintain ACT values above 500 when the body temperature is physiological and when using the cardioplegic warm blood. The risk of thrombin activation is lower.

We initiate cardiopulmonary bypass when ACT has passed 400 secondsv and is still running. I agree levels >500 are adviceable when temparture is physiologic as referred above

I am perfectly in agreement to have more than 500

420 secs but perfusionists and anaesthetist almost always over anticoagulate and is usually in the 480-500 range. I use warm plegia at 34deg.

There is no consensus on the optimal ACT and it depends on several factors. The rationale for the classical values of 400 to 500 s is difficult to find in the literature. In the early days of CPB the dose of heparin was established empirically – the dose being the minimum with which clotting in the extracorporeal circuit did not occur. The minimum safe ACT was in the region of 300 seconds based upon observations. At that time CPB circuits and bubble oxygenators were likely to be far less biocompatible than recent disposable components. Therefore, while a vast majority of centers, still use classical level for ACT (400 s to 500 s) some centers use low ACT (>250 s) with closed coated circuit, and observed decrease in post-operative bleeding without any drawback. ACT is prolonged during hypothermia, but you must remember that the measure is performed on a heated blood sample. During warm surgery, heparin catabolism is higher than during hypothermia but there is no reason to increase the ACT.

Once again, I must agree with Yves Durandy. There is no evidence for using any ACT-level, whatsoever. I could use the old adagio: "We need more RCT's!", but who is going to 'under-anticoagulate' his patients.

We initiate CPB when ACT > 400 s, but perfusionists always add 5000U heparin in prime solution while priming CPB circuits, because we don't have heparin-coated tubes. Thus it isn't uncommon that ACT goes up over 500 s during CPB. 

We initiate CBP when ACT is > 400 s, and we add 10.000 Units of heparin in the prime solution. Before I start bypass I also look at the AT III level of the patients actual blood analysis

We initiate CPB when ACT>480 sec with an ATIII in normal range.

480 sec

We prime the CPB circuit with 10000 IU Heparin. After administration of 350IU/kg (300-400) Heparin i.v. we initiate CPB when ACT is about 480 sec. If the dosage of Heparin exceeds 400IU/kg we consider to administer Antithrombin 500-1000 IU

480 seconds

More than 480 seconds

More than 400 and the test continues to increase

480