Medical Applications

JHL Consultants is a boutique programming group that specialises in developing and maintaining targeted software applications. The Heparin Heuristics app has been in development for a number of years and runs under Microsoft Windows, OSX and iOS (limited version) as well as Android.

This application was written to provide guidance for heparin dosing for cardiac procedures such as catheter ablation for atrial fibrillation. The optimal ACT for ablation procedures is considered to be  ACT of 300 to 400.

The optimal ACT for cardiac surgery is considered to be between 400 and 500.

Unfortunately, there is no accepted standard for the different ACT machines, so they all give different results for the same amount of heparin. In addition, each patient has a different sensitivity to the same heparin concentration, rendering the prediction of the ACT for any individual heparin dose very difficult.

After observing over 1,000 patients with different oral anticoagulant regimes, a heuristic approach has been developed that give a "best guess" as to the appropriate dose to provide the desired ACT for an individual patient, based on the height, weight and sex, as well as the oral anticoagulant they are taking and the pre-heparin ACT.

The initial heparin dose is calculated from the winsorized mean of the slope of the heparin-ACT dose response curve for all patients in a particular subgroup. The application learns as more patients are admitted to the database and moves toward the population mean.

Once pre-heparin and immediate post-heparin ACT results (taken ten minutes after the initial dose of heparin) are entered, the individual patient's heparin:ACT dose-response curve is known and adjustments may be made for subsequent doses. Suggestions are based on the individual patient's response to the initial heparin dose. The dose of protamine required to reverse the active heparin can be estimated from the ACT taken immediately before reversal.

In all cases, it is expected that the clinician will use these values as a guide only, and adjust doses in accordance with their own experience.

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