Le lun, 09 avr 2012 09:59:15, Koski, Greg,M.D. a ploppé:
> Hello, David. I am a cardiac anesthesiologist who needs a simple
> way to calculate accurately the residual heparin in the circulation
> at any time after an initial loading dose and a fixed continuous
> infusion. Heparin is essentially confined to the circulation and
> eliminated with an effective half like of about 1 hour. We
> administer a loading dose of 3.5 mg/kg at time zero and start an
> infusion of 1 mg/kg/hg. We generally stop the infusion at about 2.5
> to 3 hours and need to know how much heparin is remaining assuming
> a simple one compartment first-order kinetic model so that we can
> calculate how much protamine is needed to reverse the remaining
> heparin.
The quantity remaining will be something like:
Dt = (Dini + (Ir x Tinf)) / (2 x t)
With
Dt: the dose remaining at time t (in mg)
Dini: the initial dose (in mg)
Ir: the infusion rate (in mg/h)
t: the time since time zero, in hours
Tinf: the time of infusion, in hours (=t before the end of the infusion;
= 2.5 to 3 hours after the end of the infusion)
This formula should work at any time (including before the end of the
infusion). That's assuming a half-life of 1 hr.
--
PiLS
