protamine dosage calculations
Submitted by David E. White on Fri, 12/10/2010 - 12:03.
I am interested in hearing from anyone willing to share their protamine dosage calculations. Please include how the dosage is derived and who is responsible in the OR for calculating the dosage.
Hi David,
I asked around here (KGH, Kingston, Ontario) and it seems there are a few different ways the anesthesia team does it.
Some people give a 50% of total heparin dose ( as per Ferraris, 2007 Blood Conservation Guidelines, see attached page 22). So if the total loading dose was 30,000 K of heparin, regardless of what perfusion gives on bypass, they would dose the patient 150mg of protamine.
Others stick to the older regime of 1 mg of protamine per 100 units of heparin sodium.
Others again, will calculate [with a half life (t 1/2) of 90 minutes] each dose of heparin which has been given (loading doses and maintenance doses)...to estimate how much heparin is left on board, and then reverse that amount with the ratio of 1 mg of protamine per 100 units of heparin sodium. This is a more time consuming method, but apparently is most "accurate" for the purists, and will result in less protamine given on average. Dr. John Murkin I am told from LHSC, London, Ontario uses this method as well. I have read that less protamine will result in a decrease in neurological dysfunction post-CPB.
Lastly, I have been told that others give 5cc less protamine than calculated so, 30,000 K would be 250mg of protamine, regardless of what perfusion gave. Unless we gave over 20,000 K and then they would give the whole dose.
So, I am not sure if that is any help at all, but that is what my local poll gave me :)
Good luck!
Maggie