The Anesthesia Record

In studying for my final exam, it occurred to me that I haven't posted a coagulation pathway memory aid that's been passed around our class.  It seems as though we cover the coagulation cascade every semester and, every time it's covered on an exam, I thank my lucky stars for this thing:

1. The top row is “in a line” so it is the “intrinsic” pathway
2. Then pathway through Factor 7 starts from the outside so it is the “extrinsic”
3. The intrinsic pathway is longer so it is measured by PTT, the extrinsic pathway is shorter so it is measured by the PT
4. The extrinsic pathway looks like a gun and guns are used in war so you monitor Warfarin (Coumadin) using the PT (extrinsic pathway function)
5. The gun of the extrinsic pathway is shot using the your “trigger finger” [TF] so the extrinsic pathway is activated by the TF of the body or tissue factor
6. 10 is special so all the factors surrounding 10 (9, 2, 7 and 10 itself) are a little special too—all these factors are Vitamin K dependent (ie require Vit. K to be made)

1. Baby does not receive Vit K shot which factors are decreased?
2. Boy has Hemophilia A.  Which clotting test is prolonged?
3. Girl has Von Willenbrand’s Disease.  When she beings to clot which factor can build up?
4. Old man overdoses on Coumadin.  What do you give to help reverse it and how do you monitor his progress?
5. Which pathway is activated when the vessel is damaged?

1. 2, 7, 9, 10
2. Hemophilia A produces a defect in factor 8.  PTT is prolonged, but PT is normal since it bypasses factor 8
3. vWF is a part of the factor 8 complex.  Factor 9 has the potential to build up since it will not be converted to factor 10.  This is another example where the PT may be normal.
4. Coumadin competively inhibits the production of Vit. K factors so you give large doses of Vit. K.  Monitor with PT
5. Endothelial damage releases TF.  Extrinsic pathway is activated.