1. Reasons to want a shorter heparin drip time while bridging to warfarin
- HIT (white clot syndrome) - worse than other drug-induced thrombocytopenia because HIT makes you hypercoagulable-- you shower platelet fragments everywhere and clot. Typically appears on day 5 or 10 when you start heparin (assuming no recent exposure to heparin/HIT)
- Pragmatic reasons (prevent coumadin hostages)
2. Reasons to want a longer heparin drip while bridging to warfarin 
- Patient has increased risk of warfarin skin necrosis (i.e. protein C deficiency) - get big swaths of soft tissue necrosis
- Remember that just because the INR is 2 doesn't mean you're anticoagulated - factor 7 has a shorter half life and so your INR will change rapidly with coumadin, but 2, 5, and 10 are still high. So when someone comes back 2 days after you just d/c-ed them after 2 days on a heparin drip with a worse clot than they were admitted for, its not failure of coumadin, it's a failure of you properly anticoagulating them.
3. HIT
- HIT doesn't usually drop your platelets <50 - if you have platelets below that its not HIT. Or not just HIT.
- If you diagnose it, the patient is committed to 3 months of anticoagulation even if they didn't clot on it. The data shows a 50% chance of clotting in the first week
- FDA approved anticoagulants for HIT- direct thrombin inhibitors like argatroban and leparudin; factor Xa like fonda and rivaroxaban have been used but are not FDA approved for this purpose.
- PFA-4 - sensitive but not specific. Serotonin release assay - specific, takes a week to do. Don't go randomly sending off PF4-4 in people unless you have a reason to suspect HIT-- if it comes back falsely elevated (which is not uncommon) you've bought them 3 months of anticoagulation, so you don't want to be wrong.
- It's especially bad to be wrong about HIT in people who may need CT surgery-- cardiac surgeons don't want to use anything other than heparin in the bypass circuit, it works, can reverse with protamine before you return the blood to the patient, and so if the patient is carrying a HIT diagnosis then everything gets more complicated. The good news is that there's some data that you can use it during surgery even in people with HIT, and some data that heparin is OK 3-6 months after HIT but you'd rather not have to go there.
4. Blood s/p centrifugation: 
- Plasma
- Buffy coat (bottom of plasma) = platelets, should not have any red cells, which is important, this means you don't have to cross-match platelets.
- Red cells
If you spin down plasma in the cold you get cryoprecipiate
5. Platelets 
- A "six pack" of platelets- buffy coat from 6 different donors, pooled into one bag.
- More commonly, one donor will get platelet pharesis to pull a lot of platelets from one guy
6. Plasma
- FFP has all factors
- Cryo is rich in factor 8, vWF, and fibrinogen (good for DIC)
- Prothrombin factor concentrate: designed to reverse warfarin, so rich in factors 2, 7, 9, 10.
7. T+S vs T+C
- Screen: run recipient plasma against a few red cells of known antigenicity
- If its positive, you run a panel - trying to identify what the antibody that the patient is reacting against.
- Crossmatch - Indirect coombs-- looking for antibodies in the serum of the recipient that will react with the donor cells
8. Treatments for hemophilia: 
- Hemophilia A (factor 8 deficiency): Recombinant factor 8: #units/kg * 2 = % rise in factor (So to go from 0 to 80% factor 8, then you'll need 40 U/kg)
- Hemophilia B (factor 9 deficiency) Prothrombin factor concentrate (contains 2, 7, 9, and 10)
9. Transfusion reaction
- Immediate: Wrong type-- circulating anti-A or anti-B antibodies immediately attack transfused blood. Complement, cytokine release, anaphylaxis. maybe ATN, maybe death.
- Delayed: people can develop new antibodies against blood. Not life threatening (no anaphylaxis, ATN, etc). Person is fine, then a few days later, Hb drops because they've developed new antibodies.
10. Platelet transfusion: 
- Theoretically: 1 unit = 5,000-10,000 bump. But the more times you've been transfused, the less of a bump you get due to antibodies. Big spleen = you will also get less of a bump.
- "Pooled platelets are random donor platelet concentrates obtained from units of whole blood that are pooled at the time of transfusion. Single donor platelets are collected by apheresis using a cell separator. This technique allows the simultaneous collection of several units of platelets during a single donation. An average single donor platelet collected by apheresis will contain an equivalent of 6-7 units of random donor platelets. The recommended platelet transfusion dose is 1 unit per 10 kilograms of body weight when using random pooled platelets1 or one unit of single donor platelets per transfusion episode. The recommended dose is targeted to elevate the platelet count to adequate hemostatic levels (40,000-50,000/μL). Occasionally ABO antibodies can reduce platelet survival. Clinical factors such as fever, sepsis, splenomegaly, active bleeding, use of amphotericin, veno-occlusive disease, DIC, early post hematopoietic stem cell transplant period and some dialysis procedures are associated with decreased survival of transfused platelets2,3,4.  Immune refractoriness, caused by allo- or auto-antibodies with specificities to the HLA or rarely, HPA antigens, can also complicate platelet transfusion support2,3,4." {source: institute for transfusion medicine}