1. Adult Heparin gtt protocol: Initiation
- DO NOT START heparin for 24 hours after a patient gets tPA for an ischemic stroke.
- Baseline labs: PT, PTT, CBC, BMP (within 24 h of initiating therapy)
- Discontinue: other anticoagulants, aspirin > 162 mg, IM injections
2. Adult heparin gtt protocol: exclusion criteria
- Epidural catheter
- Platelets <50, PTT higher than whatever your goal PTT would be
- TTP, HIT (Not DIC - you can treat thrombotic DIC with heparin actually)
- High bleeding risk or current bleed
3. Dosing of heparin depends on body weight and indication. See chart:

4. Titration and monitoring of Heparin depends on goal PTT. Below is a sample titration algorithm:

5. Heparin titration patterns for other goal PTTs, depending on bleed risk: 

6. Bridging to warfarin: 

- Need to overlap 5 days AND have INR to goal 

- Can start warfarin the same time you start heparin for most people 

7. Goal INR and duration of anticoagulation depending on indication:

- A-fib, stroke, antiphospholipid syndrome, mechanical aortic valve: INR 2-3, FOREVER 

- Antiphospholipid syndrome with multiple clots through anticoagulation, mechanical mitral valve: INR 2.5-3.5 forever 

- Bioprosthetic heart valve: INR 2-3, 3 months. 

- First time DVT or PE provoked by time-limited risk factors (surgery, temporary immobilization, trauma, estrogen use) - INR 2-3 for 3 months, then stop. 

- First time DVT/PE that is unprovoked, INR 2-3 for 3 months, then reassess bleed risk-- if their bleed risk is high, stop; if their bleed risk is low, continue forever. 

- Multiple DVT/PE: INR 2-3 for the rest of their life. 

- All the above refer to proximal DVTs-- distal DVTs just get 3 months of therapy then stop. 

8. Lovenox & heparin & antithrombin 

- Both lovenox and heparin are able to bind Antithrombin, and antithrombin is capable of inhibiting thrombin (factor II) AND factor Xa. Heparin binding will accelerate activity of antithrombin against factor II/Xa by a factor of 1000. 

- However lovenox, because of its shorter tail, is only able to accelerate the activity antithrombin against factor Xa. So it's much more of a Xa inhibitor than a factor II inhibitor. 

- So you can check levels of both heparin and lovenox with anti-Xa levels. 

9. Pharmacokinetics: 

- Lovenox: Half life 3-6 hours after subQ injection. 

- Lovenox: Anti-Xa levels peak 3-5 hours after dosing. 

- Lovenox renally cleared, standard dose 40 for GFR>60, 30 for GFR 30-60, <30, pick a different anticoagulant, or be careful. 

- Heparin: half life depends on dose! Clearance is a combination of a fast (saturable) non-linear mechanism and a slow, first-order (non-saturable) mechanism. The fast phase -- binding to endothelial cells and macrophages, where it is depolymerized. The slow phase is renal. At IV doses of <25 U/kg (i.e. when we'll almost always be using it) it's mostly degraded through the fast mechanism, and the apparent half life is 30 minutes. At IV doses of 100 U/kg, the apparent half life is 60 minutes, and at IV doses of 400 U/kg, the apparent half life increases to 150 minutes. {source: Circulation} 

10. More data for heparin dosing depending on indication: {source} 

- DVT/PE prophy: 5000 U sq TID

- DVT/PE tx: 80 u/kg bolus, 18 u/kg/hr drip

- Catheter patency aka Heparin lock IV: 100units/mL, enough fluid to fill lumen 

- STEMI: 60 u/kg bolus (max 4000), 12 u/kg/hr drip (max 1000). goal PTT 50-70

- NSTEMI/unstable angina: 60-70 u/kg bolus (max 5000), 12-15 u/kg/hr (max 1000), goal PTT 50-70.