PROCOAGULANTS AND ANTIFIBRYNOLYTICS Flashcards
PROTAMINE BINDS TO HEPARIN IN A _ RATIO
1:1
Protamine by itself is an anticoagulant: it decreases thrombin generation by inhibiting
FACTOR V
Why is protamine given in a 1.3:1 ratio
Protamine is eliminated rapidly from the plasma (faster than heparin)
protamine half life
under 5 minutes compared to heparin half life of 1-2 hours
what causes increased bleeding after normal act
Free” heparin released from the protamine:heparin complex?
- Heparin’s variable half-life outlives protamine’s ~2 hour clinical effect?
- Heparin from tissue stores?
- Too much “reversal” protamine given (and given, and given, and given…)
- Some data suggests heparin rebound may not really occur at all (Prolene deficiency?
protamine bolus is inferior
to small calculate doses
protamine is a component oF NPH so
increased reactions in patients on NPH
PROTAMINE OTHER USES WITH LMWH
Only partially/unpredictably reverses LMWH. (which sort of limits LMWH’s use.)
*Protamine has no effect on fondaparinux
rotamine
Precautions & Problems
1) Protamine is an anticoagulant. -You will find many older perfusionists
have forgotten that! #2) Protamine reactions
-You WILL encounter these during your careers (and Mr. Hoerr will discuss them with you at length…)
Contributing Factors to Protamine Reactions
- Rapid administration, Sensitization to Protamine (it carries a Black Box warning)
- Redo Surgeries (patients who have had protamine)-Fish allergies -Diabetics (why?)(protamine in NPH) -Vasectomy (why?) -”Excessive” dosage (
PROTAMINE REACTIONS MANIFEST THEMSELVES
as anaphylaxis &/- extreme hypotension, pulmonary hypotension, and cardiovascular collapse.
• Often necessitates “crashing” back on CPB. *Minimized by:
-Slow administration
-Intra-aortic administration (why?)
-Administration with steroids and antihistamines.
VITAMIN K
Vitamin K is to Warfarin as protamine is to heparin (a little, sort of, OK, not really…maybe a little?)
• A fat soluble vitamin essential for the production of Factors II, VII, IX, & X.
• Remember, this is a classic “Boards” question!
TWO TYPES OF VITAMIN K
1) K1: Phytonadione (Mephyton) VEGETABLES INJECTION SUPPS. 2) K2: Menaquinone (MEAT POULTRY EGGS AND BUTTER)
How, what, and why does Vitamin K play a huge part in patient management & survivability ON A VAD???
vitamin K helps to prevent bleeding
k dosage for warfarin overdose
- 0-2.0 mg of K1 is given by injection for warfarin overdosage.
- This dose will lower the PT but not completely eliminate the desirable warfarin effects.
HOW TO GIVE vitamin K
MUST be given slow IV (anaphylaxis is a common side effect).
• Requires at least six hours to be effective
*So…what do you give to quickly reverse warfarin in a hemorrhagic emergency?
Typical FFP dose for warfarin overactivity is 15ml/kg.
Aminocaproic Acid (EACA) TRANEXAMIC ACID
(AMICAR) (Cyklokapron, Lysteda) Antifibrinolytics. *Both are synthetic derivatives of the amino acid lysine.
*Statistically clinically indistinguishable(SIMILAR EFFICACY), except. TRANEXAMIC ACID IS 10X MORE POTENT THAN AMICAR
Antifibrinolytics MOA
Both drugs prevent plasminogen activation and directly inhibit plasmin which prevents fibrinolysis.
ANTIFIBRINOLYTIC CLEARANCE AND how they are given
Both drugs cleared renally. • Both commonly used in “pump primes”.
how much amicar in prime
5 or 10 grams
Aprotinin
(traysol) serine protease inhibitor. Blocks plasmin and does other ill-defined “stuff” to prevent post-op bleeding
aprotinin bad stuff
kidney failure, strokes, anaphylaxis. may be used for compassionate therapy
Desmopressin MOA
(DDAVP) A synthetic form of Antidiuretic Hormone
(ADH or Vasopressin), a small protein.
• MuchlesspressoractivitythanVasopressin
• Causes the release of von Willebrand’s Factor from vascular endothelium which increases Factor VIII and Factor XII activity.
• Useful for mild Hemophilia A and von Willebrand’s Disease (duh!)
DESMOPRESSIN LAYMANS TERMS
Causes platelets adhesiveness to increase in patients with platelet dysfunction 2° to uremia or hepatic dysfunction.
• Available in many forms including a nasal spray.
***”Evidence-Based Note”: There is NO research that indicates the use of DDAVP for bleeding post-bypass decreases the use of blood products (may be somewhat beneficial when administered in advance.)
FRESH FROZEN PLASMA HOW ITS SEPARATED AND WHEN ITS GIVEN
Plasma (what’s this?) is separated from whole blood and stored at < 0 degrees Fahrenheit within eight hours of donation.
• FFP’s use has skyrocketed…often given “for bleeding” post-bypass.
• Preferably given with ABO cross-matching
• The use of TEG’s and availability of more specific treatments may alter the use-habits of FFP in the future.
FFP HAS FACTORS
-FFP contains Factors I, II, V, VII, IX, X, XI, XIII, AT-III, and proteins C & S…
…but at what concentrations?? VARIABLE
FFP USES
Used for “bleeding”
- Used for immediate warfarin reversals (why? why not Vitamin K?) CUZ ITS IMMEDIATE
- Used for AT-III deficiency (why not AT-III? what’s the dosage?) CHEAPER
- Used with large volumes of PRBC administration (why?) BEVAUSE IT HAS PLASMA
- Used for colloidal volume replacement
**20ml/kg of FFP raises a patient’s AT III levels by
20%
What risks do you think FFP presents?
Dont know if AT3 is present. variable. virus or bacterial contamination
cryoprecipatate comes from and is given
Derived from the precipitate that forms after FFP is thawed and centrifuged.
• Usually given as a “pooled” (4-6 units) product but ABO cross-matching is considered desirable. (A single Cryo unit is virtually never given!)
cryoprecipitate used for
Used for Factor I, VIII, and von Willebrand’s replacement (what’s Factor I?) fibrinogen
• BUT, levels of VIII and VWF are “iffy” and cryoprecipitate is NOT treated in any way whatsoever to decrease the risk of viral exposure!!!
cryoprecipitate unit=
15ml
15ml of cryoprecipitate= how much fibrinogen
15 ml ~ 250-350 mg fibrinogen
