Why is my Patient Bleeding? A Snapshot of Hemostasis


To view source article and take the Quiz- click on image above ūüôā

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FA 2016

Editor’s Note:

Having just finished a case where we used Angiomax as our heparin substitute, I felt that the anticoagulation pathway, is truly a complex animal, and deserves a closer review.

We have all revisted this pathway intensively throughout our careers, and of course, we have all been clinically challenged by open-heart cases that test our fundamental understanding of coagulation theory in real time, at a level that certainly reflects a fairly deep dive into esoteric hematology.

So i am keeping it simple, and found information from two sites, that in my opinion transforms the complex picture of a picture like this, by MC Escher


Into something a little more clinically palatable such as¬†this¬†¬†Salvador Dali Painting…


I hope I haven’t offended any art critics out there ūüôā

Part 2 comes out tomorrow.

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Preview Flashcards


Front                                                          Back
What is Factor I and what pathway?
Fibrinogen, Final Common Pathway
What is Factor II and IIa and? what pathway
Prothrombin and Thrombin, Final Common pathway
What is Factor III and what pathway?
Thromboplastin, Extrinsic Pathway
What is Factor IV and what pathway?
Calcium, Extrinsic Pathway
What is Factor V and what pathway?
Proaccelerin, Final Common Pathway
What is Factor VI and what pathway?
Trick Question, there is no factor VI
What is Factor VII and what pathway?
Proconvertin, Extrinsic Pathway
What is Factor VIII and what pathway?
VIII c is antihemophilic factor, VIIIvWF is Von Willenbrand’s pathway. It is part of the Intrinsic Pathway
What is Factor IX and what pathway?
Christmas Factor, Intrinsic Pathway
What is Factor X and what pathway?
Stuart Power Factor, Final Common pathway
What is Factor XI and what pathway?
Plasma Thromboplastin Antecedent, Intrinsic pathway.
What is Factor XII and what pathway?
Hageman Factor, intrinsic Pathway
What is Factor XIII and what pathway?
Fibrin Stabilizing Factor, Final Common Pathway.
Which Factors are K dependent?
2, 7, 9, 10
What assesses Heparinization? What are the normal values? What value do you want with adequate anticoagulation?
PTT, ACT. Normal is PTT 24-35, ACT 80-150. For adequate anticoagulation you want ACT 400-450.
What assesses Coumadin and what are the normal values?
PT and INR. Normal is PT 12-14 seconds, and INR is normally 1.
What pathway does Heparin affect?
Interferes with the Intrinsic and final common pathway.
What is normal Platelet count. What is the minimum to get an epidural.
normal is 150-400,000. minimum for epidural is 100,000
What is normal bleeding time?
3-10 minutes
What is normal Thrombin Time and what does it assess?
Normal Thrombin Time is 12-20 seconds. It assesses the final common pathway.
What pathway does Coumadin affect?
It affects the Extrinsic and Final Common Pathway.
How does Heparin work?
It enhances antithrombin III.
Why do we transfuse RBCs
To increase the oxygen carrying capacity of the blood.
What is the average lifespan of a platelet?
8-12 days
What is involved in platelet adhesion?
vWF (factor 8), it is made in the endothelial cells and attaches platelets to damaged endothelium
what is the most common inherited coagulation defect?
vWF defect
What are the treatments in order for vWF defect?
1st DDAVP – relies on endogenous vWF. 2nd Cryoprecipitate – contains VIII and I. 3rd factor VIII concentrate
What happens in platelet activation?
Thrombin (factor 2a) attaches to its receptor and causes platelets to change shape and release thromboxane A2 and ADP.
What happens in platelet aggregation?
Thromboxane A2 and ADP uncover fibrinogen receptors which bind fibrinogen (factor 1) and link platelets together.
How do Aspirin and NSAIDS interfere with clot formation?
They interfere with platelet aggregation by blocking the COX pathway so Thromboxane A2 isn’t produced. Aspirin is 8-12 days, NSAIDS last 24-48 hrs
What is the most common acquired platelet disorder?
Aspirin or NSAIDS
How is Fibrin Produced?
After platelet aggregation, Thrombin (IIa) produces Fibrin at the site of injury, crosslinks platelets requiring factor XIII.
How do we remember the Extrinsic pathway, and what triggers it?
4 37 cents you can buy the extrinsic pathway. Thromboplastin and factor VII. Initiated w/ damage to the outside of the blood vessel.
How do we remember the intrinsic pathway and what triggers it?
It is initiated w/ damage to the inside of the vessel.
How do we remember the final common pathway?
What reverses Heparin?
What is the primary physiologic initiator of coagulation?
Thromboplastin (factor III)
Where is thromboplastin synthesized.
Synthesized in endothelial cells.
Hemophilia A – what is it and what is treatment?
Factor VIII:c deficency. Txt with FFP and Cryoprecipitate 1st or with pooled VIII concentrate.
Hemophilia B – what is it and what is the treatment?
It is a deficiency of factor IX (christmas factor). Txt is with factor IX concentrate.
What is the best measurement of platelet function and what are the normal values?
Bleeding time, normally 3-10 minutes
What causes DIC? What are the signs and symptoms?
Sepsis, shock, ischemia. Bleeding from surgical sites, all clotting factors down, platelets down, end fibrin split products elevated.
What does FFP Contain?
All pro-coagulants except platelets. Still need to be activated by the liver.
What does cryoprecipitate contain?
Factor VIII (vWF), I (fibrinogen), and XIII (fibrin stabilizing factor.
What is antithrombin III and how does it work?
Made in liver, neutralizes Thrombin (IIa) and X, IX, XI, and XII. Binds Thrombin and X most. Enhanced by heparin 1000x
Why would a patient not respond to Heparin?
Lack of Antithrombin III. Heparin requires antithrombin III in order to enhance its action. Txt w/ FFP as long as you have a working liver.
What does Plasmin do?
It breaks down fibrin, made as plasminogen in the liver.
How is plasminogen activated?
TPA and UPA convert plasminogen to plasmin, which binds fibrin within a clot and dissolves it.
What is TPA?
Has high affinity to fibrin. Converts plasminogen to plasmin. Is made by endothelial cells. Is stimulated by thrombin and venous stasis.
what is UPA and Streptokinase?
Both have less affinity for fibrin, UPA is found in limited quantities in the blood. Streptokinase is produced by B hemolytic step.
What is Aprotinin
antifibrinolytic agent, inhibits plasmin, slows fibrin breakdown by preventing plasmin binding. used to prevent bleeds in cardiac surgery
What is Amicar
prevents fibrin breakdown by preventing plasmin from attaching to fibrin. Controls hemorrhage w/ fibrinolysis from too much plasminogen activation.
What factors are produced by endothelial cells?
vWF (VIII), TPA, Thromboplastin (III)
What is the order of platelet function?
Adhesion (vWF), Activation (Thrombin), Aggregation (Thromboxane A2 and ADP), Fibrin Production (Thrombin and Intrinsic, Extrinsic, and Final Common Pathways)

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