Outline

1. Management of the Bleeding PatientDr. Alan Tinmouth, MD, MScUniversity of Ottawa Centre for Transfusion ResearchDirector, Adult Regional Hemophilia and Bleeding Disorders Clinic

2. Outline • Overview of hemostasis • Review common coagulation tests • “Coagulopathy Poker”

3. Breakdown of Hemostasis Processes • Primary hemostasis • Platelets form temporary hemostatic plug at site of injury • Secondary hemostasis • Coagulation proteins form insoluble fibrin clot at site of initial platelet plug III. Fibrinolysis • Fibrinolytic proteins breakdown fibrin clot after endothelial repair is completed

4. Overview of Hemostasis

5. Primary Hemostasis: Platelets • Adhesion • Platelet glycoprotein Ib/V/IX adheres to subendothelium  binding is primarily to vWF • Activation • Shape change formation of pseudopods • Anionic phospholipids (phospatidylserine and phosphoethanolamine) exposed on external membrane • Glycoprotein IIb/IIIa exposed on surface • Secretion of platelet granules • Aggregation • Platelets bind to each other via Gp IIb/IIIa receptor and soluble fibrinogen and vWF  FORMATION OF HEMOSTATIC PLUG

6. Platelet Adhesion and Activation

7. Platelet Aggregation

8. Current Model of Coagulation Cascade • Initiation Phase • Exposure of factor VIIa to tissue factor (TF) on subendothelial cell starts coagulation cascade and leads to initial thrombin generation (thrombin “burst”) • Amplification Phase • Small amount of thrombin then activates platelets and other coagulation factors (factor V, VIII and XI) • Propagation Phase • Large amounts of thrombin produced on surface of platelets • Thrombin converts fibrinogen to fibrin (fibrin deposition) which is cross-linked to form stable thrombus (clot)  Formation of stable thrombus allows for endothelial repair

9. Tissue factor is spark initiating coagulation factor cascade Exposed TF activates factor VII Factor VIIa:TF activates (i) Factor VII* VIIa (ii) Factor X* Xa (iii) Factor IX* IXa Factor Xa with Va generates a small amount of thrombin II Xa IIa Initiation Phase X TF VIIa Va TF-Bearing Cell TF VIIa IX IXa * Vitamin K dependent clotting factors

10. II IIa Amplification Phase • Factor VIIa:TF inactivated by Tissue Factor Pathway Inhibitor (TFPI):Factor Xa complex • Thrombin* (II) generated on TF-bearing cell activates platelets and coagulation factors (V, VIII*, XI) VIII/vWF TFPI Xa Xa TF VIIa VIIIa Va TF-Bearing Cell XI XIa V Va Platelet VIIIa Va XIa Activated Platelet * Vitamin K dependent clotting factors

11. Activated platelets serve as phospholipid platform for generation of large amounts of thrombin Factor IXa with VIIIa (+ Ca2+) forms tenase which activates factor X* Factor Xa with Va (+ Ca2+) forms prothrombinasewhich produces large thrombin burst Thrombin then generates fibrin and fibrin clot Propagation Phase TF-Bearing Cell TF VIIa IX II IXa X Xa IIa VIIIa IXa Va XIa Activated Platelet IX

12. Formation of Fibrin Clot: Fibrin Deposition • Thrombin binds to fibrinogen and forms fibrin • Cleaves fibrinopeptide A and B to leave fibrin monomer • Thrombin activates factor XIII to XIIIa, • Factor XIIIa catalyzes cross-linking of fibrin monomers to produce stable clot IIa IIa

13. Fibrinolysis • Fibrin clots are temporary scaffolding that allow for cellular wound healing • Dissolution of clots needed to maintain vessel patency • Plasmin (converted from plasminogen) is primary agent of fibrinolysis • Fibrinolysis is controlled by • t-PA - Activator of plasminogen • PAI-1 - Inhibitor of plasminogen activation • α2 antiplasmin - Inhibitors of plasmin

14. Fibrinolytic System

15. Principle of Coagulation Tests • Screening tests are based on the addition of thrombogenic stimuli to ex vivo plasma  time to clot generation is used as the end point • Other tests of specific coagulation factors can also be performed Screening Tests: • Prothrombin time (PT) • Commonly reported as International Normalized Ratio (INR) • Activated partial thromboplastin time (aPTT) • Thrombin Time (TT)

16. Coagulation in a test tube aPTT XII XIIa PT XI XIa VIIa VII IX IXa +VIIIa X Xa +Va II IIa Fibrinogen Fibrin TT

17. Coagulopathy Poker

18. One of Kind Prolonged aPTT • Factor Deficiency (VIII, IX, XI, XII) • Inhibitor (factor VIII) • Heparin • Lupus anticoagulant / Antiphospholipid antibody • von Willebrand Disease

19. Three cases of an elevated aPTT Case 1: 68 year old male lower GI bleed & coagulation factor deficiency • INR 0.93 • aPTT 46 sec Case 2: 70 year old with SOB and hemoptysis • INR 1.02 • aPTT 65 Case 3: 51 year old with no bleeding • INR 1.1 • aPTT 120 secs Mild factor VIII deficiency – 5% Antiphospholipid antibody Factor XII deficiency – 1%

20. Evaluation of Prolonged aPTT Repeat aPTT (peripheral) ANTIPHOSPHOLIPID ANTIBODY positive Mixing Study (50:50 mix with normal plasma) correction > 3 secs of normal Antiphoslipid Antibody Testing INHIBITOR negative corrects SPECIFIC INHIBITOR FACTOR DEFICIENCY Individual Factor Levels Factor VIII, IX, XI, XII, vWF Specific Factor Levels and Inhibitor Testing

21. One of Kind Prolonged INR(PT) • Factor Deficiency (VII) • Warfarin • Liver Disease

22. Fresh Frozen Plasma or Frozen Plasma • FFP frozen within 8 hrs of collection • FP frozen within 24 hrs of collection • Contains all coagulation factors • FFP has minimum factor VIII level of 0.7 IU/ml • FP has factor VIII > 0.5 IU/ml • 200-250 mls / unit • Effect may only last 4 hrs (t1/2 of factor VII) Indications: INR / PTT > 1.5 x normal and • Bleeding or • Emergency procedure or operation

23. Fresh Frozen Plasma / Frozen Plasma Dose: • 10-15 ml/kg for bleeding patients • Sufficient to increase all individual coagulation factors by 30% (minimum hemostatic level) Alternatives • Vitamin K • 2 mg will correct INR in 12 -24 hrs • No effect on PTT (factors VIII, IX, XI) • Oral dose more effective than subcutaneous • Intravenous associated with anaphylactic reactions

24. One of Kind Thrombocytopenia • Decreased production • Increased Destruction • ► physiologic consumption • ► immune mediated clearance • Hypersplenism • ► 1/3 of platelets normally in spleen • ► minimum platelet count ~ 50 x 109/l

25. Thrombocytopenia Platelet Dysfunction Congenital Acquired Therapeutic Plat ct < 50x109/L Plat dysfunction Prophylactic Prior to invasive procedures Plat ct < 50-100x109/L Prevent spontaneous bleeding Plat ct  10x109/L Indications for Platelet Transfusions

26. Platelet Dysfunction Congenital • Bernard-Soulier Syndrome (GP Ib/IX) ► abnormal adhesion • Glanzmann Thrombasthenia (GP IIb/IIIa) ► abnormal aggregation • Gray Platelet Syndrome (α granule deficiency) ► abnormal secondary aggregation • δ storage pool density ► abnormal secondary aggregation

27. Platelet Dysfunction Acquired • Renal Failure • Cardiopulmonary Bypass • Myoproliferative Disorders • Drugs ► ASA ► NSAIDs ► Ticlopidine

28. Contraindications to Platelet Transfusions in Thrombocytopenic Patients • Immune Thrombocytopenic Purpura (ITP) ► Poor platelet recovery ► Only for patients with ongoing bleeding ► IVIG and steroids should be give concurrently • Thrombotic Thrombocytopenic Purpura (TTP / HUS) ► Platelet transfusions may aggravate thrombosis ► Only in life threatening bleeding • Heparin Induced Thrombocytopenia ► Platelet transfusions may aggravate thrombosis ► Only in life threatening bleeding

29. Prophylactic Platelet Transfusion Threshold:Surgical / Invasive Procedures 167 surgical or invasive procedure in 95 patients with acute leukemia • 29 major surgeries • 52 Hickman line insertions Results: • Transfused of pre-op platelet count < 50 x 109/l • 93% no bleeding or minor bleeding • All bleeding episodes easily controlled with further transfusion or pressure dressing Conclusion: • Minimum platelet count of 40 – 50 x 109/l safe Bishop. Am J Hematology 1987; 26: 147

30. Platelet Transfusions - Products Random Donor Platelets • Separated from whole blood donations • Dose = 5 units (250-300 mls) • ABO matched preferable but not mandatory • Increases platelet ct by 5-10 x 109/L per unit Single Donor Platelets • Collected from 1 donor by apheresis • Equivalent to 5-6 random donor platelets • Decrease donor exposure • Can be matched if patient has identified antibodies to platelets (alloimmune platelet refractoriness)

31. 45 year old male (105 kg) with recurrent nose bleeds INR 4.8 aPTT 120 secs Diagnosis: Factor Deficiency (II, V, X) Warfarin overdose Liver Disease Pair

32. Coagulation in a Test Tube XII XIIa XI XIa VIIa VII IX IXa +TF INTRINSIC +VIIIa EXTRINSIC X Xa +Va II IIa Fibrinogen Fibrin COMMON

33. Three of a kind Increased INR, aPTT and decreased Fibrinogen Diagnosis • Fibrinogen deficiency • Liver disease

34. Cryoprecipitate • Precipitate collected from plasma thawed at 40C • 10-15 mls/unit • Contains specific clotting factors from plasma • Factor VIII & von Willebrand’s Factor • Fibrinogen • Factor XIII Indications • Fibrinogen < 1.0 g/L • Dysfibrinogenemia Dose • 1 unit / 5-10 kg body weight (total 8-10 units) • t ½ of 3-5 days

35. Four of a kind Increased INR and PTT Decreased Fibrinogen and Platelets Diagnosis: Liver Disease Massive Transfusion

36. Massive Transfusion • Replacement of blood volume or transfusion 10+ units of RBCs in less than 24 hrs Complications • Thrombocytopenia • Replacement > 1.5 plasma volume* • Coagulopathy • Replacement > 1.5 plasma volume* • Hypothermia • Hypocalcemia/citrate toxicity • Hyperkalemia * May occur earlier in trauma patients

38. Recombinant Factor VIIa • Initiates coagulation by interaction with TF • Only approved for treatment of hemophilia with inhibitors • Treat/prevent bleeding in other patient groups? • Efficacy not proven • Risk of thrombosis? • Primary use is bleeding patients refractory to other treatments • Dose for hemophilia 90 ug/kg q2-3h • Lower dose often effective in other patients 30-40 ug/kg • Vials of 1.2 mg, 2.4mg, 4.8mg • Cost ~ $1000/mg

39. Multicentre RCT of rVIIa in Trauma • 280 pts with blunt or penetrating trauma • All patients receive 3 doses • 200 ug/kg followed by 100ug/kg 1h and 3h later Arrive at ER rVIIa 48h 30d trauma randomize 0 6 8 placebo Units of RBCs 48h 30d Transfusion ICU/Hosp LOS Survival Adverse Events

40. Multicentre RCT of rVIIa in Trauma • 287 patients with blunt and penetrating trauma • Non significant reduction in RBC units transfused • Significant only in blunt trauma if early deaths excluded (within 48h) • Similar overall survival - 25% vs 30% • Composite outcome incl organ dysfunction showed increased trend favouring rVIIa (29 vs. 43%) • No difference in adverse events

41. Bleeding with normal tests • Von Willebrand’s Disease • Mild Hemophilia A or B • Mild Factor XI deficiency • Platelet Function Disorder • Factor XIII deficiency • Alpha 2 antiplasmin deficiency • Plasminogen Activator Inhibitor deficiency

42. DDAVP • Synthetic vasopressin • Release of VIII and vWF from endothelium • May also help with platelet dysfunction • 2-3 fold rise in levels • Dose – 0.3 ug/kg q 12-24 hours • Tachyphylaxis may occur after 2-3 doses Uses • Mild hemophilia A • Von Willebrand Disease • Platelet dysfunction

43. Antifibrinolytics • Tranexamic acid (Cyclokapron) • 20-25 mg/kg po or 10 mg/kg IV q8h • Epsilon aminocaproic acid (Amicar) • 50-60 mg/kg po q6h • Competitive inhibition with plaminogen activator (t-PA) • Prevents fibrinolysis (clot breakdown) • Promotes thrombosis • Relative contraindication in renal bleeding Uses • Mucosal bleeding • Fibrinolytic disorders