Heme Emergencies 1 Flashcards
All of procoagulants are synthesized in the liver except?
WV
Intrinsic pathway?
- think which test?
- Think which factors? 4
Extrinsic?
- Think which test?
- Think which factors? 2
- Intrinsic pathway? Think PTT (partial thromboplastin time)
- Think VIII, IX, XI, and XII
- Extrinsic pathway? Think PT
(prothrombin time) - Think II and VII
Note: **Both pathways converge on the activation of factor X, which subsequently results in prothrombin activator converting prothrombin into thrombin
Which factors are vit K dependant?
Factors VII, X, and prothrombin (Factor II) are vitamin-K dependent and are altered by warfarin (Coumadin) which is why we use the PT-INR to monitor warfarin therapy
Antithrombotic Termination
The termination phase of the coagulation process involves two circulating enzyme inhibitors. What are these? 2
1) Antithrombin (formerly called antithrombin III)
2) Tissue factor pathway inhibitor
AND
Clotting-initiated inhibitory process, the protein C pathway
Hemostasis Physiology
Antithrombin does what? 2
- activates coagulation factors and neutralizes thrombin (the last enzyme in the pathway for the conversion of fibrinogen to fibrin)
- complexes with naturally occurring heparin to accelerate and provide protection against uncontrolled thrombus formation on endothelial surfaces.
Hemostasis Physiology
- What does Protein C do?
- Protein s?
- Protein C
A plasma protein
Acts as an anticoagulant protein by inactivating factors V and VIII - Protein S
A plasma protein
Breaks down fibrin into fibrin degradation products that act as anticoagulants
Fibrinolysis
3 steps
- Plasminogen binds fibrin and tissue plasminogen activator (tPA)
- Complex leads to conversion of the proenzyme plasminogen to active, proteolytic plasmin
- Plasmin cleaves polymerized fibrin strand at multiple sites and releases fibrin degradation products including D-Dimer
Bleeding Disorders
- Defects in Platelet number? 3
- Defects in Platelet function? 1
- Defects in the coagulation cascade? 4
- Defects in Platelet number
- ITP
- Thrombotic Thrombocytopenic Purpura
- Hemolytic-Uremic Sundrome - Defects in Platelet function
- Aspirin (drug-induced) platelet dysfunction - Defects in the Coagulation Cascade
- Hemophilia A
- Hemophilia B (Christmas Disease)
- von Willebrands Disease
- Vitamin K deficiency
- Normal platelet count?
- Thrombocytopenia?
- Milld?
- Severe?
- Normal 100,000-400,000 cells/mm
- less than 100,000 -Thrombocytopenia
- 50,000-99,999 Mild
- less than 50,000 Severe
Bleeding time normals?
2-8 minutes
PARTIAL THROMBOPLASTIN TIME
- Measures what?
- Normal value?
- Measures Effectiveness of the Intrinsic
Pathway - NORMAL VALUE
25-40 SECS
- What is thrombin time?
- Normal?
- Measure of what?
- Time for Thrombin To Convert Fibrinogen to Fibrin Monomer
- NORMAL VALUE
9-13 SECS - Measure of Fibrinolytic Pathway
Hemostasis is DEPENDENT UPON? 5
- Vessel Wall Integrity
- Adequate Numbers of Platelets
- Proper Functioning Platelets
- Adequate Levels of Clotting Factors
- Proper Function of Fibrinolytic Pathway
What questions should I ask in the history if I suspect a bleeding abnormality?
4
- Family History
- Medications
- Past Medical History
- Previous Challenges to Hemostasis
Clinical Features of anemia? 5
- Palpitations
- Dizziness
- Orthostatic Hypotension
- Exertional Intolerance
- Tinnitus
PE for anemia? 5
- Pale conjunctiva or skin
- Tachycardia
- Systolic murmurs
- Tachypnea at rest and
- hypotension
are late signs
- Presence of what are diagnostic of anemia? 3
- Determining the exact etiology of the anemia is not essential in the ED, except in when?
- Initial eval should include ? 5
- What are the initial studies needed in patients with suspected bleeding disorders?
3
- decreased RBC count,
- Hemoglobin, and
- Hematocrit
- the face of acute hemorrhage
- Hemoccult exam,
- CBC,
- retic count,
- Review of RBC indices, and
- smear
- A
- CBC with platelet count,
- PT and
- PTT
Disorders of Secondary Hemostasis
- These are problems with what?
- Intrinsic pathway? 3
- Extrinsic? 1
- Problem with the coagulation factors themselves
- Instrinsic Pathway
- Hemophilia A
- Hemophilia B
- vWF - Extrinsic Pathway
- Vitamin K deficiency
Approach to the thrombocytopenic patient
- HX? 6
- assess the number and function of platelets with what? 2
History
- Is the patient bleeding?
- Are there symptoms of a secondary illness? (neoplasm, infection, autoimmune disease)
- Is there a history of medications, alcohol use, or recent transfusion?
- Are there risk factors for HIV infection?
- Is there a family history of thrombocytopenia?
- Do the sites of bleeding suggest a platelet defect?
Assess the number and function of platelets
- CBC with peripheral smear
- Bleeding time or platelet aggregation study
Clinical manifestations: Hemophilia
(hemophilia A & B are indistinguishable)
Symptoms? 7
- Hemarthrosis (most common): Fixed joints
- Soft tissue hematomas (e.g., muscle)
- Muscle atrophy
- Shortened tendons
Other sites of bleeding - Urinary tract
- CNS, neck (may be life-threatening)
- Prolonged bleeding after surgery or dental extractions
Hemophilia signs?
- Swollen, painful joints
- Local bleeding out of proportion to injury
- Subcutaneous bleeding
- Bleeding from mucous membranes
- Abdominal pain, distension
- Hematemesis, melena
Hemophilias
- Prolongation of what?
- Hemophilia A deficiency in?
- B?
- Prolongation of the aPTT (the PT will remain normal)
- Hemophilia A (deficiency in factor VIII)
- Hemophilia B (deficiency in factor IX) (Christmas Disease)
Hemo A etiology?
X-linked recessive pattern of inheritance
Describe the PP of Hemophilia A?
What is the kind of bleeding we are really worried about in these pts?
The blood of a person with hemophilia does not clot normally.
He does not bleed more profusely or more quickly than other people; however, he bleeds for a longer time.
External wounds are usually not serious.
Far more important is internal bleeding
These hemorrhages are in joints, especially knees, ankles and elbows; and into tissues and muscles
Signs and Symptoms
Hemophila A
? 7
- Petechiae and ecchymosis are characteristically absent.
- Bleeding into joints- Knees, ankles, elbows
- Bleeding into muscles- Spontaneous hemarthoses in severe disease
- GI bleeding
- Those with mild disease bleed after major trauma or surgery.
- Those with moderately severe disease bleed with mild trauma or surgery.
- Those with severe disease bleed spontaneously.
Hemophilia A
Lab findings? 5
- PTT is prolonged
- Factor VIII:C is reduced
- vWF is normal
- PT, Fibrinogen levels are normal.
- Diagnosis is confirmed by decreased Factor VIII levels.
Hemophilia A
Treatment? 4
- Avoid ASA
- Factor VIII replacement: Recombinant Factor VIII concentrate
- Cryoprecipitate
- For mild hemophilia
DDAVP
**Can use EACA (Amicar) along with the above
Hemophilia B
- AKA?
- Caused by?
- How common?
- Prolonged what?
- Dx confirmed by?
- Also called Christmas disease
- X-linked bleeding disorder caused by deficiency of Factor IX.
- Less common than hemophilia A.
- PTT is prolonged.
- Diagnosis is confirmed by demonstrating decreased Factor IX levels.
Hemophilia B
TX? 2
- Avoid ASA
- Factor IX concentrates
Factor VIII concentrates are INEFFECTIVE
Von Willebrand’s Disease
- Etiology?
- What is it?
- What is VW required for?
- Also carries what?
- Autosomal dominant pattern
- Disorder of platelet function and coag pathway
- Deficiency of von Willebrand Factor (vWF) - vWF is required for adequate platelet adhesion
- Also a carrier molecule for Factor VIII in the plasma
- Factor VIII is rapidly degraded, limiting its availability for coagulation with vWF deficiency.