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AHN 554 > Coagulopathies > Flashcards

Coagulopathies Flashcards

1
Q

Idiopathic Thrombocytopenic Purpura (ITP) definition

A
  • Autoimmune: B cells produce IgG antibodies, directed against platelet membrane, increase platelet destruction, inhibit platelet production
  • isolated thrombocytopenia
  • no apparent associated conditions
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2
Q

ITP Classifications (4)

A
  • Primary: no identifiable underlying cause
  • Secondary: immune mediated and associated with underlying disorder
  • Chronic: lasting longer than 12 months
  • Refractory: failure to respond, relapse occurs after splenectomy
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3
Q

Incidence of ITP

A
  • Children: self limiting and usually caused by viral illness, results in bruising and mucosal bleeding
  • adults: chronic, requires periodic tx
  • More common in women (ages 20-40) than men 2:1
  • Common secondary manifestation to systemijc lupus and CLL
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4
Q

What may induce thrombocytopenia in ITP

A 
Heparin (most common in hospital setting)
Sulfonamides
Thiazides
Quinine
Gold
Cimetidine
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5
Q

S&S of ITP

A
  • Mucosal or epidermal bleeding (epistaxis, oral bleeding, menorrhagia, purpura, petechiae)
  • Patient usually systemically well, afebrile, no abnormal findings besides bleeding
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6
Q

Hallmark lab finding for ITP

A

Thrombocytopenia, <20,000 platelets, platelets are enlarged (megathrombocyte)

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7
Q

Evans Syndrome

A

coexistent dz with ITP in 10% of cases

-Anemia, retics, and spherocytes on peripheral smear

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8
Q

Most sensitive and specific antibody test for ITP

A

Monoclonal antibody immobilization of platelet antigens

-IgG platelet antibodies present in 90% of patients
Ig

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9
Q

Bone marrow findings ITP

A

normal or increased megakaryocytes

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10
Q

ITP tx

A
  • Prednisone, bleeding diminishes within a day and platelets rise within a week
  • High dose IV gamma globin: very expensive and usually used in emergency, Used in HIV patients instead of steroids
  • Splenectomy: used when prednisone fails, give Pneumococcal vaccine weeks before to minimize complications
  • Chemotherapy: done after prednisone and spleen removal don’t work, Danazol or immunosuppressive agents (vincristine, vinblastine, azathioprine, cyclophosphamide)
  • Thrombopoiesis stimulating agents
  • Platelet transfusion in life threatening instance
  • WinRho therapy
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11
Q

WinRho therapy or anti D antibody therapy

A

Only for Rh positive individuals born to Rh negative mothers.

-concentrated antibodies that bind to the Rh antigen on RBCs, helps increase platelet count but may cause anemia

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12
Q

most serious complication of ITP

A

Spontaneous intracranial hemorrhage
-less than 1% affected
at risk when platelets drop <5000

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13
Q

Heparin induced Thrombocytopenia (HIT) definition

A

Thrombocytopenia induced by heparin

Produces arterial and venous thrombosis

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14
Q

Functional HIT

A

fall in platelet count 1-4 days after starting heparin. returns to normal after heparin discontinued (most common)

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15
Q

Immunologic HIT

A

fall in platelet count within 5-10 days from starting heparin, immune mediated disorder, higher incidence of thromboembolic event

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16
Q

Antibody formation HIT

A

IgG autoantibody formation against heparin platelet factor 4 complex

17
Q

incidence/predisposing factors for HIT

A
  • most common type of drug induced thrombocytopenia
  • most common form of thrombocytopenia in the hospital
  • occurs more with unfractionated heparin than LMWH
  • more common in surgical patients due to need for DVT/VTE prophylaxis and loading dose heparin
18
Q

S&S of HIT

A
  • Asymptomatic at first
  • symptoms related to location of thromboses
  • skin necrosis at injection site
  • anaphylactic reaction
19
Q

Platelet labs suggesting HIT

A

Suspect if platelets drop >50% even if there is no thrombocytopenia

20
Q

HIT tests (4)

A
  • Heparin induced platelet aggregation assay: 90% sensitivity and 100% specificity
  • Serotonin release assay: done with above test as standard
  • Platelet C serotonin release assay: 94%sensitive and 100% specific but difficult and time consuming
  • Heparin PF4 enzyme liked immonosorbent assay: immunologic test for heparin induced antibodies
21
Q

4 Ts for clinical probability of HIT

A

The extent of thrombocytopenia
Timing of thrombocytopenia
Presence of thrombosis
Thrombocytopenia

score of 4 or higher indicates intermediate to high risk of HIT

22
Q

HIT tx

A
  • hematology consult
  • Stop heparin
  • give direct thrombin inhibitors as alternative anticoagulation: danaparoid (check renal function), argatroban (check liver function), Bivalirudin, Fondaparinux (check creatinine clearance, MUST be > 30ml/min)

-Transition to comadin when INR at goal of 2-3, platelet count has increased to over 150,000. Start with less than 5 mg per day. Minimum of 5 days of overlapping before discontinuing thrombin inhibitor

23
Q

Disseminated Intravascular Coagulation (DIC) definition

A
  • acquired coagulation disorder with hemorrhage and thrombosis that occurs as a secondary process concomitant with a pathophysiologic dz or clinical state
  • caused by consumption of many coagulation factors and platelets
  • an abnormal stimulus results in the formation of excess thrombin which causes: fibrinogen consumption, irreversible platelet aggregation, activation of the fibrinolytic system
24
Q

incidence/predisposing factors of DIC

A
  • most common cause is infection (10-20% gram negative sepsis)
  • other causes: ob complications, cancer, liver dz, trauma, burns, transfusion of ABO incompatible RBCs
25
Q

S&S of DIC

A
  • Bleeding: oozing from previously punctured sites, from multiple sites
  • sites could be oral, gingival, GI, GU
  • Acute DIC: tachycardia, hypotension, edema
  • VTE, spontaneous bruising, skin necrosis
  • Thrombosis can be superficial or deep, digital ischemia or gangrene may be the most common form, most common in pts with cancer
26
Q

Labs for acute DIC

A
  • no single lab is diagnostic
  • platelets <150,000
  • PT and PTT prolonged by 70% and 50%
  • Fibringoen, factor V, and factor VII levels are low
  • fragmented RBCs (schistocytes) on blood smear
  • Diagnosis confirmed with rapidly falling fibrinogen levels on repeat testing
27
Q

Subacute DIC labs

A

PT and PTT normal
Fibrinogen levels normal
Thrombocytopenia and elevated D dimer

28
Q

Chronic or compensated DIC labs

A

-Elevated fibrin degradation product levels >45, d dimer positive at greater than 1:8 dilution

29
Q

DIC tx

A
  • Hematology consult
  • Correct underlying cause: hypotension, sepsis, ob issues
  • Transfuse PRBCs, platelets (goal 30,000-50,000), cryoprecipitate (goal fibrinogen 150 mg/dl), FFP every 30 minutes
  • 1 unit cryoprecipitate increases fibrinogen level by 6-8mg/ml; 15 units raises level from 50-150 mg/dl
  • Prevent hypoxemia
  • HEparin therapy if thrombosis but test antithrombin III levels b/c heparin won’t be effective if antithrombin depleted
30
Q

Thrombotic thrombocytopenic purpura (TTP) what is it

A

thrombocytopenia due to the incorporation of platelets into thrombi in the microvasculature and microangiopathic hemolytic anemia, which results from shearing of erythrocytes in fibrin networks in the microcirculation

autoantibodies against ADAMTS-13 aka von Willebrand factor cleaving protease, lead to accumulation of huge von willebrand factor multimers…leading to vessel obstruction and organ dysfunction

31
Q

presentation of TTP patients

A 
affects adults
severe thrombocytopenia 
fever
typical but mild kidney dz
Decreased activity of ADAMTS-13, inhibitor usually identified
32
Q

Initial Management for TTP

A

Mortality 95% without tx
TPE :plasma exchange, everyday until LD and platelet count normal for 2 days
hemodialyis for severe renal impairment
Platelet transfusions contraindicated unless TPE underway

33
Q

Secondary tx of TTP not responding to 1st line tx

A

Rituximab, corticosteroids, IVIG, vincristine, cyclophosphamide ans splenectomy

AHN 554 (13 decks)

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