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Heme emergencies Flashcards

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1
Q

What is the only procoag that isn’t synthesized in the liver?

A
  • vWF (made in endothelial cells)
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2
Q

Intrinsic pathway?

A
  • PTT:
    VIII, IX, XI, XII

converge on activation of factor X which subsequently results in prothrombin activator converting prothrombin into thrombin

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3
Q

Extrinsic pathway?

A
  • PT:
    II, VII

converge on activation of factor X which subsequently results in prothrombin activator converting prothrombin into thrombin

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4
Q

What factors are Vit k dependent?

A
  • VII, X, and prothrombin (II) - altered by warfarin, why we use PT to monitor therapy
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5
Q

Termination phase of coag process?

A 
involves 2 circ enzyme inhibitors:
1) antithrombin 
2) tissue factor pathway inhibitor 
and 
clotting initiated inhibitory process the protein C pathway
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6
Q

What is antithrombin?

A
  • act. coag factors and neutralizes thrombin (last enzyme in pathway for conversion of fibrinogen to fibrin)
  • complexes w/ naturally occurring heparin to accelerate and provide protection against uncontrolled thrombus formation on endothelial surfaces
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7
Q

Protein C and S?

A
  • C: plasma protein, act as anticoag protein by inactivating factors V and VIII
  • S: plasma protein, breaks down fibrin into fbrin degradation products that act as anticoag
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8
Q

Process of fibrinolysis?

A

1) plasminogen binds fibrin and tissue plasminogen activator (tPA)
2) complex leads to conversion of proenzyme plasminogen to activate, proteolytic plasmin
3) plasmin cleaves polymerized fibrin strand at mult sites and releases fibrin degradation products including D dimer

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9
Q

Bleeding disorders: defects in platelet number:

A
  • ITP
  • TTP
  • HUS
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10
Q

Defects in platelet fxn?

A
  • ASA (drug induced) platelet dysfxn
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11
Q

Defects in coag cascade?

A
  • hemophilia A
  • hemophilia B
  • VW disease
  • Vit K deficiency
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12
Q

Approach to bleeding disorders?

A
  • ID and correct any specific defect of hemostasis:
    lab testing almost always needed to determine cause:
    PT, PTT, platelet count
  • use non-transfuional drugs whenever possible
  • RBC transfusions for surgical procedures or large blood loss
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13
Q

Lab eval of bleeding disorder?

A
  • platelet count: 100-400,000, under 100,000 - thrombocytopenia, under 50,000 severe (spontaneously bleed)
  • BT (old news): 2-8 min
  • PT/INR
  • PTT: intrinsic pathway - 25-40 sec
  • TT: time for thrombin to convert fibrinogen to fibrin monomer, normal value: 9-13 sec, measure fibrinolytic pathway
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14
Q

Hemostasis is dependent upon what factors?

A
  • vessel wall integrity
  • adequate number of platelets
  • proper fxning platelets
  • adequate level of clotting factors
  • proper fxn of fibrinolytic pathway
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15
Q

What questions should you ask in pt w/ suspected bleeding abnorm?

A
  • family hx
  • meds**
  • PMHx
  • previous challenges to hemostasis
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16
Q

PE findings of platelet defects or deficiencies?

A
  • prolonged superficial bleeding, epistaxis, gingival and mucosal bleeding, purpura, and petechiae
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17
Q

PE findings of coag factor defects (hemophiliacs)?

A
  • can’t effectively reinforce platelet initiated hemostasis
  • recurrent bleeding into deep structures: subq tissues, muscles, jts, retroperitoneum
  • any bleeding disorder: ecchymosis, GI bleeding, menorrhagia
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18
Q

Eval/clinical features of anemia and bleeding pt?

A
  • is it chronic or acute?
  • compensation?
  • palpitations
  • dizziness
  • ortho hypotension
  • exertional intolerance
  • tinnitus
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19
Q

PE of anemic and bleeding pt?

A
  • pale conjunctiva or skin
  • tachycardia
  • systolic murmurs
  • tachypnea at rest and hypotension are late signs
  • inquire about presence of excessive or abnorm bleeding in pt or family members (after dental extraction, menorrhagia)
  • liver disease or EToH abuse
  • drugs
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20
Q

Dx and diff of anemia and bleeding pt?

A
  • presence of decreased RBC ct, hemoglobin, hematocrit are dx of anemia
  • determining exact etiology of anemia isn’t essential in ED, except in face of acute hemorrhage
  • initial eval should include hemoccult exam, CBC, retic count, review of RBC indicese, smear
  • CBC w/ platelet count, PT, PTT are initial studies needed in pts w/ suspected bleeding disorders
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21
Q

Tx of pt w/ anemia and bleeding?

A

depends on etiology and clinical status of pt:

  • stabilize airway, assist ventilation, provide circulatory support, control direct hemorrhage
  • blood should be typed and cross matched
  • immediate transfusion of PRBCs should be considered in sx pts who are unstable
  • admit
  • heme consult
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22
Q

What are disorders of secondary hemostasis?

A 
problem w/ coag factors themselves
- intrinsic:
Hemophilia A (def in factor VIII), B (def in factor IX - christmas disease) 
vWF
- extrinsic:
vit k deficiency
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23
Q

Approach to thrombocytopenic pt?

A

hx:
is pt bleeding?
Are there sxs of secondary illness (neoplasm, infection, autoimmune disease)
- hx of meds, EToH use, recent transfusion?
- RFs for HIV?
- family hx of thrombocytopenia?
- do sites of bleeding suggest platelet defect?

assess number and fxn of platelets:

  • CBC w/ peripheral smear
  • bleeding time or platelet aggregation study
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24
Q

Clinical manifestations of hemophilia?

A
  • A and B are indistinguishable
  • hemarthrosis: MC - fixed jts
  • soft tissue hematoma: muscle - muscle atrophy, shortened tendons
  • other sites of bleeding:
    urinary tract, CNS, neck (may be life-threatening)
  • prolonged bleeding after surgery or dental extractions
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25
Signs of Hemophilia?
- swollen, painful jts - local bleeding out of proportion to injury - subq bleeding - bleeding from mucous membranes - abdominal pain, distension - hematemesis, melena
26
Etiology and pathogenesis of hemophilia A?
- fairly common - xl inked recessive pattern of inheritence - def of factor VIII - blood doesn't clot normally, doesnt bleed more profusely or more quickly just for longer time, external wounds aren't usually that serious - internal bleeding is serious: hemorrhages in jts esp knees, ankles, elbows, into tissues and muscles
27
Signs and sxs of Hemophilia A?_
- petechia and ecchymosis are absent - bleeding into jts: knees, ankles, elbows - bleeding into muscles: spontaneous hemarthoses in severe disease - GI bleeding - those w/ mild disease bleed after major trauma or surgery - those w/ moderately severe disease bleed w/ mild trauma or surgery - those w/ severe disease bleed spontaneously - hemarthrosis is a medical emergency, recurring bouts may lead to destruction of jt, and painful deformities later in life
28
Lab findings in Hemophilia A?
- PTT prolonged - factor VIII: C reduced - vWF normal - PT, fibrinogen levels normal - dx confirmed by decreased factor VIII levels
29
Tx of Hemophilia A?
- avoid ASA - factor VIII replacement: recombinant factor VIII concentrate - cryoprecipitate - for mild hemophilia: DDAVP - can use EACA (Amicar)
30
Characteristics of Hemophilia B?
- christmas disease - x linked caused by deficiency of factor IX - less common than A - clinical features: almost identical to A - PTT prolonged - dx confirmed by demonstrating decreased factor IX levels
31
Tx of hemophilia B?
- avoid ASA - factor IX concentrates - factor VIII concentrates are ineffective
32
What is Von Willebrand's disease?
- common inherited bleeding disorder - autosomal dominant - affects both sexes equally - disorder of platelet fxn and coag pathway - deficiency of vWF: reqd for adequate platelet adhesion, also carrier molecule for factor VIII in plasma - factor VIII is rapidly is degraded, limiting its availability for coag w/ vWF deficiency
33
Clincal presentation of vWD?
- manifests as primary hemostasis problem (similar to those seen in PLT disorders): easy bruising skin bleeding prolonged bleeding from mucosal surfaces (oropharyngeal, GI, uterine)
34
Signs and sxs of vWD?
- excessive menstrual and postpartum bleeding - GI bleeding - epistaxis - gingival bleeding - easy bruising - uncommon for jts to be involved
35
Lab findings in vWD?
- prolonged bleeding time - PTT may be prolonged - bleeding time: prolonged in pts w/ moderate and severe but often normal in mild vWD - PT and platelets are normal - factor VIII: C levels decreased - vWF plasma level low: measured by factor VIII antigen - may need to dist. subtype
36
Tx of vWD?
- if bleedin disorder is characteristically mild: avoid ASA and NSAIDs - for more severe tx: DDAVP: causes release of stored vWF from endothelial cells, increases factor VIII levels, can be admin subq, IV, IN - factor VIII concentrates: humate-P - EACA: good for dental procedures - several products available that contain vWF in high concentration: intermediate purity factor VIII concentrates (contain vWF as well) highly purified vWF conc cryoprecip (Not recommended)
37
Vit K deficiency: source, used for synth of what factors? Tx?
- source of vit k: green veggies, synthesized by intestinal flora - reqd fro synthesis of: factors II, VII, IX, X, protein C and S - causes of deficiency: malnutrition, biliary obsruction, malabsorption, abx therapy - tx: vit K and FFP
38
Vit K deficiency seen commonly in?
- alcoholics - chronic liver disease - biliary obstruction - intestinal malabsorption - poor dietary intake - long term use of abx
39
Lab findings of vit K deficiency?
- PT/PTT prolonged: PT more so than PTT | - tx: VIt K supp (won't work w/ liver disease)
40
Etiology and pathogenesis of ITP?
- autoimmune disease: acquired - pathologic abs bind to platelets, resulting in accelerated platelet clearance spleen rapidly removes autoabs from circulation, splenic macrophages w/ Fc receptors bind to ab coated platelets - commonly occurs in childhood: abrupt onset w/in 2-21 days after viral infection - in adults often chronic - females more than males often results from: blood transfusions IV drug use Graves can be chronic
41
Signs and sxs of ITP?
- easy bruising, petechiae, purpura: lesions will be painless, flat and nonpruritic - epistaxis - bleeding from gums - melena - hematuria - excessive menstrual bleeding - spontaneous hemorrhage rarely occurs - wet purpura (blood blisters in mouth) - retinal hemorrhage
42
Dx ITP?
- dx of exclusion - very low platelet counts - megakaryocytes should be present in marrow - normal morphology - in kids usually provoked by viral illness: spontaneously remits, no specific therapy reqd usually - in adults specific therapy reqd if platelet ct is less than 50 or if pt is bleeding
43
What drugs should you ask pt about? diseases?
- sulfonamides, thiazides, cimetidine, heparin | - SLE, other autoimmune, hepatitis, HIV
44
Labs for ITP?
- thrombocytopenia - prolonged bleeding time - very mild anemia, if at all - PT/PTT normal - bone marrow bx: normal or increased number of megakaryocytes
45
Tx of ITP?
mild acute: platelet greater than 30,000 and no mucosal bleeding, may not reqr tx other than trauma protection esp to head, and avoiding ASA - more severe ITP: less than 30,000 w/ mucosal bleeding: tx w/ ***prednisone 1-2 mg/kg/day decreases affinity of splenic macrophages for ab coated platelets, high dose until platelet ct is normal, then gradually tapered, bleeding diminishes w/in days (often 1 day), platelet ct improves w/in 2 wks
46
Tx of ITP if failure to respond to prednisone?
- splenectomy: most definitive tx - IV immunoglobulin: should be reserved for bleeding emergencies such as preparing a severly thrombocytopenic pt for surgery - pts who fail to respond to prednisone and splenectomy: danazol 600mg/day
47
Types of thrombotic microangiopathies?
- TTP - HUS (hemolytic uremic syndrome): thrombocytopenia incorporation of platelets into thrombi in microvasculature, shearing of erythrocytes in microcirc
48
What is TTP?
- process characterized by abnormal activation of platelets and endothelial cells, w/ fibrin deposition in microvasculature, and peripheral destruction of platelets and red cells
49
Etiology of TTP?
- may be asoc w/ ab against or deficiency of protease which cleaves very high MW multimers of vWF - can be induced by drugs, including ticlopidine, quinine, cyclosporine, tacrolimus, rapamycin, mitomycin C, bleomycin - increased incidence w/ preg or HIV - thought to be autoimmune: platelet consumption issue (Not destruction) - platelets being used up, not tagged and destroyed - seen primariyl in young adults: 20-50 - slight female predominance - occasionally precip by: estrogen use preg drugs infections
50
Multiple system abnorma of TTP?
- microangiopathic hemolytic anemia: results when capillaries are partially occluded by fibrin - thrombocytopenia: often w/ purpura but not usually severe bleeding - acute renal insufficiency, that may be assoc w/ anuria and may reqr acute dialysis - neuro abnormalities, usually fluctuating - fever
51
Signs and sxs of TTP?
- pt appears acutely ill - febrile - pallor - purpura - petechiae - signs of neuro dysfxn: waxes and wanes - HA confusion aphasia alt in consciousness
52
Dx features of TTP (the pentad)?
- microangiopathic hemolytic anemia (MAHA): elevated LDH, elevated bili shistocytes on periph smear THIS MUST BE PRESENT! - low platelets: MUST BE PRESENT - fever - neuro manifestations: HA, sleepiness, confusion, stupor, stroke, coma, seizures - renal manifestations: hematuria, proteinuria, elevated BUN/Creatinine
53
Lab findings of TTP?
- thrombocytopenia - marked anemia - reticulocytosis - occasional circulating nucleated RBCs - shistocytes, helmet cells - hemolysis: MAHA - elevated indirect bili elevated LDH hemoglobinuria, hemoglobinemia - coags: PT/PTT normal
54
Tx of TTP?
- survival reqrs prompt recognition and emergent tx, medical emergency!! - tx relies on plasma exchage - PLEX usually done daily until plts above 150 for 2 days - follow LDH, plts, H/H, Cr daily - adjunct therapies, including glucocorticoids, anti-platelet agents can be used but uncertian benefit - secondary measures if no response to plasma exchange include vincristine, splenectomy, rituximab - avoid platelt transfusions: they fuel the fire - assoc w/ CVA, death and lawsuits
55
Course and prognosis of TTP?
- 1/50000 incidence - inherited or idiopathic, women greater than men - 90% fatal w/o therapy - 80-90% survive w/ therapy - 1/3 pts will relapse w/in 10 yrs, most w/in 1 month of dx
56
What is HUS?
- usually classified w/ TTP as TTP/HUS - has fewer neuro sequela, more renal manifestations - usually precip by diarrheal illness, esp E coli O157:H7 or shigella - seen more in meds, usually has better prognosis - in adults often precip by estrogen use or by post partum state
57
Etiology and pathogenesis of HUS?
- unclear cause - diff vascular beds involved than in TTP - similar pathogenesis of TTP - acute renal failure, microangiographic hemolytic anemia and thrombocytopenia
58
Signs and sxs of HUS?
- same as TTP but w/ renal failure - no neuro manifestations other than those related to uremic state - diff from TTP by renal failure and lack of neuro findings
59
Lab findings of HUS?
- MAHA - less severe thrombocytopenia - striking RBC fragmentation (defining dx finding) - elevated LDH - PT/PTT normal - elevated fibrin degradation products: d dimer
60
How is HUS distinguished from DIC? TTP?
- from DIC: coag are normal - from TTP: more neuro findings w/ TTP, more renal findings w/ HUS
61
Tx of HUS?
- in kids: self limited, conservative tx of renal failure - adults: large vol plasmaphoresis w/ FFP replacement, management of renal failure: many pts have chronic renal insufficiency
62
What is DIC?
- process characterized by abnormal act of coag, generation of thrombin, consumption of clotting factors, destruction of platelets, and act of fibrinolysis - release of tissue factor substances that activate extrinsic pathway of coag - assoc w/ massive injury to endothelial lining of blood vessels - large scale intravascular aggregation of platelets and activation of coag cascade
63
Causes of DIC?
``` - obstetric emergencies: placentae abruptio septic abortion - sepsis and severe infections (gram -) - cancers - trauma - burns - hemolysis - heat stroke - snake bites ```
64
S/S of DIC?
- lead to both bleeding and thrombosis, although bleeding is far more common - bleeding: spont. bleeding and oozing at venipuncture signs or wounds, shock and widespread bleeding - thrombosis: digital ischemia and gangrene, renal necrosis, CNS dysfxn (seizures, delirium, coma), resp failure - can lead to MAHA
65
Clinical presentation of DIC?
- bleeding: petechiae and ecchymoses common in conjunction w/ blood oozing from wound sites, IV lines, catheters, blood in urine, stool, vomitus, sputum - renal dysfxn - hepatic dysfxn - resp dysfxn - shock - thromboembolism - CNS involvement
66
Lab dx of DIC?
- thrombocytopenia: less than 100,000 or rapidly deteriorating - prolonged clotting times: PT/PTT - presence of fibrin degradiation products or positive D dimer - low levels of coag inhibitors: AT III, protein C - low levels of coag factors: V, VIII, X, XIII - fibrinogen levels low
67
Tx of DIC?
- correction of underlying cause - hemodynamic support as appropriate: for pts actively bleeding: PLT transfusions (if less than 50,000), sig elevated PT? FFP, fibrinogen decreased below 50? cryoprecipitate (has fibrinogen) - BLOOD!!!
68
ASA effect on hemodynamics?
- ASA irreversibly inhibits cox in platelets - lasts for as long as 7 days - bleeding time is prolonged the most - other NSAIDs have reversible effects only lasting a few hours - effect is usually mild, therefore if severe bruising or bleeding after ASA or NSAID use should raise possibility of an underlying disorder - COX-2 inhibitors (Celebrex)- doesn't have an effect on platelet fxn
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