HEMOSTHASIS Hemosthasis has four main stages: - PowerPoint Presentation

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HEMOSTHASIS

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Hemosthasis

has four main stages:

1-vasoconstriction

(thromboxaneA2-Endotheline -

serotonine

)

2-platelet plug

3-fibrin formation

4-fibrinolysis

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Primary

hemosthasis

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Primary

hemosthasis

: bleeding control by platelet aggregation

Any problem in primary

hemosthasis

results in prolonged

BT

.

Examples:

1-thrombocytopenia

2-ASA

3-vwf disease

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For checking the coagulation

cascade we use:

PT-PTT

HEPARINE

WARFARINE

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Anticoagulation factors:

Antithrombine3(inhibits

thrombine

)

Protein-C(together with

prt

-S inhibits factor5)

Protein-S

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FIBRINOLYSIS:

Starts with

clott

formation

1-releasing

tPA

from endothelium

2-converting

Plasminogen

to

Plasmin

3-Plasmin lyses

Fibrin

(resulting

FDP and D-dimer

)

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Hemophylia

:

-type A: factor8 deficiency

-type B: factor9 deficiency

-X linked

severity:

-severe: (factor level <1%)

Spontaneous bleeding

-moderate: (1-5%)

Sever Bleeding after trauma or surgery

-mild: (>5%)

mild bleeding after

majour

trauma or surgery

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Factor XI deficiency:

-

Hemophylia

C

-prolonged PTT

-

Automosal

recessive

-bleeding after surgery trauma

-FFP before surgery

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Vwf

Disease:

-the most common congenital bleeding

Disorder

-

vwf

is responsible for:

adhesion and aggregation of platelets

transporting factor VIII in blood

-

vwf

disease: prolonged BT-PTT

-

vwf

disease

bleeding:easy

bruising/mucosal bleeding/menorrhagia

-three types :

type I:partial quantitative

type

II:qualitative

type

III:total

deficiency

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II-V-X factor deficiency:

-autosomal recessive

-sever bleeding occurs if the factor plasma level is less than 1%.

-FFP for bleeding

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VII factor deficiency:

-autosomal recessive

-sever bleeding occurs if the factor plasma level is less than 3%.

-Clinical

bleeding can vary widely and does not always correlate with the level of FVII coagulant activity in

plasma

easy

bruising and mucosal bleeding, particularly epistaxis or oral mucosal bleeding. Postoperative bleeding is also

common

-

Treatment is with FFP or recombinant factor

VIIa

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factor

XIII deficiency:

-autosomal recessive

Bleeding

is typically delayed because clots form normally but are susceptible to

fibrinolysis

Umbilical stump bleeding is characteristic, and there is a high risk of intracranial bleeding. Spontaneous abortion is usual in women with factor XIII deficiency

.

Replacement can be accomplished with FFP, cryoprecipitate, or a factor XIII concentrate

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Hereditary Platelet

Functional Defects

Bernard-

Soulier

syndrome

Glanzmann

thrombasthenia

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is a rare genetic platelet disorder, inherited in an autosomal recessive pattern, in which the platelet glycoprotein

IIb

/

IIIa

(GP

IIb

/

IIIa

) complex is either lacking or present but dysfunctional. This defect leads to faulty platelet aggregation and subsequent

bleeding

Bleeding in

thrombasthenic

patients must be treated with platelet transfusions

Glanzmann

thrombasthenia

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is caused by a defect in the GP

Ib

/IX/V receptor for

vWF

, which is necessary for platelet adhesion to the

subendothelium

. Transfusion of normal platelets is required for bleeding in these patients

Bernard-

Soulier

syndrome

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Thrombocytopenia

The most common

hemosthatic

defect which causes bleeding in patients.

1- failure

of production,(bone marrow disorders such as leukemia, myelodysplastic syndrome, severe vitamin B12 or folate deficiency, chemotherapeutic drugs, radiation, acute ethanol intoxication, or viral

infection)

2- shortened

survival,

(HIT-ITP-TTP-HUS)

3- sequestration(

Hypersplenism

)

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ITP

Primary immune thrombocytopenia is also known as idiopathic thrombocytopenic purpura (ITP). In children, it is usually acute in onset, short lived, and typically follows a viral illness. In contrast, ITP in adults is gradual in onset, chronic in nature, and has no identifiable

cause

Because the circulating platelets in ITP are young and functional, bleeding is less for a given platelet count than when there is failure of platelet

production

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First line treatment:

1-corticosteroid

2-IVIG

3-Immunoglobulin anti-D

SPLENECTOMY INDICATIONS IN ITP:

1-severe thrombocytopenia

2-high risk of bleeding

3-needing corticosteroid

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Heparin-induced thrombocytopenia (HIT)

is a form of drug-induced immune thrombocytopenia. It is an immunologic event during which antibodies against platelet factor 4 (PF4) formed during exposure to heparin affect platelet activation and endothelial function with resultant thrombocytopenia and intravascular thrombosis.12 The platelet count typically begins to fall 5 to 7 days after heparin has been started, but if it is a re-exposure, the decrease in count may occur within 1 to 2 days. HIT should be suspected if the platelet count falls to less than 100,000 or if it drops by 50% from baseline in a patient receiving heparin. While HIT is more common with full-dose unfractionated heparin (1%– 3%), it can also occur with prophylactic doses or with low molecular weight heparins.

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T

hrombotic

thrombocytopenic purpura (TTP

)

large

vWF

molecules interact with platelets, leading to activation. These large molecules result from inhibition of a metalloproteinase enzyme, ADAMtS13, which cleaves the large

vWF

molecules.15 TTP is classically characterized by thrombocytopenia,

microangiopathic

hemolytic anemia, fever, and renal and neurologic signs or symptoms. The finding of

schistocytes

on a peripheral blood smear aids in the diagnosis. Plasma exchange with replacement of FFP is the treatment for acute TTP

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DIC:

Disseminated Intravascular Coagulation (DIC). DIC is an acquired syndrome characterized by systemic activation of coagulation pathways that result in excessive thrombin generation and the diffuse formation of

microthrombi

. This disturbance ultimately leads to consumption and depletion of platelets and coagulation factors with the resultant classic picture of diffuse bleeding. Fibrin thrombi developing in the microcirculation may cause microvascular ischemia and subsequent end-organ failure if severe.

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Diagnosis:

1-thrombocytopenia

2-prolonged PT

3-low level of

fibrinogene

4-high level of FDP and D-dimer

Treatment:

The

most important facets of treatment are relieving the patient’s causative primary medical or surgical problem and maintaining adequate perfusion. If there is active bleeding, hemostatic factors should be replaced with FFP, which is usually sufficient to correct the

hypofibrinogenemia

, although cryoprecipitate, fibrinogen concentrates, or platelet concentrates may also be

needed.

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Primary

Fibrinolysis:

An acquired

hypofibrinogenic

state in the surgical patient can be a result of pathologic fibrinolysis. This may occur in patients following prostate resection when

urokinase

is released during surgical manipulation of the prostate or in patients undergoing extracorporeal bypass. The severity of fibrinolytic bleeding is dependent on the concentration of breakdown products in the circulation.

Antifibrinolytic

agents, such as ε-

aminocaproic

acid and

tranexamic

acid, interfere with fibrinolysis by inhibiting plasminogen activation.

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Niloofar

sadt

mirdamadi