Hemostasis

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Hemostasis Definition

• Prevention of blood loss

(stoppage of blood flow)

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Requirements for Hemostasis1 - Sound vasculature - healthy blood

vessels

2 - Platelets - correct # & functional

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Requirements for Hemostasis3 - Coagulation Factors - need all13

clotting factors & must be functional

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Phases of Hemostasis

1. Platelet Plug Formation

-a temporary patch to seal tears

-platelets respond to damaged endothelium

by swelling up & forming spiked process

which allow them to adhere to exposed

collagen fibers - once attached, they

release chemicals that attract more

platelets to the area & within 1 minute, a

platelet plug is formed, which reduces

blood loss

Phases of Hemostasis

2. Vascular Spasms

-Serotonin is released by the anchored

platelets which cause the blood vessel to

constrict (narrow); further reducing blood

loss

-Epinephrine may also be released to

prolong constriction

Phases of Hemostasis3. Coagulation (Clotting)

-consistency of blood changes from a viscous fluid to a semi-solid, jelly-like mass made up of meshed protein fibers with trapped RBC’s

-thromboplastin (PF3) is released from platelets & injured tissues & interacts with calcium, Vitamin K, & the clotting factors to trigger the clotting cascade - prothrombin activator is formed

Phases of Hemostasis3. Coagulation (Clotting)

-prothrombin activator ---> prothrombin ---> thrombin ---> fibrinogen ---> fibrin

-fibrin threads produced form a meshwork (net) that traps RBC’s, forming a clot; once formed, the clot will retract to pull broken edges of the blood vessel together

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Miscellaneous Clotting Information

• Normal clotting time = 3 - 6 minutes

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Miscellaneous Clotting Information

• To speed up clotting:– Sterile gauze (rough surfaces allow

platelets to stick)

– Pressure (fractures cells & thus releases more thromboplastin)

– Warmer temperature (clotting process is more efficient @ higher temperatures)

Miscellaneous Clotting Information

• Fibrinolysis - process that removes

unneeded clots when

healing has occurred.

Begins within 2 days

after clot formation and

continues slowly over

several days until clot

is dissolved

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Miscellaneous Clotting Information

• Anticoagulants - substances that

prevent blood from

clotting

Ex: heparin, EDTA, Coumadin,

aspirin, etc.

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Hemostasis DisordersUndesirable Clotting

Thrombus - clot that forms in an

undamaged blood vessel

Potential Hazard: Heart Attack

Embolus - A thrombus that breaks away

from vessel wall & floats freely

in blood

Potential Hazard: Stroke

Hemostasis Disorders

Undesirable Clotting

Causes: severe burns, trauma, fat accumulation, slow flowing blood or pooling blood as seen in immobilized patients

Treatment: anticoagulant therapy

Hemostasis Disorders

Bleeding Disorders

Thrombocytopenia (platelet deficiency)

Causes: Bone marrow cancer, radiation,

certain drugs, etc.

Symptoms: spontaneous bleeding &

many petechiae on the skin

from normal movements

Hemostasis DisordersBleeding DisordersHemophilia - “Bleeder’s Disease”Cause: Hereditary, missing one of the clotting factors

Symptoms: Prolonged & possibly life threatening bleeding from minor traumas

Treatment: Transfusions of plasma or injections of purified clotting factor

Hemostasis DisordersBleeding DisordersLiver Damage - abnormal & severe bleeding episodes

Cause: liver unable to produce plasma proteins normally - Vitamin K deficiency, hepatitis, cirrohosis

Treatment: Vitamin K supplements or whole blood transfusions

Hemostasis Lab Tests

• Vessel Integrity (blood vessel health)

Rumpel-Leede [Tourniquet Test]

-Create pressure on arm using a blood

pressure cuff for x amount of time; if

capillaries remain intact under stress,

blood vessels are healthy

<5 petichia = normal

Hemostasis Lab Tests

• Bleeding Tests (vessel integrity & platelets - number & function)

Ivy Template test

-A small blade is used to make two incisions 1mm deep x 10 mm wide on the forearm. The amount of time it takes to stop bleeding is recorded.

2.5 - 10 minutes = normal results

Hemostasis Lab Tests

• Platelets

Quantity - count # of platelets & record

amount

Quality - check for functionality by using

glass bead column to check for

adhesiveness

Hemostasis Lab Tests

• Coagulation Tests (checks for many different clotting factors)

Ex: Prothrombin Time

Add calcium reagent & brain tissue extract (thromboplastin) to blood sample & determine rate of clotting

10 - 13 seconds = normal value

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