Post on 30-Dec-2015
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
End