Hemostasis

Hemostasis Definition Prevention of blood loss (stoppage of blood flow)

Requirements for Hemostasis 1 - Sound vasculature - healthy blood vessels 2 - Platelets - correct # & functional

Requirements for Hemostasis 3 - Coagulation Factors - need all13 clotting factors & must be functional

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 Hemostasis 3.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 Hemostasis 3.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

Miscellaneous Clotting Information Normal clotting time = minutes

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 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

Miscellaneous Clotting Information Anticoagulants - substances that prevent blood from clotting Ex: heparin, EDTA, Coumadin, aspirin, etc.

Hemostasis Disorders Undesirable 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 Disorders Bleeding Disorders Hemophilia - “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 Disorders Bleeding Disorders Liver 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 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 seconds = normal value

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