hemostasis. hemostasis definition prevention of blood loss (stoppage of blood flow)

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  • Hemostasis

  • Hemostasis DefinitionPrevention of blood loss (stoppage of blood flow)

  • Requirements for Hemostasis1 - Sound vasculature - healthy blood vessels

    2 - Platelets - correct # & functional

  • Requirements for Hemostasis3 - Coagulation Factors - need all13 clotting factors & must be functional

  • Phases of HemostasisPlatelet 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 HemostasisVascular 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 HemostasisCoagulation (Clotting)-consistency of blood changes from a viscous fluid to a semi-solid, jelly-like mass made up of meshed protein fibers with trapped RBCs-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 HemostasisCoagulation (Clotting)-prothrombin activator ---> prothrombin ---> thrombin ---> fibrinogen ---> fibrin

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

  • Miscellaneous Clotting InformationNormal clotting time = 3 - 6 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 efficient @ higher temperatures)

  • Miscellaneous Clotting InformationFibrinolysis - 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 InformationAnticoagulants - substances that prevent blood from clotting

    Ex: heparin, EDTA, Coumadin, aspirin, etc.

  • Hemostasis DisordersUndesirable ClottingThrombus - clot that forms in an undamaged blood vesselPotential Hazard: Heart Attack

    Embolus - A thrombus that breaks away from vessel wall & floats freely in bloodPotential Hazard: Stroke

  • Hemostasis DisordersUndesirable ClottingCauses: severe burns, trauma, fat accumulation, slow flowing blood or pooling blood as seen in immobilized patients

    Treatment: anticoagulant therapy

  • Hemostasis DisordersBleeding DisordersThrombocytopenia (platelet deficiency)

    Causes: Bone marrow cancer, radiation, certain drugs, etc.

    Symptoms: spontaneous bleeding & many petechiae on the skin from normal movements

  • Hemostasis DisordersBleeding DisordersHemophilia - Bleeders DiseaseCause: 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 TestsVessel 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
  • Hemostasis Lab TestsBleeding 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 TestsPlateletsQuantity - count # of platelets & record amount

    Quality - check for functionality by using glass bead column to check for adhesiveness

  • Hemostasis Lab TestsCoagulation 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

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