hematology

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    • skin puncture- technique of choice to obtain blood specimen from the ff:
      • newborns and pediatric
      • extremely obese patients
      • elderly patients with fragile veins
      • patienst whose veins are reserved for therapeutic purposes
      • severely burned patients
    • puncture site:
      adult- palmar surface of the non dominant hand, 3rd or 4th finger
      children (<1 yr old)- plantar surface of medial (toe) or lateral (little toe)
    • depth of incision in skin puncture:
      adult: 2.0-2.5 mm
      infants: <2 mm
    • avoid applying pressure/squeezing/milking of the site cause it can cause:
      • hemolysis
      • introduce excess interstitial fluid
    • order of draw of skin puncture:
      1. tube for blood gas
      2. Slides
      3. EDTA microtainer
      4. Other additive microtainer
      5. Serum microtainer
    • warming of the puncture site can increase the bloodflow sevenfold. the site can be warmed using warm washcloth (40-42C) for no longer than 3-5 mins
    • most common antiseptic is 70% isopropyl alcohol
    • most common sites for venipuncture is the superficial veins of the antecubital fossa
    • in venipuncture, cleanse the site using friction scrub with movement of back and forth. distance: 3-4 inches above the venipuncture site
    • two anatomical patter of venipuncture site/veins: H and M pattern
    • veins to be used (in order preference):
      1. median
      2. cephalic
      3. basilic
    • angle between the needle and the skin is <30 degrees.
    • tourniquet application:
      length of time: <1min or 60 secs
      effects of prolonged tourniquet application:
      • hemolysis
      • hemoconcentration
      • shortened coagulation times
    • EDTA- purple/Lavender top- most routinely used in hema determination
      (8x inversion) -action is chelating of calcium. prevents platelet aggregation.
    • EDTA cuase swelling of platelets (causes approximately 20% increase in MPV during the first hour). should be based on EDTA specimens that are between 1-4 hrs old.
    • insufficient EDTA: overfilled tube ; presence of clots
      excessive EDTA: underfilled tube ; dec in HCT and ESR, degenerative changes in WBC and RBC and increase PLT
    • ORDER OF DRAW:
      1. Blood culture- yellow- 8x inversion
      2. citrated tube- light blue - 3-4x inversion
      3. Serum tube- red- glass (no additive)- 0x plastic (clot activator) 5x
      4. Heparin- green- 8x inversion
      5. EDTA- lavander- 8x
      6. Sodium flouride- gray- 8x inversion
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