2nd sem

• Arterial Puncture - blood gas analysis or pH determination
• common sites for arterial puncture

  • radial artery
  • brachial artery
• Venipuncture - collection of venous blood
• • Infants up to 18 months

  -external jugular vein

  -superior longitudinal sinus

  -temporal vein

  • 18 months up to 3 years

  -popliteal vein

  -femoral vein

  -ankle vein

  • 3 years up to adulthood

  -veins on the antecubital fossa

  -veins on the dorsal of hands and feet

  -wrist vein
• • Poorly controlled diabetes mellitus
  • hemoglobinopathies - disease affecting the structure of hemoglobin, such as sickle cell disease, can lead to fragile blood vessels and altered blood flow
  • Circulatory disorders of the lower extremities
• Open system - uses syringe
• Closed system - uses vacutainer set (vacutainer tube, two-way needle, and adapter)
• phlebotomy needles

  • hypodermic
  • multi sample
  • winged infusion
• Transparent - 16

  Yellow - 18

  Brown - 19

  Violet - 20

  Green - 21

  Black - 22

  Light blue - 23

  Red - 24

  Dark blue - 25

  Orange - 26

  Gray -27
• Butterfly method

  • used for geriatri, pediatric, delicate veins
  • allows more flexibility and precision than a needle and syringe
  • Luer attachment or multi sample Luer adapter
  • Plastic extension allow easier manipulation for the shallow angle of needle insertion
  • safety devices required to prevent accidental needlesticks
• Additives - accelerated clotting of the blood or prevents the blood from clotting
• Two methods of preventing clotting

  • binding calcium
  • inhibiting the formation of thrombin
• EDTA (Ethylenediaminetetraacetic acid)

  • chelating agent preventing blood clotting by binding calcium ions

  •preserves cellular morphology if blood smear is made immediately
• 3 forms of EDTA

  • Na2EDTA - di powder, disodium salt

  • K2EDTA - recommended by CLSI and ICSH

  • K3EDTA - liquid form
• EDTA

  • Complete blood count

  • Hemoglobin estimation

  • Hematocrit or packed cell volume estimation

  • Erythrocyte sedimentation rate by wintrobe

  • HbA1C test

  • Platelet count

  • Red cell indices

  • Differential leukocyte count
• Sodium citrate

  • prevents coagulation by binding the calcium of the blood in a soluble complex
• Heparin

  • coagulation is prevented by its interaction with antithrombin III and subsequent inhibition of thrombin
• Oxalate

  • acts by chelating calcium
• Antiglycolytic agents

  • Substance that prevent glycolysis
  • Sodium fluoride
  • preserves glucose up to 3 days and inhibits bacterial growth
  • used with potassium oxalate (anticoagulant) for rapid response
• Clot activators

  • serum has less protein

  • serum has no anticoagulant

  • doesn’t dilute specimen

  • most reagents are more compatible with serum

  • serum can be more stable than plasma w/ certain substances
• Types of activators

  • Substance that provide more surface for platelet activation

  •Glass or silica particles

  •Inert clays or celite

  •Clotting factors or thrombin

  • Thixotropic gel separator

  •Prevents cells from continuing to metabolize substances

  • Trace element-free tubes

  • Used for trace element tests, toxicology studies, and nutrient determinations
• Order of Draw

  1. blood culture
  2. coagulation tube
  3. serum w/ or w/out activator
  4. heparin
  5. EDTA
  6. sodium fluoride w/ or w/out oxalate
• TISSUE THROMBOPLASTIN CONTAMINATION PRESENT IN TISSUE FLUID:

  • Activates extrinsic coagulation pathway

  •Can interfere with coagulation tests
• FOR COAGULATION TESTS (OTHER THAN PT OR PTT)

  • Draw a few ml of blood into plain red top tube before collecting the coagulation specimen
• MICROBIAL CONTAMINATION

  • Site cleaning most important

  • Microorganisms found on the skin can contaminate blood specimens

  • Blood cultures are collected first in order of draw when sterility of the site is optimal and to prevent contamination of the needle
• Plasma - it is a yellowish fluid portion of the blood that is obtain from a gray tube after centrifugation
• antiseptics

  • zephiran
  • thiomersal
  • methiolate
  • povidone-iodine
  • Chlorhexidine Gluconate (chloraprep) • benzalkonium chloride