Differences between Capillary and 
             Venous Blood
   1. Blood from a skin puncture is a mixture of blood 
   from arterioles, veins and capillaries, and it contains 
   some interstitial and intracellular fluid.
   2. The packed cell volume (PCV), red cell count (RBC) 
   and haemoglobin concentration (Hb) of capillary blood 
   are slightly greater than in venous blood. 
   3. The total leucocyte, neutrophil, and monocyte 
   counts are higher in capillary blood
   4. Conversely, the platelet count appears to be higher 
   in venous than in capillary blood this may be due to 
   adhesion of platelets to the site of the skin puncture.
    
   A. VENOUS BLOOD COLLECTION 
   (PHLEBOTOMY)
  Equipment 
   
  1. Blood container with and/or without anticoagulants  
  2.  Tourniquet:  it  is  used  to  locate  the  patient  vein  by 
  blocking venous, but not arterial, blood flow. Blood pressure 
  cuff at 40 mm Hg can also be used as a tourniquet.
  3. Disposable Plastic Syringes and Disposable Needles
  The needles gauge refers to the diameter of the needle, the 
  lower the number, the larger the needle is  ; those of 19 or 
  21G  are  suitable  for  most  adults.  23G  are  suitable  for 
  children.
  Large  needles  (low  gauge  number)  allow  blood  to  flow 
  quickly  but  may  result  in  post  puncture  bleeding  and 
  hematomas.
  Small  needles  (high  gauge  number  ex.  23-25  gauge)  are 
  suitable for children but allow the blood to flow slowly and 
  microclots  may  form  additionally  they  may  result  in 
  hemolysis.
     Types of syringes used for venipuncture
     Vacutainer system is composed of a multi-sample vacuum 
     collection needle and a disposable tube holder.
    syringe with a syringe needle is used to collect blood from 
    patients with difficult, small or fragile veins. Collecting with a 
    syringe and needle is especially useful when the phlebotomist 
    needs to control the amount of vacuum being applied to 
    prevent or reduce the chance of the vein collapsing.
    Butterfly (Winged Collection Set) needles are used to 
    draw blood from patients with small or fragile veins.
    3. Alcohol (70%) and gauze square or alcohol wipes and gloves 
    8. Adhesive plastic strips.
     
   General guidelines for drawing blood- 
   Syringe Technique:
   1. The needle to be used should be a sterile needle. It should be of a 
     suitable  gauge  in  order  to  facilitate  rapid  flow  into  and  out  of  the 
     syringe and thus minimize hemolysis.
   2. Apply tourniquet around arm 3-4 inches above venipuncture site. Do 
     not leave tourniquet on the arm for more than 1-2 minutes.
   3. Cleanse  venipuncture  site  with  an  appropriate  antiseptic,  usually 
     betadine  ,  70%  isopropyl  alcohol  or  iodine,  using  circular  motion 
     towards the periphery. Allow area to dry before proceeding for two-fold 
     benefit:  it  prevents  the  burning  sensation  for  patient  when 
     venipuncture is performed and it prevents hemolysis of the blood.
   4. Grasp  patient's  arm  firmly,  placing  the  thumb  1-2  inches  below  the 
     chosen site to draw skin taut. This will anchor the vein. If possible, 
     make sure the patient's arm is in a downward position. This will help 
     ensure that no back-flow from the tube will go into the patient's arm
   5. Perform venipuncture entering the vein keeping bevel side of needle 
     up.
   6. Grasp barrel of syringe firmly and pull firmly on plunger until 
   required amount of blood is in the syringe.
   7. Ask patient to open fist and remove tourniquet as soon as the 
   blood begins to flow into the syringe or evacuated tube.
   8. Lightly place gauze or cotton pad upon venipuncture site.
   9. At the completion of the venipuncture, immediately after the 
   needle is removed from the vein apply direct pressure to puncture 
   site.
   10. Ask patient keep arm fully extended, elevate arm and with the 
   other hand apply pressure over puncture site for a few minutes. 
   Check site for  bleeding.  If  site  is  still  bleeding,  continue  direct 
   pressure. Do not bandage until bleeding has completely stopped. 
   Once bleeding has stopped, apply bandage over the gauze pad at 
   site. Advise patient to leave bandage on for 15 minutes.
   11.  Using  a  syringe  to  collect  blood  dictates  the  need  for 
   transferring  the  collected  blood  to  a  test  tube  before  it  clots. 
   Never forcefully eject the collected blood from the syringe into the 
   vacuum tube.