LEC 4: VENI

• The most frequently performed procedure in phlebotomy is the venipuncture.
• All phlebotomy procedures begin with the receipt of a test requisition form.
• Initial tourniquet application: 1 minute only.
• According to the CLSI, when a tourniquet is used during preliminary vein selection, it should be released and reapplied after 2 minutes.
• Pumping (repeatedly opening and closing the fist) should be prohibited, as it causes muscle movement that can make vein location more difficult; it can also cause changes in blood components that could affect test results.
• The preferred site for venipuncture is the antecubital fossa located anterior and below the bend of the elbow.
• 3 veins:

  Median Vein

  Cephalic Vein

  • Basilic Vein
• Median Cephalic Vein

  • located near the center; preferred vein for venipuncture because it is large, stationary, least painful due to less nociceptor & bruises less easily
• Cephalic Vein

  • lateral aspect; second choice; hard to palpate but fairly well anchored & the only vein can be felt in obese
• Basilic Vein

  • medial side; not well anchored & rolls easily, ↑ risk of puncturing median cutaneous nerve or the brachial artery
• H – Pattern : Cephalic, Median Cubital, Basilic Vein
• M – Pattern: Cephalic, Median Cephalic, Median Basilic, Basilic Vein
• H – Pattern: 70% of individuals
• Basal state refers to the resting metabolic state of the body early in the morning after fasting for approximately 12 hours.
• Fainting (Syncope)

  • Spontaneous loss of consciousness caused by insufficient blood flow to the brain.
• Hemoconcentration or Venous Stasis:

  • Increase in the number formed elements in blood due to decrease plasma volume.
  • Happens on prolonged tourniquet application!
• Seizures

  Tourniquet and needle should be

  removed, pressure applied to the site,

  and summon help.

  Restrain the patient only to the extent

  that injury is prevented.

  • Document the time the seizure started

  and stopped according to institutional

  policy.
• Petechiae

  • Small, non raised red hemorrhagic spots
  • May have prolonged bleeding following venipuncture.
  • Additional pressure should be applied to the puncture site following needle removal.
  • Petechiae can be an indication of a coagulation disorder, such as a low platelet count or abnormal platelet function.
• Vomiting

  • If the patient is nauseated, instruct the patient to breathe deeply and slowly apply cold compresses to the patient’s forehead.
  • If the patient vomits, stop the blood collection and provide an emesis basin or wastebasket and tissues.
  • Notify the patient’s nurse or designated first aid personnel.
  • Give water to rinse out his or her mouth and a damp washcloth to wipe the face.
• Nerve Injury

  • May result in loss of movement to the arm or hand
  • Permanent injury in the venipuncture procedure is damage to the median antebrachial cutaneous nerve.
• Thrombosis of veins

  • Formation of blood clots inside the

  lumen of the vein due to trauma.
• Thrombophlebitis

  • Inflammation of the vein caused by

  thrombus
• Hematomas

  • Blue or black skin discoloration

  commonly due to repeated trauma or

  puncture of the veins
• Damaged veins – impaired circulation

  (seen in IV drugs users, chronically ill

  patients)
• Hematoma - gives hemolyzed samples.

  COLLECT BELOW HEMATOMA
• Edema - samples are contaminated with

  tissue fluid; notify nursing personnel
• Burns – susceptible to infection
• Scars – difficult to palpate
• Tattoos – dyes cause interference in

  results
• Arm on the same side of Mastectomy –

  increases the blood level of lymphocytes

  and waste products (leads to infection)
• Lipemia or Latescence

  • This is caused by transient rise in

  chylomicrons following a meal

  containing fat

  • It causes interference with large number

  of chemical analyses because of

  turbidity.

  • It disturbs the following investigations

  particularly strongly:

  • Amylase, Bilirubin, Protein, SGOT,

  SGOT
• Status of Sample (stat, timed, routine)
• Fasting: 8-12 hours