MLSP DERMAL LAB

• Capillary blood is a mixture of arterial and venous blood and may contain small amounts of interstitial and intracellular fluids
• Depth of dermal puncture:

  • Newborns: 0.35 to 1.6 mm below the skin
  • Adults: 3.0 mm
• Dermal puncture devices include lancets, microsample containers, capillary tubes, and microhematocrit tubes
• Microhematocrit tubes are color-coded: red band for heparinized tubes and a blue band for plain tubes
• Microtainers provide a larger collection volume and present no danger from broken glass, designed to hold approximately 600 µL of blood
• Phlebotomist preparation for dermal puncture includes wearing gowns and gloves, extensive hand washing, and carrying only necessary equipment to the patient area
• Patient identification and preparation involve requisition form, verbal identification, and ID band. Excessive crying may affect the concentration of white blood cells and capillary blood gases
• Patient position for dermal puncture:

  • Seated or lying down with the hand supported on a firm surface, palm up, and fingers pointed downward for fingersticks
  • For heelsticks, infants should be lying on the back with the heel in a downward position
• Site selection for dermal puncture:

  • Heel and distal segments of the third and fourth fingers are common sites
  • Performing dermal punctures on earlobes is not recommended
  • Areas selected should not be callused, scarred, bruised, edematous, cold or cyanotic, or infected
• Warming the site dilates blood vessels and increases arterial blood flow. The site should not be warmed for longer than 10 minutes
• Cleansing the site involves using 70% isopropyl alcohol in a circular motion, allowing it to dry for maximum antiseptic action
• Performing the puncture:

  • The heel or finger should be well supported and held firmly
  • Massaging the area before the puncture may increase blood flow
• Puncture device disposal: After completing the puncture, the puncture device should be placed in an appropriate sharps container
• Sample collection:

  • The first drop of blood must be wiped away with a clean gauze
  • Blood should be freely flowing from the puncture site as a result of firm pressure
• Capillary tubes and micropipettes are held horizontally while being filled to prevent the introduction of air bubbles
• Microcollection tubes are slanted down during the collection, and blood is allowed to run through the capillary collection scoop and down the side of the tube
• Order of collection: Capillary blood gases, blood smear, EDTA tubes, other anticoagulated tubes, serum tubes
• Bandaging the patient involves applying pressure to the puncture site with gauze and elevating the finger or heel until bleeding stops
• Labeling the sample: Microsamples must be labeled with the same information required for venipuncture samples
• Completion of the procedure includes disposing of all used materials in appropriate containers, removing gloves, washing hands, and thanking the patient and/or parents for their cooperation