Lesson 7: CAPILLARY PUNCTURE

• Capillary puncture is also called skin puncture.
• Capillary puncture is a method that uses a lancet to make a small incision into the capillary bed of the skin to obtain a small volume of blood specimen.
• Lancet/Incision devices are sterile, sharp instruments that are intended for one-time use only.
• Lancet/Incision devices are designed for use in making cuts in the skin for finger or heel puncture.
• Lacer lancet is a type of lancet that produces a small hole in the skin by vaporizing water in the skin.
• Lacer lancet eliminates the risk of sharp injury because cauterizing the skin is not necessary.
• There are 2 types that are used in capillary puncture: finger puncture lancet and heel puncture lancet.
• Microcollection container is also known as microtube
• Microcollection container is a container that is a small plastic tube used to hold blood specimen collected in the capillary puncture.
• Microtube has markings on the side that show the minimum and maximum fill levels and, occasionally, comes with a narrow capillary tube.
• Microhematocrit tubes and sealants are narrow bore tubes that are made of either plastic or glass.
• Microhematocrit tubes and sealants are typically used for hematocrit determinations.
• Microhematocrit tubes and sealants can hold 50 to 75 uL and filled by capillary action. One end is sealed with sealants made of clay or plastic.
• Microscope slides are used for blood films for hematology determinations.
• Warming devices are used to increase the blood flow seven-fold by warming the puncture site.
• Capillary blood gas equipment is a special equipment used for collecting CBG speciment, which contains CBG collection tubes, stirrers, magnet, and plastic caps.
• The capillary blood specimen is a mixture of different blood and fluids which include the following: arterial, venous, and capillary blood, interstitial fluid, and intracellular fluid.
• Arterial blood is the bright red blood found in the pulmonary vein, left chamber of the heart, and arteries.
• It is the oxygenated blood in the circulatory system.

  Arterial blood
• Is the blood that travels from the peripheral veins passing through the venous system then through the right chamber of the heart.

  Venous blood
• This has dark red in color because it is deoxygenated.

  Venous blood
• Is the preferred specimen for infants, young children, elderly patients, and patients with severe burns.

  Capillary blood
• It is extracted from the venules and arterioles found in the capillary bed.

  Capillary blood
• It fills the spaces around the cells, filtered from the blood capillaries, and drained away as lymph.

  Interstitial fluid
• Is found inside the cells, facilitates the movement of fluid in the membrane and blocks the entrance of unwanted materials.

  Intracellular fluid.
• May vary from the venous values.

  Capillary reference values
• The concentration of this in the capillary blood is higher.

  Glucose
• Total protein (TP), calcium (Ca+), and potassium (K+) in the capillary blood are?

  Lower in concentrations
• This could be a good alternative to venipuncture for adults and older children under certain circumstances.

  Capillary specimen
• Circumstances wherein capillary specimen is a good alternative to venipuncture:

  1. Veins are fragile and not accessible because of scars and burns.
  2. Veins are reserved for another procedure such as chemotherapy.
  3. Clotting tendencies
  4. Extreme fear of needles
  5. Veins will be used for glucose monitoring or oral glucose tolerance test (OGTT)
• This is also the preferred method for infants and young children.

  Capillary puncture
• Reasons why capillary puncture is a preferred method for infants and young children:

  1. Health risks such as anemia and cardiac arrest
  2. Requires only a small volume of blood
  3. Venipuncture could damage veins and tissues surrounding the site
  4. Puncturing could result in hemorrhage, thrombosis, gangrene, and infection
  5. Risk of injury because restraint needed in venipuncture and,
  6. Capillary blood is the preferred specimen.
• This should not be used for erythrocyte sedimentation rate methods, blood cultures, and studies that need plasma specimen or have larger volume specimen requirement.

  Capillary puncture
• This refers to the specific sequence with which blood must be drawn and collected in tubes to avoid cross-contamination of additives between the tubes.

  Order of draw
• The order of draw of capillary puncture should be CBG specimens, EDTA specimens, other additive specimens, and serum specimens.
• Review and check accession test request.

  Step 1
• Approach, identify, and prepare the patient.

  Step 2
• Verify diet restrictions and latex sensitivity.

  Step 3
• Sanitize hands and put on gloves.

  Step 4
• Position the patient

  Step 5