Capillary Puncture and Equipment procedures

• A lancet is a sterile, disposable, sharp-pointed or

  bladed instrument that either punctures or

  makes an incision in the skin to obtain capillary

  blood specimens for testing
• Lancets are specifically designed for either

  finger puncture, or heel puncture, and must have

  OSHA-required safety feature
• Laser Lancets- A laser typically vaporizes water in the skin to

  produce a small hole in the capillary bed without

  cauterizing delicate capillaries
• Microcollection containers also called

  microtubes, are special small plastic tubes used

  to collect the tiny amounts of blood obtained

  from capillary punctures.

  They are often referred to as “bullets” because of

  their size and shape. Some come fitted with

  narrow plastic capillary tubes to facilitate

  specimen collection
• Microcollection container- Most have color-coded bodies or stoppers

  that correspond to color-coding of ETS blood

  collection tubes, and markings for minimum

  and maximum fill levels that are typically

  measured in microliters (uL) ,such as 250 uL

  and 500 uL, respectively
• A relatively new microtube, the BD

  Microtainer® MAP has a penetrable septum

  for use with automated hematology systems.

  Some manufacturers print lot numbers and

  expiration dates on each tube
• Microhematocrit tubes are disposable,

  narrow-bore plastic or plastic-clad glass

  capillary tubes that fill by capillary action and

  typically hold 50 to 75 L of blood.

  They are used primarily for manual

  hematocrit (Hct), also called packed cell

  volume (PVC), determinations.
• MICROHEMATOCRIT TUBES AND

  SEALANTS- The tubes come coated with ammonium

  heparin, for collecting Hct tubes directly from a

  capillary puncture, or plain, to be used when an

  Hct tube is filled with blood from a lavender-top

  tube.
• Heparin tubes typically have a red or green

  band on one end; nonadditive tubes have a

  blue band.
• CBG collection tubes: CBG collection tubes are

  long thin narrow-bore capillary tubes. They are

  normally plastic for safety and are available in a

  number of different sizes to accommodate

  volume requirements of various testing

  instruments
• The most common CBG tubes are

  100 mm in length with a capacity of 100 L. A

  color-coded band identifies the type of

  anticoagulant that coats the inside of the tube; it

  is normally green, indicating sodium heparin
• Stirrers: Stirrers are small metal

  filings (often referred to as “fleas”)

  or small metal bars

  that are inserted into the tube after

  collection of a CBG specimen to aid

  in mixing the

  anticoagulant.
• The magnet typically has an opening in the

  center or side so that it can be slipped over the

  capillary tube and moved back and forth along

  the tube length, pulling the metal stirrer with it,

  and mixing the anticoagulant into the blood

  specimen.
• Plastic caps:

  Plastic end caps or closures are

  used to seal CBG tubes and

  maintain anaerobic conditions in the

  specimen.

  CBG tubes typically come with their

  own caps.
• Glass microscope slides are

  occasionally used to make

  blood films for hematology

  determinations.
• Warming Devices- Warming the site increases blood flow as

  much as seven times. This is especially

  important when performing heelsticks on

  newborns. Heel-warming devices are

  commercially available.
• Capillary specimens are a mixture of arterial, venous, and capillary

  blood, along with interstitial fluid (fluid in the tissue spaces between

  the cells) and intracellular fluid (fluid within the cells) from the

  surrounding tissues.
• Because the composition of capillary blood differs

  from that of venous blood, reference (normal)

  values may also differ. For example, the

  concentration of glucose is normally higher in

  capillary blood specimens, whereas total protein

  (TP), calcium (Ca2+), and potassium (K+),

  concentrations are lower
• The CLSI order of draw for capillary specimens is as follows:

  • Blood gas specimens (CBGs)

  • EDTA specimens

  • Other additive specimens

  • Serum specimens
• Adults and Older Children recommended site for capillary

  puncture on adults and children older than 1 year is the palmar

  surface of the distal or end segment of the middle or ring finger

  of the nondominant hand.
• The puncture site should be in the central, fleshy portion of the

  finger, slightly to the side of center and perpendicular to the

  grooves in the whorls (spiral pattern) of the fingerprint.
• Puncture of the bone can cause painful osteomyelitis
• Punctures deeper than 2mm may cause bone damage. The

  vascular or capillary bed in the skin of a newborn is located at

  the dermal–subcutaneous junction between 0.35 and 1.6 mm

  beneath the skin surface
• According to CLSI, to avoid puncturing bone the only

  safe areas for heel puncture are on the plantar surface

  of the heel, medial to an imaginary line extending from the middle
• The CLSI-recommended antiseptic for

  cleaning a capillary puncture site is

  70% isopropanol.
• Prompt delivery to the lab protects

  specimen integrity and is typically

  achieved by personal delivery,

  transportation via a pneumatic tube

  system, or a courier service.
• Capillary puncture blood is less desirable for blood gas

  analysis, primarily because of its partial arterial composition

  and also because it is temporarily exposed to air during

  collection, which can alter test results.
• Overproduction of bilirubin occurs from accelerated red blood

  cell hemolysis associated with hemolytic disease of the

  newborn
• Bilirubin can cross the blood–brain barrier in infants,

  accumulating to toxic levels that can cause permanent brain

  damage or even death.

  • A transfusion may be needed if levels increase at a rate equal

  to or greater than 5.0 mg/dL per hour or when levels exceed

  18.0 mg/dL.
• Newborn/neonatal screening (NBS)

  is the state mandated testing of

  newborns for the presence of certain

  genetic (inherited), metabolic

  (chemical changes within living

  cells), hormonal, and functional

  disorders that can cause severe

  mental handicaps or other serious

  abnormalities if not detected and

  treated early.

  • Some states also screen for

  infectious agents, such as

  toxoplasma and HIV.
• Most NBS tests are ideally performed when

  an infant is between 24 and 72 hours old.

  • Because of early hospital release, some

  infants are tested before they are 24 hours old
• Specimens for NBS tests are collected by

  heel puncture and require a special state

  form.
• Blood smears are considered biohazardous or infectious until they

  are stained or fixed
• Thick blood smears are most often

  requested to detect the presence of

  malaria, a disorder caused by four

  species of parasitic sporozoan

  (types of protozoa) organisms

  called plasmodia. These organisms

  are transmitted to humans by the

  bite of infected female anopheles

  mosquitoes.
• The smear is allowed to dry for a minimum of

  2 hours before staining with fresh diluted

  Giemsa stain, a water-based stain that lyses

  the red blood cells and makes the organism

  easier to see.