Capillary Puncture AKA: capillary, dermal or skin puncture Useful for pediatric patients to avoid iatrogenic anemia

Capillary Puncture Equipment Lancet Sterile and disposable Retractable blade Either finger or heel Micro-collection containers (microtubes) Used to collect tiny amounts of blood Microhematocrit tubes Manual HCT CBG collection tubes Capillary blood gas specimens

Compositions of Capillary Specimens Mixture of arterial, venous, and capillary blood plus interstitial fluid and intracellular fluid Reference values different than venipuncture specimens Potassium levels falsely elevated with tissue fluid contamination or hemolysis of specimen

Indications for Capillary Puncture Micro volume to avoid anemia Veins need to be reserved for chemotherapy Patients with extensive burns Patients that clot easily Several unsuccessful venipunctures Patients with blenophobia No accessible veins Infants and children POCT testing: CBC, cholesterol & glucose screening

TESTS NOT DONE BY SKIN PUNCTURE Blood cultures Erythrocyte Sedimentation Rate Coagulation studies Tests requiring large volume of sera or plasma Patients where capillary puncture is not appropriate: Dehydrated patients Patients with poor circulation to extremities from shock

Order of Draw Blood gas EDTA specimens (hematology) Other additive specimens Serum specimens

Site Selection Adults and children older than 1 year Palmar surface of the end segment of the middle or ring finger Use non-dominate hand In central fleshy portion slightly to the side of center Perpendicular to grooves of fingerprint NEVER use fingers or earlobes of newborns or infants under 1 year!!

Site Selection Infants Do not to exceed 2.0 mm- Puncturing of bone can lead to osteomyelitis Stick perpendicular on the most medial or most lateral portion of the plantar surface of the heel Calcaneous may be just 2 mm below skin Warm site before puncture Use warm water or heel warmer device Do not exceed 42 degrees C

SKIN PUNCTURES Cleaning the site Always wipe away first drop of blood 70% isopropyl alcohol Never use povidone-iodine as it interferes with some tests Always wipe away first drop of blood Contains fluid plasma, tissue extracts, and possibly alcohol residue Do Not Squeeze (or “milk”) Site Results in hemolysis & increased tissue fluid contamination Do not use a “scooping” motion against the surface of the skin Activates platelets causing them to clump Can cause hemolysis

SKIN PUNCTURES Labeling of specimens: Patient name & ID number Time & Date of collection PBT initials

BLOOD GASES - NEONATES Source of blood is from catheter in umbilical artery Procedure is the responsibility of the pediatric unit or neonatal intensive care unit.

Neonatal Bilirubin Collections Used to detect and monitor increased bilirubin levels in newborns High levels result in jaundice Breaks down in presence of light Collected by heel stick Must be protected from hemolysis and light Use amber colored micro-collection container Turn off UV lamp in crib

Newborn Screening Tests Test for: PKU-phenylketonuria-a genetic disorder Hypothyroidism Galactosemia Cystic Fibrosis Blood spot collection: Heel stick blood collected by absorption onto 5 circles on a special paper Paper must not touch heel Blood must completely fill circles from one side of the paper only Contaminants include: alcohol, formula, lotion, power, urine

BLOOD SMEARS Wipe away first drop of blood, make smear immediately. EDTA Blood Tube: Make blood smears within 1 hour of collection May be stored at 4 degrees celsius (refrig.) overnight for CBC For smears: 3 - 4 hours after standing at room temperature. Acceptable smear: Blood covers half to three-fourths of the slide with a feathered edge Has no holes, lines, or jagged edges

BLOOD SMEARS Smear fixative - methyl alcohol for 1 minute Manual wedge - spreader/pusher slide; 30 degree angle Spinner - automated cell counter