Capillary Blood Collection/Skin Puncture

Blood obtained via skin puncture is a mixture of what?

undetermined proportions of blood from arterioles, venules, capillaries, plus interstitial and intracellular fluids.

How do you access capillary beds

puncturing dermis layer of skin

Warming of the puncture site does what

further arterializes the blood and increases blood flow

What are some tests that may be changed by capillary blood (versus venus)

glucose and Blood gas. pO2 and pCO2 see a dramatic difference why you want to arterialize blood.

arterialize

bring more blood from arteries to the capillaries

Heelsticks are done on what part of the population

children less than 1 yo. If they are walking then don't do it.

Finger stick is done on what part of the population

children older than 1 yo.

Other areas that can be stuck for capillary blood besides finger and heel

toe (kids) and ear.

Reasons to collect capillary blood in adults

patients with fragile, superficial or difficult veins to access. patients where multiple unsuccessful venipunctures have already been performed, especially if test requires only a small amount of blood. Patients with burns or scarring in venous blood coll

Central venous pressure lines

patient who need freq. blood draw or meds intravenously. Nurse usually collects blood and infuses meds from ports. 1st 5 mL are thrown out when collecting blood from this method

Additional reasons to collect capillary blood in adults

Patients receiving IV therapy in both arms or hands. Patients at risk for serious complications associated with venipuncture, venous thrombosis or deep venous puncture. Patients whose veins are "reserved" for intravenous therapy or chemotherapy. Point-of-

If someone has a running IV where can you draw blood and tie the tourniquet

below the IV

Where should you stay clear of blood draw and why

wrist because nerve and artery are in that area

Why is forearm not the best choice

it hurts more

Reasons NOT to collect capillary blood

severely dehydrated patients. Patients with poor circulation. Coagulation studies requiring plasma specimens. Tests that require large volumes of blood (ESR and blood culture-blood comes into contact with skin so not sterile)

Why can capillary blood not be used for coagulation studies requiring plasma specimens

blood exposed to damage tissue

Commonly performed tests using capillary blood

Point-of-Care (glucose monitoring), CBC, H&H (hemoglobin and hematocrit), Peripheral blood smear, electrolytes (Na+, K+, Cl-, bicarbonate)

What neonatal test are performed using capillary blood

neonatal blood gases, neonatal bilirubin, neonatal screening (filter paper or blood spot testing)

CLSI recommended order of draw for skin puncture

Blood gases, EDTA tubes (CBC, hematology), other additive tubes, Serum tubes (non-additive)

Amber brown tube

used to protect blood from UV light to prevent degradation of bilirubin

Heel stick should not exceed how many mm and why

2mm to prevent hitting calcutaneous bone

finger stick should go in how many mm

3mm

supplies

alcohol, gauze (cotton ball), band aid, lancet, microtainer (other collection device)

For infants, punctures must NOT be performed on

the posterior curvature of the heel. The central area of the infant's food (arch), the fingers of the newborn or less than 1 yo (flesh to close to bone). Earlobes

Why shouldn't finger stick be performed on index finger

more nerves, more sensitive

Why shouldn't finger stick be performed on pinkie finger

not enough space between flesh and bone

Why shouldn't finger stick be performed on the thumb

thicker area, has a pulse

What to do if blood stops flowing

take a dry gauze and rub on puncture site, squeeze again. Have patient stand with gauze held on finger and swing their arm below heart

How should you clean the site

concentric circles with alcohol pad

why should you wipe away 1st drop of blood with dry gauze pad

1st drop is contaminated with tissue fluid which can cause specimen dilution and hemolysis and clotting. and if you don't then blood in more likely to clot and not free flow

What orientation to the finger print should the lancet be

perpendicular

Minimum fill volume

250 microliters

Ways to warm the site

under warm water, heating pad

scooping leads to

hemolysis or platelet activation

milking and excess squeezing leads to

dilutiong, hemolysis, bruise