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