Chapter 6: Pediatric Draws and Capillary Blood Collection

Where are pediatric blood draws usually performed?

On the arm

When approaching peds patients, what is the APE strategy?

• Approach: approach the patient in a calm, friendly manner

• Position: if possible, position the patient on the parent’s lap

• Equipment: use a high gauge butterfly needle and pediatric tubes

For pediatric patients, what is the recommended draw amount?

No more than 1% to 5% of an infant’s total blood volume within a 24 hr period

capillary collection/dermal puncture

method for collecting low volume blood samples by puncturing the skin to collect capillary blood for diagnostic testing

capillary

tiny blood vessels just beneath the surface of the skin

interstitial fluid

fluid that surrounds cells and tissues

capillary action

movement of liquid through narrow spaces due to cohesion (molecule attraction) and adhesion (surface attraction) without external forces like gravity

lancet

small, sharp medical device used to puncture the skin to obtain small blood samples

What are the methods for capillary collection?

• Microcollection tube

• Microhematocrit tube

• Point of Care Testing Device

• Blood Spot Collection Card

microcollection tube

small plastic container used to collect a small amount of blood

microhematocrit tube

thin glass or plastic tube that draws blood as it beads on the skin through capillary collection

point of care testing (POCT) device

uses test strips to test the blood for immediate results

blood spot collection card

used to collect samples from newborns for screening and lab testing

How much blood do microcollection tubes hold?

Up to 0.75 mL

What is the order of draw for microcollection tubes?

EDTA, Heparin, Any other additive, Serum (EHAS)

How full should a microhematocrit tube be?

About 2/3 full

analytes

substances in the blood that are measured for diagnostic purposes

For blood spot collection cards, what will happen if blood is smeared outside the circle?

It will be rejected

Where do phlebs draw from on infants who are under 1-2?

The medial and lateral underside of the heel

For preterm infants, what is the recommended maximum heel puncture depth?

0.85 mm

For full term infants, what is the recommended maximum heel puncture depth?

2.0 mm

osteomyelitis

infection induced inflammation of the bone

Newborn screening (NBS)

A series of tests performed on neonates (newborns in the first 28 days of life) to enable the early detection and management of certain health conditions

bilirubin

substance produced when red blood cells breakdown

What can happen when bilirubin builds up in infants?

Jaundice- yellowing of skin, eyes, and mucous membranes

phenylketonuria (PKU)

genetic disorder that causes phenylaline to accumulate to dangerous levels in the body

What happens if PKU isn’t treated?

Brain damage and developmental delays

When is a PKU test collected?

Within 72 hours of birth

hypothyroidism

condition of having an underactive thyroid which results in inadequate levels of thyroid hormones

galactosemia (GALT)

rare inherited metabolic disorder caused by a deficiency of the enzyme that converts galactose into glucose

What sites shouldn’t be used for fingersticks and why?

• Thumb: has a pulse; can lead to excessive bleeding

• Index: usually callused; can be difficult and painful

• Pinky: bone is close to surface

Where should the puncture be made on fingersticks?

Fleshy side of the fingertip and perpendicular to the fingerprint grooves

hemolyze

red blood cells breaking down and releasing their contents into surrounding fluid

For children, how deep should fingertip punctures be?

1.5 mm to 2.4 mm

For adults, how deep should fingertip punctures be?

2.0 mm to 2.4 mm

hemostasis

physiological process that stops bleeding after an injury by coagulation

What are the 4 phases of blood clotting?

1. Vasoconstriction: vessel narrows causing a decrease in blood flow

2. Platelet Plug Formation: platelets in the blood first stick to the damaged endothelium, then gather together to form a temporary plug through aggregation

3. Coagulation: platelet plug is reinforced by a stable fibrin clot which occurs through a coagulation cascade, which activates clotting factors in a specific sequence

4. Clot Retraction and Fibrinolysis: clot shrinks to bring wound edges closer together, reopening the lumen of the vessel; fibrinolysis then occurs breaking down and removing the blood clot once healing is complete

aggregation

the clumping of platelets to form a temporary plug at the site of a blood vessel injury

fibrinolysis

the process by which the body breaks down and removes a blood clot

When doing a capillary stick, what should you remember to do?

Wipe away the first drop of blood b/c it has skin cells and interstitial fluid