Dermal Puncture Techniques Vocabulary

Vocabulary flashcards covering dermal puncture principles, site selection, depth safety guidelines, equipment, and CLSI capillary order of draw.

Interstitial fluid

Fluid located within the tissue spaces surrounding cells.

Intracellular fluid

Fluid contained inside the individual cells.

Capillary blood specimen composition

A mixture of arterial blood, venous blood, capillary blood, interstitial fluid, and intracellular fluid, where arterial blood comprises the largest portion.

Capillary glucose level

The concentration of glucose in capillary blood, which tests slightly higher than in venous blood due to the higher proportion of arterial blood entering under pressure.

Indications for dermal puncture

Primary collection choice for infants and children under two years old, as well as patients with fragile/inaccessible veins, patients with IV therapy in both arms/hands, or patients whose veins are reserved for IV therapy/chemotherapy.

Contraindications for dermal puncture

Conditions where dermal puncture is inappropriate, including severe dehydration, poor circulation, coagulation studies requiring plasma, or tests requiring large blood volumes.

Laser lancing device

A rarely used lancing device that vaporizes water in the skin to produce a small hole in the capillary bed.

Puncture lancing device

A dermal device recommended for fingersticks where repeated punctures are performed.

Slicing lancet

A lancing device recommended for infant heel sticks that slices through the capillary bed, providing a less painful procedure, shorter collection time, and fewer required repeat punctures.

Osteomyelitis

Infection or inflammation of the bone that can occur if a lancet punctures bone during a dermal procedure.

Infant heel warmer

A single-use heating pack applied to skin prior to puncture that increases local blood flow up to $7\times$.

Adult fingerstick site

The fleshy pad at the end of the distal phalanx of either the 3rd (middle) or 4th (ring) finger, positioned slightly off-center.

Infant heelstick site

The outer medial or lateral plantar surfaces of the heel for infants under 1 year of age, avoiding the central heel area to prevent bone and nerve damage.

Perpendicular incision orientation

The technique of puncturing across the fingerprint lines so that blood forms a rounded drop rather than running down fingerprint grooves.

Maximum infant heelstick depth

$2.5\,mm$; depths greater than this risk penetrating bone, causing osteomyelitis and permanent damage to the foot.

Infant lancet depth for $1\text{--}2\,kg$

$0.75\text{--}1.0\,mm$, specified for premature infants weighing $1\text{--}2\,kg$ ($2.2\text{--}4.4\,lbs$).

Infant lancet depth for $2\text{--}3\,kg$

$1.0\text{--}2.0\,mm$, specified for infants weighing $2\text{--}3\,kg$ ($4.4\text{--}6.6\,lbs$).

Infant lancet depth for $3\,kg$ or greater

$2.0\text{--}2.5\,mm$, specified for infants weighing $3\,kg$ ($6.6\,lbs$) or greater.

Wiping the first drop of blood

The essential step of wiping away the initial blood drop with sterile gauze to eliminate tissue fluid contamination and prevent dilution or hemolysis of the sample.

CLSI capillary order of draw

1. Capillary blood gas specimens, 2. EDTA specimens, 3. Other additive specimens, 4. Serum specimens.

Milking a puncture site

The contraindicated action of excessively squeezing or massaging a puncture site, which causes hemolysis and dilutes the specimen with interstitial fluid.