Phlebotomy Ch 10 Capillary Puncture

Question 1

What is a lancet/incision device?

Answer 1

Lancet/Incision Devices

1. Sterile, disposable, sharp-pointed or bladed instrument
2. Punctures or cuts skin to obtain capillary blood specimen
3. Designed for either finger or heel puncture

Question 2

Are some lancets designed specifically for finger punctures?

Answer 2

Yes.

Question 3

What is an important required lancet safety feature?

Answer 3

Permanently retractable blade to reduce risk of accidental sharp injury.

Question 4

Are some lancets designed specifically for heel punctures for infants? What do they do differently?

Answer 4

Some are designed specifically for heel punctures for infants
These devices don’t puncture with a needle in and out but take a slice of infants heel

Question 5

What features do micro-collection containers/microtubes have?

Answer 5

Small plastic tubes used to collect tiny amounts of blood from capillary punctures
Some come with narrow capillary tubes attached
Have color-coded bodies or stoppers & markings for min/max fill levels

Question 6

How is micro collection useful for pediatric patients?

Answer 6

Capillary specimen collection is especially useful for pediatric patients in whom removal of larger quantities of blood by venipuncture can have serious consequences.

Question 7

What are microhematocrit tubes and sealants? What are they used for/

Answer 7

Microhematocrit Tubes & Sealants
Disposable, narrow-bore plastic or plastic-clad glass tubes
Fill by capillary action & hold 50 to 75 uL
Used primarily for hematocrit determinations
One end of tube is sealed w. plastic or clay sealants

Question 8

What are capillary blood gas equipment (CBG)?

Answer 8

Capillary Blood Gas Equipment (CBG)

1. CBG collection tubes: narrow-bore plastic capillary tubes
2. Stirrers: metal filings or bars inserted into tube to mix
3. Magnet: used for mixing, in conjunction w. stirrer
4. Plastic caps: used to seal tubes

Question 9

Name capillary puncture equipment?

Answer 9

Lancet/incision devices
Finger Puncture Lancets
Heel Puncture Lancets
Microcollection / Microtubes
Microcollection Containers
Microhematocrit Tubes & Sealants
Capillary Blood Gas Equipment (CBG)
Microscope Slides
Warming Devices

Question 10

What is the composition of capillary specimens?

Answer 10

1. Mixture of arterial, venous, and capillary blood.
2. Interstitial and intracellular fluid.
3. More closely resembles arterial blood than venous blood.

Question 11

How do capillary reference values differ from venous values?

Answer 11

Capillary reference values may differ from venous values
Glucose concentrations are higher in capillary blood
Bilirubin, Total protein (TP), calcium (Ca2+), and potassium (K+) concentrations are lower in capillary blood

Question 12

What are some reasons to perform (indications) capillary puncture in older children and adults?

Answer 12

Available veins are fragile or must be saved for other procedures
Several unsuccessful venipunctures have been performed
Patient has clot-forming tendencies
Patient is apprehensive or has an intense fear of needles
There are no accessible veins (IVs in both arms, scars, burns)
For POCT procedures such as glucose monitoring

Question 13

What are reasons for performing capillary puncture in infants and young children?

Answer 13

Small blood volume & risk of anemia
Risk of cardiac arrest when large quantities of blood are removed
Venipuncture is difficult & may damage veins & surrounding tissues
Puncturing deep veins can cause hemorrhage, venous thrombosis, infection, & gangrene
Risk of injury due to restraint needed for venipuncture
Capillary blood is preferred specimen for some tests (NBS)

Question 14

What are some tests that cannot be collected by capillary puncture?

Answer 14

1. Most erythrocyte sedimentation rate methods
2. Coagulation studies that require plasma specimens
3. Blood cultures
4. Tests that require large volumes of serum or plasma

Question 15

What is the CLSI order of draw for capillary punctures?

Answer 15

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

NOTE: NBS should be collected separately from a separate puncture

Question 16

What challenge occurs with collection of capillary punctures?

Answer 16

Puncturing the skin releases tissue thromboplastin which activates the coagulation process. Specimens must be collected quickly to minimize the effects of platelet clumping and microclot formation AND to obtain the correct amount of blood before the site stops bleeding.
Note:
CBGs first to minimize exposure of the blood to air and clotting is unacceptable
EDTA specimens second as clotting is unacceptable
Other additives next can be affected by clotting but not as much as EDTA/hematology
Serum last as they are suppose to clot

Question 17

What are the steps for capillary puncture?

Answer 17

Step 1: Receive, review, & accession test request
Step 2: Approach, greet, & identify patient
Step 3: Explain the procedure & obtain consent
Step 4: Verify collection requirements & identify sensitivities & potential problems
Step 5: Sanitize hands & put on gloves
Step 6: Position the Patient
Step 7: Select the puncture site.
Step 8: Warm the site if applicable.
Step 9: Clean and air dry site.
Step 10: Prepare Equipment
Step 11: Grasp the Finger or Heel Firmly
Step 12: Position lancet, puncture the site, & discard lancet.
Step 13: Lower finger or heel & apply gentle pressure until blood drop forms.
Step 14: Wipe away first blood drop.
Step 15: Fill and Mix Tubes/Containers in Order of Draw
Step 16: Place Gauze, Apply Pressure, Elevate Site
Step 17: Label & Prepare Specimens for Handling & Transport
Step 18: Check the Site, & Apply Bandage
Step 19: Discard Used Materials, Thank Patient, Remove Gloves, Sanitize Hands
Step 20: Transport Specimen to the Lab Promptly

Question 18

What are the types of special capillary puncture procedures?

Answer 18

1. Neonatal bilirubin collection
2. Newborn/neonatal screening:
   - Phenylketonuria
   - Hypothyroidism
   - Galactosemia
   - Cystic fibrosis
3. Routine blood film/smear preparation.
4. Thick blood smear preparation.

Question 19

What is the newborn screening specimen collection form?

Answer 19

1. Newborn screening specimen collection equipment & blood spot collection form
2. Link to Cadham newborn Screening

You just put blood on these circles and then mail it into Cadham.
One drop into each circle. Don’t go back and layered the blood in the circle (so no more than one drop).

Question 20

What is a thick blood smear preparation and what is it used for?

Answer 20

Thick blood smear preparation
Used to test for malaria
Diagnosed by presence of organism in peripheral blood smear
A very large drop of blood is placed in center of glass slide

Question 21

How do you prepare a thick blood smear?

Answer 21

1. A very large drop of blood is placed in center of glass slide.
2. Drop is spread with corner of another slide or cover slip until it is the size of a dime.
3. Allow to dry for a minimum of 2 hours before staining.

Question 22

Why don’t you puncture the index finger?

Answer 22

It is usually more calloused and harder to puncture as well as more sensitive. (TB, Table 10-2)