Procedure 10-1 outlines the steps for a capillary collection. In addition to these specific steps, you should always greet the patient, identify the patient, and obtain consent, as you would for a routine venipuncture.
The puncture should be made near the fleshy center of the chosen finger. Avoid the edge of the finger, as the underlying bone is too close to the sur- face. As indicated in Figure 10-4, the puncture should be made perpendicular to (across) the ridges of the fingerprint, which lessens the flow of blood into the grooves.
Capillary Collection Sites for Infants For children younger than 1 year, there is too little tissue available in any of the fingers. For this reason, dermal puncture is performed in the heel (Figure 10-5). As shown in Figure 10-6, only the medial and lateral borders of the plantar (bottom) surface can be used. The center of the plantar surface is too close to the calcaneus, as is the poste- rior (back) surface. The arch is too close to nerves and tendons. For older infants, the big toe may be used if the heel is unacceptable. Be aware that the heel may be callused on young children who have begun to walk.
A B Yes C No
FIGURE 10-4 Dermal puncture in adults and children is performed on the third (middle) or fourth (ring) finger, on the palmar surface near the fleshy center of the distal segment.
FIGURE 10-5 BD Microtainer Quikheel Lancet. (Courtesy and
© Becton, Dickinson and Co.)
FIGURE 10-6 Dermal puncture in infants is performed on the heel, on the medial and lateral borders only.
AVOID THAT ERROR!
When phlebotomist Brandon Mayhew entered the waiting
room and saw his next draw, 1-month-old Derek Stevens, he knew he would need to be especially careful to make this dermal collection as smooth as possible for both the infant and the nervous mother. He greeted them warmly, smiled at Derek, and quickly cleansed the infant’s big toe, which Brandon had chosen as the puncture site. Once it was dry, he collected the sample without delay, applied a bandage, labeled the tubes, and thanked the patient. Two weeks later, Derek was admitted to the hospital with a bone infection, and Brandon was named in a lawsuit for injuring Derek. What did Brandon do wrong?
What should he have done? And what should he do now?
PROCEDURE 10-1
Capillary Collection
1. After documenting on the requisition that you are performing a capillary collection, sanitize your hands and put on gloves.
2. Assemble your equipment.
Use the patient’s age and the tests ordered to determine which type of collection tube you will need, what type of skin puncture device to use, and whether to use a warming device.
3. Select and clean the site.
Warm the area first, if necessary. If the site feels cold, it should be warmed for at least 3 minutes at a temperature no greater than 42° C. If a wet washcloth is used, be sure to remove any residual water, as residual water will cause hemolysis and dilution of the specimen.
Use 70% isopropyl alcohol to clean the site.
Allow the site to dry completely. In addition to causing stinging, contamination, and hemolysis, residual alcohol interferes with the formation of rounded drops of blood on the skin surface. (Use of povidone–iodine is not recommended for dermal punctures, because it may elevate test results for bilirubin, uric acid, phosphorus, and potassium. Remember the acronym BURPP to help you learn this group of tests.)
Massaging the finger proximal to the puncture site (closer to the palm) can help increase blood flow. To avoid hemolysis, massage gently, and do not squeeze.
FLASHBACK
Proper hand sanitation and gloving techniques were covered in Procedures 4-1 and 4-2.
Continued
PROCEDURE 10-1—cont’d
Capillary Collection
4. Position and hold the area.
Hold the finger or heel firmly. This prevents it from moving during the puncture and reassures the patient.
Grasp the patient’s finger with its palmar surface up, holding it between your thumb and index finger.
To hold the patient’s heel, place your thumb in the arch, wrap your hand over the top of the foot, and place your index finger behind the heel.
5. Make the puncture, and dispose of the blade properly.
Align the device so the cut is made across the fingerprint ridges or heel lines. This allows the blood to flow out and make a rounded drop, rather than run into the grooves.
Puncture the skin slightly lateral to the center of the finger (that is, slightly toward the pinky finger), so that the hand can be tilted for easier blood flow into the container.
Do not lift the device immediately after the puncture is complete. Count to two before lifting the device to ensure that the blade has made the puncture to the full depth and then fully retracted. Scraping of the skin may occur if the blade is not retracted.
Dispose of the used blade immediately in an appropriate collection container.
Failure to obtain blood: If you are unable to obtain sufficient blood with the first puncture, the policy at most institutions is to attempt one more puncture. You must use a sterile lancet to make the new puncture.
After two unsuccessful punctures, notify the nursing station and contact a different phlebotomist to complete the procedure.
PROCEDURE 10-1—cont’d
Capillary Collection
6. Prepare to collect the sample.
Wipe away the first drop of blood with a clean gauze pad to prevent contaminating the sample with tissue fluid.
Keep the finger in a downward position to help encourage blood flow.
You can alternate applying and releasing firm pressure proximal to the site to increase flow, but avoid constant massaging, as this will cut off flow, cause hemolysis, and introduce tissue fluid back into the sample.
7. Collect the sample.
Once blood is flowing freely, position the container for collection.
Microcollection tubes should be slanted downward. Lightly touch the scoop of the tube to the blood drop, and allow the blood to run into the tube. Do not scrape the skin with the container. This causes hemolysis, activates platelets, and contaminates the sample with epithelial skin cells.
Tap the container lightly to move blood to the bottom. Close the lid after the sample has been collected. Invert the tube 8 to 10 times after filling if additives are present. Be careful not to overfill the microcollection tube con- taining anticoagulant because the ratio of anticoagulant to blood will be exceeded and microclots will form. The collection will need to be repeated due to inaccurate test results.
Order of collection: Platelet counts, complete blood counts (CBCs) and other hematology tests are collected first, followed by chemistry tests.
Be mindful of specimens that require special handling before transport.
Continued
8. Complete the procedure.
Apply pressure to the puncture site using a clean gauze square. Once bleeding has stopped, you can bandage the site for older children and adults. Do not use a bandage on children younger than age 2, as they may remove the bandage and choke on it. When drawing blood from children and infants, be especially careful that all equipment has been picked up and bed rails have been placed back in position.
Label the microsample container, and place it in a larger holder for transport to the laboratory.
As always, thank the patient.
PROCEDURE 10-1—cont’d