c4-CAPILLARY PUNCTURES.docx

CAPILLARY PUNCTURES =================== Capillary collection method --------------------------- Dermal punctures, also called capillary blood collections or finger sticks, are done for a variety of reasons. They can be performed for tests that require a small amount of blood, when a patient does n...

CAPILLARY PUNCTURES =================== Capillary collection method --------------------------- Dermal punctures, also called capillary blood collections or finger sticks, are done for a variety of reasons. They can be performed for tests that require a small amount of blood, when a patient does not have an accessible vein, but a blood collection is essential, or if the test requires capillary blood. A dermal puncture can also be ordered for a patient who is at risk of iatrogenic anemia, since a smaller volume of blood is used for tests performed using this method. Capillary blood collections are common for many point-of-care (POC) blood tests, including glucose, cholesterol, and hematocrit. The patient\'s age, health status, and requested tests all assist in determining whether a venipuncture or capillary blood collection is necessary. For infants younger than 1 year old, a capillary collection is the preferred method because it requires less blood. Infants\' veins are small, and numerous venipuncture procedures can result in damage to the vessels. Capillary collections require less blood and therefore reduce the chance of iatrogenic anemia. Some older adults have compromised veins that are difficult to find. In these cases, use a capillary collection to obtain the blood for testing. Patients who are underweight also run the risk of iatrogenic anemia. Because a smaller amount is needed for a microcollection tube, the use of a capillary collection helps reduce this risk. A dermal puncture blood specimen contains three types of blood: arterial, capillary, and venous. When a dermal puncture is chosen over a venipuncture, document this on the medical requisition to alert the laboratory that the blood has a different composition than venous blood. Even in healthy adults, you can use a capillary blood collection when there is no need for a large volume of blood, when the test is to be performed repeatedly (such as for home glucose testing), or when the test being performed requires capillary blood. In adults, capillary blood collections are performed on the middle or ring finger of the nondominant hand. In infants up to 1 year old, capillary blood collections are performed on the heel. When the testing requires only a small amount of blood, the patient\'s condition indicates that a venipuncture is not appropriate, or the blood test requires a dermal puncture, you may need to perform a finger or heel stick. The following is the step-by-step dermal puncture procedure: 1. Introduce yourself. 2. Identify the patient using at least two methods of identification. 3. Position the patient. The patient should be sitting or lying down. It can be helpful to have the patient place their hand below the level of the heart. 4. Wash hands. 5. Don gloves. 6. Assemble the equipment: disposable gloves, isopropyl alcohol swabs (or the antiseptic specified by the workplace), adhesive bandage, gauze, lancet, and microcollection tubes. 7. Check the warmth of the hand chosen. A warmed site makes the blood flow easier. 8. Identify the site. For adults and children older than 1 year, use the middle or ring finger (third or fourth digit) for a dermal puncture. The little finger is too thin, and the bone is too close to the surface. The index finger is likely to be too sensitive or have thick calluses. The thumb has a pulse, so it should be avoided as well. It is preferable to use the fleshy off-center side of the finger for the dermal collection. The tip of the finger is more sensitive, has fewer capillaries, and can have calluses. Never perform a finger stick on a finger that is cold, cyanotic (blue), scarred, swollen, or has a rash. If you are not sure whether the finger is suitable for a finger stick, use another finger. If the finger is thickly callused, choose another finger. 9. If the patient\'s fingers are cold and the blood supply is limited, have the patient open and close their hand a few times or rub their hands together vigorously. You also can instruct the patient to place their hand below the level of the heart for 30 seconds. Or have the patient wash their hands in warm water to raise the temperature, remove any contaminates, and increase blood flow. 10. Cleanse the site with isopropyl alcohol. Let it air-dry. 11. Puncture the site with the lancet. When using an incision lancet (one that will make a little slash in the skin), make the puncture perpendicular to the fingerprint lines. This will help the blood form into a large drop that is easy to collect. Cuts made parallel to the fingerprint lines cause the blood to flow down the finger, making the blood more difficult to collect. (Many facilities provide and encourage the use of auto-lancets, which regulate the skin puncture depth. This is safer for the patients and simpler for the phlebotomist.) 12. Dispose of the lancet into the biohazard sharps container. 13. Wipe away the first drop of blood. This helps remove any alcohol or tissue fluid from the blood collection. 14. Allow the blood to drip into the collection tube. Cap the tube when it is filled. If the blood flow is slow or stops, you can have the patient drop the hand below the level of the hear. You can provide pressure to the first joint of the finger with a press­ and-release technique, allowing the blood to form large drops. Do not "scoop\" the blood to speed collection, because this can affect accuracy of test results. If you are collecting multiple tubes, you should have a container for the filled but uncapped tubes while you are collecting another tube. Do not take longer than 2 minutes to fill each tube. Gently invert filled tubes to mix. 15. After capping the tubes, use a gauze pad and apply pressure to the puncture site for several minutes. When the bleeding has stopped, put an adhesive bandage over the puncture site if the patient is an adult or responsible child. Children can remove the bandage and swallow it. Adhesive bandages can irritate or tear the skin of infants. 16. Label every specimen before leaving the patient\'s bedside. 17. Thank the patient. 18. Observe for any complications. 19. Collect all garbage from the area. Check the floor for anything that might have fallen during the collection. 20. Remove gloves. 21. Wash hands. When performing a dermal puncture for other blood tests (glucose, cholesterol, hematocrit), follow the manufacturer\'s instructions specific for each test. The steps will remain the same except for how the blood is collected and the method the blood is put in the cassette, cuvette, or strip. Follow the instructions for a dermal collection (including wiping away the first drop of blood) and avoid milking the finger, which can hemolyze the specimen or in other ways alter test results. A heel stick is used to obtain capillary blood from infants younger than 12 months. The veins of infants are too small for a standard venipuncture, and infants do not have sufficient tissue on their fingers for a finger stick. Heel sticks can be used for almost any blood test. The following is the step-by-step procedure for a heel stick. 1. Assemble the equipment: disposable gloves, a heel warming device (optional), isopropyl alcohol swab (or the antiseptic specified by your workplace), a sterile lancet no deeper than 2 mm, microcollection tubes, and a gauze pad. 2. Choose the right lancet. Each lancet will puncture the skin to a specified depth. For example, if the child\'s weight is equal to or less than 1 kg, choose a lancet that punctures the skin to a depth of 0.65 mm. Never use a lancet that goes deeper than 2 mm. A common size used for infants is a 1 mm depth lancet. 3. Position the patient. If possible, a child should be supine. Check with the patient\'s nurse or provider to see whether there are restrictions about positioning. 4. Apply the heel warmer for 3 to 5 minutes. 5. Wash your hands, and don gloves. 6. Select a site. The best sites for a heel stick are the lateral or medial sides of the heel. The skin between the lateral and medial sides should be considered a secondary site. Do not use the back of the heel-there is too little skin/tissue in that area, and a lancet puncture can damage the bone. Do not use a site that was recently used or has a hematoma or scratch. 7. Cleanse the site. 8. Place the lancet on the skin and make the puncture. After the puncture has been made, use your thumb and fingers to gently squeeze the heel. Do not squeeze for a long time or use excessive pressure. Doing so can affect the accuracy of the test results. 9. Wipe away the first drop of blood. 10. Touch the open tip of the collection tube to the puncture site. The blood should drip into the tube. Allow the blood to passively drip into the tube. Do not scoop the blood to speed collection, because this can affect the accuracy of the test results. 11. If the flow of blood stops, wipe away any surface clots with a gauze pad, and stop squeezing the heel. These actions will remove surface clots that have stopped the blood flow and allow the capillaries to refill. 12. When the tubes are filled and capped, use a gauze pad and apply pressure to the puncture site to stop further bleeding. 13. Observe for any signs of complications. 14. Label all tubes before leaving the patient. 15. Bandage as appropriate for an infant. Capillary order of the draw --------------------------- The order of the draw is equally important for dermal puncture collections, but for distinctly different reasons. The order of the draw for a venipuncture is followed to help prevent additive cross-contamination. With dermal punctures, because the blood begins to clot as soon as the flow begins, the order of the draw helps ensure that the sample is collected in an order that has the least negative effect on the blood test. The following is the CLSI order of the draw for capillary collection. - **Blood gas collections:** When a blood gas is performed on an infant, the patient can cry or hold their breath during the procedure. Collecting any blood gases first helps ensure that the blood that is tested is as close as possible to what is in the patient\'s body. - **Purple, lavender, pink, or pearl cap tubes contain the additive EDTA**. Because clotting of the blood can alter the hematology of the specimen, it is important to collect any EDTA tubes as close to first as possible. - **Green:** Green cap tubes contain the additive heparin. - **Any other additive specimens.** - **Serum:** Red or gold cap tubes contain no additive or clot activator. Because the blood from a dermal puncture starts to clot as soon as the blood flow begins, and the serum is required to clot.