Chapter 31

1. Indications. Capillary blood sampling is the most common procedure done in neonatal intensive care nurseries.

1. Collection of blood samples when only a small amount of blood is needed or when there is difficulty obtaining samples by venipuncture.

1. Capillary blood gas sampling.

1. Blood cultures when venous access is not possible.

1. Newborn metabolic screen.

2. Equipment. Sterile lancet (2-mm lancet if <1500 g or 4-mm lancet in larger infants). Automated self-shielding lancets are associated with fewer complications and decreased pain (BD Quickheel Preemie and Tenderfoot Preemie are 1.75 mm for >1000 g; BD Quickheel Infant and Tenderfoot Newborn are 2.5 mm for term up to 6 months; Tenderfoot Micro-Preemie are for <1000 g); alcohol swabs, 4 × 4 sterile gauze pads, a capillary tube (for rapid hematocrit and bilirubin tests) or larger BD Microtainer collection tubes (if more blood is needed [eg, for blood chemistry determinations]), filter paper card for newborn screening (if appropriate), clay to seal the capillary tube, a warm washcloth, gloves, and a diaper.

3. Procedure

1. Wrap the foot in a warm washcloth and then in a diaper for 5 min. Although not mandatory, it will produce hyperemia which increases vascularity, making blood collection easier. It is mandatory when collecting a sample for a blood gas or pH determination. A warming pad may be used, but its temperature should not exceed 40°C. Commercial packs are now available to heat the heel, and these should be applied for 5 min.

1. Eutectic mixture of lidocaine and prilocaine (EMLA) was not found to be effective in heelsticks. Automated devices cause less pain. Oral sucrose, swaddling, and a pacifier can also be used for pain reduction. (See Chapter 69.)

1. Choose the area of puncture (Figure 31–1A). Avoid the center of the heel because this area is associated with an increased incidence of osteomyelitis. Heelsticks are contraindicated with local infection, significant edema, or poor perfusion.

1. Wipe the area with an alcohol swab, and let it dry. If the area is wet with alcohol, hemolysis may occur, altering the results of blood testing.

1. Using a standard heel lancet, encircle the heel with the palm of your hand and index finger (see Figure 31–1A). Make a quick deep (<2.5-mm) puncture.

1. Wipe off the first drop of blood with gauze. Gently squeeze the heel, and place the collection tube at the site of the puncture. The capillary tubes should automatically fill by capillary action. It may be necessary to gently "pump" the heel to continue the blood flow to collect drops of blood in a larger tube. Allow enough time for capillary refill of the heel, and apply pressure so the incision is opened with each pumping maneuver.

1. Avoid excessive squeezing, which may cause hemolysis and give inaccurate results. Seal the end of the capillary tube with clay; collect the larger samples in the BD Microtainer or similar tubes.

1. Always do the blood gas sample first and send it to the lab at once.

1. For filter paper newborn screening, the paper can be directly applied to the heel or the blood can be transferred to a capillary tube and then applied to the filter paper.

1. Maintain pressure on the puncture site with a dry sterile gauze pad until the bleeding stops; elevate the foot. A 4 × 4 gauze pad can be wrapped around the heel and left on to provide hemostasis; adhesive bandages are not recommended.

1. Using an automated lancet (eg, BD Quickheel Infant or others), hold the device 90 degrees to the surface. The device can ...

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