45: Venous Access: Venipuncture (Phlebotomy)

Note: Cochrane review states that venipuncture, by a skilled operator, is the method of choice for blood sampling in term infants. It was found to be less painful than heelstick sampling and a more effective sampling method.

1. To obtain a blood sample for routine analysis or blood culture. Venipuncture typically allows a larger volume of blood (recommended if ≥1 mL needed) to be collected and is the method of choice for obtaining blood cultures. It is preferred over capillary blood sampling for certain tests (drug levels, hemoglobin/hematocrit, karyotype, coagulation studies, cross-matching blood, and ammonia, lactate, and pyruvate). Arterial blood is preferred for lactate, pyruvate, and ammonia.

2. To obtain a central hematocrit. Venipuncture is more reliable than heelstick.

3. Administer medications.

4. Venous blood gas. This can be used in some diseases (neonatal sepsis/respiratory distress syndrome [RDS]) to diagnose acid-base imbalance if an arterial blood gas can't be obtained. Although arterial blood gas is preferred, venous samples show good validity in terms of pH, Pco₂, and HCO₃.

Gloves, 23- or 25-gauge safety engineered scalp vein needle or needle (23 gauge preferred to reduce risk of hemolysis or clotting), alcohol swabs, 3 povidone-iodine swabs (for blood culture), appropriate specimen containers (eg, red-topped tube), a tourniquet or rubber band (for the scalp), 4 × 4 sterile gauze pads, syringe, transilluminator for vein imaging (optional) (see Chapter 40).

1. Use distal venous sites first to preserve venous access. Decide which vein to use. Use Figure 43–1 as a guide. Veins to use: antecubital fossa, dorsum of the hand or foot, wrist, greater saphenous vein at the ankle, scalp vein, external jugular. Avoid draws proximal to IV sites.

2. In cases of difficult vein localization. Transillumination for vein imaging can be used and is described in Chapter 40.

3. Have an assistant restrain the infant. If an assistant is not available, restrain the specific area selected for venipuncture by taping the extremity on an armboard.

4. Pain management

   1. The American Academy of Pediatrics (AAP) recommends topical anesthesia (eg, eutectic mixture of lidocaine and prilocaine [ELMA], applied 30 minutes prior to procedure) and a combination of oral sucrose/glucose and nonpharmacologic pain prevention and relief techniques (combination is more effective).

   2. Other recommendations based on venipuncture studies (often with conflicting results): sucrose/human milk was comparable to EMLA in one study. Combination of sucrose and EMLA showed better results than sucrose alone in preterm infants. Some recommend liposomal lidocaine 4% since it has a faster onset of action and it does not require occlusion dressing.

5. “Tourniquet” the extremity to occlude the vein. Use a rubber band (for the head), a tourniquet, or an assistant's hand to encircle the area proximal to the vein. Removing and reapplying may optimize the distension of the vein.

6. Prepare the site with antiseptic solution. For blood cultures, wipe at least 3 times in concentric circles starting at the puncture site.

7. With the bevel up (for optimal blood flow and less chance of occlusion by wall of vein), puncture the skin, and then direct the needle into the vein at a 25- to 45-degree angle. Use the vessel bifurcation if possible.

8. Once blood enters the tubing. Attach the syringe and collect the blood slowly (or administer the medication).

9. Remove the tourniquet. Then remove and press the button to shield the needle. Apply gentle pressure on the area until hemostasis has occurred (usually 2–3 minutes). Distribute blood samples to the appropriate containers; gently mix tubes with additives.

1. Infection is a rare complication that can be minimized by using sterile technique. Septic arthritis of the hip has been reported from femoral venipuncture.

2. Venous thrombosis/embolus is often unavoidable, especially when multiple punctures are performed on the same vein and the vein is large.

3. Hematoma or hemorrhage is avoided by applying pressure to the site long enough after the needle is removed to ensure hemostasis. If a coagulation defect is present, hemorrhage can occur.

4. Scarring of the dorsum of the hand from multiple venipunctures in very low birthweight (VLBW) neonates.

5. Cervical dural puncture from internal jugular venipuncture in an infant. This is secondary to insertion of the needle at excessive depth.

6. Laceration of artery near the vein.