24: Arterial Access: Umbilical Artery Catheterization

I. INDICATIONS

1. Frequent or continuous measurements of arterial blood gases.

2. Continuous arterial blood pressure monitoring.

3. Access for exchange transfusion (to withdraw blood).

4. Angiography.

5. Administration of emergency resuscitation medications and fluids. Note: Umbilical vein preferred.

6. Infusion of maintenance solutions.

7. Short-term infusion/emergency infusion of volume expanders, parenteral nutrition, and/or medications (controversial). Parenteral nutrition can be given through a UAC, a route that has been used in some centers, especially in very low birthweight (VLBW) infants; however, the umbilical artery is not preferred and should be used with caution. The maximum dextrose concentration that can be administered using this method is 15%. If necessary, antibiotics can be given via UAC, but this also is not a preferred method. Indomethacin, vasopressor medications (epinephrine, dopamine, dobutamine), calcium boluses, and anticonvulsants should not be given via the UAC (umbilical venous catheter [UVC], central venous line preferred).

8. Blood products (controversial, emergency only). Blood products can be given via a UAC, but UVC or peripheral/central access preferred. UAC is less preferred, as this may enhance the risk of thrombosis.

II. EQUIPMENT

1. Basic. Prepackaged umbilical artery catheterization trays (usually include sterile drapes, tape measure, a needle holder, suture scissors, hemostat, forceps, scalpel, 3-way stopcock), umbilical tape, silk tape (eg, Dermicel), 3–0 silk suture, gauze pads, antiseptic solution, sterile gown, gloves, mask, hat, 10-mL syringe, 0.5% normal saline (NS) flush solution (0.25% NS for very small infants to decrease hypernatremia risk), NS with heparin (0.25–1.0 U/mL) in continuous infusion calibrated pressure transducer for pressure monitoring. Ultrasound equipment is optional to guide catheter insertion.

2. Umbilical artery catheter (sizes 2.5F, 3.5F, 5F, 12–15 inch). Size recommendations vary based on institutional guidelines. Some general guidelines:

   1. UAC recommendation 1. 2.5F if <800–1000 g, 3.5F >1000 g, 5F in a term infant.

   2. UAC recommendation 2. 3.5F if <1.2 kg or 1.5 kg, 5F for an infant weighing >1.2 or 1.5 kg.

   3. If using catheter without a hub. Cut off wide part of catheter and insert blunt needle: No. 18 for 5F, No. 20 for 3.5F.

   4. Single-lumen UAC recommended. Multiple-lumen catheters are not recommended (recommended for UVC use only). End-hole catheters are associated with a decreased risk of aortic thrombosis when compared with side-hole catheters. Avoid side-hole catheters.

   5. Feeding tubes used as catheters. Associated with increase in thrombosis; avoid use.

   6. Cochrane review notes that there is no benefit of using a heparin bonded polyurethane catheter versus the standard polyvinyl chloride (PVC) catheter. A catheter made of Silastic (silicone) is more difficult to use because it is softer but may reduce aortic thrombosis compared with PVC tubing. Teflon or polyurethane catheters have been associated with fewer infections and thrombogenicity than PVC or polyethylene catheters.

III. PROCEDURE

1. Important UAC tips

   1. The 2 umbilical arteries (1 umbilical artery in ∽1% of births) are muscular walled vessels (2–3 mm) that carry deoxygenated blood from the fetus to the placenta. The umbilical arteries are ...