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INTRODUCTION

Umbilical vessel catheterization was first described by Diamond in 1947 for an exchange transfusion in a neonate.1 Umbilical vessel catheterization serves many important functions in the ill neonate and is a reliable method of obtaining rapid vascular access.2 Umbilical vessel catheters may be used for fluid resuscitation, blood transfusion, medication administration, frequent blood sampling, and cardiovascular monitoring.2-6 The use of these catheters carries risk of morbidity and mortality. Either the umbilical artery or vein may be used for vascular access. The umbilical arteries begin to constrict immediately after birth and can typically be cannulated during the first few days of life. The umbilical vein can be accessed up to 7 to 10 days after birth (i.e., when the umbilical stump dries up).7

Umbilical artery catheterization is more desirable than umbilical vein catheterization. The umbilical artery allows frequent arterial blood gas sampling and continuous blood pressure monitoring and administration of substances (e.g., blood products, fluids, and medications). Umbilical artery catheterization is more difficult and time consuming to perform. Umbilical vein catheterization is the preferred procedure for the infant in shock and in need of rapid resuscitation. Arterial access can be obtained later in the controlled environment of the Neonatal Intensive Care Unit (NICU). Umbilical vessel catheterization can lead to serious complications and should be reserved for the patient in whom intraosseous or peripheral venous access cannot be rapidly secured.6,8

ANATOMY AND PATHOPHYSIOLOGY

The fetal circulatory system differs from that of the neonate (Figure 71-1).7 Oxygenated blood from the placenta travels via the umbilical vein, through the ductus venosus in the liver, to the inferior vena cava (IVC), and into the right atrium. Oxygenated blood from the IVC preferentially enters the left atrium through the foramen ovale. It then enters the left ventricle followed by the aorta. This oxygen-rich blood supplies the brain prior to mixing with the oxygen-poor blood coming through the ductus arteriosus. Deoxygenated blood from the superior vena cava (SVC) enters the right ventricle and is pumped to the pulmonary artery. It then passes through the ductus arteriosus to meet the oxygenated blood in the aorta.

Pulmonary vascular resistance decreases dramatically as the infant takes its first breath. The systemic vascular resistance increases when the umbilical cord is clamped. These changes in resistance cause the foramen ovale to close. The ductus arteriosus closes within 24 to 48 hours due to the release of prostaglandins and increased blood oxygen tension. The ductus venosus closes when the umbilical cord is clamped.

The umbilical vein and arteries can be easily differentiated by examination of a cross section of the umbilical cord (Figure 71-2). The umbilical vein is a single thin-walled vessel with a large lumen. It ...

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