Intravenous catheter placement for pediatric patients is a critically important technical skill for health care professionals in the emergency department (ED). A combination of small veins, moving targets, “baby fat,” and dehydration may preclude successful venous cannulation even by experienced professionals. The use of ultrasound technology has been shown to improve rates of successful intravenous cannulation in both the central (1,2) and peripheral (3,4) circulation. In fact, evidence-based recommendations from the Agency for Healthcare Research and Quality (AHRQ) suggest that ultrasound guidance for placement of central venous catheters should become standard procedure (5).

When indicated for the pediatric patient, access to the central circulation can be achieved via the internal and external jugular, subclavian, basilic, umbilical, and femoral veins. The internal jugular, subclavian, and femoral veins are traditionally located using landmark-based approaches (see Chapter 19). Anatomic variation, thrombus, accidental arterial cannulation, and risk of injury to surrounding structures pose significant barriers to success using the blind approach. Ultrasound guidance has been shown to increase the rate of successful central venous cannulation via the internal jugular vein in adults and infants and via the subclavian and femoral veins in adults (1,2). Despite limited evidence currently available regarding ultrasound-assisted central access using the subclavian or femoral veins in children, it is likely that the improved success rates seen in adults would extend to the pediatric population.

Literature supporting ultrasound-assisted peripheral access has generally focused on the placement of peripherally inserted central catheters (“PICC lines”), usually via basilic or cephalic veins in the antecubital fossa or upper arm, and success rates approaching 99% have been reported (3,6). In theory, the same principles should apply when cannulating any large (greater than 3 mm) peripheral vein, even with a standard intravenous catheter.

Ultrasound-assisted central line placement should be regarded as a minor surgical procedure to be performed by an experienced physician. It should be done in an appropriate hospital setting such as the ED, operating room, cardiac catheterization laboratory, or intensive care unit. The technique is quickly learned and has been shown to reduce both the time and number of needle insertions required to successfully cannulate central veins. To date, little evidence exists on the use of ultrasound-assisted peripheral access in pediatrics, but the increased success rates achieved with central venous access may prove to be applicable in accessing larger peripheral veins as well.

Veins may be distinguished ultrasonographically from arteries by the fact that they have thinner walls, are more easily compressed, and lack arterial pulsations. In addition, veins are distended by maneuvers that impede venous return, such as dependent placement, application of tourniquets, and the Valsalva maneuver, whereas arterial diameter will remain relatively constant in response to these maneuvers (Fig. 137.1). While a “standard” location can be described for most large veins (see Chapters 19 and 73), considerable anatomic variability exists among individuals. Visualization of the vein provided by ultrasound improves success by removing the “blind” component of the initial puncture. For example, ultrasound studies have demonstrated that in approximately 6% of patients the internal jugular vein is thrombosed, absent, or unexpectedly small on one side. The vein also may be located more laterally in the neck than expected, whereas in 10% of children it runs directly anterior to the carotid artery (7,8).

Another important ultrasonographic concept is that of Doppler flow, which can be appreciated both audibly and visually, depending on the ultrasonographic equipment. Venous flow produces a uniform pattern, likened audibly to a windstorm or radio static, whereas arterial flow has a definite pulsatile quality (Fig. 137.2). Two-dimensional ultrasound visualization of the vein has proven superior to Doppler flow alone in facilitating central venous access, but using Doppler flow as an adjunct to two-dimensional visualization provides confirmation that the target is a vein rather than an artery.

Ultrasound-assisted venous access may be indicated in any situation where venous access is expected to be difficult and
a practitioner familiar with the use of two-dimensional ultrasound is available. As mentioned above, evidence-based recommendations from AHRQ suggest that ultrasound guidance for placement of central venous catheters should become standard practice (5). Landmark-based central venous catheter placement can be complicated by the inadvertent selection of an absent, small, or thrombosed vessel. Such problems are clearly revealed by ultrasound scanning and thereby may be avoided.