Pediatric emergency medicine trisk 4516 4516
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the clavicle and should only be undertaken by the experienced sonographer.
Peripheral Venous Cannulation
Peripheral IV catheter placement can be challenging, especially in infants and
obese children. Research suggests that bedside ultrasound may improve success
rates of peripheral catheter placement in children with difficult access or after two
failed attempts. The most common anatomical sites attempted under ultrasound
guidance are the brachial, cephalic, and basilic veins of the upper arm. In obese
children, ultrasound can be useful to locate the antecubital veins when palpation
proves difficult.
Technique
Cannulation of the peripheral veins uses the same principles as CV catheter
placement. The desired vein for cannulation should be identified in cross section
and long axis. Once the relevant anatomy has been reviewed, compressibility of
the vein should again be noted. Color Doppler may be used; however, in smaller
veins, the velocity of the blood flow may not be adequate to generate a color
change or Doppler signal. The vein imaged should be centered on the screen and
catheter placement should be placed with the same technique as CV catheter
placement ( Videos 131.25 and 131.26 ).
Pitfalls
There are several pitfalls when placing an ultrasound-guided peripheral catheter.
First, standard IV catheters are usually not long enough to reach the deeper veins
of the upper arm; therefore, longer catheters should be used. Second, peripheral
veins are much easier to compress than central veins and it is not uncommon for
the inexperienced sonographer to apply too much pressure with the probe, thereby
compressing the vein. A simple way to avoid this is to place a generous amount
of gel, providing a “step-off,” so that the transducer does not touch the skin.
Third, the angle of insertion of a peripheral catheter may be shallower than that of
a central catheter. One must avoid the temptation to take a steeper approach when
using ultrasound guidance because this often leads to inability to advance the
catheter over the needle. Finally, novice sonographers may have difficulty
following the needle tip. Whenever possible, simulation should be used to
practice prior to performing the procedure on a patient.
Thoracentesis
Of the “centesis” procedures, thoracentesis is the most commonly performed in
the ED. Ultrasound is helpful because it differentiates pathology such as
