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