Pediatric emergency medicine trisk 4515 4515
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FIGURE 131.23 Wire in vessel.
When differentiating arteries from veins using compressibility, it should be
noted that if the sonographer pushes with extreme pressure, the walls of the artery
could touch one another, especially in hypotensive patients.
Using ultrasound statically should always be performed after the patient has
been positioned. Repositioning the patient after identification can lead to changes
in anatomic relationships and may result in failed attempts at catheterization.
When inserting the needle, proceduralists need to be cautious about not
inserting the needle too slowly. If the needle is inserted too slowly, tenting will
occur, the walls of the vein will be pushed together and the needle can transverse
both walls. Furthermore, it is important that the vein and artery are alongside each
other in the transverse view. If not, and tenting occurs, it is easy to cannulate the
underlying artery instead of the vein.
The proceduralist must pay attention to both the ultrasound image on the screen
and the site of the procedure. Inexperienced sonographers may focus too heavily
on the screen and a flash of blood in the hub will go unnoticed. A methodical
approach, along with experience, can help minimize this occurrence.
Although ultrasound-guided catheter placement of the subclavian vein has been
described in the literature, it is much more difficult due to the shadows created by
