There is now a strong evidence base for use of POCUS to confirm PICC tip position, and a growing number of users are using POCUS to assist in UVC insertion

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PICC Position

Multiple studies have shown efficacy of the technique, with application of POCUS leading to reduced number of line manipulations and radiographs. POCUS appears particularly valuable when imaging 1Fr gauge PICC lines, which are difficult to visualize on x-ray. The technique does remain user-dependent, with significant scope for failure to visualize a line in the vasculature or heart; as well as scope to misinterpret image artefact as a line. For this reason great care should be taken to interrogate for line position from multiple views and often with multiple probe types. In particular lines rapidly become invisible to ultrasound when the ultrasound beam is not directly perpendicular to the line itself, so consideration of probe position and line path is key. It is often helpful to record multiple cine-loops and slow them down to visualize the tip position. See below for approach to confirmation of line position with POCUS.

Take Care!

The process of locating a catheter tip can be very challenging and requires skill and patience. Incorrect alignment of the ultrasound beam with respect to the path of the catheter within the vessels and heart chambers may result in underestimation of the catheter length and erroneous conclusion of the position of the catheter tip. Always estimate the tip position based on length from insertion point so you have an idea of where the tip is expected to be. If the tip is not where you expect then it may simply be that it is not readily visible on ultrasound – see below.

PICC in Upper Limb

The PICC line should be visualized in either the left or right brachiocephalic vein using either the high frequency linear probe or the sector (cardiac) probe. Remember that the brachiocephalic veins are relatively superficial (depth less than 2cm in most neonates) so minimal depth is required. Then track the line until it enters the superior vena cava. Confirmation of the site of the proximal SVC is best obtained from a high parasternal view with the two brachiocephalic veins forming the upper limbs of a ‘Y’ shape. Occasionally a PICC can be seen entering the jugular veins rather than the SVC, this is only appreciated from these brachiocephlic views Next visualize the full length of the SVC from a parasternal/sagittal view. The SVC is best found by isolating the ascending aorta and the tilting to look fractionally to the subject’s right side. The SVC can be followed from the brachiocephalic junction to the right atrium.

**Even if no line is initially apparent it is vital to follow the SVC down to the right atrium. If the angle of insonation is not perpendicular to the line it can be invisible to ultrasound**

Finally image the right atrium from both the parasternal short axis and bicaval views. Again a range of views is required to avoid missing a line which is not at a 900 angle to the ultrasound plane.

PICC in Lower Limb

The PICC line should be visualized in the IVC as it courses along the right side of the spine towards the right atrium. If the line tip is substantially below the level of the diaphragm it is often obscured by bowel gas and only visible on x-ray, though imaging from a coronal retroperitoneal view may help. Next visualize the full length of the IVC from a midline sagittal view. The IVC must of course be distinguished from the descending aorta.

**Even if no line is initially apparent it is vital to follow the IVC up to the right atrium. If the angle of insonation is not perpendicular to the line it can be invisible to ultrasound**

Finally image the right atrium from both the parasternal short axis and bicaval views. Again a range of views is required to avoid missing a line which is not at a 900 angle to the ultrasound plane.


References

  1. Katheria AC, Fleming SE, Kim JH. A randomized controlled trial of ultrasound-guided peripherally inserted central catheters compared with standard radiograph in neonates. Journal of perinatology 2013;33:791-4..