Probe Movements

It is necessary to manipulate the probe throughout the scan to create screen images that allow for full assessment of the veins. There are four basic probe movements:

• Sliding
• Rocking
• Angling
• Rotating

Sliding: This is the most commonly used probe maneuver. Simply slide the probe face along the surface of the skin in any direction. Sliding is used to "follow" the course of a vein or artery and can be used when holding the probe head in either the transverse or sagittal plane.

Rocking: This is a tilting motion made along the long axis of the probe face (end to end) with the probe held in a stationary position. Begin with the probe in the upright (90º) position along the sagittal or long plane; tilt the probe off 90º along the long axis of the probe face. The movement is like that of a rocking chair with one rocker pushing down slightly toward one end of the probe while allowing the other end to come up slightly without losing contact with the skin. Rocking is useful for visualizing blood flow through a section of a vessel.

Angling: Begin with the probe in an upright stationary position along the transverse plane of the vessel. Tilt the probe over slightly, keeping uniform pressure and skin contact all along the long edge. This creates an angle of incidence less than 90º and is useful for "spot checking" flow when imaging in the transverse plane. Angling is a useful maneuver to differentiate arteries from veins.

Rotating: This is a turning motion of a stationary probe to adjust orientation of the probe from the transverse to sagittal position. Rotating is helpful to view fine details of the vein wall and is recommended when a segmental view of the vein is desired.

Gel

High frequency sound waves cannot travel through air; they require a transmission medium to aid in the process. Transmission gel eliminates surface air between the probe head and the skin allowing sound wave transmission from the probe, through the skin and back again. Apply gel to the probe face in sufficient quantity to eliminate any surface air between the probe and skin. Use gel liberally to create the best transmission of an image. When gel becomes thin from skin absorption or probe movement, image quality deteriorates and structures are more difficult to see on the screen.

Sterile gel is provided in the probe cover packets for use with sterile insertion procedures. Many facilities are currently using sterile gel packs for all patient ultrasound applications. Large volume gel dispenser use is discouraged due to episodes of contamination.