The Physics Of Ultrasound: Part 2

Abstract

Positioning the probe at 90° to the structure that you wish to image is essential for the best acuity and also to prevent losing smaller important structures such as nerves on the ultrasound screen.
A good knowledge of the regional anatomy being visualised and an awareness of different forms of artefact, can help distinguish pathology from artefact.
Red blood cells reflect ultrasound and this is the basis for measuring blood flow with Doppler ultrasound.
Use an ultrasound system with a high frequency transducer (up to 13MHz) for superficial blocks that are less than 3cm deep. This allows for the best resolution of the neural structures and surrounding tissue. Deeper blocks will require a lower frequency transducer that provides better penetration of the ultrasound beam into the tissue.
Operator ergonomics is vastly improved by careful attention to patient positioning and the preparation of all the equipment prior to the procedure.