Chapter 29. Introduction to Ultrasound-Guided Regional Anesthesia
Benefits of ultrasound-guided nerve blocks include:
A. Visualization of the anatomy in the area
B. Visualization of the needle tip
C. Visualization of real-time local anesthetic spread
D is correct. There are many practical advantages of ultrasound for nerve blockade. Ultrasound allows visualization of the anatomy of the region of interest. This allows visualization of the needle pathway to the target while avoiding structures that might be damaged by the needle. Ultrasound also allows visualization of the needle tip as it is passed through the tissues, confirming alignment with the intended path, reducing the likelihood of inadvertent needle trauma to unintended structures. Real-time ultrasound imaging also permits continual visualization of local anesthetic (LA) solution delivery to ensure proper distribution.
The mnemonic PART is used to describe the components that optimize an ultrasound image. “P” refers to:
A. Placing the transducer in a position over the extremity at which the underlying nerve is expected to be in the field of view
B. Minimizing the distance to the target and compressing the underlying subcutaneous adipose tissue
C. Fine-tuning of the view of the target structure
D. Bringing the face of the probe into a perpendicular arrangement with the underlying target to maximize the number of returning echoes
B is correct. The mnemonic PART stands for Pressure, Alignment, Rotation, and Tilting. All of these maneuvers can improve ultrasound image by different mechanisms. “P” refers to pressure, which involves applying force on the probe to minimize the distance to the target via compression of superficial structures, including subcutaneous adipose tissue.
A is incorrect. Refers to alignment, which involves placing the transducer in a position over the extremity/trunk at which underlying nerve is expected to be in the field of view.
C is incorrect. Refers to rotation, which involves turning the probe slightly to fine-tune the target structure.
D is incorrect. Refers to tilting the probe, which improves the image by bringing the face of the probe into a perpendicular arrangement with the underlying target to maximize the number of returning echoes, thus providing the best image.
In performing a brachial plexus block, at which of the following locations will the nerves appear most hypoechoic?