Transducers for ultrasonic limb plethysmography.

Shifts in blood content of tissues cause dimension changes which can be measured with an ultrasonic dimension gauge. We have previously described the construction of a limb plethysmograph which uses this principle. Although other workers have described the construction of ultrasonic dimension gauge transducers intended for use inside animals, these transducers are not ideal for plethysmographic application. In this report we describe the design, construction, and performance characteristics of transducers suitable for limb plethysmography. Good signal quality is obtained with minimum care in transducer placement. These transducers incorporate a rugged external housing which provides for simple attachment to the calf by use of double-sided adhesive collars.