Ultrasonic Measurement of Sound Velocity in Whole Blood a Comparison between an Ultrasonic Method and the Conventional Packed-Cell-Volume Test for Hematocrit Determination

Abstract

A new ultrasonic instrument for the determination of sound velocity in tissue is described. The instrument has been used in this investigation to measure the sound velocity in heparinized whole blood samples. The corresponding hematocrit values of the blood samples were determined by the packed cell volume test. The measurements in the hematocrit range of approx. 30–55 indicate a high degree of correlation between the hematocrit value and the respective blood sound velocity (S.E.E.= 1.3 and r = 0.96). Repeated measurements of the same blood samples up to 1 hr after collection of the blood show very small changes in reading of sound velocity, provided the samples were kept at a constant temperature and well stirred. The ultrasonic measurement is quick and simple to perform, and the blood specimen is not changed by the measuring process.

Key Words:

• Hematocrit
• packed cell volume
• sound velocity
• ultrasound