Development and In-Vitro Evaluation of a Doppler Volume Flow Meter

Abstract

Determination of blood volume flow (e.g. cardiac output) is very useful in the treatment of low birthweight neonates (< 1500 g). The clinically accepted method employs thermodilution. This, however requires central catheterisation. This treatment is invasive and therefore only acceptable in critical situations. For early detection of impending circulatory failures a non-invasive, accurate, reproducible monitoring method is required. Quantitative measurements of volume flow by means of Doppler ultrasound is a possible solution. To determine blood volume flow by ultrasound Doppler technique the following parameters are required: Doppler angle, beam profile, shape of the velocity profile and vessel size. Since this information is not available or inaccurate volume flow measurements are still not satisfactory. Hottinger and Meindl presented a new method in 1974, the attenuation-compensated volume flow meter1. A few papers dealing with this technique were presented so far2-4. A commercial system also has been developed but is no longer on the market probably because of unsatisfactory results. Since from the physical point of view the method is attractive it has been illucidated by a new development.