| Autor: |
J. Adamus, Paolo Fidanzati, Robert Olszewski, Wojciech Secomski, Andrzej Nowicki, Piero Tortoli |
| Rok vydání: |
2006 |
| Předmět: |
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| Zdroj: |
IEEE Ultrasonics Symposium, 2005.. |
| Popis: |
The goal of this work was to develop a clinically applicable method for noninvasive measurement of hematocrit based on Doppler ultrasound. The method uses of a 20 MHz unfocused transducer (2 mm diameter) in a multigate Doppler system. The ultrasound attenuation coefficient in blood is obtained by measuring the power of the signal coming from gates at different depths. A robust averaging method is introduced, which provides stable and repeatable results by using the echo- signals from all depths inside the vessel. A large amount of in vitro and in vivo data has been collected. In vitro measurements have been done on porcine blood, with samples of whole blood and separated plasma with hematocrit ranging from 3.0% to 65.0%. Steady and pulsatile flow conditions, similar to those existing in the human brachial artery, have been simulated using a peristaltic pump. The attenuation coefficient, determined from the reduction of Doppler amplitude with increasing depth, indicated the linear relation to hematocrit. The resulting correlation coefficient was R = 0.999 for the continuous blood flow and R = 0.992 for pulsatile flow. In vivo measurements have been performed in the brachial artery in 33 patients with hematocrit in the range 32.0% - 46.1%. The mean absolute error has been 3.5% with a SD of 2.7%. |
| Databáze: |
OpenAIRE |
| Externí odkaz: |
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