Title :
Determination of wave intensity in flexible tubes using measured diameter and velocity
Author :
Feng, J. ; Khir, A.W.
Author_Institution :
Brunel Univ., Uxbridge
Abstract :
Wave intensity (WI) is a hemodynamics index, which is the product of changes in pressure and velocity across the wave-front. Wave Intensity Analysis, which is a time domain technique allows for the separation of running waves into their forward and backward directions and traditionally uses the measured pressure and velocity waveforms. However, due to the possible difficulty in obtaining reliable pressure waveforms non-invasively, investigating the use of wall displacement instead of pressure signals in calculating WI may have clinical merits. In this paper, we developed an algorithm in which we use the measured diameter of flexible tube´s wall and flow velocity to separate the velocity waveform into its forward and backward directions. The new algorithm is also used to separate wave intensity into its forward and backward directions. In vitro experiments were carried out in two sized flexible tubes, 12 mm and 16 mm in diameters, each is of 2 m in length. Pressure, velocity and diameter were taken at three measuring sites. A semi-sinusoidal wave was generated using a piston pump, which ejected 40 cc water into each tube. The results show that separated wave intensity into the forward and backward directions of the new algorithm using the measured diameter and velocity are almost identical in shape to those traditionally using the measured pressure and velocity. We conclude that the new algorithm presented in this work, could have clinical advantages since the required information can be obtained non-invasively.
Keywords :
biomechanics; blood flow measurement; blood pressure measurement; blood vessels; diameter measurement; velocity measurement; diameter measurement; flexible tube; hemodynamics; piston pump; semisinusoidal wave; size 12 mm; size 16 mm; size 2 m; time domain technique; velocity measurement; wall displacement; wave intensity determination; Arteries; Equations; Fluid flow measurement; Hemodynamics; In vitro; Pressure measurement; Shape measurement; Time domain analysis; Time measurement; Velocity measurement; Algorithms; Animals; Arteries; Blood Flow Velocity; Blood Pressure; Blood Pressure Determination; Computer Simulation; Diagnosis, Computer-Assisted; Humans; Models, Anatomic; Models, Cardiovascular; Pulsatile Flow; Reproducibility of Results; Sensitivity and Specificity;
Conference_Titel :
Engineering in Medicine and Biology Society, 2007. EMBS 2007. 29th Annual International Conference of the IEEE
Conference_Location :
Lyon
Print_ISBN :
978-1-4244-0787-3
DOI :
10.1109/IEMBS.2007.4352459