<title>In-vitro laser anemometry blood flow systems</title>

Abstract

Lasers are used in a wide variety of medical applications. While laser catheters have been developed for highly accurate velocity measurements these are invasive; nonmvasive techniques are more desirable but not as precise. The laser is, however, a great tool for in vitro measurements. Several groups internationally are using the laser in the study of local velocity distribution in microscopic areas of specially constructed models. Laser Doppler anemometry is widely used to measure the local, time-dependent velocities, while phase Doppler anemometry has been developed to measure particle size, distribution and velocity. Most recently, laser analyzer techniques have been developed for analyzing the particle size of two phase flow systems. It has become increasingly important for physicians to visualize blood flow. In addition to the techniques mentioned above, several laser sheet techniques have been developed for precise measurements. This paper presents a short review of laser techniques and shows some applications especially for the laser-Doppler anemometer.

Numerical modelling of simulated blood flow in idealized composite arterial coronary grafts: Transient flow

“…It is still controversial whether or not undivided side-branches can steal blood flow from the coronary circulation and consequently lead to graft failure and angina (Singh and Sosa, 1984;Royse et al, 1999). Many scientists have studied both experimentally (Liepsch et al, 1993;Moore et al, 1992;Pedersen et al, 1994) and numerically (Ku and Giddens, 1983;Samagaio and Vlachos, 1989;Palmen, 1994) the flow fields in bends and bifurcations. An overview of such aspects is given by Zheng and Yang (1992), Liepsch (2002), and Migliavacca and Dubini (2005).…”

The MOST - Monitor for Oxygenation of Surface and Tissue.

“…Quantification of these parameters requires estimation or actual computation of the optical pathlength (as previously discussed). Blood flow measurements are also obtainable by using laser Doppler methods Liepsch et al, 1993;Mendelson, Ochs, 1988). While many parameters beyond oxygenation (and blood flow) have the potential to be non-invasively monitored by optical methods, such devices are not currently available for use in the clinical environment.…”

On the choice of the number of samples in laser Doppler anemometry signal processing

“…Laser Doppler anemometry ͑LDA͒ systems for measuring flow velocities, widely used in industry and research, [1][2][3][4][5] present intrinsic advantage over classical methods. These attractive features are the noninvasive nature of the measurement, its high spatial resolution ͑some hundreds of micrometers over 2 or 3 mm typically͒, and its precision ͑about 1%͒.…”