Hostname: page-component-78c5997874-j824f Total loading time: 0 Render date: 2024-11-05T04:31:11.475Z Has data issue: false hasContentIssue false
  • English
  • Français

Characteristics of pressure-wave propagation in a compliant tube with a fully collapsed segment

Published online by Cambridge University Press:  20 April 2006

Masashi Shimizu
Masashi Shimizu
Affiliation:
Department of Control Engineering, Tokyo Institute of Technology, Oh-Okayama, Meguro-ku, Tokyo
Get access Rights & Permissions [Opens in a new window]

Abstract

In order to model the fluid dynamics of Korotkoff sound generation when the artery under the cuff is fully collapsed during most of the heart cycle, the characteristics of pressure-wave propagation in a long silicone-rubber tube were studied experimentally. The central portion of this tube was designed to collapse to zero cross-sectional area as a result of high negative transmural pressure, thus simulating a collapsed artery. Propagation of a single half-sinusoidal pressure wave in and around this segment was studied in detail by pressure, velocity and tube-longitudinal-shape measurements.

A very steep wave front (shock wave) capable of producing a short tapping sound was formed by an overtaking phenomenon in the fully collapsed tube segment and it propagated into the inflated tube distal to the collapsed segment. An empirical equation relating the flow rate penetrating into the collapsed segment, the incident-wave pressure and the external pressure Pc over the collapsed segment was obtained. This equation predicts that the pressure-wave propagation in a fully collapsed segment depends only on the flow rate into the collapsed segment.

The initial internal pressure of the tube distal to the collapsed segment Pd is one independent variable in the high-cuff-pressure condition. The amplitude of the steep wave front and the shape of the pressure wave in the inflated tube distal to the collapsed segment are governed by Pc–Pd and the flow rate penetrating the collapsed segment. For the same flow rate, if Pc–Pd is lower than a critical value, the amplitude of the pressure in the distal tube decreases with increasing Pd because of positive pressure-wave reflection at the exit of the collapsed segment. On the other had, if Pc–Pd is higher than that value, no wave reflection occurs and the amplitude of the pressure wave is independent of Pd. In the latter case a severe constriction exists near the distal end of the collapsed segment, and flow occurs as two thin high-speed jets.

Type
Research Article
Information
Journal of Fluid Mechanics , Volume 158 , September 1985 , pp. 113 - 135
Copyright
© 1985 Cambridge University Press

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

Burch, G. E. & De Pascuale N. P. 1962 Primer of Clinical Measurement of Blood Pressure. C. V. Mosby.
Jan D. L., Kamm, R. D. & Shapiro A. H. 1983 Filling of partially collapsed compliant tubes. Trans ASMEK: J. Biomed, Engng 105, 12.Google Scholar
Kamm, R. D. & Shapiro A. H. 1979 Unsteady flow in a collapsible tube subjected to external pressure or body forces. J. Fluid Mech. 95, 1.Google Scholar
Kececioglu I., McClurken M. E., Kamm, P. D. & Shapiro A. H. 1981 Steady, supercritical flow in collapsible tubes. Part 1, Experimental observations. J. Fluid Mech. 109, 367.Google Scholar
Kenner T. 1976 Pulse wave reflection at the collapsed segment of an artery in Riva-Rocci's method. Pflügers Archiv 364, 285.Google Scholar
Lighthill M. J. 1972 Physiological fluid dynamics: a survey. J. Fluid Mech. 52, 475.Google Scholar
London, S. B. & London R. E. 1964 Comparison of indirect pressure measurement (Korotkoff) with simultaneous direct brachial artery pressure distal to the cuff. Adv. Intl Med. 13, 127.Google Scholar
London, S. B. & London R. E. 1967 Critique of indirect diastolic end point. Arch. Intl Med. 119, 39.Google Scholar
Mccutcheon, E. P. & Rushmer R. F. 1967 Korotkoff sounds. Circulat. Res. 20, 149.Google Scholar
Pedley T. J. 1980 The Fluid Mechanics of Large Blood Vessels. Cambridge University Press.
Shimizu, M. & Tanida Y. 1983 On the mechanism of Korotkoff sound generation at diastole. J. Fluid Mech. 127, 315.Google Scholar
Ur, A. & Gordon M. 1970 Origin of Korotkoff sounds. Am. J. Physiol. 218, 524.Google Scholar
Wallace J. D., Lewis, D. H. & Khlil S. A. 1961 Korotkoff sounds in humans. J. Acoust. Soc. Am. 33, 1178.Google Scholar