BLOOD FLOW MEASUREMENTS
1965; Elsevier BV; Linguagem: Inglês
10.1016/b978-1-4831-6701-5.50031-0
Autores Tópico(s)Flow Measurement and Analysis
ResumoThis chapter discusses the blood flow measurements. A significant advance in the measurement of blood pressure was the discovery that a thin flexible tube called a catheter can be safely passed along a blood vessel so that pressures at points remote from the surface of the body can be measured. The manometers originally used for making these pressure measurements had a poor time response so that only mean values were obtained but modern pressure transducers have a frequency response, which is quite adequate for obtaining detailed measurements of the variation of pressure with time. The present clinical diagnosis of defects in the circulation depends largely on such measurements of pressures. However, the purpose of the circulation system is to provide an adequate supply of blood to every part of the body so that the really important parameter is the actual blood flow rate rather than the pressure in the blood at any particular point. The present diagnostic techniques are, therefore, essentially indirect ones and they are based on deductions derived from oversimplified models of the circulation. To understand the difficulties inherent in the direct measurement of blood flow rates, it is convenient to describe briefly the circulatory system and to compare it with an equivalent system such as may be found in engineering practice.
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