A blood-perfusion flowmeter
Includes bibliographical references. === A variety of methods have been used for measuring blood flow in large vessels. However, almost all of these methods are unsuitable for measuring perfusion flow in tissue. Basically all attempts at perfusion flow measurement have used either a tracer method (r...
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| Format: | Dissertation |
| Language: | English |
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University of Cape Town
2015
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| Online Access: | http://hdl.handle.net/11427/12437 |
| Summary: | Includes bibliographical references. === A variety of methods have been used for measuring blood flow in large vessels. However, almost all of these methods are unsuitable for measuring perfusion flow in tissue. Basically all attempts at perfusion flow measurement have used either a tracer method (radio-active dyes, microspheres) or a thermal method where the rate of heat clearance from a heated probe is used as a measure of local flow. Tracer methods suffer from the fact that they give essentially a single measurement of flow and this only after tissue has been removed and analysed. Thermal methods on the other hand can give continuous measurement. What is actually being measured in the thermal method is the apparent thermal conductivity of the tissue in the immediate vicinity of the probe. The apparent thermal conductivity increases with flow as heat from the probe is not only conducted away by the surrounding tissue but is also carried away by the perfusing fluid. The way in which local perfusion is related to thermal conductivity and the methods used to measure thermal conductivity have led to criticisms of thermal methods. This work deals with instrumentation to eliminate some sources of error in thermal methods and automate the whole measurement procedure. It also includes a critical review of thermal methods in general and previous work in the field in particular. |
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