Standardization of a Device for Continuous Observation of Local Flow in Tissue
As our experimental set-up for continuous recording of local blood flow in the cerebral cortex of a laboratory animal with chronically implanted miniature thermistors (based on the heat clearance principle) gave satisfactory results for routine tests of pharmacological agents during anoxia, hypoxia, hypercapnia, etc., experiments, we intended to standardize the apparatus, to increase accuracy, to facilitate calibration and to enhance flexibility with respect to the operator.
The exponential aspect in the thermistor resistance/temperature characteristic is linearized by applying a logarithmic converter in the thermistor amplifier. Calibration to the centigrade temperature scale is performed by a three digit numerical adaptation of two thermistor constants determined in a thermostatic-cryostatic bath (zero and slope). A heating power measuring circuit is provided so that the dissipation constant of the thermistor implanted in tissue can be obtained and the thermal conductivity of the tissue can be estimated.
Linearity of the relation between cooling of the heated thermistor and local flow, for small cooling values as they are registered in vivo, is still being investigated.
KeywordsLocal Flow Heated Thermistor High Frequency Wave Local Cerebral Blood Flow Warm Blood
Unable to display preview. Download preview PDF.
- Coremans, J., Vermariën, H., Vereecke, F., and Bourgain, R.H., in press, Assessment of the in vivo recording of local cerebral blood flow using a thermistor device, in: Oxygen Transport to Tissue, Plenum, New York.Google Scholar
- Sachse, H.B., 1975, Semiconducting temperature sensors and their applications, John Wiley.Google Scholar
- Van Waeyenberge, M., Vermariën, H., De Backer, H., Manil, J. and Bourgain, R.H., in press, Discriminant parameters representing cerebral function during anoxic anoxia investigations, in: Oxygen Transport to Tissue, Plenum, New York.Google Scholar
- Vermariën, H., Coremans, J., Vereecke, F., and Bourgain, R.H., 1985, A thermistor device for the continuous recording of mass transport velocity in tissue based on the heat clearance principle, in: Oxygen Transport to Tissue VI, D. Bruley, H.I. Bicher and D. Reneau, eds., Plenum, New York.Google Scholar