Computer-based system for continuous on-line measurements of tissue blood perfusion

We describe a new system for an almost continuous, on-line measurement of local blood perfusion in living tissue. The technique uses a thermal method based on measurements of the tissue temperature decay after a short pulse (approximately equal to 3 s) of local heating. The instrumentation system consists of six small thermistor microprobes, a probe interface unit and a DEC LSI-11/23 microcomputer. The system is equipped with six thermistor channels, and the number can be increased with further signal conditioning modules, thereby increasing the locations at which blood perfusion can be measured. The results agree favourably with values for tissue blood flow obtained simultaneously using either the microspheres method or an electromagnetic probe. The system has been in use for three years and there is good reason to believe that it can be reliably applied in many situations where a continuous multichannel monitor of local blood perfusion is necessary.