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Biomedical subjects

S Mizushina

Publications and source records attributed to S Mizushina.

7 recordsLinked to original sources
PubMed1992

Non-invasive thermometry with multi-frequency microwave radiometry.

The present status of the development of a non-invasive thermometer based on microwave radiometry at our laboratory is reported. We have developed a model fitting technique combined with a Monte Carlo technique to retrieve temperature-depth profiles from multi (4-6)-frequency-band microwave radiometric data along with confidence intervals (2-sigma) of tissue temperatures as a function of depth. In order to make the radiometric technique compatible with the heating, brightness temperatures are measured through a 1 cm thick water bolus. Results of phantom experiments are presented to demonstrate the above capabilities of the method. Numerical simulation studies have shown that 2-sigma intervals would be 1.0 K or less over a 0-4 cm range and 1.4 K at 5 cm from the surface with using a six-band, 1-5 GHz radiometer having brightness temperature resolution of 0.03 K (3 s integration time). The six-band instrument is currently being assembled at our laboratory.

Body Temperature↗
PubMed1988

Cardiac pacemaker regulated by respiratory rate and blood temperature.

A new method using respiratory rate and temperature as the guides for optimal pacing is proposed. A pacemaker was fabricated which senses these two parameters simultaneously. The pacemaker functions by calculating the cardiac rate, which would be derived from the respiratory rate and the blood temperature. The higher of the two rates is adopted as the cardiac pacing rate, i.e., at which stimuli will be delivered. The operation was tested in a mongrel dog with complete atrioventricular block. After the induction of anesthesia, a thermistor temperature probe was inserted into right atrium and a respiratory rate sensor was attached around the chest. After administration of a pyrogenic drug, both respiratory rate and blood temperature increased. The pacing rate was increased from 178 beats/minute(bpm) at 36.4 degrees C, blood temperature, and 26.5 acts/minute(apm), respiratory rate, to 233 bpm at 40.1 degrees C and 40.0 apm. Cardiac output was increased from 2.15 liters/minute(l/pm) at the beginning to 2.50 l/pm at maximum. The transition of the guide from respiratory rate to temperature was observed at about 38 degrees C.

Animals↗
PubMedDate not supplied

A temperature-sensitive cardiac pacemaker.

An artificial cardiac pacemaker which is sensitive to the temperature of blood in the right atrium has been fabricated. For a temperature change of 20 degrees C the circuit achieves 90% of its final response within a period of 18 s. In the authors' opinion this is satisfactory since changes in blood temperature are generally small. Cardiac output in dogs rose from 2.37 +/- 0.65 to 4.54 +/- 1.15 l/min when the rate was increased from 202.6 beats/min(b.p.m.) at 37.6 degrees C to 231.6 b.p.m. at 41 degrees C. Cardiac output was found, from statistical observation, to be improved at temperatures over 39.6 degrees C.

Animals↗
PubMedDate not supplied

Microcomputer-based cardiac pacemaker-control system through blood temperature.

A microcomputer-based temperature-sensitive cardiac pacemaker system and some preliminary experiments are described. The system consists of a microcomputer, a twin 5 in floppy disk unit, expansion and interface units, a visual display unit and a printer. It senses the blood temperature in the right atrium, determines the pacing rate and supplies the heart with stimulating pulses. System-heart interfacing is performed by the separate pacing and sensing units which communicate with the computer via a peripheral interface IC in an expansion unit. The pacing rate is determined by software, rather than a combination of hardware elements. The temperature response time of the system, from 25 degrees C to 40 degrees C is about 26 s, and this would seem to be satisfactory given that smaller and slower changes in blood temperature are normal.

Animals↗
PubMedDate not supplied

A fuzzy approach to the rate control in an artificial cardiac pacemaker regulated by respiratory rate and temperature: a preliminary report.

Fuzzy theory was applied to the rate control of a cardiac pacemaker which uses two parameters, respiratory rate and temperature, as the parameters for rate regulation. Using 25 fuzzy reasoning rules derived from five mongrel dogs, the pacing rates in three animals were calculated and compared with the intrinsic heart rates. It is concluded that the fuzzy method is well suited for the rate determination of a multi-parameter rate-responsive cardiac pacemaker.

Algorithms↗