Applicability of the two-compartment coaxial cylindrical model for ambulatory measuring of cardiac output with spot-electrodes / 生物医学工程学杂志

The principle of ambulatory cardiac output (CO) measuring technique is introduced in this paper. Experimental studies about the applicability of the two-compartment coaxial cylindrical model for ambulatory measurement of cardiac output with spot-electrodes have been carried out with using our newly-developed multi-channel impedance mapping system. The key factors using a spot-electrode array instead of a conventional band-electrode array for non-invasive CO) measurement are elaborated. The variations of the electric impedance pulsatile component (deltaZ waveform) and the two kinds of typical modes of deltaZ distributions measured by six electrodes on the midsternal (midian) line from the medial portion at the level of clavicle to the portion above the xiphisternum are discussed. The applicability of the two-compartment coaxial cylindrical model for ambulatory measurement of CO with spot-electrodes is analyzed. Synthesizing the deltaZ distributions and their typical changing models on the midsternal (midian) line during blood inflowing into aorta is the optimal positions of a pair of spot-electrodes for voltage pick-up at the level of clavicle for the upper electrode and the position at the level of nipple for the lower electrode when spot-electrode is being used to measure non-invasive CO.

Optimal electrode array for ambulatory measuring of cardiac output based on the electrical impedance method / 生物医学工程学杂志

Principle of ambulatory cardiac output (CO) measuring technique is introduced in this paper. A lot of experimental studies of the current distribution on the thorax under the condition that the current injection electrodes were adhered to different positions were carried out by using a developed multi-channel impedance mapping system. The static impedance contour maps (Zo-map) and its pulsatile component contour maps (deltaZ-map) under different measuring conditions were analyzed, and the applicability of a two-compartment coaxial cylindrical model using a spot-electrode array instead of the conventional band-electrode array for ambulatory CO measurement, as well as the optimal spot-electrode array, were discussed. Based on the experimental results and the daily use of the ambulatory CO measuring technique, the optimal spot-electrode array meeting the condition of the two-compartment coaxial cylindrical model was determined as that a pair of spot-electrodes for current injection was located on the positions behind the ears and on the right lower abdomen, and a pair of spot-electrodes for voltage pick-up places on the medial portion at the level of clavicle and on the portion above the xiphisternum.

Development of a handy-type monitoring system for cardiovascular haemodynamic functions based on the volume-compensation and electrical admittance method / 中国医疗器械杂志

A handy-type monitoring system for cardiovascular haemodynamic functions based on the volume-compensation and electrical admittance method is developed. In this system, the inconvenient and discomfort due to cuff occlusion of the biological segment for BP measurement is improved by developing a new device using a local pressurization method, the stability for the physiological information detection is improved by developing a new detecting system, and the noise during detection using the system is greatly reduced by using a newly developed nozzle-flapper type electro-pneumatic converter. Also, for electrical admittance cardiography to estimate CO, the applicability of a two-compartment coaxial cylindrical model and the optimal position of a spot-electrode array that is used to replace the conventional band-electrode are discussed in this research. Experimental result shows that the monitoring system should satisfy non-invasive BP and CO measurement on beat by beat, and the comfort of measurement is significantly improved.

An instantaneous blood pressure measuring system at the wrist based on the volume-compensation method / 中国医疗器械杂志

An instantaneous blood pressure measuring system at the wrist based on the volume-compensation method is developed, and the characteristics and accuracy of the system is evaluated. The radial artery at the wrist is used as the detecting object, and a pad-type cuff as well as a newly designed electro- pneumatic converter is used in the system. Also, the comparative experiments between the system and the invasive blood measuring device (direct method) indicated that, the results obtained from the two methods are well correlated not only in rest condition, but also in a stressful condition. Therefore, the system is capable of non-invasive measuring instantaneous blood pressure in the radial artery.

AMBULATORY MONITORING OF THE BIOLOGICAL INFORMATION DURING EXERCISE USING A PORTABLE DIGITAL-RECORDER / 体力科学

In order to obtain the physiological information during such outdoor exercises as cross-country running or skiing, mountain climbing or diving in the sea water etc, we developed a new device employing MEMORY IC. for monitoring and recording various biological information from the subjects during exercise with no restraint. The device is composed of detecting, data processing and recording units. The application of a semiconductor, CMOS MEMORY I.C. to the recording unit enabled us to construct the instrument, which is very compact (150g) and tolerant to the mechanical vibrations as well as the enviromental disturbances. The recorded data are read out by a microcomputor system. This device was applied to ten subjects during running, where the heart rate, respiration rate and body temperature were recorded. They covered a distance of 9 km within 60 minutes. The heart rate of five trained men was stabilized at nearly fixed level during running which was consistent results with those by the treadmill, but in the untrained men different results were shown from the trained. The heart rate of the untrained men showed that they encoutered the limits of the capacity on the way of running. These results showed wide applicability of this device for the physiological analysis of outdoor exercises.