Recent artificial respiration therapy has to be accomplished based on the relevant clinical assessment such as the monitoring of intrapulmonary regional ventilation dynamics of the patients. However, almost all respirators and bedside monitoring systems provide insufficient real-time information during artificial respiration. From this point of view, a ventilation dynamics monitoring system was developed for obtaining the intrapulmonary regional information by use of the bioelectrical impedance method. This system was able to measure 4-channel bioelectrical impedance (60 kHz) of divided thoracic areas simultaneously. Furthermore, the differential pressure-type pneumotachograph was also equipped in the system to calibrate the measurement impedance data to the ventilatory volume of the absolute value. Comparing with complicated systems already reported in the past study, the most advantageous performance of this device was the simpler operation and clear graphical display in the clinical use. These were realized by use of the high-performance LSI and microcomputer system. To evaluate the performance and availability of the system, seven healthy adult volunteers were tested during the variety of spontaneous respirations. In this study, reproducibility and linearity of partial
ΔZ versus corresponding ventilatory volume change were examined against various electrode arrangements. As the results, the obtained impedance changes
ΔZ in the regional pulmonary parts and the sum of them showed clear correlation for the ventilatory volume change which corresponded to the physiological regional ventilation dynamics (coefficient of correlation:
r = around 0.9). By calibrating these data (
ΔZ and sum of them) with the pneumotachograph, partial absolute ventilatory volumes were able to estimate within around 10% of error range. In conclusion, this system will be useful as a bedside breathing monitor to the simple and easy prehension of regional ventilation dynamics for the respiration therapy.
View full abstract