A carbon fiber electrode was developed to detect sympathetic nerve activity for purpose of physiological artificial heart control. Contact impedance of a carbon fiber electrode was between that of collagen fiber electrode and Ag electrode. Renal sympathetic nerve activity was recorded by means of the carbon fiber electrode in intact nerve of rabbits. Relationship of heart rate and integrated renal sympathetic nerve activity(IRSNA)was shown quantitatively by recording vital reaction at administration of ganglionic-blocking agent. In chronic experiment, renal sympathetic nerve activity was able to be recorded during two weeks in awake rabbits. These results indicate that there is an ability to detect sympathetic nervous system activity and application to artificial heart control in this carbon fiber electrode.

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method of PTT(Pulse transit time)estimation. PTT was defined as duration time from chest vibration to Plethysmogram(PTG)and PTT'was defined from Electrocardiogram(ECG)R-wave to PTG respectively. The measurement showed the difference between PTT and PTT'was negligible. Therefore, it is possible to use the time from ECG R-wave to PTG for PTT. This result shows consistent tendencies with previous findings. The Present method makes it easier to estimate PTT because of the high S/N ratio of ECG waveform. Some problems of practical application are also discussed.

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This paper describes a membrane oxygenator for long term lung assist. A Membrane Oxygenator has been used for extracorporeal circulation as ECMO. However, the major oxygenators which have microporous membrane cause plasma leakage that deteriorates the performances for long term circulation. The authors developed a fine silicone hollow fiber which is twice the mechanical strength, low diameter and thin wall thickness. The fine silicone hollow fiber has almost the same transfer performance as microporous hollow fiber when it used in extracapillary flow type. However, extracapillary flow type which causes partial and accumulate flow easily has possibility of causing thrumbus and reduction of gas transfer performance. On the other hand, an intracapillary flow type oxygenator can make laminar flow in the hollow fibers. It is able to keep gas transfer performance stably for long term circulation without thrumbus. One of the disadvantages of intracapillary flow type is large pressure drop. Therefore, using softness of the silicone material, the authors designed and manufactured an oxygenator which has expanded inlet for decreasing pressure drop. This intracapillary oxygenator consists of25000silicone hollow fibers with a length of8cm inserted in the housing. The surface area of the membrane is3.0m ². The priming volume is390mL. Gas transfer performance of the oxygenator was evaluated by in vitro experiments. Oxygen and carbon dioxide transfer rate were 52mL/min and95mL/miri, and pressure drop was30mmHg at a blood flow rate1L/min. The oxygenator developed in this study can be used for extended duration in such application as extracorporeal membrane oxygenator.

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