Hiroyuki Horio

Development of a curved multi-tube (CMT) catheter for percutaneous umbilical blood sampling and control methods of CMT catheters for solid organs

We have proposed the concept of curved multi-tube (CMT) catheter for this system. This system makes safe minimally-invasive surgery possible, because all complex mechanisms are arranged outside of the body. In this paper, we present the development of a robot named FORMS (fetus operation robot using master slave system) which aimed at pulling out blood from umbilical cord. We also present the control method of curved multi-tube catheter for solid organs like brain and liver, and the various applicable fields of CMT catheters in medical treatments and industries.

On a portable memory device for physical activities and informations of maternal perception

The condition of patients must be known to attending doctors for adequate management of a disease, particularly of high risk pregnancy. For this purpose, we have developed a portable computerized disease condition memory device to record the physical activities with maternal perception of fetal movement and uterine condition in daily life, both at home and during work. This device taken out by the patient is a small battery-driven CMOS 8 bit computer system (size: 107 x 80 x 30 mm, 240 g) and is equipped with push-botton switches on the upper side and a mercury switch inside it. The time of maternal perception of fetal movement and uterine contraction are recorded by the patient pressing the corresponding switch. Meanwhile the mercury switch serves as a acceleration sensor and the physical activities were measured by counting ON-OFF actions of the mercury switch caused by her movements. Consequently, the device has recorded physical activities automatically by wearing this unit all day long. The continuously recordable time is more than two weeks. The evaluation about the sensitivity of physical activity measurement has indicated that the mercury switch sensor was well related to the oxygen consumption rate in rest and mild exercise. Using this device to five pregnant women, the data showed the quantitative difference in physical activities between rest in bed and normal home life, and daily changes could be clearly observed. From these results, the physical activities and the condition of the patient in daily life can be followed by this device.

Analysis of the tcPO2 response to blood interruption in infants and adults

The transcutaneous PO2 (tcPO2) response to blood interruption (BIS test) was measured in 6 healthy adults and 28 infants, including premature infants. The response was similar in both infants and adults with a time lag at the beginning of blood interruption, a subsequent linear decrease, a time lag at the end of blood interruption, and an exponential recovery to the final steady state. The linear decrease of tcPO2 in the BIS test had a correlation coefficient of more than 0.98 in all subjects and indicated the cutaneous oxygen consumption rate independent of the oxygen pressure. There was a significant difference in oxygen consumption according to birth weight in the infants (< 2 kg, 2-3 kg, and > 3 kg). The recovery time constant for infants was 13 seconds which was about 1.4 times faster than that for adults, and it increased significantly along with a higher birth weight. The time lag at blood interruption was longer than that at blood recovery. The time lag for infants was significantly shorter than that for adults, and in infants there was a significant difference between the group with a birth weight < 2 kg and the others (p < 0.005). All of the parameters of the BIS test suggested the physiological immaturity of premature infants.