Recently, demand for ECMO (Extra-corporeal Membrane Oxygenation)，ECLS (Extra-corporeal Life Support)，PCPS (Percutaneous Cardiopulmonary Support) and long-term cardiopulmonary supports is expanding exponentially, however, membrane oxygenator still remain problem of long-term use. In this study, PFC (Perfluorocarbon)-Blood contact type oxygenator (PBC-OX) without hollow fiber was developed. PFC is harmless to the body, and has high gas solubility and insolubility in blood. When oxygenated PFC comes in contact with blood, blood gas exchange transpires and the PFC spontaneously separates from the blood because of its insolubility and higher specific gravity. In vitro experiments using bovine blood were carried out to evaluate the performance of PBC-OX. As the result, PaO₂ and PaCO₂ were kept in the normal value (PaO₂ >80 mmHg, PaCO₂<40 mmHg). The free hemoglobin concentration was less than 60 g/dl. These results show that the performance of PBC-OX is comparable to that of membrane oxygenators.

View full abstract

In order to clarify the effect of arching spine during epidural anesthesia on deformation of the ligamentum flavum, elastic tensile force inside the ligamentum flavum was measured. The ligamentum flavum of porcine spine was pushed 3 mm with a tester of rubber hardness. Elastic tensile force inside the ligamentum flavum was obtained from reaction force-time waveform with the tester. Small retractor was employed to enlarge the width of the vertebral bones as substitute of arching spine. Maximum needle insertion force and deformation of the ligamentum flavum were plotted against the elastic tensile force inside the ligamentum flavum before needle insertion. The larger elastic tensile force inside the ligamentum flavum resulted in the smaller deformation of the ligamentum flavum, whereas no correlation was observed between the maximum needle insertion force and the elastic tensile force inside the ligamentum flavum.

View full abstract

Body surface area (BSA) is currently used as a standard to determine the anatomical compatibility of a patient with a ventricular assist device (VAD). However, it is difficult to accurately evaluate that of the patient with the threshold limit value of BSA to implant VAD because BSA is only calculated by the patient's height and weight. The purpose of this study is to establish a new quantitative standard which is more accurate than BSA. The parameters which represent anatomical characteristics of chest and abdomen were measured using CT images of 27 subjects. The 17 subjects with BSA of not less than 1.7 were defined as the control group assuming that the threshold limit value of BSA is 1.4. Mahalanobis distance (MD) between the 10 test subjects with BSA of not over 1.5 and the control group were calculated by means of the parameters. MD of the test subjects with BSA from 1.4 to 1.5 ranged from 2 to 44. It is confirmed that the subjects with large MD have incompatible anatomical characteristics to implant VAD in comparison with the subjects with small MD. Results suggested that MD may be able to become a new quantitative index more accurate than BSA.

View full abstract

This paper describes a control method for step descent involving two wheelchair robots. These robots are connected using a passive link and work together when they encounter a high step that a single vehicle could not overcome. The system does not require precise measurement of the step height using external sensors. Instead, it uses a simple sensor to determine the link angle, which depends on the inclination of the vehicle. When descending steps, the robot system compares its descent ability with data from the step-height sensor. A theoretical analysis was carried out to clarify the relationship between the link angle and the vehicle inclination, and this was then used to evaluate whether or not the step was too high to descend. An autonomous locomotion robot system was constructed based on this approach, and the experimental results validated the effectiveness of the control method.

View full abstract