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Biomedical subjects

N Kabei

Publications and source records attributed to N Kabei.

8 recordsLinked to original sources
PubMed1994

Concept designs of nonrotating-type centrifugal blood pump and basic study on output characteristics of the oscillating disk-type centrifugal pump.

When designing a turbo-type blood pump as an artificial heart, the gap between a rotating shaft and a pump housing should be perfectly sealed to prevent any leakage or contamination through a seal. In addition, blood coagulation in a blood chamber must be avoided. To overcome these problems, we proposed five different nonrotating-type turbo pumps: a caudal-fin-type axial-flow pump, a caudal-fin-type centrifugal pump, a nutating-column-type centrifugal pump, a nutating-collapsible-tube-type centrifugal pump, and an oscillating-disk-type centrifugal pump. We selected and developed the oscillating-disk-type centrifugal pump that consists of a disk, a driving rod, a seal, an oscillation mechanism, and a pump housing. The disk is mounted on the end of the rod, which is connected to a high-speed DC motor through an oscillation mechanism. The rod and the disk do not rotate, but they oscillate in the pump housing. This movement of the disk generates forward fluid flow around the axis (i.e., the rotational fluid flow). Centrifugal force due to fluid rotation supports the pressure difference between the outlet and the inlet. The diameter of the disk is 39 mm, the maximum inner diameter of the pump housing is 40 mm, and the volume of the blood chamber for 25 degrees' oscillation is 16.9 ml. The performance of the pump was tested in a mock circulatory system.(ABSTRACT TRUNCATED AT 250 WORDS)

Equipment Design↗
PubMed1988

A portable pneumatic driving unit for a left ventricular assist device.

The authors developed a portable air driving unit for an artificial heart. As the portable energy source of the driver, a commercially available Ni-Cd battery was used. A linear compressor was selected as a portable size compressor. To reduce the number of parts to be assembled, a new type of pneumatic system was employed. In this system, the pressure level was regulated by varying the output flow rate of the compressor instead of using a pressure regulator and large air reservoirs. A one-board microcomputer and pressure sensors were used to control the pressure level. The total weight of the unit is 9.5 Kg. After assembling the components into the portable unit, a blood pump was connected to examine the output characteristics of the system. It was confirmed that the unit could drive the blood pump continuously for more than 2 hours under the following conditions: output flow rate of the blood pump = 5 L/min and output pressure = 100 mmHg.

Assisted Circulation↗
PubMed1975

Continuous measurement of myocardial oxygen consumption (MVO2) and hemodynamic response during transapical left ventricular bypass (TALVB).

Continuous measurement of hemodynamic parameters during acute TALVB and MVO2, with the use of a fiberoptic coronary sinus catheter, has demonstrated complete removal of ventricular pulsations and reduced mean left ventricular pressure, with maintenance of the systemic circulation. Myocardial O2 demand has been shown to significantly decrease during maximum LV decompression in the presence of a minimally changing O2 supply.

Animals↗
PubMedDate not supplied

Right ventricular balloon pumping.

Right ventricular balloon pumping (RVBP), i.e., using a balloon inserted into the right ventricular cavity to expel the blood into the pulmonary artery, was developed in this study. The balloon, which had an unstretched volume of approximately 15 ml, was made of polyurethane. In this experiment the balloon was inserted into the right ventricle via the right auricle or the apical area of the right ventricle. It was found that even when the natural heart was not beating, the pulmonary arterial blood flow could be maintained above 80 ml/min . kg body weight and the central venous pressure could be kept normal by combining RVBP and LVA. When the natural heart was beating but weak, the amount of increase of the pulmonary arterial blood flow induced by the application of RVBP depended on the degree of right heart failure, but RVBP could supply a sufficient flow rate to compensate for the failure of the right ventricle. Regurgitation through the tricuspid valve was scarcely ever found during RVBP.

Animals↗
PubMedDate not supplied

Insulin release from monolayer cultures of adult rat pancreatic islets.

The dynamics of insulin secretion were studied in monolayer cultures of adult rat pancreatic islet cells. Free cells were dissociated from adult rat pancreatic islets by the enzymatic dispersion method, with minor modifications, and were cultured on 25 mm round plastic cover slips. The monolayer culture consists mainly of B cells as identified by immunohistochemical staining. A small number of A, D and PP cells of pancreatic islets were also distinguished in the culture. After 14 days' culturing, the culture plate was placed in a Rose chamber through which the medium was pumped and from which the effluent was collected at various time intervals for insulin determination. It was observed that the physiological insulin secretion in cultured adult rat pancreas to glucose is characterized by an early phase of rapid onset and short duration and a late phase that rapidly increases and comes to a plateau for as long as the stimulus is applied. This result indicates that the monolayer culture of adult rat pancreatic islets is a promising method of supplying hybrid artificial endocrine pancreas.

Animals↗