[Anemia, diet meal planning in anemia and diet therapy].
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Anemia↗
Biomedical subjects
N Mitsui
Publications and source records attributed to N Mitsui.
Peroneal artery aneurysm treated by transcatheter coil embolization and temporary balloon occlusion in Behçet's disease.
Peroneal artery aneurysms in Behçet's disease have not been described to date. We present such a patient who was treated successfully using transcatheter embolization.
Aneurysm↗
Development of an outside flow membrane oxygenator using a silicone hollow fiber.
A new membrane oxygenator was devised and assessed for performance in animal experiments. A silicone fiber membrane oxygenator, heat exchanger, and arterial blood reservoir are the components. The oxygenator is an outside flow type with minimum intrapulmonary resistance and, consequently, gas transfer is by gravity venous drainage. This device was used to conduct normothermic cardiopulmonary bypass (CPB) in 10 sheep over a period of 8 hrs (high flow group: 6 sheep, mean flow, 4.7 + 0.5 L/min; low flow group: 4 sheep, mean flow, 1 L/min). Performance was evaluated with gas transfer capacity, hematologic examination during CPB, and scanning electromicroscopic (SEM) appearance of the membrane after CPB. Blood gas was maintained with high PO2 and acceptable PCO2 levels throughout CPB. Plasma free hemoglobin was significantly low and fibrinogen was also maintained within physiologic levels. Scanning electron microscopy showed no thrombus formation on the membranes of either group. These results indicate this oxygenator to be quite adequate for gas exchange and prevention of blood cell trauma; it is also applicable to pulsatile or separating CPB because of the arterial blood reservoir.
Animals↗
First significant animal survival with a Wankel-type left ventricular assist device.
The authors' laboratory is developing a device for heterotopic left ventricular assistance. It consists of a titanium Wankel-type rotary pump, driven by an hermetically sealed electric motor. In our animal experiments, the motor-pump unit was implanted in the thoracic wall. The pump was connected to the left heart chambers by left atrial cannulation, and to the descending aorta. The motor was connected to the power and control unit by an electric wire through the skin. In this report, the authors describe the first significant animal survival with this system. Laboratory results were encouraging for hemolysis. The pump failed at 13 days due to a deposit of fibrin and blood cells in the gear housing. This problem was not surprising since similar events have been encountered with centrifugal devices. However, further design improvements should allow longer animal survival and clinical application.
Animals↗
Control of pulsatile rotary pumps without pressure sensors.
When ventricular assistance is achieved with a volumetric pump driven by an electric actuator, overpumping can cause venous collapse. To prevent this problem, pump speed must be monitored and controlled. The authors developed a regulatory system based on the current intensity signal from the electric motor. This signal is processed and compared with predicted values calculated according to a mathematical model at the beginning of each ejection phase. If a difference is detected, pump speed is adequately adjusted. The great advantage of this system is elimination of the need for an implantable pressure sensor. It requires a simple and ubiquitous electronic component, i.e., a resistor, that can be easily integrated into the motor control circuit and does not require calibration.
Animals↗
Control of a rotary pulsatile cardiac assist pump driven by an electric motor without a pressure sensor to avoid collapse of the pump inlet.
Our ventricular assist device uses a valveless volumetric pump operating on the Maillard-Wankel rotary principle. It is driven by an electric motor and provides a semi pulsatile flow. At each cycle, blood is actively aspirated into the device, and overpumping results in collapse at the pump inlet. To prevent overpumping, it is necessary to ensure that pump intake does not exceed venous return. Poor long-term reliability rules out the use of current implantable pressure sensors for this purpose. To resolve this problem, we have developed a method of control based on monitoring of the intensity of electric current consumed by the motor. The method consists of real time monitoring of current intensity at the beginning of each pump cycle. A sudden change in intensity indicates underfilling, and motor speed is reduced to prevent collapse. The current consumed by the motor also depends on the afterload, but the form of the signal remains the same when afterload changes. After demonstrating the feasibility of this technique in a simulator, we are now testing it in animals. We were able to detect and prevent collapse due to overpumping by the cardiac assist device. This system also enables us to know the maximum possible assistance and to thus adapt assistance to the user.
Algorithms↗
Development of an air lift pump oxygenator.
The authors devised an air lift pump oxygenator, comprised of double cylinders connected together and filled with perfluorocarbon (FC-75, 3M) as an oxygen carrier. While the oxygen enters the FC-75 through the lower inlet of one cylinder, the oxygenated FC-75 is lifted by an air lift pump and circulates in the two cylinders. FC-75 adds oxygen to the blood that infuses from the lower inlet of the other cylinder. The oxygenated blood is separated from the FC-75 by gravity and infused into the subject. The size of the cylinder is 2.2 cm in internal diameter and 17 cm in effective oxygenation height. The capacity of the oxygenator is 160 ml. PO2 went from 62 mmHg to 96 mmHg and PCO2 decreased from 31 mmHg to 25 mmHg at a blood flow of 50 ml/min and an oxygen flow of 2 L/min. Maximum blood flow was 60 ml/min and the blood reserve capacity was 20 ml/min. The air lift pump oxygenator has advantages, such as simple structure, no motor, and a small priming volume.
Blood Flow Velocity↗