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Biomedical subjects

M Sakaki

Publications and source records attributed to M Sakaki.

41 records · Page 3Linked to original sources
PubMedDate not supplied

Peripheral circulation during nonpulsatile systemic perfusion in chronic awake animals.

Peripheral circulation (PC) during nonpulsatile (NP) perfusion is not satisfactorily understood, although it is known that animals can survive with chronic NP flow. In awake goats, PC was analyzed by hemodynamic and hormonal parameters, tissue blood flow of the ear measured by a noninvasive laser Doppler flowmeter, and distribution of the body surface temperature monitored by thermography. An NP systemic circulation was established in five 40-64 kg goats with a centrifugal pump (MD-10, Iwaki Pump, Japan) that replaced a pulsatile ventricular assist device 2 weeks postoperatively; this was done without anesthesia. Nonpulsatile total left heart bypass was obtained, with flow rates of 78-165 ml/kg/min. Systemic vascular resistance and blood adrenalin and noradrenalin levels were not affected by the depulsation. Tissue blood flow during NP perfusion was well maintained and showed comparable values to those during pulsatile systemic circulation. Vasomotion of 10-20 cycles/min was obvious in the tissue blood flow pattern, indicating adequate PC at each sampling point. Thermography before and after depulsation indicated no change of temperature distribution, and displayed warm peripheral areas. In conclusion, PC of animals on chronic NP systemic perfusion is adequately maintained.

Animals↗
PubMedDate not supplied

Hybrid respiratory support system with extracorporeal placental oxygenation.

The authors developed a novel hybrid system for long-term respiratory support with extracorporeal placental oxygenation. In this system, the patient's blood is oxygenated with O2 saturated artificial blood across the villous membrane during passage through the fetal circuit of the placenta, which is placed in a specially constructed artificial uterus. Human term placentas were obtained immediately after vaginal delivery and used for the experiments. The gas transfer performance of the current apparatus was 60 ml/min for O2 and 40 ml/min for CO2 at a blood flow rate of 1.0 L/min. From these results (and the assured blood compatibility of the placenta), the authors conclude that this system will become one of the most promising modalities for prolonged extracorporeal oxygenation.

Biocompatible Materials↗
PubMedDate not supplied

Continuous monitoring of artificial heart pump performance.

Continuous monitoring of pump performance is essential and effective for optimal driving of a pulsatile blood pump. The authors contrived a practical method for continuous estimation of blood volume in a pump by measurement of electrical impedance (Z). This method was evaluated with the air-driven, diaphragm type pump. The pump was made from polyurethane and had two metal connectors at the inlet and the outlet ports. Z was measured by charging the alternating current (50 kHz, 0.4 mA) between two connectors as electrodes. In in vitro tests, Z reached maximum value during full-empty and minimum value at full-fill. The blood volume calculated by an empirical equation of Z was linearly related to the real blood volume (r = 0.99). In in vivo tests with goats, pump output estimated by this method was linearly related to pump output measured with an electromagnetic flowmeter and effectively evaluated pump performance. For calibration, this method needed only to measure Z at full-fill. This method was useful as a controller of a full-fill to full-empty drive. It was concluded that this method is a practical estimate of pump performance, even if implantable diaphragm type pumps are used, and easily applicable to any kind of pulsatile pump.

Animals↗
PubMedDate not supplied

An implantable left ventricular assist system with an electrical impedance monitoring and control system.

The authors developed an implantable left ventricular assist system (LVAS) for bridge to transplant of rather small sized adults. The pump was made of segmented polyether polyurethane and was 86 mm in diameter, 50 mm in height, with a 70 ml nominal stroke volume. A percutaneous drive line was connected with an external pneumatic control drive unit (CDU). In chronic animal experiments using 11 adult goats, the pump was installed between the LV apex and the descending aorta and was placed in the abdominal wall. Five goats were killed after 4 to 14 weeks while in good physical condition, and one is ongoing. There were no prominent thromboembolic symptoms despite no anti-thrombogenic agent being used. The new electrical impedance-based monitoring and control system (Z system) was installed in the CDU. In this Z system, automatic calibration was performed periodically for several seconds while the drive condition was changed to ensure full-fill of the blood pump. The full-fill to full-empty drive was well controlled by this Z system. In conclusion, the new Z system is practical and useful for monitoring and control of an implantable pump, giving this LVAS a promising place in clinical use.

Adult↗