There is an assistant lung as one of utilization of artificial kidney for multi-purposes. Experimental and clinical studies in its gas exchanger were performed with coil type artificial kidney of EX-03 (membrane area: 0.84m2, Cuprophane membrane). Oxygenation method were liquid-membrane-blood diffusion for retaining of this function. Its efficiencies for oxygenation showed as follows: PO2 was 221mmHg/200ml/min/0.84m2 for single flow, and PO2 was 343mmHg/200ml/min/0.84m2 for air-liquid flow in dialysate pass-ways. In this time, pressure gradients of PCO2 in in let and out let side of assistant lung showed 75mmHg/200ml/min/0.84m2 with 4.5ml/min of ultra-filtration rate. Consequently, our experimental and clinical studies showed excellent results in carbonic acid gas exception than in oxygen addition.
Polyvinyl chloride (PVC) materials are widely used in medical and paramedical applications for their excellent mechanical properties and ease of molding and fabrication, however their safety is controversial. Simple in vitro evaluation methods are proposed to select safer PVC materials and devices. Test samples of the same sheet size were extracted in distilled water at 37° or 70°C The eluates obtained were analyzed spectrophotometrically and the absorbance of ultraviolet absorption at 220nm was measured. The elution was followed with time and elution (or absorbance) -time curve was obtained. After appropriate time of extraction. all the eluates were discarded, water was renewed. and the extraction was continued further This repeated extraction test gave an important criter on as to the persistency of elution of the leaching substances. Rate and tterststencv of elution, and amount of leachable substances were determined. Hemolysis test was performed by direct contact of the tes samples with red blood cell. Commercial medical PVC tubings, administration set and blood bags were compared, and found to show different elution characteristics and hemolysis rate. It is recommended to use the PVC materials or device which show low degree of elution and hemolysis.
Pulmonary insufficiency has been one of the most serious problem for the animals replaced totally by the artificial heart (TAH animal). Twenty-five goats, survived various times from 13 to 710 hours, were studied pathologically. Light microscopic findings at the lungs were classified into six groups. The most important findings of them are massive, diffuse congestion with hemorrhage and their chronic change. These findings seem to be related with acute deterioration of the pulmonary microcirculation and increased permeability of its capillary beds. The main etiologic factors, causing above findings, were thought to be surgical operation, anesthesia, continuous heparin injection and artificial heart function itself. In addition to routine pathological technics, microangiography and electron microscopy were carried out and some useful inf ormations were found out through them.
The isolated white rabbit kidney was perfused with electrolytes solution and fluorocarbon (FC) emulsion for 9 hours at room temperature. As control the isolated kidney was left in saline for 9 hours at room temperature. The cell viability of the kidney and analysis of the perf usates were studied biochemically with following results. 1. The oxygen consumption of the peripheral tissue was almost normal in FC group, while it was depressed in electrolytes group. 2. pH and base excess of the perf usate was within normal limits in FC group, while they were not in electrolytes group. 3. The potassium concentration and LDH activity of the perfusate seemed to reflect the lesser damage in FC group than in electrolytes group. 4. The preserved kidney with FC-emulsion showed excellent retention of mitochondrial function, while it was depressed in electrolytes and saline groups, which was due to hypoxia. 5. The activities of the glycolytic and gluconeogenetic key enzymes remained at high levels in the FC emulsion group. In contrast, there was a definite fall in those enzymic activates in the electrolytes and saline groups, which is probably the result of fatigue of the enzymes associated with reduced mitochondrial function due to hypoxia. 6. The reabsoption and production of the urine was kept in normal range on account of well preserved renal function by FC emulsion. In conclusion, therefore, the fluorocarbon used in this experiment is capable of transporting oxygen enough to maintaine the viability of the renal cells and renal function.
In an attempt to clarify the healing mechanism of the synthetic vascular prostheses, we have examined cytochemical and morphological feature of inner and outer capsules of prostheses implanted in dogs by means of light and scanning electron microscopy. Dacron prostheses of 5.5cm long and 8 or 10mm in internal diameter were implanted in thoracic aorta in 60 mongrel dogs. Sticky substance adhered on the surface of dacron fibers either implanted or dipped into blood was observed under scanning electron microscopy. On the other hand, these fibers covered with sticky substance reacted positively against Millon reagent and were not stained with Sudan Black B. But after enzymatic digestion by tripsin, they were stained with Sudan Black B. These results suggest that the surface of the dacron fibers is covered with lipid and protein and they combined quite possibly with each other as lipo-protein. Because such hydrophobic substance as dacron has affinity with oils and lipids, the dacron fiber is able to easily covered with lipid-side of lipoprotein. This is the first phenomenon on implantation of synthetic vascular prosthesis in order to become stable in living body. However, the sticky substance which was observed under scanning electron microscopy was not identified yet as lipoprotein. Our group is proceeding further investigation by means of transmission electron microscopy to clarify the nature of this sticky substance.
In 12 patients with chronic renal failure and without obvious signs of congestive heart failure, cardiac functions and blood volume were analyzed immediately before and after hemodialysis. Investigations were performed through dye dilution method using external arterio-venous shunt. The patients were divided into two groups. One group was consisted of 6 patients socially rehabilitated and the other group was of 6 patients non-rehabilitated. An increase of cardiac output was resulted from hemodialysis in social rehabilitation group, whereas a slight decrease on cardiac output was caused in non-rehabilitation group. There were no significant differences in a decrease of total blood volume, body weightloss and a fall of arterial pressure following dialysis between two groups. In non-social rehabilitation group, cardiac output, stroke volume and arterial pressure were higher than those in rehabilitation group before hemodialysis. It was concluded that the change of cardiac output following hemodialysis was affected mainly not by dialysis technique but rather by predialysis condition of patient.
Upon intracardiac surgery using extracorporeal circulation, hemolysis due to intracardiac suction device is a main problem. Factors affecting hemolysis of roller pump induced suction mechanism are friction of roller pump, suction of blood with air and scattered movement of residual blood in suction circuit. We studied the intracardiac suction device controlled with pulsatile negative pressure electronically to minimize hemolysis. The device is consisted with cylinder 420mm in height and 58mm in diameter containing of reserving chamber, ball valve chamber and discharging chamber. As the characteristic features of this device, we found that pulsatile negative pressure is much effective to suck and return the blood to the oxygenator than continuous and constant negative suction. The pulsatile negative pressure is obtained from vacuum pump controlled by electronic device which is consisted with pulse oscillator, rate controller, driver circuit and solenoid valve. Maximum suction capacity was approximately 4, 000ml/min when applied negative pressure of 30mmHg for 1.2sec. in every 1.8sec. of interval. Upon comparison of hemolysis, it showed ess than 20% of intracardiac suction device by roller pump itself.