1. Reports on pathogenesis of hepatic coma and on the artificial liver up to present are briefly summarized.
2. Artificial liver unit devised by us consists of both blood dialysis and enzyme perfusion circuit. Hollow fiber b/HFO-1 as dialyzer is used. The first step of our studies depends on establishment of physicochemical natures of membranes and possibility of enzymatic elimination of toxic substances, especially of ammonia. In the closed perfusion circuit, mixtures of glutamic dehydrogenase, α-ketoglutaric acid and NADH are enclosed. Ammonia dialyzed through dialysis circuit is trapped and bound with α-ketoglutaric acid with conversion to glutamic acid in the perfusion circuit. NAD thus formed is converted into NADH by another dehydrogenase and reductive form of substrate. The unit is suitable for enzymatic ammonia disposal.
3. The second step is efficacy of unit when it is combined with animals. Liver failure dogs are made by portacaval shunt subsequently with ligation of hepatic artery. They expire within 6-8 hrs with elevation of blood ammonia. Two hrs after portacaval shunt and ligation of hepatic artery, the femoral vessels of liver failure dogs are connected with the artificial liver unit. While perfusion, the elevation of blood ammonia is prevented with corresponding production of glutamic acid.
4. The third step is enzymatic disposal of toxic substances other than ammonia such as amino acids or amines. In addition with enzymatic system of ammonia detoxification, combination of several kinds of enzyme preparations to be enclosed in the perfusion circuit is now attempted and in progress.

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Fluorocarbon particles are said to be chemically inert. However, detailed analysis of the influence of intravascular fluorocarbon upon the internal organs of the animals was not established.
Histological examinations were performed after intravenous injection of fluorocarbon into the Wister-strain rats.
Fluorocarbon disappearance curve from blood showed almost exponential. Its T-1/2 was 30 minutes. Increases in splenic, hepatic, and pulmonary weight and their fluorocarbon content did not correlate, which meant the weight gain was not due to simple trapping. Granulomas were found in the liver and spleen. In the lungs, interstitial round cell infiltration and thrombosis were marked.
In a long period of time, fluorocarbon deposited in the lungs was a substantial percentage of the injected amount.
Leukocytosis with neutrophilia, in correspondence with the shift in the bone marrow, was seen. Platelet count was decreased. Reticular cells and histiobasophils were increased in the bone marrow.
From these experiments, intravascular fluorocarbon activates the Reticuloendothelial system, making granulomas and mobilizing the reticular cells. Fluorocarbon is accepted as a foreign body in the experimental animals.
It is strongly suggested that fluorocarbon is not biologically safe and causes certain disturances to the animals.

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1mm and 2mm in diameter silastic capillaries were used to construct the membrane oxygenator.
The surface area was 0.68 and 0.56m2 respectively. Each capillary was held with a medical grade adhesive so tightly enough to make a capillary bundle.
These bundles were placed into a polycarbonate cylinder 5cm in diameter, 50cm in length. Partial bypass was performed between the right atrium and femoral artery with this membrane oxygenator, with flow rate of 80-330ml/min, oxygen flow rate 5.0, 7.5, 10.0l/min.
Oxygen up-take, PO₂, PCO₂, oxygen saturation and other parameters were compared in these two oxygenators.
The data were excellent in the 1mm diameter capillary bundle oxygenator. as follows (O₂ flow: 10.0l/min):
Oxygen uptake: 11.1-41.1ml/min·m2
PO₂: arterial side 82-174mmHg
venous side 50-56mmHg
Difference of arterio venous oxygen saturation: 40.6-49.7%

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The effects of respiratory support on blood gases were investigated in computer models of O₂ and CO₂ gas transports in the membrane oxygenator—patient system. The O₂ and CO₂ gas exchange model for a one-squaremeter Landé-Edwards membrane oxygenator was constructed through the experiments and the theoretical analyses of the transfer of O₂ and CO₂. The distressed lung was modeled by considering decreased alveolar ventilation, ventilation—perfusion inequality and increased anatomical shunt. Simulation studies at a steady state were performed in both veno-venous and veno-arterial perfusions.
By the calculations which indicate the degree of improvement in arterial O₂ and CO₂ tensions followed by increasing a bypass flow rate, the followings were predicted. 1) The improvement of arterial blood is considerably dependent on the factors of respiratory insufficiency. The expected improvement is the greatest in decreased alveolar ventilation, medium in ventilation—perfusion inequality and relatively less in direct shunting, when other conditions are identical. 2) In the range of low bypass flows, no significant differences in the improvement are seen among the perfusion methods. In the range of high bypass flows, however, veno-arterial perfusion reduces the assisting effect because the maximum improvement is attainable at an appropriate bypass flow rate. On the other hand, veno-venous perfusion increases the assisting effect with increasing a bypass flow rate. 3) In CO₂ tension the improvement is obtained at a relatively low flow rate, compared with in O₂ tension. But, the additional improvement with high bypass flow is not to be expected even in veno-venous perfusion.
The experiments on dogs with decreased alveolar ventilation exhibited the similar effects to the simulation. The method of perfusion, the number or the size of oxygenators and the rate of bypass flow could be determined by this quantitative analysis.

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At the present time, it is a matter of common knowledge that the vascular prosthesis which is used for clinical routine work is all crimped. During the observation on the reparative process of implanted arterial prosthesis, we have found that useless deposit of blood cells took place to flatten the corrugated inner surface of the prosthesis, and as a result, a thick fibrin layer has been formed in due process. The phenomenon has delayed the organization of the inner surface of the prosthesis, having led to the formation of a very thick pseudointima.
On the other hand, we have implanted the non-crimped prosthesis of the same material into dog's femoral arteries and, after compared with the crimped vascular prosthesis, we have come to a conclusion that the disadvantageous character of the crimped vascular prosthesis could be completely got rid of in the case of the latter experiment. In addition to this, an excellent reparative process could have been clearly observed, having pseudointima very thin.
We have again concluded that the use of the noncrimped vascular prosthesis for small arterial replacements has been very effective.

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We have further appreciated the clinical features of REDY SYSTEM—new type of sorbent-based artificial kidney.
REDY has fine ability of correcting metabolic acidosis of uremic patients. The sources of bicarbonate are dialysate and infusate acetate, and the hydrogen ions are removed by zirconium phosphate in the form of anmonium ions.
Dialysate ammonia concentration do not exceed 2.7mg/dl, so it may be safely used in the patients of normal hepatic function.
The dialysances of small molecule substances are somewhat inferior compared to usual single pass method, because of low QD (200ml/min).
In the course of experiments, so called disequilibrium syndrome is seldom encountered.

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The ball electrode for electrically induced ventricular fibrillation during cardiac surgery was deviced.
Ventricular fibrillation was easily induced with the ball electrode attached to left ventricular epicardium in the pericardial cavity.
In this way, fifty-eight patients during moderately hypothermic cardiopulmonary bypass, and six patients under normothermic cardiopulmonary bypass by means of the technique, so called, transapical aortic infusion, were operated without showing myocardial damage.
After defibrillation by electrically induced direct current shock, normal cardiac function was usually resumed without massage.
Advantages of deliberatelly induced ventricular fibrillation in open heart surgery during normothermic cardiopulmonary bypass are that it maintains a quiet operative field preventing air emboli, and that heart block caused by surgical repair can be found soon after electrical shock.

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In this paper the structure and use of the multilayer cannula needle, designed to simplify percutaneous catheterization in hemodialysis, is introduced. The cannula needle is used mainly in cases with acute renal failure, and sometimes in cases of chronic renal insufficiency requiring weekly maintenance of hemodialysis.

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