Circulation Circuit Research Articles

Decrease of Total Serum Cholesterol and Apolipoproteins A1 and B Levels during and after Extracorporeal Circulation

Cholesterol, apolipoproteins A1 and B and triglycerides were evaluated before, during and after extracorporeal circulation during cardiac surgery to a precise degree and chronology of variations. Cholesterol, apolipoprotein B and triglycerides show a significant and persistent decrease following initiation of extracorporeal circulation. Triglycerides decrease is due to factors such as heparin administration. Cholesterol and apolipoprotein B decrease does not appear to be due either to contact with extracorporeal circulation circuit nor hypothermia. Decrease of hepatic VLDL and HDL production or modifications of LDL-cholesterol cell clearance are possible explanations.

開心術後の凝血能の経時的変化 血小板容積分布を中心として

We investigated the platelet volume and other blood coagulation parameters in early postoperative periods in patients who underwent cardiac surgery. They were 11 (coronary artery bypass grafting, 5; prosthetic valve replacement, 6) in total numbers, and their mean age was 52.3 (41-61).We tested their blood for platelet numbers, and mean platelet volume (MPV) as well as plasma levels of beta-thromboglobulin (β-TG), fibrinogen (Fbg), antithrombin III (ATIII) and plasminogen (Plg). The tests were done on the preoperative day, immediately after the operation, 1d, 2d, 5d, 1w, 2w, 3w and 4w after the operation.The platelet number fell from 21.2±5.7×104 (M±SD)/μl to 7.9±2.1×104/μl immediately after the operation and showed its lowest value (5.3±3.1×104/μl) two days after the operation. Then it showed dramatic increase through 1st and 2nd weeks and reached its maximum value of 39.3±7.1×104/μl two weeks postoperatively. Plasma β-TG reached its highest value of 107.6±35.3ng/ml immediately after the operation. MPV changed from preoperative values of 8.96±0.73μm3 to 8.11±0.5μm3 immediately after the operation. MPV changed from preoperative values of 8.96±0.73μm3 to 8.11±0.5μm3 immediately after the operation and then gradually increased. The value reached its maximum value of 9.27±0.63μm3 on the fifth postoperative day. Fibrinogen levels increased mono-exponentially after the surgery and returned to its preoperative value very slowly.These results suggested the destruction and consumption of the platelet within extracorporeal circulation circuit during cardiac surgery. Rapid rebound increase in platelet numbers and changes in coagulation parameters may explain the hypercoagulable state in the early postoperative period following cardiac surgery.

Reactor plant of the AST-500 heat supply station

The core and the heat-exchangers of the primary and secondary circuits are located in the reactor vessel. The upper space of the reactor above the level of the coolant performs the function of the primary circuit pressure compensator~ Heat removal from the core is effected by natural circulation of the coolant. The ascending part of the circulation circuit includes a section with the individual control rod tubes and, located above them, the general control rod section. The general control rod section is a shaft with little covering by structural components. A uniform supply of coolant to the tubular systems of the heat-exchangers is provided through openings made in the shell of the pipe and equipment unit~

超低体温法の実験的研究 特に肝,腎の変化について

Function of the liver and kidney were studied during experimental profound hypothermia.Dogs were rapidly cooled below 10°C at the esophageal temperature by extacorporeal circulation combined with heat exchanger and rewarmed after 3060 minutes of complete circulatory cessation.In one group the perfusion rates were kept in constant, while in the other group the perfusion rates were gradually reduced in the course of cooling, and slowly increased in rewarming.In some experiments low molecular weight dextran was used during extracorporeal circulation.Following results were obtained.1) Portal venous blood flow was measured by direct method which was revealed 19.3cc/kg/min before experiment. The flow was markedly diminished in the cooling procedure, and decreased to 27.9% of the control value at the end of cooling. The flow increased gradually by rewarming and returned to 62.5% of the control at the end of rewarming.The portal flow was influenced with changes of body temperature, arterial blood pressure, perfusion rate, portal vascular resistance and development of splanchnic pooling. But there were found no direct correlations between portal flow on one hand and esophageal temperature, arterial blood pressure and perfusion rate on the other.2) Intestinal vascular resistance and portal pressure elevated shortly after the beginning of cooling and remained in high level through cooling and rewarming.It seemed that splanchnic pooling might develope in some extent at that time. although the pooled blood returned to the extracorporeal circulation circuit in most cases at the end of rewarming. The splanchnic pooling in the course of rewarming was marked especially in the group where perfusion was performed at constant flow rate.3) Portal venous oxygen saturation was higher than that in mixed venous blood, showing 83.5% before experiment. Oxygen saturation could be close to arterial blood oxygen saturation iu cooling. and gradually falling in rewarming. It decreased below the control value at the end of rewarming.4) Carbon dioxide content in portal venous blood was decreased through cooling and rewarming, and slightly increased after perfusion.5) Portal blood pH calculated to 37°C became lower in cooling and returned to the control value by rewarmiing.6) Renal blood flow was measured by direct method, showing 17.53cc/kg/min as the initial control value. The flow rapidly reduced shortly after induction of cooling, and decreased to 16.4% of the control value at the end of cooling, and gradually increased in rewarming. It reached to 42.7% of the control at the end of rewarming.Just like as in portal blood frow, the renal flow was influenced with changes of body temperature, arterial blood pressure, perfusion rate, renal vascular resistance and development of ventricular fibrillation, but no direct correlations were found between renal flow on one hand and esophageal temperature, arterial blood psessure, and perfusion rate on the other.Especially, the ventricular fibrillation had an important effect upon the renal flow. The flow was markedly reduced when ventricular fibrillation persisted for a long time during rewarming.7) Renal vascular resistance elevated rapidly immediately after beginning of cooling, and it was remained in high level through cooling and rewarming. The resistance dropped suddenly when esophageal temperature rose to 35°C, and it falled nearly to the control value after perfusion.8) Renal venous blood oxygen saturation was 93.2% before experiment. Oxygen saturation increased and difference between arterial and venous blood disappeared during cooling.Oxygen saturation becreaed during rewarming and falled below control value at the end of rewarming.9) Carbon dioxide content in renal venous blood was approximately half of the value in the normal mixed venous blood before experiment, and it decreaed through cooling and rewarming.

The nuclear reactor circulation circuit as a radiation source

The solution of the problem of circulation circuits with a single radioisotope, which has been found earlier [1], is applied to the general case where several radioisotopes having radioactive progeny are formed in the substance to be activated. The problems of the absolute maximum circuit power and the consumption of neutrons per unit power for a number of elements which can be used as substances to be activated in the circuit are considered. From among them, the most promising are indium and its alloys.

Feed Distribution and Hunting in Marine Water-Tube Boilers

Data and experience are given concerning the phenomenon of hunting in naval water-tube boilers and its elimination by arranging the internal feed water distributing piping to spray the water in the steam space of the boiler drum. Various internal feed-distributing arrangements are described, and calibration tests are given of various designs of feed-distributing piping. The paper discusses the factors causing circulation in a water-tube boiler, the conditions essential to give the equilibrium necessary for steady boiler operation, and the variations which occur in the steam volume below the water level in a boiler with changes in boiler load. The characteristics of boiler hunting are discussed and an analysis is given of the various factors in the hunting cycle. It is shown that hunting is due to the existence of a continuing time-lag between the rate of feed supply and the rate of steam generation, and that the time-lag and hunting are eliminated if the feed supply is heated to boiling point before it enters the circulation circuit. A review is made of feed-distributing arrangements in service, and various points are suggested to which consideration should be given to obtain a feed-distributing arrangement which will obviate hunting with highly rated water-tube boilers. Features concerning the water level control in naval boilers fitted with augmentors are discussed.