Jinko Zoki

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In the 46 patients who underwent operative repair of thoracic and thoraco-abdominal aortic aneurysm, 9 cases showed hypoxemia (PO₂<70mmHg, FiO₂ 1.0) and rectal temperature lowered less than 34°C in 10 cases intraoperatively. On August 1991, we began to utilize left heart bypass with membrane oxygenator and internal heat exchanger as temporary support. Activated clotting time was maintained between 200 and 250 s during the support. Hemoconcentrator also attached to the inflow side of left heart bypass, and sucked blood from the operative field could be transfused quickly. As applying this system, good clinical results were obtained. The diagnosis of 11 patients was as follows: 7 with descending thoracic aortic aneurysm, 1 with thoraco-abdominal aortic aneurysm, 1 with type A dissection, 1 with type B dissection and 1 with aortic coarctation. The average PaO₂ in the proximal portion of cross-clamped aneurysm was 165.2mmHg and the average of the lowest point of temperature was 35.0°C. It was very easy to prevent from hypoxemia and temperature drop during surgery. But platelet count and fibrinogen value decreased after the support, that were major complications in this procedure. It is necessary to develop a new system without the disturbance on blood coagulation factors.

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Safety and ease of use are key issues during whole body hyperthermia using extracorporeal circulation, also known as extracorporeal systemic hyperthermia (ESH). We used the technique of percutaneous puncture by 9F introducer for stabilizing blood flow and protecting against infection. We were able to accomplish safe control of blood temperature through proportional integration of ESH. Ten cases in which ESH was used were evaluated, and the following results were obtained. After about 40min from the start of ESH, pulmonary artery temperature exceeded 41°C, and it stabilized between 41.5° and 42°C after 90min. The maximum blood inflow temperature was set at 45°C which required a blood inflow rate of 0.8l/min to maintain. (The 9 F introducer allows for a maximum blood inflow rate of 1.4l/min.) At this temperature of 45°C, cardiac output and heart rate increased 2.6 times and 1.8 times, respectively. Forty-three patients with advanced primary non-small cell lung cancer also underwent ESH. Analgesic effect was observed in about 70% of the 25 cases with pain. The survival rate was not influenced by the stage of the disease, tumor effect, or the number of times treated with ESH. Among stage IV patients, the average survival period was 11 months.

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The bubble formation inside the membrane oxygenator on the routine cardiopulmonary bypass technique was studied. When the heat-exchanger was turned off after recirculation was stopped, air bubble, which was 6.0ml and 5.2ml respectively, was observed inside the hollow fiber chamber of Compactflo D-703 and Monolyth. In case of Compactflo, the bubble was completely infused into the arterial side under the pump flow of 4l/min. However, in Monolyth, no bubble was infused into the arterial side, because of the lower location of the outlet-port. The mechanism was suspected that the air bubble was moved into the priming solution due to the negative pressure, which was induced inside the hollow fiber chamber as the heat-exchanger was tuned off. In spite of the efforts for better heat-exchanger efficiency and lesser priming volume, the safety of the oxygenator was spoiled. The design of the membrane oxygenator would have to be modified with this notion in mind.

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The purpose of this study is to compare the effects of veno-pulmonary extracorporeal membrane oxygenation (VP-ECMO) with veno-arterial ECMO (VA-ECMO) in 11 dogs. Under normal respiratory condition (G-C) and respiratory failure (G-RF), PaO₂ at carotid artery and SvO₂ at pulmonary artery were measured. Thereafter we established the bypass of VP-, and VA-ECMO (G-VP, G-VA) from the right atrium to pulmonary or femoral artery. PaO₂ in G-C, G-VP and G-VA were significantly higher than in G-RF. SvO₂ in G-VP was significantly higher than others. Left and right ventricle stroke work (L & RVSW) in each states were measured and not significant difference. Pulse pressure in G-VP kept about 80% of G-C, but in G-VA, Pulse pressure went off, and aortic flow became non-pulsatile flow. Then, the results suggested that the effects of oxygenation in VP-ECMO was as good as in VA-ECMO, and kept right and left ventricular function.

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