TAKAYUKI NISHIGAKI

Patients requiring hemodialysis have a variety of dialysis-associated complications. In particular, hypotension, which is a potential complication of chronic hemodialysis patients, unexpectedly occurs during treatment and interrupts the continuation of dialysis, creating a feeling of distress for patients. In light of stabilizing the blood pressure during dialysis, we have focused on the venous return as a factor leading to the stabilization of blood volume changes(ΔBV) and investigated the possibility that accelerated venous return results in maintaining the blood pressure during hemodialysis. The subjects of this study were 18 hemodialysis patients on maintenance hemodialysis. We used a sequential pneumatic compression massage tool(foot pump) to accelerate the venous return during hemodialysis. The venous return was accelerated by continuous massage with the foot pump during hemodialysis. Conditions of the massage were classified into 4 categories: condition 1 was no massage(control), condition 2 was slight massage, condition 3 was hard massage, and condition 4 was automatic massage. Values of ΔBV and blood pressure were observed under these conditions. As a result, a more significant stabilization of ΔBV and the blood pressure in hemodialysis sessions with massage was noted compared to sessions without massage. Sensory changes were also studied and compared: pre-dialysis, post-dialysis, and after returning home. In condition 2, significantly more favorable results of sensory changes were obtained after than before dialysis. Consequently, this research showed that the prevention of dialysis-induced hypotension by accelerating the venous return is feasible.

Heart transplantation in children is not permitted and ventricular assist device of children has not developed in Japan. An operation or an adjunct treatment by extracorporeal membrane oxygenation (ECMO) is an exclusive treatment of the children with severe cardiac failure. However, the ECMO system for children is behind developing in comparison with one for adults. In particular, the ECMO system can cause the problems which deteriorate the patients' conditions. Major problems of the ECMO system are as follows: priming volume and blood-contacting surface area in the ECMO system are large for children. Therefore, it is necessary that ECMO device will be developed to improve the treatment outcome. Our future goal is to downsize the ECMO device. In this fundamental research, we focused on evaluating the temperature characteristics of the ECMO system. Our experimental devices consisted of two parts: a simulated patient's side and the ECMO system's side. We measured temperature differences between inlet and outlet of the ECMO system under the seven experimental conditions. We compared temperature differences between ECMO control conditions: fluid flow rate, V/Q (oxygen flow rates/fluid flow rates), temperature around ECMO system and temperature of inlet oxygen gas. The results showed that the temperature differences were significantly influenced by V/Q and temperature around ECMO system. There were no significant differences with temperature of inlet oxygen gas. In conclusion, we found that the ECMO system can have the thermal heating effect when the temperature around ECMO system was at 43 degrees Celsius, and oxygen flow rate was 5.0L/min. These results suggested that we would develop the small applicable heating system instead of the conventional large heat exchanger, and it would realize that the ECMO system could be downsized.