体外循環における溶血の実験および臨床的研究

抄録

The recent development and progress in hemodilution perfusion without donor blood have made it possible to perform extracorporeal circulation for two to three hours with reasonable safety.However, this procedure, being unphysiologic in nature, is still fraught with many difficulties that remain to be overcome.Remarkably, hemolysis resulting from the use of a pumpoxygenator is related to the postoperative occurrence of acute renal failure and lung complications.Its presence or absence is thus determinant of operative results in many instances.Anothertype of hemolysis that is caused by prolonged assisted circulation for respiratory insufficiency hasalso become a significant problem of lethality.Such circumstances prompted the author to undertakethe present experimental study which was intended to minimize the degree of hemolysisthat occurs in association with the use of a De Bakey Roller-pump, a device in routine favoriteuse.Using a model circuit, measurements were made of flow rate, pressure in circuit and plasma Hb level under varying experimental conditions in order to determine the critical occlusion of Latex tube.The results indicated that the flow rate per minute was kept most stationary andthe correlation between the degree of hemolysis and the number of revolutions of pump wasfound to be closest when physiologic saline was used for the regulation of occlusion.Actualclinical patient subseuently underwent extracorporeal circulation with the use of physiologic salinefor the regulation of occlusion.From a series of patients undergoing open heart surgery duringthe period from February 1, 1974 through February 28, 1979, thirteen cases in whom a No.7 or No.9 arterial cannula was employed were chosen for the study.They had an average age of28.3 years, with the male-to-female ratio being 1: 1.2 and the average perfusion time, 1 hourand 14 minutes.The time course of hemolysis was evaluated in terms of plasma-hemoglobin, haptoglobin and hemoglobinuria.The plasma-hemoglobin was found elevated immediately afterthe completion of extracorporeal circulation and returned to normal on the first postoperative day.In two cases of AVR, however, the amount of free hemoglobin was well in excess of the bindingcapacity of haptoglobin with plasma-hemoglobin and there was mapifest hemoglobinuria onthe first postoperative day.The renal threshold for plasma-hemoglobin was at around 120 mg/dl.The haptoglobin level, on the other hand, was lowest on the first postoperative day and returnedto normal by the third postoperative day.In all clinical cases the postoperative course was uneventful, none developing acute renal failure and/or lung complications.