Various kinds of circuit systems for cardiopulmonary bypass using a membrane oxygenator have been considered. The author considered comparing three types of circuit simultaneously using a switch circuit when two membrane oxygenators were used, and found that a new type circuit, which contains one oxygenator (low flowresistance oxygenator only) in a gravity drainage line and one oxygenator (high flow-resistance oxygenator also available) in a recirculation line, had a great advantage of stable oxygenation and an easy control of the oxygenation level within the desired value with a flow rate control of a recirculation pump.
For the purpose of clinical application, we have improved a hard shell reservoir which is convenient for this circuit system, controlled oxygenation circuit system. The reservoir is separated by a septum located in the center, of which the sides are jagged, so that blood communication between the two chambers is possible. Both chambers are open to the atmosphere, so air bubbles are easily trapped.
Twenty infants and children underwent cardiopulmonary bypass using this controlled oxygenation circuit system. Among them, 5 patients with transposition of the great arteries and two patients of total anomalous PV drainage were operated upon using the technique of surface cooling and limited cardiopulmonary bypass. Remaining 13 cases of VSD with pulmonary hypertension and others were operated upon under total cardiopulmonary bypass. The results were satisfactory. The patient's ages, body weight, hematocrit value, plasma sodium concentration, and plasma free hemoglobin and also blood gas data were shown.
