EXTRACORPOREAL MEMBRANE-OXYGENATION USING A CENTRIFUGAL PUMP AND A SERVO REGULATOR TO PREVENT NEGATIVE INLET PRESSURE

Background. We studied whether negative inlet pressure created by a ce ntrifugal pump during extracorporeal membrane oxygenation damages bloo d. Methods. Fresh, whole human blood and primer were circulated throug h a test circuit, applying an inlet pressure of 0, -50, or -100 mm Hg. Thereafter, hemolysis and kidney function were compared between 6 pat ients treated before and 14 patients treated after inclusion in our se tup of extracorporeal membrane oxygenation with a servo inlet pressure regulator. Results. In vitro, negative inlet pressure caused substant ial hemolysis, leukocyte and platelet destruction, and complement acti vation. Maximal plasma free hemoglobin concentrations were 199 mg/100 mL before use of the servo inlet pressure regulator and 40 mg/100 mL a fterward (p = 0.06), and serum creatinine peaked at 330 and 115 mu mol /L, respectively (p = 0.03). The minimal 24-hour diuresis normalized f or weight was 4.8 mL/kg before use of the servo inlet pressure regulat or and 45.6 mL/kg afterward (p = 0.03). Three of 5 evaluable patients before use of the servo inlet pressure regulator and 1 of 14 patients after inclusion in this setup experienced anuria (p = 0.04). Conclusio ns. There were strong indications that reduction of negative pump inle t pressure with the servo regulator prevented hemolysis and kidney dam age. (C) 1997 by The Society of Thoracic Surgeons.