[A manually operated cardiopulmonary bypass circuit with two self-inflating reservoir-pumps]

We improved our manually operated cardiopulmonary bypass circuit by adding another reservoir-pump in parallel to continue the venous blood withdrawal. The two reservoir-pumps were alternately and maximally compressed by hand, and hydrodynamics of the device was examined in vitro by using a physiological saline solution. When a 21 Fr, 52 cm catheter for venous drainage and a 17 Fr, 17 cm catheter for arterial infusion were used, the bypass flow rate was about 2.1 l.min-1 even under no waterhead. It was further increased to about 3.1 l.min-1 by adding a head of 60 cmH2O. The upper body of a patient undergoing resuscitation is occupied by other personnel performing mandatory procedures such as cardiac massage and endotracheal intubation. Therefore, the catheter insertion site is limited to the femoral vessels, and a long arterial return catheter will be necessary for a better cerebral oxygen supply. When a 17 Fr long arterial return catheter with 52 cm in length was used, the maximal flow rate achieved about 2.8 l.min-1 under a head of 60 cmH2O, though slightly smaller than that with the 17 cm catheter. This double reservoir-pump circuit with a long arterial return catheter will facilitate emergency cardiopulmonary bypass during acute critical resuscitation and much improve the perfusion to the vital organs.