How long can the previously assembled cardiopulmonary bypass circuit stay sterile?

The sterility of previously assembled cardiopulmonary bypass circuits was investigated for 100 extracorporeal circuits. The closed circuits were assembled using aseptic technique and remained in the pump room until time of use. The mean time from point of setup to point of priming for the 100 consecutive circuits was 32 hours, with a range of 19 to 89 hours. Circuits were primed with the calculated volume of priming solution, circulated for 5 minutes and tested for microbial contamination by withdrawing 20 ml of the priming solution and 10 days incubated in Thioglycolate and Sabouraud culture mediums. All were found to be free of microbial contamination. The results of this investigation demonstrate that the sterility of the extracorporeal circuit, pre-assembled in advance of actual priming, can be maintained over an extended interval when standard aseptic technique is used. This allows the utilization of a pre-assembled circuit for emergency cardiopulmonary support.