Sterility and Oxygenator Function in Pre-Primed Extracorporeal Membrane Oxygenation: A Prospective Clinical Study

Aim: Minimizing cardiac arrest times is critical in extracorporeal cardiopulmonary resuscitation (ECPR). Pre-primed extra corporeal membrane oxygenator (ECMO) is used for this, but knowledge is limited to experimental studies. We prospectively investigated oxygenator function and sterility in dry plus wet pre-priming in a clinical setting.

Methods: This prospective clinical study included 107 ECMO circuits used at Sahlgrenska University Hospital between October 2019 and December 2021. Circuits underwent dry set-up, followed by wet priming when the previous wet-primed circuit was used. Sterility was assessed by culturing the priming solution. Oxygenator function parameters, including sweep gas flow, fraction of oxygen (FiO₂), and oxygenator resistance, were analyzed at ECMO initiation and during treatment using linear mixed models.

Results: Median total set-up time was 14 days (range 0-97), with a median wet prime time of 6 days (range 0-57). 103 of 105 circuits with culture results were negative, two showed bacterial growth (coagulase-negative staphylococci and Cutibacterium acnes). Wet prime time did not significantly affect initial oxygenator function. Oxygenator resistance and FiO₂ increased during ECMO treatment (0.035 mmHg/L min^-1 (95 % confidence interval (CI) 0.015-0.055) P < 0.001, and 2.19 % (0.92-3.46) P = 0.009), but these changes were unrelated to wet prime time.

Conclusion: Wet pre-priming of ECMO circuits for up to 57 days did not affect oxygenator function. The low incidence of bacterial growth (1.9 %) suggests that pre-primed ECMO generally maintain sterility and can facilitate rapid ECPR initiation. However, bacterial growth highlights the need for caution in non-urgent cases. Culturing the circuit at initiation can mitigate this risk.