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 (FiO(2)), 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 FiO(2) 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.