Comparison of wet-primed versus traditional ECMO circuits in clinical practice: a retrospective study using propensity score matching

Extracorporeal membrane oxygenation (ECMO) provides crucial life-support for severe cardiac or respiratory failure, where early initiation improves survival and neurological outcomes. Wet priming, involving pre-filled, pre-connected ECMO circuits, may shorten initiation times, but its clinical impact remains uncertain. A single-center retrospective analysis was conducted to compare wet-primed ( n = 66) and traditional ( n = 46) ECMO circuits across three domains: oxygenator function, circuit sterility, and patient outcomes. Propensity score matching (PSM) was used to balance the baseline characteristics between groups. The key outcome measures included oxygenator performance, circuit sterility, intensive care unit (ICU) mortality, and 4-h lactate clearance. All of these were assessed and compared. Oxygenator performance, which included parameters, such as pressure drop, oxygen transfer efficiency, and CO₂ removal, did not significantly differ between the two groups. Furthermore, all wet-primed circuits tested negative for bacterial growth, confirming its sterility. Although there were no significant differences in ICU mortality or other prognostic indicators between groups, wet priming was associated with a reduction in median arrest-to-ECMO initiation time by 16 min (59 min vs. 75 min). Furthermore, wet priming resulted in a significantly higher 4-h lactate clearance (39.30% vs. 14.30%, p = 0.045). Wet-primed ECMO circuits are associated with improved early circulatory stabilization without compromising oxygenator function or circuit sterility. However, no significant differences in clinical outcomes were observed between patients supported with wet-primed and traditionally primed ECMO circuits.