The recent article by Ko et al., entitled “The effects of extracorporeal blood purification (oXiris^®) in patients with cardiogenic shock who require VA-ECMO (CLEAN ECMO): a prospective, open-label, randomized controlled pilot study,” reported that extracorporeal blood purification with the oXiris membrane did not significantly reduce endotoxin levels or improve clinical outcomes in patients with cardiogenic shock requiring veno-arterial extracorporeal membrane oxygenation (VA-ECMO) [1]. While the authors should be commended for conducting a randomized pilot trial in this challenging population, several aspects of the interpretation of the negative findings merit further discussion.

Although the study focused on cardiogenic shock associated with circulating endotoxin [1], caution is warranted when drawing parallels with endotoxic septic shock. The endotoxin activity assay (EEA) threshold at which endotoxin absorption therapies, such as polymyxin B hemoperfusion (PMX) (Toray, Japan) or the oXiris membrane (Baxter, Meyzieu, France), should be initiated in this context remains uncertain. In septic shock, an EEA value ≥ 0.6 (Spectral Medical Inc., Toronto, ON, Canada) has been proposed as a potential threshold for intervention [2, 3]. Furthermore, the endotoxin-binding capacity of a PMX cartridge is finite [4]. When EEA values exceed approximately 0.9, adsorption capacity may become saturated, potentially rendering hemoperfusion ineffective in endotoxic septic shock.