Kinetics of SuPAR hemoadsorption in critical COVID-19 patients on renal replacement therapy

SARS-CoV-2 viral infection is associated with a rapid and vigorous systemic inflammatory response syndrome. Soluble urokinase-type plasminogen activator receptor (suPAR) is a novel biomarker, both indicative of inflammation and propagating it. Hemoadsorption has been proposed as a potential therapy in COVID-19 patients, therefore the aim of this study is to determine suPAR kinetics during hemoadsoprtion.

This was a prospective observational study of critical COVID-19 patients, enrolled when hemoperfusion therapy was initiated. Hemoadsorber was integrated into the continuous renal replacement therapy circuit. The first series of suPAR measurements was performed 10 minutes after the start of the session, sampling both incoming and outgoing lines of the adsorber. A second series of the measurements was performed beforefinishing the session with the same adsorber. Statistical significance level was set < 0.05.

This study included 18 patients. In the beginning of the session the fraction of suPAR cleared across the adsorber was 29.5% [16-41], and in the end of the session it decreased to 7.2% [4-22], 4 times lower, p = 0.003. The median length of session was 21 hours, with minimal duration of 16 hours and maximal duration of 24 hours. The median suPAR before the procedure was 8.71 [7.18-10.78] and after the session was 7.35 [6.53-11.28] ng/ml. There was no statistically significant difference in suPAR concentrations before and after the session (p = 0.831).

This study concluded that in the beginning of the hemoadsorption procedure significant amount of suPAR is removed from the circulation. However, in the end of the procedure there is a substantial drop in adsorbed capacity. Furthermore, despite a substantial amount of suPAR cleared there is no significant difference in systemic suPAR concentrations before and after the hemoadsorption procedure.