Slow recruitment secondary to limited capacity during Covid-19 pandemic

The main goal of this pilot study is to assess the time course of eicosanoid profiles in intensive care unit (ICU) patients requiring packed red blood cell (PRBC) transfusion. Moreover we will analyze the change of levels of eicosanoids in patient plasma prior and after a PRBC transfusion as well as its correlation with levels of eicosanoids in the transfused PRBCs. These data will then be used to determine the estimated effect size necessary for the planning of future larger studies. We hypothesize that transfusion of PRBCs will modulate the eicosanoid profile in ICU patients.

According to the Protocol filed with the Institutional Review Board of the Medical University of Vienna and patient's informed consent, subsequent sub analyses using samples of this study (e.g., determination of extracellular vesicles in PRBC samples and patient's plasma) will be performed.

Exclusion Criteria:

• Age <18 years or >99 years
• Pregnancy
• <12h since last PRBC transfusion
• intake/administration of acetylsalicylic acid in groups 2 and 3
• intake/administration of cysteinyl leukotriene receptor antagonists (e.g. montelukast)
• intake/administration of celecoxib, etoricoxib, parecoxib, ibuprofen, diclofenac, and naproxen in all groups
• glucocorticoids given within 24h of transfusion in groups 1 and 3
• treatment with calcineurin inhibitors (e.g. tacrolimus) in groups 1 and 3
• treatment with alemtuzumab in groups 1 and 3
• administration of protamine for heparin reversal in groups 2 and 3

Group 1: routine postoperative ICU patients after open aortic surgery Group 2: routine postoperative ICU patients with immunosuppression after lung transplantation Group 3: mixed postoperative ICU patients