Data Collection and Analysis

Patient characteristics and presented laboratory and clinical parameters were obtained from medical records. The individual laboratory parameters were taken from daily routine blood results. Changes in laboratory and clinical parameters related to PE treatment were evaluated before the first, after the first, after the third, and after the last PE procedure. To assess PE-related long-term effects, the same parameters were evaluated 3 and 5 days after the last PE. Observation of laboratory and clinical parameters in the control group was started when patients showed the same potential indicators of a dysregulated COVID-19-related immune response. In the control group, laboratory and clinical parameters were observed for 7 consecutive days. All laboratory parameters were measured in the accredited Central Laboratory of the Heidelberg University Hospital.