NIV Congres

Introduction Pretransplant removal of anti-blood group ABO antibodies is the cornerstone of all current ABO-incompatible transplantation programs. It involves plasmapheresis (PF) with plasma exchange or followed by specific immuno adsorption. Plasmapheresis by centrifugation is associated with an increased bleeding tendency because of loss of platelets. In our protocol, plasmapheresis is performed with a plasmafilter followed by immunoabsorption of anti-ABO antibodies using the Glycorex device. The bleeding complications of this technique are not known.

Material and Methods We analyzed recipients of an ABO-i kidney transplant between March 2006 and May 2012 (n=51). Controls were recipients of a ABO-compatible kidney transplant matched for age of donor and recipient and PRA in this period (n=102). Cases differed from controls in the preoperative regimen which included immuno adsorption, rituximab, tacrolimus, mycophenolate mofetil, prednisone and immunoglobulines. All patients received tacrolimus, mycophenolate mofetil and prednisone after transplantation. Data on the number of thrombocytes before and directly after immuno adsorption, red blood cell transfusions (EC) during two postoperative weeks were collected.

Results In the ABOi group on average 4 PF were performed before transplantation. In the first 30 patients PF was also performed postoperatively. After the last preoperative PF the number of platelets had an average decrease of 32%. In 23% of patients the platelets dropped below 100 x109/L, specifically in patients that had low numbers of platelets before PFs started (191 vs 238 x10e9/L). ABO-i recipients received 2.2 (EC) versus 0.7 in controls. Major bleeding (hemodynamic instability or >2 EC per episode) was observed in 25% of patients. The majority of these major bleedings occurred the day of surgery (8/13 patients). The number of immuno adsorptions was positively correlated (r=0.35, p=0.013) with the number of EC. In patients with a platelet count <100 x10⁹/L after the last PF the average number of PF was 7.17 versus 5.26 when platelets remained >100 x10⁹/L (p<0.05).

Discussion ABO-i kidney transplants recipients are at increased risk of bleeding, especially when more immuno adsorption procedures are performed. We hypothesize that the thrombocytopenia seen in our patients is caused by adherence of platelets to the plasma membrane in combination with the lack of recovery by the intensity of the immuno adsorption scheme.