Changes in mechanical fragility and free hemoglobin levels after processing salvaged cardiopulmonary bypass circuit blood with a modified ultrafiltration device.

Modified ultrafiltration (MUF) is available for the salvage of post-cardiopulmonary bypass circuit blood. This study evaluated the extent of hemolysis, the mechanical fragility index (MFI), and the amount of plasma free hemoglobin (PFHb) created after processing with the MUF device. Several RBC parameters were measured on pre- and post-MUF device processed samples of blood from 12 patients undergoing cardiac surgery. The MFI and total amount of PFHb did not change significantly between the pre- and post-processing samples: MFI, pre: .19 +/- .06 versus post: .19 +/- .06, p = .76; total amount of PFHb, pre: .24 +/- .21 g versus post: .20 +/- .12 g, p = .42. There was significantly more hemolysis in the post-processing samples compared with the pre-processing samples, .33 +/- .24% versus .96 +/- .48%, respectively, p < .001. Although percent hemolysis was increased following processing with the MUF device, the total amount of PFHb and RBC sublethal injury were not increased. The clinical significance of these findings needs to be determined.