Background: In patients undergoing total knee replacement (TKR) most blood loss occurs postoperatively and return of unwashed filtered shed blood (USB) from postoperative drainage may represent an alternative to allogeneic blood transfusion (ABT). We evaluated the impact of USB return, with or without leucocytes, on the acute-phase response (APR) after TKR.
Patients and methods: Forty-eight TKR patients, intended to receive postoperative USB, entered the study. Blood samples were obtained before and 6, 24, 72 h and 7 days after surgery, and from the USB before and after it passed through a 40-microm filter (Group F40) or a leucocyte-reduction filter (Group LRF). Haematimetric parameters, APR proteins (albumin, prealbumin, ceruloplasmin, haptoglobin, C-reactive protein), complement C3 and C4, and cytokines (IL-1beta, IL-6, IL-8, IL-10, and TNF-alpha) were measured in all samples.
Results: Twenty-eight patients (Group F40=14, Group LRF=14) received a mean of 1.2 USB units, without any clinically relevant incident, and did not need additional ABT. Sixteen out of the 20 remaining patients who received neither USB nor ABT served as a control group for the postoperative APR study. All patients showed the typical postoperative APR profile and there were no significant differences between groups for APR parameters, postoperative complications, or hospital stay.
Conclusions: Postoperative blood salvage and return, with or without a LRF, after TKR does not present any clinically relevant side-effects and does not modify APR induced by surgery. These findings seem to confirm the clinical experience that postoperative USB return is safe and questions the beneficial effect of using LRF.