Is serum gentamicin concentration modified with autologous cell-saved blood transfusion after total knee arthroplasty using tranexamic acid? A randomised control trial.

Background: Self-transfusion has been proven as an effective management of blood loss after total knee arthroplasty (TKA). Considering that the high local concentration of antibiotic from bone cement is delivered intravenously through the self-transfusion process, systematic toxicity has never been evaluated. In addition, the effectiveness of self-transfusion with the routine concomitant use of other modern blood-salvage strategies, like tranexamic acid, should also be assessed. Therefore, we performed a randomised study to assess: 1) the safety of self-transfusion in TKA by comparing the gentamicin concentrations resulting from the use or not of autologous blood transfusion; 2) the efficacy of self-transfusion in TKA, with the concomitant administration of tranexamic acid.

Hypothesis: Self-transfusion in TKA elevates the serum gentamicin concentration and the potential risk of nephrotoxicity.

Methods: The serum concentration of aminoglycosides was measured in two groups of 20 patients each, after TKA, according to the use of self-transfusion. Hemoglobin, renal function and calculated blood loss were compared at several points in time between groups.

Results: The only time where there was a statistically significant difference in serum gentamicin, was at 48h postoperatively between groups [0.3 ug/mL±0.21, range: 0.15 to 0.72 vs. 0.14ug/mL±0.1, range: 0 to 0.35 (p=0.02)]. There were no significant differences in total blood loss [1341mL±501, range: 830 to 2230 vs. 1263mL±459 range: 840 to 2480 (p=0.67)] and need of allogeneic blood transfusion [3 units vs. 2 units] between groups.

Conclusion: The use of autologous blood transfusion was found to be safe, in terms of nephrotoxicity of aminoglycosides after TKA, but it seemed to be ineffective as a blood salvage strategy, when used concomitantly with the administration of tranexamic acid.

Level Of Evidence: II; low-powered randomised study. CLINICALTRIALS.

Gov Registration Number: NCT04505748.