The effects of differing anticoagulant regimes on blood quality after cell salvage in coronary artery bypass grafting (CABG): a pilot study

Background: Cell salvage reduces allogenic blood transfusion requirements in surgery. We present a pilot study exploring the impact of anticoagulant choice, citrate or heparin, on the quality of cell salvaged blood in adults undergoing coronary artery bypass grafting (CABG).

Materials and methods: Elective on pump CABG patients were randomly allocated to citrate or heparin anticoagulation. We measured red blood cell characteristics and inflammation in both the blood collection reservoir and the washed red blood cell concentrate. Postoperatively, the level of biomarkers and the coagulation profile in the peripheral blood as well as the transfusion requirements of allogenic blood products were studied.

Results: Thirty eight patients were included, 19 in the citrate group and 19 in the heparin group. Baseline characteristics were similar. In the washed red blood cell concentrate, Mean Hb (g/dl) and Ht (%) were lower in the citrate group [Hb: 18.1 g/dL (SD 1.3) vs. 21.1 (1.6), p < 0.001; Ht: 59.9% (54.7-60.9) vs. 63.7% (62.3-64.8); p < 0.001]; Mean corpuscular volume (MCV, μm 3) was higher [99.1fL (9.4) vs. 88 (4.2), p < 0.001] and mean corpuscular hemoglobin concentration (MCHC, g/dl) lower in the citrate group [31.9 g/dl (29.6-32.4) vs. 33.6 (33.1-34.0) p < 0.001]. Thrombocyte count (1000/μl) was higher in the citrate group [31.0 (26.0-77.0) vs. 13.0 (10.0-39.0); p = 0.006]. There were no differences in the requirement for allogenic blood products' transfusion (intraoperatively and postoperatively) or in the coagulation parameters after washed red blood cell concentrate infusion. Higher IL-10 was found in the citrate group in the blood collection reservoir, higher neutrophil-derived myeloperoxidase (MPO) in the heparin group after washed red blood cell concentrate infusion.

Conclusion: Though red blood cells in washed red blood cell concentrate were more swollen and diluted in the citrate group with more residual thrombocytes, published quality guidelines were met in both groups. Our pilot study suggests that differences in inflammatory markers in the blood collection reservoir and after infusion of washed red blood cell concentrate indicate a possible pro-inflammatory effect of heparin compared to citrate. A larger study is warranted to confirm these results and their possible clinical consequences. Trial registration ClinicalTrials.gov : NCT02674906. Registered 5 February 2016.