Potassium as a surrogate marker of debris in cell-salvaged blood

Centrifuge-based cell salvage systems have decreased the use of homologous blood transfusions. Although the evidence is anecdotal, the risk associated with the use of salvaged erythrocytes seems related to cellular and chemical contaminants. We sought to determine if potassium can be a surrogate marker for cellular debris and to measure the residual heparin level. Four units of expired whole blood were heparinized and concentrated with a Sequestra 1000 (Medtronics), Parker, CO) cell salvage device. The potassium, free hemoglobin, leukocyte, and platelet counts were sampled after each 250-mL normal saline wash aliquot, to a total wash volume of 1500 mL, whereas the heparin samples were obtained at wash volumes 0 and 1000 mL. Potassium, leukocyte, and platelet concentrations at wash volumes 0 and 250 mL were significantly greater than at all other volumes (P < 0.001). After 500 mL of saline wash, the change in these values was not significant. The mean (+/- SD) heparin levels (units/mL) at wash volumes 0 and 1000 mL were 10.2 (+/-3.1) and 0.11 (+/-0.02), respectively (P < 0.007). The r(2) values for free hemoglobin, leukocytes, and platelets versus potassium were 0.006, 0.992, and 0.995, respectively. No convenient test has been validated as an indicator of salvaged erythrocyte cleanliness. This in vitro study suggests that residual potassium concentration seems to be a good indicator of quality after washing with a contemporary intraoperative salvage system.

No convenient test has been validated as an indicator of salvaged erythrocyte cleanliness. This in vitro study suggests that residual potassium concentration seems to be a good indicator of quality after washing with a contemporary intraoperative salvage system.