Effects of washing with different crystalloid solutions on the oxygen delivery capacity and membrane integrity of salvaged erythrocytes: a comparative study in a rat model

Abstract Background Normal saline (NS) is commonly used for washing salvaged erythrocytes during intraoperative cell salvage (ICS), although its nonphysiological ionic composition and limited buffering capacity may affect erythrocyte function. This in vitro study aimed to investigate the effects of washing with NS, Acetated Ringer’s solution (AR), and Lactated Ringer’s solution (LR) on the functional and membrane properties of salvaged erythrocytes in a rat model. Methods Erythrocytes obtained from male Wistar rats ( n = 6 per group) were subjected to simulated salvage and washed with five times the volume of NS, AR, or LR (blood-to-washing-solution volume ratio, 1:5). Hematocrit, hemolysis, 2,3-diphosphoglycerate (2,3-DPG), erythrocyte morphology, oxygen dissociation characteristics, intracellular and extracellular pH, osmotic fragility, and membrane Na⁺-K⁺-ATPase and Ca²⁺-Mg²⁺-ATPase activities were evaluated. Results Hematocrit, hemolysis, and 2,3-DPG levels did not differ significantly among the three groups. Compared with NS, AR and LR were associated with better preservation of erythrocyte morphology, lower osmotic fragility, and higher membrane ATPase activities, with the most pronounced differences observed in the LR group. LR-washed erythrocytes also showed a rightward shift of the oxygen dissociation curve and a higher P 50 (48.54 mmHg), indicating reduced hemoglobin–oxygen affinity under the experimental conditions. Intracellular pH-related fluorescence intensity was higher in the AR and LR groups than in the NS group. Conclusions In this in vitro rat model, balanced crystalloid solutions, particularly LR, were associated with better preservation of several functional and membrane properties of salvaged erythrocytes than NS. These findings support further in vivo and clinical evaluation of LR as a potential alternative washing solution for ICS.