Isolyte S, a physiologic multielectrolyte solution, is preferable to normal saline to wash cell saver salvaged blood: Conclusions from a prospective, randomized study in a canine model

Objective: The purpose of this study is to compare normal saline with isolyte S as the wash solutions during high-volume cell saver autologous blood transfusion. Normal saline, the standard wash solution in cell saver autologous blood transfusion, is associated with acid-base and electrolyte derangements. Isolyte S is a physiologic, balanced multielectrolyte crystalloid solution that approximates the electrolyte content of plasma. Design: Open-label, prospective, randomized study. Setting: Research laboratory in a Department of Veterans Affairs medical center. Subjects: Fourteen mongrel dogs, weighing 22 to 23 kg each. Interventions: Fourteen mongrel dogs were prospectively randomized to receive normal saline (n = 7) or isolyte S (n = 7). Animals were anesthetized, received heparin for anticoagulation, and underwent 18 cycles of cell saver autotransfusion. In each cycle, 125 mL of blood was arterially withdrawn, and washed with either normal saline (mEq/L) (sodium 154, chloride 154) or isolyte S (mEq/L) (sodium 141, potassium 5, magnesium 3, chloride 96, phosphate 1, acetate 28, and gluconate 23). The washed blood was retransfused. Measurements and Main Results: Acid-base and electrolyte analyses were performed throughout the study on the systemic blood of each group and compared. By the end of the study, the Isolyte S group has a normal pH and an increased bicarbonate concentration (mEq/L; normal values 24 to 32; normal saline 9.0 ± 1.9 vs. isolytes S 13.2 ± 3.0 [p < .01] and an increased magnesium concentration (mg/dL; normal values 1.6 to 2.4; normal saline 1.6 ± 0.2 vs. Isolyte S 2.2 ± 0.2 [p < .0001]. Additionally, the Isolyte S group had a lower chloride concentration (mEq/L; normal values 95 to 110; normal saline 130 ± 9 vs. Isolytes S 117 ± 7 [p < .02]) and a lower potassium concentration (mEq/l; normal values 3.5 to 5.0; normal saline 4.4 ± 0.5 vs. Isolyte S 3.7 ± 0.3 [p < .01]. There were no significant difference between normal saline or isolyte S in the values of PCO₂, lactic acid, sodium, total and ionized calcium, inorganic phosphorus, total protein, albumin, hemoglobin, and hematocrit. Conclusions: Fewer systemic acid-base and electrolyte derangements were observed when blood was washed with isolyte S. Differences between the normal saline and isolyte S group are ascribed primarily to the constituents of the wash solution. We conclude that isolyte S, a physiologic, balanced, multielectrolyte solution, should be considered as the wash solution in high-volume autologous cell saver blood processing and transfusion.