10 - Acid–Base Issues in Fluid Therapy

Summary

NaCl 0.9% is an established cause of metabolic acidosis. The underlying mechanism, a reduction in plasma strong ion difference [SID], is comprehensibly explained by the principles of the Stewart approach. Both fluid-induced hyperchloremia and metabolic acidosis can be avoided using various balanced solutions that do not cause alterations in plasma [SID]. Many balanced solutions are commercially available, using various alkalinizing agents such as lactate, acetate and gluconate. Their only drawback when compared with NaCl 0.9% is their higher cost. Although there no definitive evidence of their clinical benefit in low volumes in patients with a low severity of illness, some data suggest kidney injury under treatment with NaCl 0.9%, an effect that seams to appear in a dose-dependent manner. Awaiting definitive conclusions, the use of balanced solutions in sicker patients who are in need of large amounts of fluids seems to be a pragmatic choice.