Why is saline so acidic (and does it really matter?)

Abstract

Commercial 0.9% saline solution for infusion has a pH around 5.5. There are many reasons for this acidity, some of them still obscure. It is also true that infusion of normal saline can lead to met-abolic acidaemia, yet the link between the acidity of saline solution and the acidaemia it can en-gender is not straightforward. This commentary draws together the known and putative sources of acidity in saline solutions: it turns out that the acidity of saline solution is essentially unrelated to the acidaemia complicating saline infusion.