Intensivists have repeatedly been warning on the potential effect side effects when infusing bigger quantities of normal saline like acidosis and potentially worse outcomes. It is well recognized that infusion of normal saline can lead to metabolic acidosis, but the link between the acidity of saline solution and the acidaemia it can produce might be not straightforward!
This article from the beginning of this year shows a surprising insight on the various components involved when using normal saline infusions and comes to the conclusion that the acidaemia complicating saline infusions is actually unrelated to the acidity of the normal saline solution itself. It turns out that in vitro the acidity of a normal saline solution is mainly due to dissolved CO2 and PVC degradation of the bag containing the solution. The metabolic acidosis by saline infusions in vivo though mainly results from from buffer base dilution and is not directly related to the pH of the infusion at all. Got interested?
Reddi B, et al. Int J Med Sci. 2013 Apr;10(6):747-50