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Updated: May 11, 2026

Real-Time, Semi-Automated Fluorescent Measurement of the Airway Surface Liquid pH of Primary Human Airway Epithelial Cells
Published on: June 13, 2019
Why is saline so acidic (and does it really matter?)
1Intensive Care Unit, Royal Adelaide Hospital; Clinical Senior Lecturer, Discipline of Acute Care Medicine, University of Adelaide, Adelaide, Australia. benja-min.reddi@adelaide.edu.au
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 metabolic acidaemia, yet the link between the acidity of saline solution and the acidaemia it can engender 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.
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