In recent years the discussion about the importance of maintaining the physiological pH in the airways emerged (http://link.springer.com/article/10.1007/s00408-004-2511-6).
In Mid 2012 research showed that an acidic modified Airway Surface liquid (ASL) fluid lining of the lung, reduced the subjects own immune response to kill bacteria. (http://www.nature.com/nature/journal/v487/n7405/abs/nature11130.html)
It was found that the average physiologic pH of the lung is 7.4. The National Institute of Health defines the typical physiological pH of the human lung 7.38- 7.42 (average 7.4). However the United States Pharmacopeia (USP) for inhaled saline allows a pH ranging from 4.5 to 7. The average saline pH in products in commerce is 6.2.
PharmaCaribe filed a new 510(k) and made the rational case for approval outside of the USP monograph guidelines for a pH of 7.4, which was cleared for commerce March 2013, PulmoSal (pH+).
At the NACFC 2014 Dr. Jane Burns from the Seattle Children’s Hospital and University of Washington in Seattle, WA USA published a poster called “pH-dependent differential Pseudomonas Aeruginosa Killing in CF Sputum incubated in hypertonic saline solutions” which clearly showed that a hypertonic saline solution with a pH of 7.4 provides a more unfriendly environment for Pseudomonas Aeruginosa colonization compared to other hypertonic saline solutions which are made to USP.