A saline aerosol is not bactericidal, which limits its use.
Brine inhalations is a procedure that is less and less used due to its limitations. This is due to the fact that the brine aerosol is not bactericidal, therefore inhalations with its use can be carried out only in the open air or individually using a nebuliser.
Another problem is the merging of the aerosol particles. The aerosol forms larger particles. This is an important parameter, because in order for the aerosol to be considered therapeutic and to be used in inhalations, the size of the aerosol particles must be less than 5μm. This is due to the fact that larger particles have no chance of being taken by the respiratory system that has natural filtration systems beginning in the nose, so they are useless in inhalations.
In terms of NaCl concentration, we can distinguish hypotonic, isotonic and hypertonic solutions. Hypotonic solutions have a concentration lower than the physiological salt concentration (0.9%), isotonic with a concentration equal to 0.9%, while the concentration of hypertonic solutions exceeds 0.9%. Hypotonic and isotonic solutions cause moisturization of the mucous membrane and have an irrigation effect on the body. In addition, they soothe mucous membranes, reducing its hypersensitivity and congestion. This promotes gentle stimulation of gland functions, which helps remove mucus. Hypertonic solutions cause dehydration, contraction and irritation of the mucosa. In addition, they increase the activity of mucous and serous glands, cause hyperemia and have anti-oedematous effects.
The use of saline aerosols poses a risk of bronchospasm in people with bronchial hypersensitivity, which may cause bronchial smooth muscle contraction.
It is the main cause of the characteristic symptoms of asthma, such as shortness of breath, wheezing or coughing. Hypertonic brine solutions (i.e. concentrations above 0.9%) are used for diagnostic purposes because they cause increased secretion and cough. This allows obtaining material for diagnostic testing.
In brine inhalations a salt spray of 1-5% is used, so we actually inhalate 95-99% water. For these and other reasons, saline inhalations are replaced with dry salt aerosol inhalation, which is safer and more effective.