[Effects of nebulized distilled water on tracheal reaction in asthmatic patients]

To investigate the mechanism of bronchial spasm induced by inhalation of ultrasonically nebulised distilled water (UNDW) ultrasonically nebulised solutions including hypoosmolar (distilled water, 0.3% NaCL) isoosmolar (0.9% NaCL) and hyperosmolar solutions (2.7% NaCL, 3.6% NaCL, 4.6% KCL 22.2% dextrose) were used for challenge test in 12 asthmatic patients and 10 healthy subjects as controls. The dose of solution required to induce a 20% reduction in FEV 1 (FD 20-FEV 1) was recorded. In another 10 asthmatic patients, a challenge with UNDW was conducted after pretreatment with sodium cromoglycate (SC), Ipratropine Bromide (IB) to investigate the protective effect of the two medicines. The results showed that distilled water and three hyperosmolar solutions which were of the same osmotic pressure (3.6% NaCL, 4.6% KCL and 22.2% dextrose) were most potent in inducing bronchoconstriction, and no significant difference in PD 20-FEV 1 was found among them 0.3% and 2.7% NaCL were next and 0.9% NaCL was the least potent. Normal subjects showed no response to the solutions. The SC gave significant protection to nine of the ten patients, and IB gave it to five of the ten. Our results indicate that a change in the osmolarity of the fluid lining the respiratory tract may be an important determinant of the airway response; sodium cromoglycate which inhibits the mediator release of mast cell can reduce the airway response to UNDW.