REPLY TO DR. MATTHEWS
To the Editor: In answer to Dr. Matthews' letter, we would like to make the following comments.
Our experimental protocol was established to test "mist therapy" as it is generally used in acute lower respiratory tract infection, ie, without additives. We were unable to demonstrate any remarkable effect.
Mist therapy could theoretically be effective in lower respiratory tract infections for either of two reasons: (1) It could minimize respiratory water loss and thereby decrease the effect of systemic dehydration on the fluidity of bronchial secretions. The apparatus was more than adequate for this purpose. (2) Mist particles reaching the lower respiratory tract may directly dilute secretions and so aid in their expulsion. The number of particles entering the lower respiratory tract is principally a function of initial concentration of small-sized particles, minute ventilation, and evaporative losses. Assuming a minute ventilation as high as five liters per