[Deposition of aerosols into the airways (author's transl)]

The rate of powder absorbed in the lung greatly depends on the particle diameter, and amounts to 40--50% for 1 micrometer particles and 15--20% for 5 micrometer particles. Of importance for therapy was the information that single breath will deposit in the lung 15% of a powder aerosol of 2 micrometer diameter. The liquid aerosols as prevalently used in the therapy, were retained in the lung at a rate of 15% of the original amount when using ultrasonic apparatus. If calculated per minute of inhalation time, the amount absorbed by the lung amounted to 0.2 ml and that by the upper respiratory tract to 0.06 ml. Best deposition in the lung was obtained when inhaling in a closed system with valve-controlled aerosol stream, when using a mouthpiece, and when the test person inhaled with low respiratory rate, deep inspirations, short respiratory pause and complete exspiration. Mark inhalation with closed mouth gave only one tenth of the lung deposition reached with the breathing method described. The use of a mask showed good results, however, when the test person was breathing with open mouth. Only 0.07 ml/min were retained with jet nebulizer and mouth respiration. Combination with intermittent pressure respiration showed no convincing results.