EFFECT OF DEPTH OF INHALATION ON AEROSOL PERSISTENCE DURING BREATH HOLDING

To determine the effect of depth of inhalation on aerosol persistence in the respiratory tract during breath holding, an aerosol bolus was inhaled, followed by 200-800 ml of clean air to a lung volume slightly below TLC. The breath was then held from 0.5 to 20 sec, after which a forced exhalation was made and aerosol recovery was measured as a fraction of that inhaled. In this way persistence was measured as a function of inhaled volume and of time of breath holding for six normal subjects. The bolus results were then compared with those for complete aerosol inhalations in which persistence was measured in the same way. Results on each subject by the two procedures agreed well, but there were considerable differences between subjects. It was concluded that depth of inhalation has a greater effect on persistence than would be predicted from some current lung models.#B017303