An increase in laryngeal aerosol deposition by ultrasonic nebulizer therapy with intermittent vocalization

In acute or chronic laryngitis as well as pharyngitis, nebulization with steroid and antibiotics is considered to be a safe and effective treatment. However, the optimal dose, frequency, duration, and method of administration by ultrasonic nebulization is not known. To evaluate whether there is continual improvement using ultrasonic nebulizer therapy, the deposition rate of aerosol particles into the upper airway was studied. We analyzed the deposition rate in the upper airway by a counting system of radioactive isotope (99mTc-diethylene triaminepentaacetic acid; 99mTc DTPA). Volunteers in good health inhaled an aerosol containing 99mTc DTPA under various conditions of inhalation. Deep and slow inhalation at a respiratory rate of 12 breaths/minute resulted in a high deposition rate of 99mTc DTPA in the lung and a low deposition rate in the larynx. In contrast, faster inhalation at a respiratory rate of 36 breaths/minute resulted in an increase in the isotope deposition rate in the larynx. Furthermore, when the volunteers vocalized intermittently during the fast inhalation at a respiratory rate of 36 breaths/minute, the isotope deposition rate in the volunteer's larynx was higher than in all other inhalation conditions. These results suggest that fast inhalation with intermittent vocalization is one of the important inhalation methods used to improve the deposition rate of aerosol particles into the upper airway with an ultrasonic nebulizer.