An Investigation of Nebulized Bronchodilator Delivery Using a Pediatric Lung Model of Spontaneous Breathing

BACKGROUND: The literature lacks comparative data on nebulizer aerosol delivered via mask versus T-piece, to spontaneously breathing pediatric subjects.

PURPOSE: To compare total inhaled drug mass delivered via standard pediatric aerosol mask versus via T-piece, with increasing distance.

METHODS: We used a sample of 5 nebulizers, operated under manufacturers' conditions, with a standard pediatric aerosol mask and with a T-piece capped at one end, at 0 cm, 1 cm, and 2 cm from an inhalation filter placed at the inlet of a pediatric test lung. Inhaled drug mass was analyzed with spectrophotometry. Aerosol particle size was measured separately from the breathing simulations, using a laser particle sizer to determine fine-particle mass (particles < 4.7 μm) and fine-particle fraction as percent of total mass. The fine-particle fraction was used to estimate the fine-particle mass.

RESULTS: The mean ± SD values for inhaled drug mass as a percentage of nominal dose, at 0 cm, 1 cm, and 2 cm, with the mask were 2.88 ± 0.79%, 1.61 ± 0.65%, and 1.3 ± 0.42%, respectively, and with the T-piece were 4.14 ± 1.37%, 3.77 ± 1.04%, and 3.47 ± 0.64%, respectively. There was a statistically greater inhaled drug mass with T-piece than with mask, overall (p < 0.01), and a significant decrease with mask or T-piece as distance increased (p < 0.01). The difference between mask and T-piece for inhaled drug mass at 2 cm was statistically significant (p < 0.018). The mean ± SD values for fine-particle mass estimated as a percentage of total drug mass at 0, 1, and 2 cm, with the mask were 1.39 ± 0.36%, 0.78 ± 0.29%, and 0.64 ± 0.20%, respectively, and with the T-piece were 2.1 ± 0.63%, 1.84 ± 0.45%, and 1.71 ± 0.27%, respectively.

CONCLUSION: Inhaled drug mass was greater with T-piece than with a standard pediatric aerosol mask under the conditions studied.