High speed photographic analysis of aerosols produced by metered dose inhalers

Abstract

The design of pressurized metered dose inhalers (MDI) used to assess asthma is variable. We have examined the aerosol spray flumes generated by four commercially available MDI products using high speed video photography. For this purpose a moulded jacket was designed which could hold the inhaler in an immovable position during actuation. Fresh inhalers were fitted in the jacket after thorough shaking and three successive actuations 30 s apart were filmed with a high speed video camera (200 frames s-1). The aerosol, ejected at high velocity into calm room air, was seen to have a 'jet' phase followed by a 'cloud' phase as a result of particle dispersion. Filming was continued till the flume could no longer be visualized on the TV monitor. High speed photography was used to record flumes seen on the video monitor, to enable characterization of flume appearance, dimensions and mean velocity.

In vitro comparison of the amount of salbutamol available for inhalation from different formulations used with different spacer devices

“…The aerosol produced by the Ventolin® MDI was moving faster than that produced by the Airomir® MDI. Others have also measured the speed of aerosols from MDIs [15], producing results similar to those of the present study for a Ventolin® MDI. Particles from the Ventolin® MDI would have reached the end of the Aerochamber® (11 cm length) some 8 ms after MDI actuation, compared with 23 ms for Airomir®.…”

Overcoming the Adverse Effect of Humidity in Aerosol Delivery via Pressurized Metered-Dose Inhalers during Mechanical Ventilation

“…This time, a large prototype was used as spacer device. The dimensions of the prototype were chosen based on a high-speed photographic analysis of the pMDI cloud (22). The results shown in Table 2 confirmed the prediction of an inhaled mass quantity similar to the amount obtained with heated and dry air with the Aerochamber (see Table 1, 37Њ C and RH ϭ 8%).…”

Evaluation of droplet velocity and size from nasal spray devices using phase Doppler anemometry (PDA)

“…Dhand et al (1988) suggested a high-speed video recording method to analyze the aerosol velocity, * Corresponding author. Tel.…”