Chest
Clinical Investigations: Airways IrwaysInhalation of Single vs Multiple Metered-Dose Bronchodilator Actuations from Reservoir Devices: An In Vitro Study
Section snippets
In Vitro Lung Model
An in vitro model of patient use of the MDI spacer assembly was used to assess the amount of β-agonist drug available with single vs multiple actuations of an MDI (Fig 1). Inspiratory breathing was simulated by connecting the mouthpiece of the MDI spacer assembly to one side of a dual-chambered test lung, with a one-way Rudolph valve to route the gas inspired from the reservoir out to the room on exhalation. The other side of the test lung was inflated by a ventilator (Nellcor-Puritan Bennett
Results
For all devices tested, ambient temperature averaged 19.9°C with an SD of 0.21, and a range of 19.6 to 20.1°C. Relative humidity was 62.4%, with an SD of 6.42% and a range of 54 to 69.7%.
Table 1 summarizes the total doses measured at the reservoir mouthpiece for all three brands of reservoir, with each of the single and multiple actuation techniques. There were significant differences overall across brands of reservoir (p=0.001) and across numbers of actuations (p<0.001) with respect to dose
Discussion
Although the availability and use of reservoir devices offers the possibility of simplifying MDI use for subjects as far as hand-breathing coordination is concerned, the use of such devices also introduces further possible permutations in the aerosol delivery system. One such variation is the introduction of multiple actuations into a reservoir device, followed by a single inhalation from the device, to obtain the dose to the lung. Our investigation of this technique found that the use of two
Conclusion
Based on the results obtained in our study, we conclude that the maximal amount of aerosol albuterol from an MDI reservoir combination will be obtained using a single actuation followed by inhalation. However, the use of two actuations in rapid succession (ie, within seconds) followed by inhalation can give an increase in total dose, with some loss of efficiency. Three actuations followed by inhalation gives less increase in total dose compared to the double actuation, with greater loss in
References (14)
- et al.
The use of reservoir devices for the simultaneous delivery of two metered-dose aerosols
J Allergy Clin Immunol
(1990) - et al.
Patient error in use of bronchodilator metered aerosols
BMJ
(1976) Problems patients have using pressurized aerosol inhalers
Eur J Respir Dis
(1982)- et al.
Deposition of pressurised aerosols in the human respiratory tract
Thorax
(1981) - et al.
Oropharyngeal deposition and delivery aspects of metered-dose inhaler aerosols
Am Rev Respir Dis
(1987) - et al.
Deposition of pressurized suspension aerosols inhaled through extension devices
Am Rev Respir Dis
(1981) - British Thoracic Society. Guidelines for the management of asthma in adults: II. Acute severe asthma. BMJ 1990;...
Cited by (0)
This study was funded by a research grant from Diemolding Healthcare Division, Canastota, NY. The authors have no financial or other interest in the products investigated.