Although the use of pressurised aerosol inhalers is widespread, little is known about the actual deposition of the aerosol in the respiratory tract, since this has previously been difficult to measure. We have incorporated Teflon particles (mean various conditions and for assessment of theracentages of the dose deposited on the conducting airways and in the alveoli are unknown. In this paper we present the first direct measurement of the deposition of pressurised inhalation aerosols, using an objective in vivo radioactive technique. MethodsIn order to study the deposition of pressurised aerosols, we have incorporated Teflon particles (density 2'1 gm cm-3), generated by the spinning disc technique,7 into metered-dose inhalers. A fine suspension of fluorocarbon resin (Teflon 120, Dupont) in a mixture of 40% ethanol and 99mtech-netium (Tc) was delivered to the centre of the rapidly rotating disc. The particles generated (mean diameter 2 ,tm, standard deviation 0 4 ,tm) were allowed to settle onto the base of a large airtight tank inside which the generator was situated. After collection, the 99mTc was firmly sealed within the particles by heating at 2400C for five minutes.The pressurised canisters and valves used in this study were those available commercially for the delivery of terbutaline sulphate (Bricanyl, Astra Pharmaceuticals). Eight mg of the Teflon particles were placed inside an open canister, and 2 ml of 52 on 9 May 2018 by guest. Protected by copyright.
The effect on aerosol deposition from a pressurised metered dose inhaler of a 750 cm3 spacer device with a one way inhalation valve (Nebuhaler, Astra Pharmaceuticals) was assessed by means of an in vivo radiotracer technique. Nine patients with obstructive lung disease took part in the study. The pattern of deposition associated with use of a metered dose inhaler alone was compared with that achieved with the spacer used both for inhalation of single puffs of aerosol and for inhalation of four puffs actuated in rapid succession and then inhaled simultaneously. On each occasion there was a delay of 1 s between aerosol release and inhalation, simulating poor inhaler technique. With the metered dose inhaler alone, a mean (SEM) (1-8)% of the dose reached the lungs and 80*9 (1 9)% was deposited in the oropharynx. With single puffs from the spacer 20-9 (1.6)% of the dose (p < 0.01) reached the lungs, only 16-5 (2.3)% (p < 0.01) was deposited in the oropharynx, and 55-8 (3 1)% was retained within the spacer itself. With four puffs from the spacer 15-2 (1.5)% reached the lungs (p = 0-02 compared with the metered dose inhaler alone, p < 0-01 compared with single puffs from the spacer), 11-4 (1.2)% was deposited in the oropharynx, and 67*5 (1.8)% in the device itself. It is concluded that the spacer device gives lung deposition of metered dose aerosols comparable to or greater than a correctly used inhaler and oropharyngeal deposition is greatly reduced. The spacer should be used preferably for the inhalation of single puffs of aerosol but may also be used for the inhalation of up to four puffs actuated in rapid succession and then inhaled simultaneously.Metered dose inhalers have several advantages for respiratory treatment as they contain several hundred doses and are compact, unobtrusive, and apparently easy to use. The spray from a metered dose inhaler consists, however, of rapidly moving, large propellant droplets, most of which impact in the oropharynx, only about 10% penetrating into the bronchial tree.' 2 This small proportion may be further reduced by poor inhaler technique. Many patients misuse their inhalers,3 and failure to synchronise firing of the aerosol with inhalation is probably the most widespread problem.45
ABSTRACr The size distribution of saline and bronchodilator (terbutaline) aerosol droplets generated from four widely used jet nebulisers (Acorn, Upmist, Turret, and Inspiron Mini-neb) has been measured with a Malvern 2200 Laser Particle Sizer. The mass median diameter of aerosol droplets generated by each nebuliser was strongly influenced by the driving flow rate of compressed air. By increasing the flow rate from 4 to 81 min-' mass median diameters were halved (p < 0-01) and there was an increase in the mass of aerosol within the optimum respirable range (<5 ,m). To achieve this range the following individual flow rates were required: Turret 4 1 min-', Acorn and Upmist 6 1 min-t, and Inspiron Mini-neb 8 1 min-t. A significant inverse relation (p < 0.001) was found between mass median diameter and the geometric standard deviation, indicating that the aerosols were smaller but more heterodisperse at high flow rates. Changes in drug concentration had little effect on aerosol size. In 72% of the nebulisations followed to dryness there was no significant change in mass median diameter during the course of nebulisation and in the remainder it was less than 1-3 Am.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.