The purpose of this section is to identify (through a review of the literature) the proper technical characteristics of type of aerosol and pattern of inhalation, in order to achieve the best standardization of the tests. Several conventional jet nebulizers are suitable for producing the aerosol to be inhaled, provided that the aerodynamic mass median diameter of the particles generated from the specific solution to be used will be in the 1 to 4 μm range. The aerosol must be generated at 34°C, saturated, with possibly no charges on the particle surfaces. Only one kind of solution should be employed, and even if several solutions, at progressively higher concentrations in saline of the pharmacological agent have to be administered, the solutions must have the same osmolarity as the film lining over the internal surface of the bronchi. The inspired volume must be about 1 liter. Inspiratory flow must be in the range of 1 to 2 l/sec. At least 5 seconds of breath holding must follow the inhalation. It is not possible yet to make a choice of quantitative standardization of the administration, i.e. continuous production, use of a reservoir of aerosol, use of specific dose meters. Such a device (developed at the Johns Hopkins University, in Baltimore) is being tested by this work group. If it is necessary to use a reservoir of aerosol, this may be done only if the container characteristics can be examined; the latter must be thermostated. Whatever the pattern in use, the only output of active product from the generator can be quantified with some accuracy. The inhaled quantity is far more difficult to measure, while the retention is usually unknown. The authors admit that bronchial provocation tests performed by means of aerosols are not precise, at least as regards some of their aspects, despite sophisticated efforts at standardization.
Technical aspects of non specific bronchial provocation tests
ROMANO, Canzio;
1979-01-01
Abstract
The purpose of this section is to identify (through a review of the literature) the proper technical characteristics of type of aerosol and pattern of inhalation, in order to achieve the best standardization of the tests. Several conventional jet nebulizers are suitable for producing the aerosol to be inhaled, provided that the aerodynamic mass median diameter of the particles generated from the specific solution to be used will be in the 1 to 4 μm range. The aerosol must be generated at 34°C, saturated, with possibly no charges on the particle surfaces. Only one kind of solution should be employed, and even if several solutions, at progressively higher concentrations in saline of the pharmacological agent have to be administered, the solutions must have the same osmolarity as the film lining over the internal surface of the bronchi. The inspired volume must be about 1 liter. Inspiratory flow must be in the range of 1 to 2 l/sec. At least 5 seconds of breath holding must follow the inhalation. It is not possible yet to make a choice of quantitative standardization of the administration, i.e. continuous production, use of a reservoir of aerosol, use of specific dose meters. Such a device (developed at the Johns Hopkins University, in Baltimore) is being tested by this work group. If it is necessary to use a reservoir of aerosol, this may be done only if the container characteristics can be examined; the latter must be thermostated. Whatever the pattern in use, the only output of active product from the generator can be quantified with some accuracy. The inhaled quantity is far more difficult to measure, while the retention is usually unknown. The authors admit that bronchial provocation tests performed by means of aerosols are not precise, at least as regards some of their aspects, despite sophisticated efforts at standardization.
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