Surgery – Diagnostic testing – Respiratory
Patent
1996-11-04
1998-10-06
Hindenburg, Max
Surgery
Diagnostic testing
Respiratory
12820014, 12820023, A61M 1100
Patent
active
058170286
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates to a method and device useful to provoke airway narrowing and/or the induction of sputum. More particularly the invention relates to the use of dry powdered substances to induce a change in the osmolarity of the airways to induce narrowing and/or the induction of sputum.
BACKGROUND ART
Asthma is a chronic inflammatory disease of the airways resulting in bronchial hyperresponsiveness to a wide variety of chemical, physical, and allergenic stimuli. This sensitivity is manifested by narrowing of the airways and a reduction in the forced expiratory volume in one second (FEV.sub.1). Bronchial provocation testing, measuring changes in FEV.sub.1 in response to inhaled stimuli, is well established as a technique for identifying and assessing the severity of airway hyperresponsiveness in persons suspected of having asthma (J Allergy Clin Immunol 1979; 64:1-250, Sterk et al Eur Respir J 1993,6(Supp 16):53-83. The most commonly used provocative agents are histamine and methacholine that act directly on specific receptors in the airways causing bronchial smooth muscle contraction. Challenges with these agents have a high negative predictive value but a low specificity for asthma when performed in a random population. Recently there have been problems with availability of these agents and accreditation for their use in humans. Currently the only product approved for human use by the Federal Drug Administration in the USA is Provoline (Hoffman La Roche) which is methacholine chloride.
Bronchial provocation testing with dry powders containing respirable particles of allergens (e.g. flour, red cedar wood dust, resins, gums) has also been used to identify specific allergens in order to establish a relationship between exposure to the suspected agent and the onset of asthma. These are most commonly used to investigate occupational asthma.
In the last 10 years the inventor's laboratory has developed and standardised a bronchial provocation test using wet aerosols of hyperosmolar saline generated by an ultrasonic nebuliser (Anderson et al., in Provocation Testing in Clinical Practice, pp 249-278, Marcel Dekker Inc. 1994). This test is now well established in Laboratories throughout Australia and is listed in the Medical Benefits Schedule Book. This challenge test is also included in the report of the working party of the European Community for Steel and Coal (Sterk et al., Eur Respir J, 1993,6(Supp 16):53-83). It has recently been recommended by the Bronchial Provocation Committee of the International Study of Asthma and Allergy in Children.
Hyperosmolar saline challenge appears to be a very useful technique to identify persons with current asthma and those who suffer exercise-induced asthma. It is also very useful to evaluate the drugs used in the treatment of asthma.
The major disadvantage of using wet aerosols of hyperosmolar saline is that an ultrasonic nebuliser is required and this is expensive. Another disadvantage is that ultrasonic nebulisers require maintenance for cleaning and sterilisation. Further a weighing machine is required to measure the output for each test as the nebulisers differ in output over time and between machines. Another disadvantage, as with other wet aerosols, is that the person administering the challenge is also exposed to the aerosol as more than half of the amount generated by the nebuliser is expelled into the environment. Further the personnel are also exposed to saliva from the patient. There are also some difficulties encountered by the patient and these include the use of a nose peg, the production of a lot of saliva and the taste of salt. The time taken to perform the challenge with a wet aerosol in a mild asthmatic or healthy control maybe 70 minutes. This comprises preparation of solution and apparatus (about 10 minutes), actual challenge time which for mild asthmatics may be up to 30 minutes, and finally post challenge cleaning and sterilisation (about 30 minutes).
It is also known that wet aerosols of salt can be used for the
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Central Sydney Area Health Service
Hindenburg Max
Huane Stephen
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