We have assessed the physical and dynamic characteristics of 23 home jet nebulizer/compressor combinations currently available in the UK and Europe. The combinations were evaluated in terms of pressure-flow characteristics, aerosol mass distribution, volume output, electrical costs, and sound level. In addition, we determined the effect of nebulizer fill volume on aerosol mass distribution and volume output. One nebulizer was used with six different compressors, and four compressors were tested with three different nebulizers. The pressure-flow relationships showed a wide variation between models, as did flow-rate at the nebulizer (range 3.0-8.0 L.min-1). The mean +/- SD volume nebulized after 10 min using an initial fill volume of 2.5 and 5.0 mL was 46 +/- 9 and 34 +/- 12%, respectively. The mass median aerodynamic diameter (MMAD) over a 5 min nebulization ranged 2.6 to 10.2 microns. Nine of the nebulizations produced an MMAD of less than 5 microns at both fill volumes. Changing nebulizer/compressor combinations affected flow rate, MMAD and volume output. Sound levels varied between models. Running costs were low, with all using less than 74 kilowatt hours of energy per year. We conclude that there is a wide variation in performance of nebulizer/compressor combinations for use with nebulized bronchodilators. Correct matching of the nebulizer/compressor is seen to be important to ensure optimum performance.(ABSTRACT TRUNCATED AT 250 WORDS)
The ability of two low resistance barrier filters (Collins DC-1 and Pall Pf 305) to remove bacteria from expired air was assessed. A specially designed coupling device was used to hold each filter or a disposable plain cardboard mouthpiece a fixed distance (4.5 cm) from a blood agar plate. Volunteers performed maximal forced vital capacity manoeuvres through the assembled apparatus and bacteria impinged on to the agar plate were enumerated. Both filters allowed the transmission of approximately one-third of expired colony forming units. The efficacy of these filters for reducing the likelihood of cross-infection during spirometry is not supported by this study.
1. Beta-agonists affect bronchodilation of the airways by their action on the bronchial smooth muscles. 2. Anticholinergic drugs affect bronchodilation of the airways by blocking the effect of acetylcholine and its bronchoconstrictor action. 3. Receptors are protein molecules found in cell membranes; they can selectively bind to messenger molecules and transduce a chemical signal into a response in a target cell.
1. When lung function is being measured, it is important that it is accurately interpreted and reported. 2. Clinical history and previously recorded values should be taken into account. 3. When correctly interpreted, measurements can provide useful information to aid diagnosis.
General practice in the 1840s B N Nathan 126 British Diabetic Association educational holidays Martyn G Thomas 127 Note to authors of letters: Please note that all letters submitted for publication should be typed with double spacing. Failure to comply with this may lead to delay in publication. Open access to spirometry with chest x-ray Sir, Open access chest x-rays are available to patients referred by their general practitioners in 967o of health districts (British Thoracic Society report, 1987). Many referrals are for dyspnoea or wheezing. In 1984, an open access service to general practitioners in the Bristol and Weston health district, based at the Bristol Royal Infirmary, was set up to provide a combined chest x-ray and spirometry service with a written report. We have reviewed the first three years of this service to determine its usefulness. The service Patients may attend between 09.00 and 10.00 hours each weekday. They are sent directly with a request card, allowing the general practitioner to give a brief clinical history and request spirometry with or without chest x-ray. Each patient is carefully questioned by a technician and a modified Medical Research Council questionnaire completed. Measurements of one second forced expiratory volume, forced and relaxed vital capacity and peak expiratory flow are made before and after inhalation of a bronchodilator. If requested , a posterior anterior and left lateral chest x-ray are obtained. The total time for attendance is about one hour. An experienced physician reports on the spirometry and chest x-ray. A written report with suggestions for treatment or further investigations where appropriate is sent out within a week. If a major abnormality is detected, the general practitioner is contacted immediately. Questionnaires were sent out to 284 general practitioners within the health district; 72 had previously used the service on one or more occasions. Forty one of the 72 (57%) returned their questionnaire. All regarded the service as useful and the reports helpful in the diagnosis and management of their patients. Three thought that possibly more information could be given in the report about further investigations or treatment. Forty one per cent of respondents wanted automatic referral for more detailed studies if the results were inconclusive, while 17% suggested that further investigations should be made available: exercise tests (three), blood gases (one), allergy skin tests (two) and carbon monoxide transfer factor (one). Of the 212 general practitioners who had not used the …
