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Biomedical subjects

D Pavia

Publications and source records attributed to D Pavia.

At least 91 records · Page 5Linked to original sources
PubMed1982

Chest physiotherapy: a review.

Postural drainage enhances mucociliary clearance and produces larger sputum volumes than an equivalent control period in disease characterised by excessive tracheobronchial secretions. Postural drainage, percussion and vibration will improve pulmonary function only in patients with large sputum volumes. There is no evidence that sputum yield is increased by the addition of percussion and vibration. From radioaerosol studies effective cough is limited to central airways. Breathing exercises may be of some immediate value in asthma but are without long term advantages and probably do not alter the ventilation of the underlying lung. IPPB probably does not improve delivery of bronchodilators and is of no benefit (and possible harmful) in the long term treatment of chronic bronchitis. Infective exacerbations of chronic bronchitis not characterised by copious volumes of sputum, uncomplicated pneumonia and routine post-operative states are not indications for chest physiotherapy. The value of regular physiotherapy on ventilation, gas exchange, work of breathing and incidence of infective exacerbations is uncertain but exercise training and rehabilitation of chronic obstructive airways disease improves exercise tolerance and mobility.

Breathing Exercises↗
PubMed1981

Deposition of pressurised aerosols in the human respiratory tract.

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 diameter 2 micrometer) with aerodynamic properties similar to those of bronchodilator drug crystals into pressurised aerosol canisters. Controlled inhalations by eight patients with obstructive airways disease showed that on average 8.8% of the dose was deposited in the lungs (3.0% in the alveoli and 5.8% on the conducting airways) and 80% in the mouth. These figures are in good agreement with previous indirect estimates of deposition based on metabolic studies. The remainder of the dose was either expired (1.0%) or deposited in the aerosol actuator (9.8%). This method should have wide application for measurement of deposition patterns under various conditions and for assessment of therapeutic effects.

Aerosols↗
PubMed1981

Objective in vivo analysis of anti-smoking cigarette filters.

Cigarette filters have been introduced to reduce inhaled smoke and also as a means of breaking the smoking habit. Twelve volunteers smoked cigarettes through four ventilated anti-smoking filters (MD-4, Miles Laboratories) and one reference cigarette without an anti-smoking filter in a single-blind, crossover manner. The amount of smoke inhaled was monitored by a radiotracer technique using the isotope 81mkrypton. Compared to the reference cigarette the amount of isotope reaching the lung was reduced to 76%, 63%, 43%, and 37% for filters 1 to 4, respectively, which was less than the reduction to 70%, 40%, 30%, and 20% predicted by the manufacturers. In the case of filters 2, 3, and 4, the observed reductions in isotope inhalation were significant (p less than or equal to 0.01) but were also significantly less (p less than or equal to 0.01) than the manufacturers' predictions.

Adult↗
PubMed1981

Is cough as effective as chest physiotherapy in the removal of excessive tracheobronchial secretions?

The relative value of chest physiotherapy (including cough) and cough alone for the removal of excessive tracheobronchial secretions has been assessed in six patients with stable chronic obstructive lung disease. After labelling with inhaled radioactive tracer particles, clearance of secretions from selected central and peripheral lung regions was followed with a gamma camera linked to a computer. Cough alone and chest physiotherapy (including cough) were equally effective in the enhancement of central lung clearance. Physiotherapy but not cough along accelerated peripheral lung clearance (p less than 0.05). Sputum yield was greater during physiotherapy than during cough (p less than 0.05). These findings confirm the value of chest physiotherapy and high-light the limitation of cough in patients with excessive tracheobronchial secretion and impaired mucociliary clearance.

Bronchi↗
PubMed1981

Deposition of pressurized suspension aerosols inhaled through extension devices.

Only a small fraction of the dose from a pressurized aerosol inhaler reaches the lung, because most is deposited on the upper airways by inertial impaction. We have investigated the effects on aerosol deposition of two spacer devices (a 10-cm tube and a 22-cm cone) by incorporating teflon particles (mass median aerodynamic diameter, 3.2 micrometer) labeled with 99mTc into pressurized canisters. Ten subjects with obstructive airway disease inhaled the aerosol in a controlled manner from a conventional actuator alone or in combination with the tube or the cone. Radioaerosol distribution was measured using a shadowshield whole body counter. Deposition on the conducting airways was significantly improved by both spacers, but alveolar deposition was unchanged. Initial oropharyngeal deposition was reduced by both spacers in all 10 patients. We conclude that the spacer devices may have a role to play in aerosol therapy by increasing drug availability to the lung, while at the same time decreasing unwanted drug deposition in the oropharynx.

Adrenal Cortex Hormones↗
PubMed1981

Lung mucociliary clearance in patients wit Young's syndrome.

Lung mucociliary clearance was measured in 14 patients with primary obstructive azoospermia and chest involvement (Young's syndrome) using the objective, in vivo radioaerosol technique. Lung mucociliary transport was significantly reduced in patients with Young's syndrome compared to 14 control subjects matched for physical characteristics, tobacco consumption and initial topographic distribution of tracer particles within the lungs. This finding indirectly supports the hypothesis that congenital abnormality in the propulsion of sperm in the ciliated epididymis results in the absence of sperm in the ejaculate.

Adult↗
PubMed1981

How should a pressurized beta-adrenergic bronchodilator be inhaled?

Although the manufacturers of pressurized aerosol bronchodilators issue instructions for using the inhalers, little or no experimental verification exists. Furthermore, the instructions often fail to take into account known facts about aerosol deposition. We have reviewed the evidence for the most effective mode or modes of inhalation of pressurized aerosol bronchodilators, some of which has arisen from experiments performed in our laboratory. In order to achieve a maximal effect following inhalation of terbutaline sulphate bronchodilator aerosol (Bricanyl, Astra Pharmaceuticals), the canister should be actuated during a slow (25 l min-1), deep inhalation and breath held subsequently for 10 s. Bronchodilatation may be reduced if aerosol is inhaled rapidly (80 l min-1) or if breath is held for 4 s. We have considered the applicability of these simple rules to other types of bronchodilator and to all patients, irrespective of their diagnosis or degree of airway obstruction. The lung volume at which aerosol is released into the airstream, the importance of coordinating inhalation with aerosol actuation, and the relative merits of "open" and "closed" mouth inhalation techniques are also discussed.

Adrenergic beta-Agonists↗
PubMed1981

Airways penetration of inhaled radioaerosol: an index to small airways function?

Several reports have claimed that inhaled radioaerosol particles show diminished lung penetration in subjects with impaired small airways function. Lung penetration may be estimated from the ratio of peripheral to central deposition, from the proportion of particles retained after 24 hours, from visual classification of gamma camera images or by computer analysis of the inhomogeneity of such images. Several approaches can characterise many young symptom-free smokers, or subjects with mild asthma, as "abnormal". Yet there is no convincing evidence from review of the literature and our own work that tests based on radioaerosol deposition are superior to other "small airways tests". Studies of particle deposition are, however, vital to the use of aerosols for investigating mucociliary clearance in the small airways.

Aerosols↗
PubMed1981

Pulmonary disorders associated with Sjögren's syndrome.

Pulmonary disease is recognized to occur as a complication of Sjögren's syndrome and we have studied 17 patients, the majority middle-aged women, with this association. Eight had sicca syndrome alone and nine had Sjören's syndrome in association with a connective tissue disease. Various pulmonary disorders were found: 10 had diseases mainly affecting pulmonary parenchyma (recurrent pneumonia, granulomatous infiltration, pseudolymphoma and fibrosing alveolitis) and six had disorders of the airways (bronchitis, bronchiectasis and asthma). One patient presented with a mediastinal immunoblastic lymphoma. To test the hypothesis that physical factors such as the retention of viscid mucus may play a part in the development of lung disease in Sjögren's syndrome, we have measured mucociliary clearance in patients with Sjögren's syndrome using 99Tc-labelled polystyrene particles. The mucociliary clearance rate was found to be normal from central airways and the whole lung clearance rate was significantly increased in Sjögren's syndrome compared with normal controls. The latter was attributed to the failure of penetrance of the radioaerosol into the periphery of the lung consistent with obstruction of small airways in Sjögren's syndrome. The patients with Sjögen's syndrome and lung disease were characterized by a number of immunological markers irrespective of the presence or type of associated connective tissue disorder. The commonest found were speckled antinuclear antibody by indirect immunofluorescence, antibodies to the acidic nuclear antigen B by counterimmunoelectrophoresis, increased serum DNA binding, increased levels of circulating immunoglubulins, rheumatoid factor in high titre and circulating soluble immune complexes as detected by Clq binding assay.

Adult↗
PubMed1980

Mucociliary clearance in patients with chronic autonomic failure.

Mucociliary clearance was measured in four patients with chronic autonomic failure and normal ventilatory function using a method of scanning the clearance of inhaled polystyrene particles tagged with 99mTc. Previous surgical and experimental evidence has suggested that autonomic denervation might be expected to impair clearance. However, the four patients in this study showed no significant difference in clearance rate compared to groups of sex-matched control subjects. A fifth patient was found to have impaired mucociliary clearance. However she had the symptoms and ventilatory function of smoking-related chronic obstructive bronchitis, a condition which has previously been shown to impair mucociliary clearance.

Adult↗
PubMed1980

Simple instructions for using pressurized aerosol bronchodilators.

Although the manufacturers of pressurized aerosol bonchodilators issue instructions for using the inhalers, little or no experimental verification exists. Bronchodilatation has been measured after controlled inhalations of 500 μg terbutaline sulphate given in a systematic series of investigations to 8 patients with reversible airways obstruction at 2 different inhalation flow rates (25 1/min and 80 1/min), 3 different lung volumes (20%, 50% and 80% vital capacity) and followed by 2 different breath-holding pauses (4 and 10 seconds). The results indicate that patients may release the aerosol at any time during the course of a slow deep inhalation which should be followed by 10 seconds of breath-holding. This will ensure an optimal bronchodilator response.

Aerosols↗
PubMed1980

Clearance of lung secretions in patients with chronic bronchitis: effect of terbutaline and ipratropium bromide aerosols.

A placebo controlled, double-blind, cross-over study was carried out to examine both the bronchodilator properties and the effect on lung mucociliary clearance of terbutaline (Bricanyl), a beta agonist, and ipratropium (Atrovent), a synthetic anticholinergic drug. Both were given regularly (two puffs four times a day for 1 week) from pressurised metered dose inhalers to patients with chronic obstructive bronchitis. A total of 10 patients completed the terbutaline study and 12 patients the ipratropium study; of these, seven patients were common to both studies. Measurements of the pulmonary function indices, forced expiratory volume in 1 s, forced vital capacity (FVC), peak expiratory flow rate and the flow rate at 50% of FVC measured from maximal expiratory flow-volume curves, confirmed the bronchodilator action of both drugs in these patients. Clearance of lung secretions was measured by the non-invasive, radioaerosol technique. No evidence was found that either drug had any effect on the rate of mucociliary clearance. The radioaerosol tracer particles used for measuring lung clearance, although inhaled under strictly controlled conditions, were deposited significantly more towards the lung periphery after treatment with ipratropium only. This suggested that ipratropium reduced the resistance to the entry of inhaled aerosols in the small airways.

Aerosols↗