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Biomedical subjects

W K Morgan

Publications and source records attributed to W K Morgan.

At least 91 records · Page 5Linked to original sources
PubMed1983

Histamine bronchial challenge: effect on regional ventilation and aerosol deposition.

We studied regional changes in ventilation and aerosol deposition after histamine challenge in six patients with asthma and two with rhinitis and a history of wheezing. All were known to have bronchial hyperreactivity and all showed an increased response to histamine. Ventilation and aerosol deposition studies, using xenon-133 and an aerosol of sulphur colloid tagged with technetium 99m, were performed while they were sitting. Before administration of histamine radioaerosol scintiscans were abnormal in five of six patients; after histamine challenge all were abnormal and central deposition was significantly greater in all of them. The decrease in aerosol penetration correlated with the percentage decrease in FEV1, indicating that the efficiency of aerodynamic filtration depends on the degree of airway narrowing. In six of the eight subjects the distribution of ventilation changed from predominantly basal to predominantly apical after histamine, which suggests the airways response was greater, at least initially, in the better ventilated regions. This indicates a close relationship between regional ventilation and the site of histamine deposition and has implications for the delivery of aerosolised agents in general.

Adult↗
PubMed1981

A clinical and roentgenographic correlation of diaphragmatic movement.

Diaphragmatic excursion was determined by percussion in 29 patients by two observers and then compared with measurements made from inspiration and expiration chest roentgenograms. The range of movement as determined by percussion was related to spirometric indices of ventilatory capacity. Our study showed wide interobserver variation in the clinical measurements and a poor correlation with diaphragmatic excursion measured roentgenographically. Although we were able to demonstrate a significant correlation between forced vital capacity (FVC) and clinically determined range of diaphragmatic movement, five patients had a reduced FVC despite the fact that the clinical determination of diaphragmatic movement was greater than 2 cm. Both observers missed paradoxical movement in the one patient in whom it was present. We conclude that percussion of th diaphragms for the purpose of estimating the range of movement is of limited clinical value and should no longer be recommended as part of the physical examination.

Adolescent↗
PubMed1980

Respiratory disability in coal miners.

It has been suggested that the assessment of ventilatory capacity alone is inadequate for the determination of disabling occupational respiratory impairment in coal miners. The Department of Labor has accepted this view and now routinely requests blood gas analyses in those claimants not meeting the ventilatory criteria. We tested the validity of this contention by selecting two groups of coal miners claiming total disability. The first consisted of 150 claimants who were referred for spirometry, while the second consisted of 50 claimants who had been referred for blood gas studies. Of those in group 1, eight met the extent criteria for disability, while only two of those in group 2 satisfied the criteria, and, in both, cardiac disease was responsible. We conclude that blood gas analyses are unnecessary in the determination of pulmonary disability in coal miners.

Blood Gas Analysis↗
PubMed1980

Respiratory effects of exposure to dust in taconite mining and processing.

Taconite is a low-grade iron ore consisting of iron, quartz, and numerous silicates. Taconite from the eastern tip of the Mesabi Iron Range contains the amphibole silicate cummingtonite-grunerite, which is a mineral relative of amosite asbestos. In the present study, data were collected from 249 men with 20 or more years of exposure to taconite dust and 86 men without history of intimate exposure to taconite dust. Bronchitic symptoms and impairment of expiratory flow correlated significantly with history of cigarette smoking, but not with exposure to dust. Chest radiographs revealed three cases of possible silicosis. No case of definite interstitial fibrosis, ill-defined diaphragm, pleural calcification, or mesothelioma was found. We conclude that (1) cigarette smoking is significantly correlated with bronchitic symptoms and impairment of expiratory flow; (2) taconite workers are at risk of silicosis; (3) if dust containing cummingtonite-grunerite has biologic activity comparable to that of dust from asbestos, it is not evident after 20 years of low-level exposure.

Adult↗
PubMed1979

Pulmonary haemorrhage and haemolytic anaemia due to trimellitic anhydride.

Two young men who had been exposed at work to epoxy resin powder containing trimellitic anhydride (TMA) presented with haemolytic anaemia and repeated haemoptyses. They did not return to work at the factory and the symptoms and the anaemia resolved spontaneously. Seven similar cases have lately been presented at meetings, so it seems that TMA, already known to cause respiratory syndromes such as asthma, can also lead to several extrapulmonary toxic effects, including haemoptyses and haemolytic anaemia. Studies on these patients' sera with TMA haptenised protein and cells pointed to an immunological mechanism.

Adolescent↗