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Biomedical subjects

M D Lougheed

Publications and source records attributed to M D Lougheed.

5 recordsLinked to original sources
PubMed1999

Nylon flock-associated interstitial lung disease.

A work-related interstitial lung disease has been diagnosed in workers at five nylon flock facilities in three different states and a Canadian province. The National Institute for Occupational Safety and Health hosted a workshop at which consulting pulmonary pathologists reviewed lung tissue samples from all the cases for which lung biopsy material was available (15 of 20 cases known in January 1998). After independent review and scoring of these lung tissue specimens, the pathologists reached consensus that the histopathological findings revealed a characteristic lesion-a lymphocytic bronchiolitis and peribronchiolitis with lymphoid hyperplasia represented by lymphoid aggregates. The pathologists noted that the pathological findings were distinctive when compared with known lung conditions. The clinical presentation for the cases generally included cough, dyspnea, restrictive ventilatory defect with reduction in diffusing capacity, and interstitial markings on chest radiographs or high-resolution computed tomography (HRCT) scans. Six of the cases improved after removal from workplace exposure without medical treatment. Six others, who had recovered with medical treatment and removal from the workplace, had relapses in both symptoms and objective findings after attempting to return to nylon flock work. With this and other evidence supporting the existence of chronic interstitial pneumonitis associated with nylon flock processing, workshop participants recommended surveillance for early identification of affected workers and their removal from further workplace exposure.

Adult↗
PubMed1995

Desquamative interstitial pneumonitis and diffuse alveolar damage in textile workers. Potential role of mycotoxins.

Five of 88 workers at a textile plant developed interstitial lung disease. Biopsy specimens from the three initial cases demonstrated desquamative interstitial pneumonitis and diffuse alveolar damage. Two of these patients developed hypoxemic respiratory failure despite high-dose corticosteroid therapy. A survey of the remaining textile workers (questionnaires, chest radiographs, and pulmonary function tests) revealed one new case. This patient, and one other with a compatible presentation, improved clinically upon leaving the workplace and did not require therapy. A comprehensive assessment of the work environment was performed in search of potentially toxic respirable agents. We propose that these cases represent desquamative interstitial pneumonitis-like reactions, occupationally related to aflatoxin inhalation.

Adult↗
PubMed1993

Variability of the plateau response to methacholine in subjects without respiratory symptoms.

BACKGROUND: Interpretation of measurements of limited maximal airway narrowing, or plateau response, requires knowledge of its variability within subjects and between methods. METHODS: The repeatability of the plateau response to inhaled methacholine with a dosimeter (D) method (maximal dose 210 mumol) and a tidal breathing (T) method (730 mumol), and the agreement of the two methods, were measured in 16 subjects with mild or no asthma. Two tests by each method (D1,D2,T1,T2) were performed in random order over four consecutive days, with a third dosimeter (D3) test one week later. The dose producing a decrease in forced expiratory volume in one second (FEV1) of 10% (PD10) and the plateau were calculated from each dose-response curve. RESULTS: A plateau was reached in all five tests in 12 subjects and in all tests except D3 in 14 subjects. PD10 was inversely related to the plateau (r = -0.95 for D, r = -0.77 for T). The 95% ranges for differences between two determinations of the plateau in a subject were +/- 11.9% (change in FEV1), +/- 19.2%, and +/- 20.3%, estimated from D1-2 and 1-3, and T1-2 tests, respectively. From the same tests the 95% ranges for the difference of a single determination from an individual's true mean value were +/- 8.3%, +/- 13.6%, and +/- 14.3%. The limits of agreement between methods indicated that 95% of the measurements of the plateau by tidal breathing ranged from 15.2% below to 13.3% above those obtained by dosimeter. There was no significant bias between methods. Tachyphylaxis over 24 hours occurred with PD10 but not with the plateau response. CONCLUSIONS: The plateau response is a subject characteristic which is independent of the method of inhalation challenge testing. Repeatability of the plateau is low in this group of subjects with low airway responsiveness.

Adult↗
PubMed1993

Breathlessness during acute bronchoconstriction in asthma. Pathophysiologic mechanisms.

The purpose of this study was to examine potential contributing factors to breathlessness during bronchoconstriction, in particular, to evaluate the role of lung hyperinflation. We also wished to elucidate qualitative aspects of the unpleasant sensory experience and to identify factors that contribute to intersubject variability in subjective and objective assessments of airflow obstruction. We studied sensory-mechanical interrelationships during and after induced bronchoconstriction in 21 subjects with mild stable asthma. Breathlessness (Borg scale), spirometry, and inspiratory capacity (IC) were measured after each dose during methacholine bronchoprovocation to a maximal change (delta) in FEV1 of 50%. Breathing pattern, specific airway resistance (SRaw), plethysmographic thoracic gas volume, and maximal inspiratory mouth pressure (MIP) were recorded at baseline, at maximal response, and at full symptom recovery. End-expiratory lung volume (EELV) was derived from IC. Borg increased from 0.4 +/- 0.1 (very, very slight) at baseline to 5.0 +/- 0.5 (severe) at maximal bronchoconstriction (mean +/- SEM, p < 0.001). FEV1 fell significantly (p < 0.001) to 48% predicted at maximal response. Of the 21 subjects, 19 reported increased inspiratory rather than expiratory difficulty and predominantly described sensations of reduced inspiratory capacity and unrewarded inspiratory effort. Stepwise multiple regression analysis using delta Borg (outcome variable) versus changes in spirometry, SRaw, IC, and breathing pattern components, selected delta IC as the principal contributing factor: delta Borg = 0.09 (delta IC, %fall); n = 193, r = 0.86, p < 0.001. delta IC continued to contribute significantly (p < 0.001) to the variance in Borg ratings after accounting for delta FEV1, and it was the strongest predictor of symptom recovery (p < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Acute Disease↗