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Biomedical subjects

J A Dosman

Publications and source records attributed to J A Dosman.

At least 91 records · Page 5Linked to original sources
PubMed1986

Pulmonary function in Pi M and MZ grainworkers.

Twenty-eight men with the Pi MZ phenotype who have been employed in the Saskatchewan country grain elevators and thus regularly exposed to high levels of grain dust, were case matched for age, years of employment, employment status, smoking status, and smoking history with grainworkers of type Pi M. Individuals answered a questionnaire, had a chest roentgenogram, skin tests, and performed a battery of pulmonary function tests. There were no differences between the two groups in prevalence of symptoms or atopy. Although not statistically significant, the MZ group had three times as many individuals with abnormal roentgenograms suggestive of COPD as the M group. The Pi MZ grainworkers had consistently poorer mean results for the pulmonary function tests with significantly lower mean values for FEV1, FEV1/FVC, MMFR, and Vmax50, leading us to suggest that Pi MZ individuals may be at higher risk of COPD than Pi M individuals, but only in the presence of other risk factors such as grain dust exposure.

Adult↗
PubMed1984

Relationship between bronchial response to respiratory heat exchange and nonspecific airways reactivity in asthmatic patients.

In this study we have examined the relationship between the bronchial response to inhaled histamine and the bronchial response to breathing cold air at rest in nine control subjects and nine patients with asthma. Dried warm air (mean temp: +/- 1SD: 25.4 +/- 1.6 degrees C) and cold air (-19.7 +/- 2.6 degrees C) were breathed for 10 minutes each during quiet breathing at rest prior to as well as during both measurements of forced expired spirograms and the phase 3 slope of the single-breath oxygen test (delta N2/L). Subjects were also challenged with inhaled aerosolized histamine to determine the concentration required to reduce the forced expired volume in one second (FEV1) by 20 percent (PC20). Both asthmatic and control subjects had significantly greater respiratory heat exchange breathing cold as compared to warm air (p less than 0.01 in both cases). Control subjects did not change FEV1 or delta N2/L breathing cold air. Asthmatic patients increased delta N2/L from a mean warm air value of 2.41 +/- 1.31% N2/L to a mean cold air value of 5.39 +/- 4.55% N2/L (p less than 0.05). There was a significant linear correlation between the percent increase in delta N2/L from warm to cold air and 1/log10PC20 (r = -0.97, p less than 0.001) and also the percent decrease in FEV1 and log PC20 (r = -0.76, p less than 0.03) in the asthmatic patients. We conclude that cold air-induced alterations in ventilation/distribution and expired flow rates in asthmatic patients are related to pre-existing nonspecific airways reactivity.

Adolescent↗
PubMed1984

Pi type MZ and an increased risk of pneumonia.

Among 114 men of Pi type or MZ, 42% (17/40) of those of Pi type MZ reported having been told by a physician that they had had pneumonia at least once whereas only 18% (13/74) of those of Pi type M did so (p less than 0.05). This significant difference could not be accounted for by differences in age, smoking status, occupation or baseline lung function (FEV1). Examination of medical records of those reporting pneumonia for the preceding 20 years provided confirmation of the diagnosis of pneumonia and support for the association; 12% (5/40) of the MZ group but only 3% (2/74) of the M group had confirmed episodes of pneumonia during the preceding 20 years. Since alpha 1-antitrypsin has been implicated as a factor in inflammatory response, reduced levels may permit the development of more frequent and/or more serious episodes of pneumonia.

Adolescent↗
PubMed1984

Nighttime ventilation improves respiratory failure in secondary kyphoscoliosis.

Four patients with cardiorespiratory failure caused by secondary kyphoscoliosis were studied. Polycythemia, cor pulmonale, restrictive lung pattern (functional residual capacity (FRC), 17 to 27% predicted; vital capacity (VC), 11 to 23% predicted), and abnormal arterial blood gases, primarily hypoventilation (PaO2, 31 to 44 mm Hg; PaCO2, 52 to 73 mm Hg), were seen in all. Supplementary oxygen, digoxin, diuretics, 15 min of intermittent positive-pressure breathing with inspired pressure (PI) 25 cm H2O 4 times daily, and tracheostomy failed to produce improvement. However, 12 h of nighttime ventilation (NTV) with PI 28 to 35 cm H2O through a permanent tracheostomy proved effective. Within 72 h, dyspnea at rest, restless sleep, and frequent waking resolved. Within 8 to 22 days, the PaO2 was approximately 58 mmHg and the PaCO2 was approximately 41 mm Hg while breathing 21% oxygen spontaneously during the day. The right heart failure resolved within 2 to 7 wk, and the hemoglobin count decreased to approximately 165 g/L within 2 to 6 months. There was a mean increase of 700 ml (72%) in functional residual capacity and 430 ml (49%) in vital capacity. The patients were discharged 2 days to 5 wk after NTV commenced. Daytime activity increased, approaching a normal life style. The improvement was sustained over a mean follow-up period of 3.4 yr. Problems included recurrent episodes of tracheobronchitis, mild self-limiting hemoptysis, and speech modification. Nighttime ventilation may be an effective alternative for long-term treatment of cardiorespiratory failure caused by secondary kyphoscoliosis.

Adult↗
PubMed1984

Pulmonary function and respiratory symptoms in potash workers.

Over 94% of the workers in each of four Saskatchewan potash mines participated in a respiratory health surveillance program that included a questionnaire and pulmonary function tests. Compared with a nonexposed control group, potash workers had higher prevalences of cough, dyspnea, and chronic bronchitis but better pulmonary function. Prevalences of symptoms and pulmonary function abnormalities were similar among workers at the four mines tested and at the various job locations. Potash dust, diesel fumes, and other air contaminants may have an irritant effect that leads to the increased prevalences of cough and chronic bronchitis. Although we found no adverse effects of the potash mine environment on pulmonary function, these findings reflect a healthy worker effect or some selection process that makes the potash workers appear healthier in a cross-sectional study.

Adult↗
PubMed1983

Characteristics of airway tone during exercise in patients with asthma.

In 10 nonasthmatic subjects and 11 patients with asthma, we measured pulmonary resistance (RL), functional residual capacity (FRC), and specific conductance (sGaw) before, during, and after submaximal treadmill exercise. Nonasthmatic subjects did not change RL, FRC, or sGaw from base-line resting values during or after exercise. In patients with asthma, RL decreased significantly during exercise, both when exercise was begun from the control resting state and from conditions of elevated RL after a preceding period of exercise. When asthmatic patients inhaled a standardized dose of aerosolized histamine, the increase in RL during exercise was significantly less than the increase in RL when they breathed histamine at rest. When patients hyperventilated at rest with tidal volumes, breathing frequencies, and end-tidal CO2 tensions similar to those during exercise conditions, bronchodilatation also occurred, and the increase in RL following inhaled histamine during isocapnic hyperventilation was also less than at rest. Since bronchodilatation and inhibition of histamine-induced bronchoconstriction occur during both exercise and isocapnic hyperventilation, we suggest that the mechanism of bronchodilatation during exercise may not necessarily be related to metabolic factors associated with exercise.

Adolescent↗
PubMed1983

Effects of grain dust exposure and smoking on respiratory symptoms and lung function.

In four groups of individually-matched subjects (nonsmoking grain workers, smoking grain workers, nonsmoking community controls, and smoking community controls) we measured pulmonary function variables from the spirogram, from the maximal expiratory flow-volume curve breathing air and helium, and from the single breath nitrogen test as well as symptom prevalences from a questionnaire in order to assess the relative effects of smoking and occupational exposure to grain dust in Saskatchewan country grain elevators. There were similar increased prevalences of respiratory symptoms and reductions in pulmonary function associated with either grain dust exposure or smoking, but the effects of smoking were slightly more pronounced. The combined effects of grain dust and smoking on lung function appeared to be additive except in the least exposed workers (five years or less) where a synergistic effect was observed in tests of peripheral airways dysfunction.

Adolescent↗
PubMed1982

Effects of smoking and occupational exposure on peripheral airway function in young cereal grain workers.

We studied two groups of young male cereal grain elevator workers: 82 lifetime nonsmoking grain workers (2.5 +/- 1.2 yr of dust exposure) who were 22.7 +/- 3.5 yr of age, and 82 smoking grain workers (6.1 +/- 4.1 pack-years of smoking) individually matched to the nonsmoking grain workers for age (22.7 +/- 3.3 yr) and years of work in the grain industry (2.6 +/- 1.3 yr). We also studied the following groups of community control subjects: 82 nonsmoking community control subjects individually matched to the nonsmoking grain workers for age (22.8 +/- 3.7 yr), and 82 smoking community control subjects individually matched to the smoking grain workers for age (22.7 +/0 3.6 yr) and smoking history (6.0 +/- 4.0 pack-years). We measured forced expiratory volume in one second (FEV1), forced vital capacity (FVC), FEV1/FVC %, the maximal mid-expiratory flow rate (FEF25-75), the flow at 50% (Vmax50) and 25% (Vmax25) of a maximal expiratory flow-volume maneuver, the percent increase in the maximal expiratory flow at 50% FVC breathing a mixture of 80% helium-20% oxygen as compared with air (delta Vmax50), and the slope of Phase III of the single breath nitrogen test (delta N2/L). We also assessed the prevalence of respiratory symptoms from responses to a standardized questionnaire. Smoking was associated with an increased prevalence of cough, wheezing, and dyspnea, and a mildly decreased FEV1/FVC %. Two variables were used as indexes of small airway dysfunction, a lower delta Vmax50 and a higher delta N2/L. Only the group of workers who both smoked and were occupationally exposed to grain dust had evidence of small airway dysfunction. The differences in delta N2/L and delta Vmax50 were greater than was expected from an additive model, suggesting that the combined effects of occupational exposure to grain dust and inhalation of cigarette smoke may have a synergistic effect leading to small airway dysfunction in young cereal grain workers.

Adult↗
PubMed1981

Effect of inspiratory flow rate on the esophageal pressure gradient in upright humans.

We measured pressures in 2 lung regions in 5 seated subjects with 2 esophageal balloons placed 7.2 +/- 0.6 cm (mean +/- SE) apart in the mid-thorax in order to obtain the esophageal pressure gradient (EPG). Pressure differences between the lower thoracic balloon and a balloon placed in the stomach were obtained to measure transdiaphragmatic pressure (pdi). Inspiratory maneuvers were made from functional residual capacity (FRC) at either low inspiratory flow rates (slow VI) (mean slow VI: 0.22 +/- 0.05 L/sec) or at rapid flow rates (fast VI) (2.15 +/- 0.15 L/s). At FRC the mean EPG was 0.19 +/- 0.04 cm H2O/cm. The mean EPG was consistently lower at 500 cc above FRC during fast VI (0.14 +/- 0.03 cm H2O/cm) than during slow VI (0.28 +/- 0.05 cm H2O/cm) (P less than 0.001, paired 't' test). Fast VI results in amplification of pressure in the lower as compared to the upper region wih reduction in EPG. Diaphragmatic contraction appears to influence alterations in EPG during fast VI.

Adult↗
PubMed1981

Between-technician variation in the measurement of spirometry with air and helium.

A study using a two-period cross-over design was conducted to determine the between-technician variation in the measurement of variables derived from spirograms with subjects breathing room air and also breathing a mixture of 80% helium and 20% oxygen (He-O2). Twenty-four subjects were allocated systematically into three 2-period cross-over studies (blocks) of 8 subjects each (4 in each sequence in each block). There were 3 technicians in the study, and the subjects in each block were tested by a pair of technicians. The following variables derived from the tracings were analyzed statistically: forced expiratory volume in one second (FEV1), forced vital capacity (FVC) while breathing room air and also while breathing He-O2, maximal mid-expiratory flow rate (MMRF), FEV1/FVC %, and the per cent decrease in time between 60% VC and 40% VC for the spirograms comparing He-O2 with air (delta t). Analyses were performed to assess the presence of residual effects in the cross-over design, the between-technician difference in the administration of the tests, and in the interpretation of tracings. The results indicated that: (1) significant differences were observed between technicians in the administration of the tests to obtain FVC while the subjects breathed room air and while they breathed He-O2, (2) there were significant differences between the 3 technicians in the interpretation of MMFR, and (3) the between-technician variation in the administration of the tests with respect to delta t and with He-O2 in general were not significantly different from that of the other spirometric variables studied.

Adult↗
PubMed1981

Sensitivity and specificity of early diagnostic tests of lung function in smokers.

What are the relative sensitivities and specificities of the "early" tests of lung dysfunction? We describe the findings from a study of virtually the entire population of a rural pollution-free community. Using abnormal spirometry as a marker of obstructive disease, we evaluated the two tests obtained from the single-breath nitrogen curve, closing volume (CV/VC) and the slope of the alveolar plateau (delta N2/L), as well as combinations of the two tests. While CV/VC is highly specific (92.3 percent in male and 94.0 percent in female subjects), it lacks sensitivity (36.8 percent in male and 13.3 percent in female subjects) and is abnormal in only 10.0 and 6.5 percent of male and female smokers, respectively, a percentage not dissimilar from the percentage with abnormal spirometry. However, delta N2/L, abnormal in 24.1 percent of male smokers and 28.8 percent of female smokers, rates reasonably well with regard to both sensitivity (63.2 percent in male and 66.7 percent in female subjects) and specificity (79.3 percent in male and 74.0 percent in female subjects). The group of smokers with abnormal delta N2/L did include fair numbers with abnormal spirometry (20.7 percent in male and 16.1 percent in female subjects). A combination of the two tests (abnormal in either delta N2/L and/or CV/VC) has good sensitivity (68.4 and 80.0 percent for male and female subjects, respectively) and specificity (74.3 and 69.0 percent for male and female subjects, respectively).

Adult↗
PubMed1980

Chronic bronchitis and decreased forced expiratory flow rates in lifetime nonsmoking grain workers.

To determine whether clinical symptoms and pulmonary function abnormalities were more common in lifetime nonsmoking grain elevator workers exposed to grain dust than in lifetime nonsmoking community control subjects who were not occupationally exposed to dust, we obtained an occupational health questionnaire, spirometric variables, and flow-volume curves on 90 lifetime nonsmoking grain workers and 90 lifetime nonsmoking community control subjects. For these groups we calculated the prevalence of chronic bronchitis, defined as daily production of phlegm for 3 months/yr for at least 2 yr. The prevalence of chronic bronchitis was higher in nonsmoking workers (23.1%) than in nonsmoking control subjects (3.3%) (p less than 0.01). Nonsmoking grain workers had lower mean values than did nonsmoking control subjects for maximal mid-expiratory flow rate (p less than 0.01) and for maximal expiratory flow at 50% of vital capacity (p less than 0.01). We conclude that exposure to grain dust inlifetime nonsmoking grain workers is associated with an increased prevalence of chronic bronchitis and evidence of airflow obstruction.

Adult↗
PubMed1980

Increased nonspecific bronchial reactivity in cigarette smokers with normal lung function.

Seventeen lifetime nonsmoking male teachers and 17 smoking male teachers with normal lung function were compared. The smokers showed a significantly greater prevalence of cough (p < 0.01), sputum production (p < 0.05), and wheezing (p < 0.01), but not dyspnea. There was no difference in the prevalence of a history of allergy, or the number of positive reactions to allergy prick skin tests, or in elevated serum IgE. Lung volumes, expiratory flow rates, specific airway conductance (SGaw), and the slope of phase III of the single breath O2 test were not significantly different. The geometric mean provocation concentration of histamine required to reduce the SGaw by 35% (PC35) was significantly lower in the smokers (1.84 mg/ml) than in the nonsmokers (4.83 mg/ml) (p < 0.005). Increased nonspecific bronchial reactivity may be a factor contributing to the development of airway obstruction in smokers.

Bronchi↗