PubMed Health⌕ Search

Biomedical subjects

D V Bates

Publications and source records attributed to D V Bates.

At least 19 recordsLinked to original sources
PubMed1992

Discordance of airflow limitation and ventilatory inhomogeneity in asthma and cystic fibrosis.

Although it is known that both airflow rates and gas distribution are impaired in asthma and cystic fibrosis (CF), the concordance of the change in these defects between two points in time has not been studied. On two separate occasions, the FEV1, FVC and slope of Phase III (SBN2/L%) of the single breath nitrogen test were determined, as well as the concordance between the change in these indices in 14 healthy subjects, 14 subjects with asthma, and seven subjects with CF. The coefficient of variation within a test session averaged less than 5% for the FEV1 and less than 10% for the SBN2/L% within each group. The change in FEV1 correlated with the change in FVC in all three groups, but did not correlate with the change in SBN2/L% in any group. In seven of the 14 cases of asthma and six of the seven cases of CF (outliers), the differences in the indices (expressed as the change in percent predicted) were greater than the differences observed in the control group. In three of the asthmatic and four of the CF outliers, the changes were as predicted, that is, both tests returned toward normal, or both became more abnormal. In two of the asthmatic and CF outliers both the FEV1 and SBN2/L% increased, while both decreased in the other two asthmatic outliers. Although some of the same factors will affect both indices, a worsening of ventilation inhomogeneity, which will affect the SBN2/L%, could occur with an improvement in ventilatory flow rate. Alternatively, airflow limitation could worsen but be accompanied by an improvement in ventilation homogeneity.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1990

Asthma attack periodicity: a study of hospital emergency visits in Vancouver.

Attendances at the emergency departments of the nine acute care hospitals serving the Vancouver region, with a population of just under a million people, were recorded from July 1, 1984 to October 31, 1986. Of about 25,500 visits a month, 2.7% were for respiratory conditions; and of these, 41.3% were for asthma. Data from 11 air monitoring stations were also tabulated on a daily basis, giving mean maximal hourly values for SO2, NO2, and O3; daily aerosol sulfate measurements from one station were also analyzed, together with daily temperature data and measurements of the coefficient of haze. In 3 consecutive years, a peak in asthma attendances was noted, starting in the last week of September, and continuing for 3 weeks. In these periods, weekly visits for asthma reached 130 patients; during the rest of the year, the weekly visits for asthma varied between 30 and 90. This peak affected children and adults between the ages of 15 and 60, but no increase was seen in those over 60 years. Although pollution levels increased sharply in the fall, a day-by-day analysis showed that the rise in asthma attendances preceded the increase in NO chi and SO2 levels for the region, expressed as the mean of the hourly maxima across all stations. It seems unlikely that a specific pollen is responsible for this, or that house mite replication is the cause. Soya beans are not shipped out of Vancouver. The cause of the peak has not been identified. Variations in emergency visits by day of the week have been recorded; in children and in those aged 15-60, more visits occur on Sundays than on other days, but this does not occur in those over 60. There is no significant variation in environmental data by day of the week. Intercorrelations between environmental variables and emergency visits have been calculated separately for the periods May 1 to October 31, and November 1 to April 31. SO2, NO2, and SO4 are strongly intercorrelated in both periods; ozone is strongly related to temperature, but less strongly correlated to sulfate than is the case in Southern Ontario. In summer, total emergency visits (but not respiratory visits) are strongly correlated with temperature in all age groups (the hotter the day, the more visits occur); but respiratory visits are not related to temperature, ozone, or NO2 levels. However, in the 15-60 age group, asthma and respiratory visits are correlated in summer with SO2 and SO4 levels (P = less than 0.001).(ABSTRACT TRUNCATED AT 400 WORDS)

Adolescent↗
PubMed1989

Mechanism of action of ozone on the human lung.

Fourteen healthy normal volunteers were randomly exposed to air and 0.5 ppm of ozone (O3) in a controlled exposure chamber for a 2-h period during which 15 min of treadmill exercise sufficient to produce a ventilation of approximately 40 l/min was alternated with 15-min rest periods. Before testing an esophageal balloon was inserted, and lung volumes, flow rates, maximal inspiratory (at residual volume and functional residual capacity) and expiratory (at total lung capacity and functional residual capacity) mouth pressures, and pulmonary mechanics (static and dynamic compliance and airway resistance) were measured before and immediately after the exposure period. After the postexposure measurements had been completed, the subjects inhaled an aerosol of 20% lidocaine until response to citric acid aerosol inhalation was abolished. All of the measurements were immediately repeated. We found that the O3 exposure 1) induced a significant mean decrement of 17.8% in vital capacity (this change was the result of a marked fall in inspiratory capacity without significant increase in residual volume), 2) significantly increased mean airway resistance and specific airway resistance but did not change dynamic or static pulmonary compliance or viscous or elastic work, 3) significantly reduced maximal transpulmonary pressure (by 19%) but produced no changes in inspiratory or expiratory maximal mouth pressures, and 4) significantly increased respiratory rate (in 5 subjects by more than 6 breaths/min) and decreased tidal volume.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1989

The Ontario Air Pollution Study: identification of the causative agent.

Previously published data from the Ontario Air Pollution study are reviewed. It has been shown that there is a consistent association in summer between hospital admissions for respiratory disease in Southern Ontario, and daily levels of SO4, O3, and temperature. No association exists for a group nonrespiratory conditions. Multiple regression analyses are presented that show all environmental variables account for 5.6% of the variability in respiratory admissions and that if temperature is forced into the analysis first, it accounts for 0.89% of the variability only. Distribution plots of standardized residuals are presented. In June of 1983, there were an exceptional number of ozone episodes (defined as occasions when ozone was greater than 82 ppb for 3 or more hours in a calendar day) in this region. A separate analysis of hospital admissions for acute respiratory diseases for the month of June for several years shows no demonstrable excess in June of 1983; previously regional analyses have indicated that ozone is associated with increased levels in July and August over a 9-year period. It has also been found that daily SO4 data collected at one monitoring site in the center of the region are not correlated with respiratory admissions, whereas the SO4 values collected every sixth day, on different days of the week, at 17 stations in the region had the highest correlation with respiratory admissions.(ABSTRACT TRUNCATED AT 250 WORDS)

Acid Rain↗
PubMed1987

Air pollution and hospital admissions in Southern Ontario: the acid summer haze effect.

Air pollution data from 17 sampling stations between Windsor and Peterborough in Southern Ontario, for January, February, July, and August in 1974 and 1976 to 1983, have been analyzed. Each station reported O3, NO3, SO2, and the coefficient of haze (COH) every hour and aerosol sulfates for a 24-hr period every sixth day using glass-fiber filters. Data on mean daily temperature and relative humidity for the region were also recorded. It is shown that there are high correlations between different pollutants and between these and temperature in the summer. In the summer, sulfate levels were significantly correlated with relative humidity. In winter, the highest correlation was between COH and NO2. Over the 9-year period, SO2 levels in both winter and summer have fallen considerably; there have been no significant trends in O3, NO3, or COH data. Aerosol sulfates increased between 1976 and 1980 in both summer and winter and have since declined slightly. Hospital admission data for the 79 acute care hospitals serving the region, which contains about 5.9 million people, have been analyzed on a daily basis for the same months of the same years. Total admissions and total respiratory admissions have declined about 15% over the period, but asthma admissions appear to have risen. The asthma category of admissions is complicated by the effects of a change in ICD coding in 1979. It has been shown that significant correlations exist between O3, SO4, SO2, and temperature, on the one hand, and deviations from the mean respiratory admissions for that day of the week, for that season, for that year, on the other. These correlations exist if asthma is excluded from the diagnoses. In winter, asthma admissions are correlated with temperature only. A group of nonrespiratory conditions showed no correlations with air pollutants in winter or summer. Stepwise multiple regression analysis based on each year considered individually indicates that in summer SO4 and temperature account for about 5% of the variance in respiratory or asthma admissions. It is shown that the mean of the hourly ozone maxima has a high correlation with the maximal 8-hr average for ozone, and that using this index instead of the mean of the hourly maxima does not increase the correlation coefficient with respiratory disease. Another analysis has been performed by grouping the hospitals and sampling stations into nine separate regions.(ABSTRACT TRUNCATED AT 400 WORDS)

Air Pollutants, Occupational↗
PubMed1985

A longitudinal study of pulmonary function in coal miners in Lorraine, France.

A longitudinal study of pulmonary function and radiological change has been conducted on 141 nonsmoking coal miners and 256 smoking coal miners from Lorraine, France. At the time of the first examination occasioned by radiological change or shortness of breath, the men averaged between 46.6 years and 50.9 years of age, and they retired approximately 8 years after entering the study. They have been followed for average periods of about 18 years and a mean of five FEV1 observations per man were made over that period. Changes in radiological category have been documented. Average rates of decline of FVC and FEV1 were similar, and varied between -47 ml/yr in nonsmoking miners still alive, to -78 ml/yr in deceased smoking miners. These accelerated rates were similar before and after retirement from the mine.

Age Factors↗