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PubMed2002

Association between air pollution and lung function growth in southern California children: results from a second cohort.

A cohort of 1,678 Southern California children, enrolled as fourth graders in 1996, was followed for 4 years to determine whether the growth in lung function of the children was associated with their exposure to ambient air pollutants. These subjects comprised the second cohort of fourth grade children participating in the Children's Health Study. Significant deficits in lung function growth rate were associated with exposure to acid vapor, NO(2), particles with aerodynamic diameter less than 2.5 microm (PM(2.5)), and elemental carbon. For example, the average annual growth rates of maximal midexpiratory flow and forced expiratory volume in 1 second were reduced by approximately 11% (p = 0.005) and 5% (p = 0.03), respectively, across the observed range of acid exposure. Exposure to acid vapor was also associated with reductions in the ratio of maximal midexpiratory flow to forced vital capacity (p = 0.02), whereas exposure to ozone was correlated with reduced growth in peak flow rate (p = 0.006). Larger deficits in lung function growth rate were observed in children who reported spending more time outdoors. These findings provide important replication of our previous findings of an effect of air pollution on lung function growth that were based on the first fourth-grade cohort from the Children's Health Study (Am J Respir Crit Care Med 2000;162:1383-1390).

Air Pollutants↗
PubMed1975

Functional abnormalities in young asymptomatic smokers with special reference to flow volume curves breathing various gases.

Functional abnormalities have been described in healthy, asymptomatic young smokers. Fifteen subjects between 22 and 30 years of age, who smoked but were completely asymptomatic, were compared with 10 nonsmokers of the same age group using lung volumes, maximal expiratory flow rates, closing volumes, and maximal expiratory flow volume curves breathing air and a helium-oxygen mixture. Lower maximal mid-expiratory flow rates, higher closing volumes, and significant differences in flow volume curves with the helium-oxygen mixture were found in smokers. Special attention was given to the volume expressed as percentage of vital capacity at which the flows with air and the helium-oxygen mixture were equal for each subject ("equal-flow volume"). This volume was found to be significantly higher for smokers than nonsmokers. The authors offer explanations for these differences and suggest that smoking may alter compliance, as reflected by abnormal closing volumes, and resistance of the small airways as determined by differing responses in flow rates after helium-oxygen breathing at low volumes.

Adult↗
PubMed1979

Comparison of various methods for reading maximal expiratory flow-volume curves.

To determine the best procedure for reading maximal expiratory flow-volume curves 2 sets of 5 curves were obtained one hour apart in 89 subjects and processed digitally according to 8 different methods. Four indices were considered: the forced expiratory flows at 25, 50, and 75 per cent of the forced vital capacity, and the maximal mid-expiratory flow. When selecting the curve yielding the largest forced vital capacity or the largest sum of forced vital capacity and forced expiratory volume in 1 sec, flow values were significantly lower (P less than 0.001) and were often less reproducible than those obtained with most of the other methods. Computing the mean of the indices among the curves with the 2 largest forced vital capacities also provided comparatively low values, but with with better reproducibility. In contrast, maximal flows were probably overestimated by using the highest values among the curves having forced vital capacity or a surface area within 5 per cent of the largest, or when reading the indices on a composite curve obtained by superimposing individual breaths at residual volume. More reproducible and, probably, unbiased data may be drawn from the composite curves obtained by superimposing the breaths either at total lung capacity or on the descending limb.

Adult↗
PubMed1991

Ventilatory parameters in healthy nonsmoking adults of Adriatic islands (Yugoslavia).

Forced expiratory volumes and flows (forced vital capacity (FVC), forced expiratory volume in one second (FEV1) peak expiratory flow (PEF), maximal expiratory flow at 25% (MEF25%), 50% (MEF50%) and 75% (MEF75%) of the FVC) have been measured in 909 healthy nonsmoking men and women, ranging in age from 18-86 yrs, who live on Eastern Adriatic islands (Yugoslavia). This area is essentially free from air pollution. The results have been analysed in terms of age and height and regression equations for each sex were derived. The equations for FVC and FEV1 were reliable and those for forced expiratory flows were not. Comparisons were made with prediction equations derived for other populations, especially with those which are commonly used in daily medical practice.

Adolescent↗
PubMedDate not supplied

Influence of matching volume on reproducibility of maximal expiratory flow-volume curves.

We examined the influence of "matching volume" on intrasubject variability of the descending limb of maximal expiratory flow-volume (MEFV) curves on air and helium-oxygen (He) in 18 healthy subjects and 28 patients with airflow limitation. Duplicate forced expirations were analysed according to four methods of alignment. With the first method, flows corresponding to identical percentiles of separate FVC (SEPVC) were compared. With the remaining three, we aligned curves at TLC, mid-vital capacity (VC50) and RV, respectively, for comparison of: a) flow at identical percentiles of the averaged FVC and b) expired volume at identical percentiles of the averaged peak flow. In healthy subjects, variability of flow at 50% and 75% of expired FVC (FEF50 and FEF75) did not change significantly with method, except that FEF75 on air varied more with method SEPVC than with VC50. In airflow limitation, FEF75 was significantly less reproducible when curves were matched at RV than at TLC, both on air and He. Over the latter part of expiration, an arbitrary index of variability of flow-defined volume also indicated that method RV gave the poorest precision in patients. We conclude that selection of matching volume does not influence the variability of MEFV-curves in health. In airflow limitation, however, TLC appears to be the most reliable volume for alignment.

Adolescent↗
PubMed1996

A five year follow-up of lung function among chemical workers using flow-volume and impedance measurements.

Impedance of the respiratory system, measured using the forced oscillation technique (FOT), has repeatedly been proposed as a tool for occupational health screening. The aim of this study was to compare the outcome of impedance measurements and flow-volume curves, and to study relationships between lung function decline and specific exposures and smoking. Both measurements were applied in 136 chemical workers from seven main production/personnel groups during a 5 year follow-up (1990-1995). The prevalence of airway obstruction (forced expiratory volume in one second (FEV1) < 80% of predicted) at both time-points was about 5% but did not necessarily include the same subjects. The average decline in FEV1 over 5 yrs was 200 mL (predicted decline 160 mL). Although most impedance parameters correlated to flow-volume parameters in both years, a rapid 5 year decline of FEV1 (> 330 mL) was only accompanied by a significant decrease in the reactance at 8 Hz (X8) and an increase in the resonance frequency (f0). Interestingly, decline in FEV1 was significantly dependent on age, years of employment, pack-years, FEV1, and all impedance parameters at the start in 1990 (r = 0.35; p = 0.01). Similarly, the increase in f0 was significantly dependent on age, years of employment, pack-years, f0, FEV1, forced vital capacity (FVC), peak expiratory flow (PEF) and maximal mid-expiratory flow (MMEF) at the start (r = 0.56; p < 0.01). Those with a rapid decline in FEV1, were relatively more represented among acid workers (relative risk (RR) = 2.14), maintenance workers (RR = 2.1) and bulk/transport workers (RR = 1.78), but none of these was significant. Lung function, however, was significantly lower in the bulk/transport workers (n = 14) compared to the rest, based both on flow-volume (FEV1, FVC) and impedance (X8, f0) measurements. Smoking had a significant effect on most flow-volume parameters but only for frequency dependence among the impedance outcomes. It is concluded that alterations in impedance parameters do reflect changes in flow-volume curves induced by age. smoking and occupational exposure. Therefore, these data are a valuable extension to current cross-sectional data.

Acids↗
PubMed1989

Effects of thoracic gas compression on maximal and partial flow-volume maneuvers.

Airway hysteresis can be evaluated by comparing maximal (MEFV) and partial (PEFV) expiratory flow-volume curves. The maneuvers are often obtained from pulmonary function systems that are subject to gas-compression artifacts. Because gas-compression artifacts might differentially affect PEFV vs. MEFV curves, we simultaneously obtained MEFV and PEFV curves by use of a spirometer and a volume-displacement plethysmograph (a method not subject to gas-compression artifacts) in normal and asthmatic subjects. Plethysmographic flow rates exceeded spirometric flow rates on all MEFV and PEFV maneuvers. When maximal flow exceeded partial flow (or vice versa) in the plethysmograph, the same result was virtually always observed for spirometric measurements. Alveolar pressure (PA) was higher on MEFV than on PEFV maneuvers in asthmatic subjects; comparisons between PA (on PEFV and MEFV maneuvers) in normal subjects varied at different lung volumes. Ratios of Vmax on PEFV maneuvers to Vmax on MEFV maneuvers (Vmax-p/Vmax-c) obtained from a volume-displacement plethysmograph differ quantitatively from ratios determined in systems subject to gas-compression artifacts; qualitatively, however, failure to account for thoracic gas compression ordinarily will not influence the ability to identify airway hysteresis (or lack thereof) by use of Vmax-p-to-Vmax-c ratios.

Adult↗
PubMed1992

Detrimental effect of hypotonic cromolyn sodium.

In a randomized, double-blind, placebo-controlled, crossover study, inhalation of the commercially available nebulized form of cromolyn sodium resulted in a significant decrease in forced midexpiratory flow rate between the 25th and 75th percentile points, equivalent to that observed for distilled water, in children with chronic asthma. We conclude that inhalation of the current hypotonic concentration of cromolyn sodium may be detrimental.

Administration, Inhalation↗
PubMed1983

Changes in the normal maximal expiratory flow-volume curve with growth and aging.

On the basis of their answers to a self-administered questionnaire, 697 nonsmoking healthy subjects were chosen from a randomly selected sample representative of the white non-Mexican-American population of Tucson, Arizona, enrolled in a longitudinal study of respiratory health. For each subject, the first satisfactory set of flow-volume data obtained during the first 3 consecutive surveys was selected for analysis. For forced vital capacity (FVC) and forced expiratory volume in one second (FEV1), the single best value for each subject was selected. Other flow-volume measurements were derived from the single test with the best sum FEV, plus FVC. These data were used to derive improved prediction equations for each sex by age group for 5 spirometric and flow-volume variables. The resulting predicted values demonstrate the effects of development, maturation, and senescence on ventilatory function. "Normal" limits are proposed that take into consideration the between-subject variability and non-Gaussian distribution of the various measurements.

Adolescent↗
PubMed1984

Association of respiratory viral infections with pulmonary deterioration in patients with cystic fibrosis.

In a two-year prospective study, we examined the effect of respiratory viral infections on pulmonary function in 49 patients with cystic fibrosis (mean age, 13.7 years). Nineteen normal siblings (mean age, 14) served as controls. Subjects were assessed quarterly and at the time of any respiratory illness. Each assessment included nasal washes for viral isolation and blood drawing for respiratory viral serologic studies. Pulmonary-function tests were performed at least twice yearly. Respiratory illnesses were reported significantly more often in the patients (3.7 per year) than in the normal siblings (1.7 per year), although the frequency of proved viral infections (1.67 per year) was identical. In the patients with cystic fibrosis significant correlations (P less than 0.0001) were found between the annual incidence of viral infections and every measure of disease progression in the two-year period, including the rate of decline of the Shwachman score (r = 0.71), the percentage of ideal weight for height (r = 0.80), the forced vital capacity (r = 0.85), the forced expiratory volume in the first second (r = 0.84), the forced midexpiratory flow rate (r = 0.68), and the frequency (r = 0.53) and duration (r = 0.84) of hospitalizations for respiratory exacerbations. We conclude that frequency of viral respiratory infections is closely associated with pulmonary deterioration in patients with cystic fibrosis.

Adolescent↗
PubMed1975

Comparison of maximal mid-expiratory flow, flow volume curves, and nitrogen closing volumes in patients with mild airway obstruction.

Maximal mid-expiratory flow (MMEF), maximal expiratory flow volume (MEFV) curves obtained with a wedge spirometer, and nitrogen closing volumes were determined in 38 patients with mild airway obstruction. Seventeen patients had asthma in remission and 21 had bronchitis. In all of them the forced expiratory volume in one second was within the normal range. Results were compared with predicted data in the literature and with a group of normal control subjects. In the patients with asthma, compared to predicted flow rates, MMEF was abnormal in 5, MEFV curves were abnormal in at least 8; closing volume was abnormally increased in only one patient, and an abnormal slope of the alveolar plateau was present in 4 additional patients. In the patients with bronchitis, compared to predicted flow rates, -MEF was reduced in 5, MEFV curves were abnormal in at least 7; increased closing volumes were present in 6, and the slope of the alveolar plateau was abnormal in 3 other patients. When flow rates were compared with those of normal control subjects, MMEF was about as frequently abnormal as MEFV curves, suggesting that the discrepancy between abnormal MMEF AND MEFV curves was due to variability of the predicted data. The results indicated that flow rates can be abnormal in subjects with normal closing volumes and a normal slope of the alveolar plateau, and that MEFV curves can be more sensitive than closing volume in detecting abnormalities in patients with mild airway obstruction. The results suggested that the use of both MEFV curves and the closing volume test for screening would defect functional abnormalities more frequently than either test alone.

Adult↗
PubMed1976

The maximal expiratory flow-volume curve. Normal standards, variability, and effects of age.

From a randomly selected population representative of the white population of Tucson, Ariz., satisfactory flow-volume data were obtained for 3,115 persons. Data from the 746 subjects who were totally free of symptoms or history of cardiorespiratory disease and who had never smoked were used in determining "normal" prediction equations for spirometric parameters and maximal expiratory flows. The maximal expiratory flow-volume curve showed considerable intersubject variability, but little change in shape of the mean maximal expiratory flow-volume curve was seen with advancing age when the effects of disease, insult, or injury were excluded.

Adolescent↗
PubMed1977

Comparison of albuterol and isoproterenol aerosols in bronchial asthma.

Albuterol and isoproterenol aerosols were compared with placebo in a double-blind manner in 18 patients with bronchial asthma. Both drugs elicited significant improvement in flow rates and vital capacity. Duration of action was longer with albuterol than with isoproterenol. Neither was associated with significant increases in heart rate or blood pressure.

Adolescent↗
PubMed1979

Correlation between the function and structure of the lung in smokers.

To study the relationship between morphologic changes and alteration of lung function, the excised lobes of 21 smokers and one nonsmoker who required lobectomy for small peripheral tumors were inflated and fixed in formalin, and measurements of bronchiolar narrowing and degree of emphysema were made. All patients had comprehensive pulmonary function tests (including diffusing characteristics, the single-breath N2 test, measurements of elastic recoil, and flow-volume measurements with air and helium) performed before lobectomy. Eight of the lobes excised from the smokers had emphysema of grade 15 or more, the greatest being grade 50. Lobes from 11 patients had evidence of airway narrowing. There were 6 lobes with both emphysema and airway narrowing. Pulmonary function was abnormal in some aspect in all lobes except that from the nonsmoker. Whereas the tests of diffusing capacity, particularly the fractional uptake of CO, correlated with the degree of emphysema, the tests of elastic recoil were not predictive of this early degree of emphysema. The degree of small-airway narrowing correlated with maximal mid-expiratory flow rate and the single-breath N2 test. The maximal flow/static recoil pressure curves were the most sensitive indicators of airway abnormality in the patients with emphysema.

Aged↗
PubMed1986

Asbestos and airflow limitation.

To assess the effect of asbestos on the airways, researchers studied 45 shipyard workers who were lifelong nonsmokers and had asbestos-related abnormalities seen on their chest roentgenograms. Patients with interstitial lung disease, bronchial asthma prior to asbestos exposure, recurrent pneumonias, or significant cardiovascular disease were excluded from the study. In addition to chest films, they had spirometry performed before and after bronchodilator inhalation, lung volumes, diffusing capacity, and arterial blood gases. Forced vital capacity and forced expired volume in one second were normal in all patients. Maximum midexpiratory flow rates (MMFR) were abnormal (MMFR less than 75% of predicted) in 13 patients (29%). Therefore, 29% of lifetime nonsmokers with asbestos exposure exhibited evidence of small airways dysfunction. An abnormal MMFR in these workers may be due, in part, to asbestos exposure and could conceivably indicate a population at risk for pulmonary fibrosis and/or obstructive airways disease.

Asbestos↗
PubMed1996

Airway responses in healthy and asthmatic subjects following exposure to low ambient air temperature.

Ventilatory capacity following exposure to low ambient air temperature (-5 degrees C) was measured in 46 male and 37 female medical students. In healthy subjects there was an increase in all test parameters during a four-hour exposure as compared to preexposure values. However, six students with bronchial asthma showed a decrease in ventilatory capacity tests following exposure to low temperature. The changes in healthy subjects as well as in asthmatics were most pronounced for the maximal flow rates at 50% and the last 25% of the vital capacity (FEF50, FEF25). The mean increase in FEF25 for healthy subjects was recorded up to a +15.1% and +6.4% increase in nonsmokers and smokers, respectively. In asthmatics, the largest decrease of FEF25 was -21.5%. Authors' data indicated that environmental exposure to low ambient air temperature caused an increase of ventilatory function tests in healthy subjects and a decrease in asthmatics, particularly in flow rates at lower lung volumes.

Adult↗