Peak Expiratory Flow In Adults Research Articles

Effect of ambient ozone and its interactions with ambient PM2.5 and temperature on peak expiratory flow in adults with asthma

Numerous studies have linked air pollution to asthma. However, limited information exists on the effect of ambient ozone (O3), or its interactions with fine particulate matter (PM2.5) or temperature on peak expiratory flow (PEF) of in asthmatic adults. We conducted a longitudinal study including 99 adult asthma patients and documenting 7153 person-days PEF records. Utilizing linear mixed-effect and distributed non-linear models, we investigated the associations between ambient O3 exposures over lag0-14 days with morning and evening PEF, as well as diurnal PEF variability. Findings revealed significant associations between ambient O3 exposure with reduced morning and evening PEF, with varied associations for exposures across different lag days. Specifically, the most pronounced association with morning PEF was found for exposure at lag4, with a change of −0.211 (95%CI: −0.360, −0.062) L/min per 10 μg/m3 increase; for evening PEF, the strongest association was observed for exposure at lag0, with a change of −0.379 (95%CI: −0.721, −0.037) L/min per 10 μg/m3 increase. However, no significant association between O3 and diurnal PEF variability was found. Furthermore, we observed significant interactions between O3 and PM2.5 exposures from lag6 to lag9 on morning and evening PEF, and significant interactions between O3 and temperature from lag1 to lag11 on morning PEF and from lag0 to lag11 on evening PEF. Stronger associations between O3 and PEF were observed in males, those aged over 40 years, overweight individuals, smokers and those with non-allergic asthma. These results underscore considering combined pollution and climate impacts in asthma management and supporting policies.

The effect of acute outdoor air pollution on peak expiratory flow in individuals with asthma: A systematic review and meta-analysis

ObjectivesAcute exposures to outdoor air pollution have been shown to reduce lung function in children with asthma, but the effect on adults with asthma has not been established in a meta-analysis. The objective of this study was to conduct a systematic literature review and meta-analysis of studies that assessed the relationship of outdoor air pollution and peak expiratory flow (PEF) in adults with asthma. MethodsStudies that contained data on outdoor air pollution levels (PM10, PM2.5, or NO2) and PEF in adults with asthma were eligible for inclusion. Effect estimates were quantified for each air pollution measure using random effects models. Heterogeneity was investigated with the Q-test and I2 statistics. Meta-regression and subgroup analyses were conducted to determine differences in effect by air pollution measures and the inclusion of smokers. ResultsA total of 22 effect estimates from 15 studies were included in this review. A 10 μg/m3 increase in acute PM10 exposure was associated with a −0.19 L/min (95% CI: 0.30, −0.09) change in PEF. For both PM10 and PM2.5, the inclusion of current smokers was a significant source of heterogeneity among studies (meta-regression: p = 0.04 and p = 0.03). Among studies that only included non-smokers, a 10 μg/m3 increase in acute exposure to PM10 and PM2.5 was associated with changes in PEF of −0.25 L/min (95% CI: 0.38, −0.13) and −1.02 L/min (95% CI: 1.79, −0.24), respectively. ConclusionsThis study provides evidence that acute increases in PM10 and PM2.5 levels are associated with decreases in PEF in adults with asthma, particularly among non-smokers.

Peak expiratory flow in the standing and sitting positions is equivalent in adults: a cross-over study.

It is uncertain whether peak flow measurement is best done in the standing or sitting position. In this cross-over study, study participants were randomized to perform the initial peak expiratory flow (PEF) measurement in either standing or sitting position. The highest of three readings in each position were compared using paired t-test. A mean difference of <±25 l/min was set as the equivalence limits. Test of equivalence of standing and sitting PEF measurements was done using MedCalc Software. Test of agreement of standing and sitting PEF was assessed by Lin's concordance correlation coefficient and Bland-Altman limits of agreement. Of the 100 study participants, 50% of them had asthma. There was a statistically significant difference between the standing and sitting PEF in adults suffering from asthma [mean difference 11 l/min, 95% confidence interval (CI) = 4 to 19], but not in the healthy individuals (mean difference 3 l/min, 95% CI = -6 to 12). The observed differences in PEF were small and may not be clinically important. In adults with and without asthma, the standing and sitting PEF were highly correlated and satisfied the test of equivalence. The PEF in the standing and sitting positions was equivalent in adults. Therefore, performing PEF in either position is acceptable. However, health care practitioners should be aware of the small reduction in PEF when it is done in the sitting position. It is desirable that the position used is documented and the same position is used wherever possible.

Measuring peak expiratory flow in adults with asthma.

Measuring peak expiratory flow in adults with asthma.

β2-Adrenergic receptor Gly16Arg polymorphism and impaired asthma control in corticosteroid-treated asthmatic adults

β2-Agonists are the most commonly prescribed asthma medication, and the β2-adrenergic receptor gene has been studied extensively. A single-nucleotide polymorphism causing the substitution of arginine (Arg) for glycine (Gly) at position 16 (Gly16Arg) of the β2-adrenergic receptor affects the response to β2-agonists. Regular exposure to β2-agonists results in down-regulation and uncoupling of β2-adrenoreceptors with associated subsensitivity or tachyphylaxis of response.1 Retrospective studies have reported an impaired therapeutic response in terms of peak expiratory flow in adults treated with long-acting β2-agonists (LABAs).

The Po River Delta (north Italy) indoor epidemiological study: effects of pollutant exposure on acute respiratory symptoms and respiratory function in adults.

The authors studied the effects of relatively low doses of nitrogen dioxide and respirable suspended particulate matter (i.e., < 2.5 mu) on acute respiratory symptoms and on peak expiratory flow in 383 adults (15-72 yr of age) who lived in the Po River Delta area, located near Venice. During 2 wk-1 wk in winter and 1 wk in summer--the authors monitored each participant's house to measure nitrogen dioxide (in parts per billion) and respirable suspended particulate (microgram/m3) concentration. Information on sex, age, height, weight, daily activity patterns, active and passive smoking, chronic respiratory diseases, daily peak expiratory flow, and presence of acute respiratory symptoms during the weeks monitoring occurred were also collected. Peak expiratory flow variation was studied as mean amplitude percentage (i.e., amplitude/mean) and percentage of diurnal variation (maximum/minimum). The exposure indices to nitrogen dioxide (nitrogen dioxide--index of exposure) and to respirable suspended particulate matter (respirable suspended particulate matter-index of exposure) were computed as the product of pollutant concentration and time of exposure. The authors considered indices as "low" or "high" on the basis of the median value. The median nitrogen dioxide was 20 ppb in winter and 14 ppb in summer; the highest nitrogen dioxide levels occurred in the kitchen in the winter (33 ppb) and summer (20 ppb). The median respirable suspended particulate matter was 68 micrograms/m3 in winter and 45 micrograms/m3 in summer. Only in winter were there significant associations between bronchitic/asthmatic symptoms and "high" nitrogen dioxide and respirable suspended particulate matter indices. In subjects who did not smoke, a significant influence of the "high" respirable suspended particulate matter-index of exposure was also observed in summer. With respect to peak expiratory flow and its variability, respirable suspended particulate matter-index of exposure was associated with an increase of both amplitude/mean and maximum/mean; however, with respect to the nitrogen dioxide--index of exposure, the association was significant only in subjects with chronic respiratory diseases (i.e., asthma and bronchitis). These relationships were significant only in winter. In conclusion, the results of the current study indicate that there is an association between relatively low doses of pollutants and acute respiratory symptoms and peak expiratory flow in adults.

How the Discrepancy between Symptoms and Peak Expiratory Flow Rate Influences Evaluation of Asthma Severity

Recent asthma guidelines recommend the assessment of severity levels based on the most severe symptoms and peak expiratory flow rate (PEFR). Discrepancies are frequently encountered in the use of these variables in determining the severity levels of asthmatics. The objective of this study was to determine the difference in asthma severity levels as assessed by either symptoms alone or by PEFR alone, as compared with the assessment by the asthma guidelines. Severity levels that were determined by recent asthma guidelines for 60 asthmatic patients were reassessed, based on symptoms alone and PEFR alone. They were compared for any significant differences to the asthma guidelines. Asthmatics were aged between 15 and 70 (mean 34) years, and 63.8% were females. Severity levels by symptoms alone were different from the guidelines in 27 cases (45%). Of these, 89% showed a tendency toward higher severity levels. Severity levels by PEFR alone were different in only three cases (5%). In both comparisons, differences of severity levels were significant (P<0.0001), but assessment by symptoms alone showed more deviation (x(2) =162.1) than PEFR alone (x(2) =73.1). The study documented significant discrepancies in asthma severity assessed by symptoms alone and PEFR alone, when compared to the recent asthma guidelines. Severity assessed by symptoms alone showed lower levels, and the use of PEFR tended to categorize some asthmatics into a more severe level.

New regression equations for predicting peak expiratory flow in adults.

An earlier study of peak expiratory flow (PEF) in normal adults contained too few men aged over 55 and women aged over 65 for the regression equations to be used for prediction in older people. A subsequent study was therefore carried out on an additional 23 men and 29 women aged 55 or over who were lifelong non-smokers and satisfied the same strict criteria of normality that had been used in the original study. The data from both studies were combined and a new model used to calculate equations for the regression of PEF on age and height in the two sexes. With this model predicted values could be derived for men and women aged between 15 and 85. These new equations gave predicted values in men and women aged less than 55 and 65, respectively, which were almost identical with those reported previously. The new regression equations for PEF enable values to be predicted for people aged 15-85 and so enhance the accuracy of testing in the elderly.