Lung mechanical properties distinguish children with asthma with normal and diminished lung function

BACKGROUND

Children with asthma, even those with severe persistent disease, can have forced expiratory volume in 1 second (FEV₁ ) values ≥100% of predicted, while others have diminished FEV₁ .

OBJECTIVE

We sought to characterize the lung mechanical properties underlying these two asthma phenotypes and the mechanisms explaining the paradox of severe asthmatic children, whom when clinically stable can have an FEV₁ >100% of predicted, but during an acute bronchospastic episode can experience a life-threatening asthma event.

METHODS

Lung mechanics were evaluated in three groups of children: asthmatics with FEV₁ ≥100% (HFEV₁ ; n = 13), asthmatics with FEV₁ ≤80% (LFEV₁ ; n = 14) and non-asthmatic controls (n = 10). A linear mixed model was used to examine the relationship between volume and static transpulmonary pressures obtained at total lung capacity (TLC); actual TLC %of predicted and flow; and static transpulmonary pressure and flow.

RESULTS

HFEV₁ asthmatics had larger airways (FEV₁ z-scores 1.12 vs -2.37; P < .05), greater lung volumes (mean % of predicted TLC 134.8% vs 109.6%; P < .05) and lower airway resistance (mean %of predicted Raw 101.9% vs 199.9%; P < .05) compared to the LFEV₁ group. Moreover, HFEV₁ asthmatics had significantly reduced elastic recoil pressure (pressure-volume curve shifted upward and to the left) and higher lung compliance (0.21 vs 00.9 L/cm H₂ O; P < .05) compared to the LFEV₁ group. The pressure-flow curves revealed the LFEV₁ group to have significantly increased resistance to flow in the upstream segment of the airways at all lung volumes studied compared to HFEV₁ .

CONCLUSION AND CLINICAL RELEVANCE

HFEV₁ asthmatic children display distinct lung mechanical proprieties compared to their LFEV₁ asthmatic peers. With loss of elastic recoil pressure, the HFEV₁ group could generate normal FEV₁ due to proportionally enlarged airways and reduced airway resistance, while airflow limitation in the LFEV₁ is due to increased airway resistance. Loss of elastic recoil and interdependence during acute bronchoconstriction episodes may predispose the HFEV₁ group to catastrophic reductions in airflow.

Smoking affects response to inhaled corticosteroids or leukotriene receptor antagonists in asthma

RATIONALE

One-quarter to one-third of individuals with asthma smoke, which may affect response to therapy and contribute to poor asthma control.

OBJECTIVES

To determine if the response to an inhaled corticosteroid or a leukotriene receptor antagonist is attenuated in individuals with asthma who smoke.

METHODS

In a multicenter, placebo-controlled, double-blind, double-dummy, crossover trial, 44 nonsmokers and 39 light smokers with mild asthma were assigned randomly to treatment twice daily with inhaled beclomethasone and once daily with oral montelukast.

MEASUREMENTS AND MAIN RESULTS

Primary outcome was change in prebronchodilator FEV(1) in smokers versus nonsmokers. Secondary outcomes included peak flow, PC(20) methacholine, symptoms, quality of life, and markers of airway inflammation. Despite similar FEV(1), bronchodilator response, and sensitivity to methacholine at baseline, subjects with asthma who smoked had significantly more symptoms, worse quality of life, and lower daily peak flow than nonsmokers. Adherence to therapy did not differ significantly between smokers and nonsmokers, or between treatment arms. Beclomethasone significantly reduced sputum eosinophils and eosinophil cationic protein (ECP) in both smokers and nonsmokers, but increased FEV(1) (170 ml, p = 0.0003) only in nonsmokers. Montelukast significantly increased a.m. peak flow in smokers (12.6 L/min, p = 0.002), but not in nonsmokers.

CONCLUSIONS

In subjects with mild asthma who smoke, the response to inhaled corticosteroids is attenuated, suggesting that adjustments to standard therapy may be required to attain asthma control. The greater improvement seen in some outcomes in smokers treated with montelukast suggests that leukotrienes may be important in this setting. Larger prospective studies are required to determine whether leukotriene modifiers can be recommended for managing asthma in patients who smoke.

Job and industry classifications associated with sarcoidosis in A Case-Control Etiologic Study of Sarcoidosis (ACCESS)

OBJECTIVES

To determine whether specific occupations and industries may be associated with sarcoidosis.

METHODS

A Case Control Etiologic Study of Sarcoidosis (ACCESS) obtained occupational and environmental histories on 706 newly diagnosed sarcoidosis cases and matched controls. We used Standard Industrial Classification (SIC) and Standard Occupational Classification (SOC) to assess occupational contributions to sarcoidosis risk.

RESULTS

Univariable analysis identified elevated risk of sarcoidosis for workers with industrial organic dust exposures, especially in Caucasian workers. Workers for suppliers of building materials, hardware, and gardening materials were at an increased risk of sarcoidosis as were educators. Work providing childcare was negatively associated with sarcoidosis risk. Jobs with metal dust or metal fume exposures were negatively associated with sarcoidosis risk, especially in Caucasian workers.

CONCLUSIONS

In this study, we found that exposures in particular occupational settings may contribute to sarcoidosis risk.

Use of regularly scheduled albuterol treatment in asthma: genotype-stratified, randomised, placebo-controlled cross-over trial

BACKGROUND

The issue of whether regular use of an inhaled beta2-adrenergic agonist worsens airflow and clinical outcomes in asthma is controversial. Retrospective studies have suggested that adverse effects occur in patients with a genetic polymorphism that results in homozygosity for arginine (Arg/Arg), rather than glycine (Gly/Gly), at aminoacid residue 16 of the beta2-adrenergic receptor. However, the existence of any genotype-dependent difference has not been tested in a prospective clinical trial.

METHODS

Patients with mild asthma, not using a controller medication, were enrolled in pairs matched for forced expiratory volume in 1 s (FEV1) according to whether they had the Arg/Arg (n=37; four of 41 matches withdrew before randomisation) or Gly/Gly (n=41) genotype. Regularly scheduled treatment with albuterol or placebo was given in a masked, cross-over design, for 16-week periods. During the study, as-needed albuterol use was discontinued and ipratropium bromide was used as needed. Morning peak expiratory flow rate (PEFR) was the primary outcome variable. The primary comparisons were between treatment period for each genotype; the secondary outcome was a treatment by genotype effect. Analyses were by intention to treat.

FINDINGS

During the run-in period, when albuterol use was kept to a minimum, patients with the Arg/Arg genotype had an increase in morning PEFR of 23 L/min (p=0.0162); the change in patients with the Gly/Gly genotype was not significant (2 L/min; p=0.8399). During randomised treatment, patients with the Gly/Gly genotype had an increase in morning PEFR during treatment with regularly scheduled albuterol compared with placebo (14 L/min [95% CI 3 to 25]; p=0.0175). By contrast, patients with the Arg/Arg genotype had lower morning PEFR during treatment with albuterol than during the placebo period, when albuterol use was limited (-10 L/min [-19 to -2]; p=0.0209). The genotype-attributable treatment difference was therefore -24 L/min (-37 to -12; p=0.0003). There were similar genotype-specific effects in FEV1, symptoms, and use of supplementary reliever medication.

INTERPRETATION

Genotype at the 16th aminoacid residue of the beta2-adrenergic receptor affects the long-term response to albuterol use. Bronchodilator treatments avoiding albuterol may be appropriate for patients with the Arg/Arg genotype.

A case control etiologic study of sarcoidosis: environmental and occupational risk factors

Past research suggests that environmental factors may be associated with sarcoidosis risk. We conducted a case control study to test a priori hypotheses that environmental and occupational exposures are associated with sarcoidosis. Ten centers recruited 706 newly diagnosed patients with sarcoidosis and an equal number of age-, race-, and sex-matched control subjects. Interviewers administered questionnaires containing questions regarding occupational and nonoccupational exposures that we assessed in univariable and multivariable analyses. We observed positive associations between sarcoidosis and specific occupations (e.g., agricultural employment, odds ratio [OR] 1.46, confidence interval [CI] 1.13-1.89), exposures (e.g., insecticides at work, OR 1.52, CI 1.14-2.04, and work environments with mold/mildew exposures [environments with possible exposures to microbial bioaerosols], OR 1.61, CI 1.13-2.31). A history of ever smoking cigarettes was less frequent among cases than control subjects (OR 0.62, CI 0.50-0.77). In multivariable modeling, we observed elevated ORs for work in areas with musty odors (OR 1.62, CI 1.24-2.11) and with occupational exposure to insecticides (OR 1.61, CI 1.13-2.28), and a decreased OR related to ever smoking cigarettes (OR 0.65, CI 0.51-0.82). The study did not identify a single, predominant cause of sarcoidosis. We identified several exposures associated with sarcoidosis risk, including insecticides, agricultural employment, and microbial bioaerosols.

Familial aggregation of sarcoidosis. A case-control etiologic study of sarcoidosis (ACCESS)

Despite reports of familial clustering of sarcoidosis, little empirical evidence exists that disease risk in family members of sarcoidosis cases is greater than that in the general population. To address this question, we estimated sarcoidosis familial relative risk using data on disease occurrence in 10,862 first- and 17,047 second-degree relatives of 706 age, sex, race, and geographically matched cases and controls who participated in the multicenter ACCESS (A Case-Control Etiology Study of Sarcoidosis) study from 1996 to 1999. Familial relative risk estimates were calculated using a logistic regression technique that accounted for the dependence between relatives. Sibs had the highest relative risk (odds ratio [OR] = 5.8; 95% confidence interval [CI] = 2.1-15.9), followed by avuncular relationships (OR = 5.7; 95% CI = 1.6-20.7), grandparents (OR = 5.2; 95% CI = 1.5-18.0), and then parents (OR = 3.8; 95% CI = 1.2-11.3). In a multivariate model fit to the parents and sibs data, the familial relative risk adjusted for age, sex, relative class, and shared environment was 4.7 (95% CI = 2.3-9.7). White cases had a markedly higher familial relative risk compared with African-American cases (18.0 versus 2.8; p = 0.098). In summary, a significant elevated risk of sarcoidosis was observed among first- and second-degree relatives of sarcoidosis cases compared with relatives of matched control subjects.

Long-term effects of budesonide or nedocromil in children with asthma

BACKGROUND

Antiinflammatory therapies, such as inhaled corticosteroids or nedocromil, are recommended for children with asthma, although there is limited information on their long-term use.

METHODS

We randomly assigned 1041 children from 5 through 12 years of age with mild-to-moderate asthma to receive 200 microg of budesonide (311 children), 8 mg of nedocromil (312 children), or placebo (418 children) twice daily. We treated the participants for four to six years. All children used albuterol for asthma symptoms.

RESULTS

There was no significant difference between either treatment and placebo in the primary outcome, the degree of change in the forced expiratory volume in one second (FEV1, expressed as a percentage of the predicted value) after the administration of a bronchodilator. As compared with the children assigned to placebo, the children assigned to receive budesonide had a significantly smaller decline in the ratio of FEV1 to forced vital capacity (FVC, expressed as a percentage) before the administration of a bronchodilator (decline in FEV1:FVC, 0.2 percent vs. 1.8 percent). The children given budesonide also had lower airway responsiveness to methacholine, fewer hospitalizations (2.5 vs. 4.4 per 100 person-years), fewer urgent visits to a caregiver (12 vs. 22 per 100 person-years), greater reduction in the need for albuterol for symptoms, fewer courses of prednisone, and a smaller percentage of days on which additional asthma medications were needed. As compared with placebo, nedocromil significantly reduced urgent care visits (16 vs. 22 per 100 person-years) and courses of prednisone. The mean increase in height in the budesonide group was 1.1 cm less than in the placebo group (22.7 vs. 23.8 cm, P=0.005); this difference was evident mostly within the first year. The height increase was similar in the nedocromil and placebo groups.

CONCLUSIONS

In children with mild-to-moderate asthma, neither budesonide nor nedocromil is better than placebo in terms of lung function, but inhaled budesonide improves airway responsiveness and provides better control of asthma than placebo or nedocromil. The side effects of budesonide are limited to a small, transient reduction in growth velocity.

Elastic properties of the excised lungs of NZB/W mice and their correlation with histopathologic changes

Lung volume and the pressure-volume (PV) relationships of the lung were determined in excised lungs of an animal model of human systemic lupus erythematosus, which develops in NZB/W mice, and correlated with histopathologic changes. In young, 4-month-old NZB/W mice, and in nonautoimmune BALB/c mice at any age, there were minimal histologic changes or alterations in lung function. The NZB/W mice developed histologic changes with aging. Perivascular, peribronchial, and interstitial changes developed and were associated with a significant reduction in total lung capacity as well as changes in the pressure-volume characteristics of the lung, which are compatible with a restrictive process.

Long-term betaxolol therapy in glaucoma patients with pulmonary disease

We evaluated the use of topically administered betaxolol 0.5% in 101 glaucoma patients (47 men and 54 women) who had chronic obstructive pulmonary disease, asthma, or timolol-induced bronchoconstriction. Betaxolol 0.5% was administered twice daily and patients were reexamined at three-month intervals for up to two years. In addition to measurement of intraocular pressure, pulmonary function tests were obtained before therapy (baseline), two or three weeks after initiating betaxolol therapy, and at yearly intervals. Before treatment with betaxolol, the mean ratio of forced expiratory volumes in one second (FEV1) to forced vital capacity (FVC) was 66.3% (n = 101). After two weeks of betaxolol treatment, mean FEV1/FVC ratio was 66.2% (n = 101). After one year of betaxolol therapy, mean FEV1/FVC ratio was 60.1% (n = 24), and after two years it was 54.4% (n = 5). Nine patients developed symptoms that may have been associated with betaxolol treatment and were withdrawn from the study. Five of these patients developed symptomatic pulmonary obstruction between one and 554 days after initiating betaxolol treatment. Topically administered betaxolol was well tolerated by most glaucoma patients with concomitant pulmonary disease.

Elastic recoil of the lung in cigarette smokers: the effect of nebulized bronchodilator and cessation of smoking

The mechanical properties of the lung, forced vital capacity, flow-volume relationships, lung volume, and single-breath N2 curve were determined in 16 nonsmokers and 19 smokers. Pulmonary elastic recoil, Pst (1), was significantly lower at all lung volumes, as were flow parameters, whereas lung volumes were higher in smokers of both sexes. The variables derived from forced vital capacity and single-breath N2 were significantly different from nonsmokers in male smokers but not in female smokers. The inhalation of nebulized bronchodilator was attended by a significant decrease in Pst (1) and in upstream flow resistance in smokers. After cessation of smoking Pst (1) decreased to values similar to those seen after bronchodilator administration, whereas resumption of smoking led to reversal of the pressure-volume curve. The data suggest that the elastic properties of the lungs are altered in cigarette smokers, but the extent of the disturbance is masked by constriction of the alveolar ducts or peripheral airways while smoking, and that these are unmasked by the administration of nebulized bronchodilator or by cessation of smoking.