Relationship between response to inhaled salbutamol and methacholine bronchial provocation in children with suspected asthma

Relationship between bronchial hyperresponsiveness and lung function in children age 5 and 6 with and without asthma

BACKGROUND AND OBJECTIVE

It is unknown whether wheezy children have bronchial hyperresponsiveness (BHR) or which lung function parameters are correlated with BHR in children. We evaluated the relationship between BHR parameters and the lung functions by minimizing the effects of age and height in asthmatic, non-asthmatic wheezers and healthy children.

METHODS

The subjects comprised of 154 children aged 5 and 6 years (78 males, 76 females), who were divided into three groups: asthmatics, non-asthmatic wheezers and healthy controls. Spirometry and a methacholine inhalation challenge by the oscillation method were performed.

RESULTS

The age of the study cohort was 5.9 ± 0.2 years (mean ± standard deviation), and the height was 114.4 ± 5.3 cm. No significant differences in height, weight, body mass index or lung function were observed in the three groups. The minimal dose of methacholine to start bronchoconstriction, a parameter of bronchial sensitivity, was lower in asthmatics and non-asthmatic wheezers than that in controls. The speed of bronchoconstriction in response to methacholine, a parameter of bronchial reactivity, was strongly correlated with baseline respiratory resistance (Rrs cont) in all three groups.

CONCLUSIONS

Our data suggest that it not possible to distinguish preschool children with asthma from non-asthmatic wheezers based on their bronchial sensitivity and that the baseline Rrs has a strong effect on the bronchial reactivity in children.

Evaluation of airway responsiveness using colored three-dimensional analyses of a new forced oscillation technique in controlled asthmatic and nonasthmatic children

BACKGROUND

Bronchodilator response (BDR) is routinely used in asthma management. A new forced oscillation technique (FOT) is able to quickly measure respiratory system resistance (Rrs) and reactance (Xrs) at each tidal breath phase. The present study evaluated bronchial changes by using the new FOT.

METHODS

Respiratory resistance and reactance were measured using FOT in 132 children (age, 10.86±4.78 years; M:F=88:44), including asthmatic (n=98) and nonasthmatic children (n=34), pre- and post-bronchodilator inhalation in an asymptomatic state. Whole-breath or within-breath changes in Rrs and Xrs were measured and compared pre- and post-bronchodilator inhalation and between each group. All patients performed spirometry and forced expiratory nitric oxide pre- and post-bronchodilator inhalation.

RESULTS

Spirometric parameters showed significant positive changes at V50 and V25 in both groups; however, these changes were not significantly different between the groups. eNO was significantly higher in the asthmatic group than in the nonasthmatic group; however, there was no significant change pre- and post-inhalation in either group. Rrs in the asthma group was significantly higher in the expiratory phase than in the inspiratory phase. Rrs and Xrs before and after bronchodilator inhalation were significantly different in the asthma group alone, except for the expiratory-inspiratory phase of each of these parameters. Changes in Rrs and Xrs at 5Hz (R5 and X5) in a whole-breath and the inspiratory phase were significantly different between the groups.

CONCLUSIONS

Changes in X5 and R5 reflect bronchial reversibility. The new FOT is useful for asthmatic children.

Asthma outcomes: pulmonary physiology

BACKGROUND

Outcomes of pulmonary physiology have a central place in asthma clinical research.

OBJECTIVE

At the request of National Institutes of Health (NIH) institutes and other federal agencies, an expert group was convened to provide recommendations on the use of pulmonary function measures as asthma outcomes that should be assessed in a standardized fashion in future asthma clinical trials and studies to allow for cross-study comparisons.

METHODS

Our subcommittee conducted a comprehensive search of PubMed to identify studies that focused on the validation of various airway response tests used in asthma clinical research. The subcommittee classified the instruments as core (to be required in future studies), supplemental (to be used according to study aims and in a standardized fashion), or emerging (requiring validation and standardization). This work was discussed at an NIH-organized workshop in March 2010 and finalized in September 2011.

RESULTS

A list of pulmonary physiology outcomes that applies to both adults and children older than 6 years was created. These outcomes were then categorized into core, supplemental, and emerging. Spirometric outcomes (FEV(1), forced vital capacity, and FEV(1)/forced vital capacity ratio) are proposed as core outcomes for study population characterization, for observational studies, and for prospective clinical trials. Bronchodilator reversibility and prebronchodilator and postbronchodilator FEV(1) also are core outcomes for study population characterization and observational studies.

CONCLUSIONS

The subcommittee considers pulmonary physiology outcomes of central importance in asthma and proposes spirometric outcomes as core outcomes for all future NIH-initiated asthma clinical research.

The reciprocal influences of asthma and obesity on lung function testing, AHR, and airway inflammation in prepubertal children

Although asthma and obesity are among the major chronic disorders their reciprocal or independent influences on lung function testing, airways hyperresponsiveness (AHR) and bronchial inflammation has not been completely elucidated. In 118 pre-pubertal Caucasian children anthropometric measurements functional respiratory parameters (flow/volume curves at baseline and after 6-minute walk test [6MWT]) together with bronchial inflammatory index (FeNO) were assessed. The study population was divided into four groups according to BMI and the presence or absence of asthma: Obese asthmatic (ObA) Normal-weight asthmatic (NwA), Obese non-asthmatic (Ob), non-asthmatic normal-weight children (Nw). Baseline PEF and MEF(75) (%-expected) were significantly different across the four groups with significantly lower values of MEF(75) in ObA and Ob children when compared to Nw children (P = 0.004 and P = .0001, respectively) and this independent role of obesity on upper respiratory flows was confirmed by multiple analysis of covariance. After 6 MWT respiratory parameters decreased only in ObA and NwA children and 12 children presented a positive fall in FEV(1), in contrast no changes of respiratory function testing were detected in Ob and Nw children, and only 2 Ob children presented a significant fall in FEV(1). FeNO analysis demonstrated significantly higher values in ObA and NwA children when compared to Ob (P = 0.008 and P = 0.0002, respectively) and Nw children (P = 0.0001 and P = 0.0003, respectively), although a significant difference was found between Ob and Nw children (P = 0.0004). Multiple analysis of covariance confirmed an independent role of asthma on this parameter. In conclusion while AHR and airway inflammation are clearly associated with an asthmatic status, obesity seems to induce reduction of upper airways flows associated with a certain degree of pro-inflammatory changes.

The response to bronchodilators in adults is not predictive of bronchial-hyperreactivity

BACKGROUND

In some subjects with suspected asthma who have normal spirometry, administration of bronchodilators (BD) improves expiratory flow rates. The predictive value of this phenomenon in adults is not known.

OBJECTIVES

To evaluate the predictive value of the response to BD for bronchial hyper-responsiveness (BHR) using the metacholine challenge test (MCT). Patients and methods. The study population included 62 non-smoking adult patients (41.9% women) 29.5 +/- 15.5 years of age (range 18-64 years) with suspected asthma with normal spirometry that underwent MCT within 1 week. The response to BD (200 mu g inhaled salbutamol) was compared between subjects with positive and negative MCT using cutoff levels of provocative concentrations of metacholine causing a 20% decrease in forced expiratory volume in 1 second (FEV(1)) (PC(20)) of 4 and 8 mg/mL.

RESULTS

Mean (+/- SD) baseline FEV(1) was 87.8 +/- 12% of predicted. After BD administration the mean FEV(1) increased by 4.3 +/- 3.9%. The prevalence of BHR was 17.7% and 25.8% for PC(20) for PC(20) of 4 mg/mL and 8 mg/mL, respectively. The post-BD FEV(1) increment for subjects with positive and negative MCT tests was 3.9% +/- 3.3% versus 4.4% +/- 4.1%, respectively; p = 0.89, using cutoff of 4 mg/mL. The corresponding figures for cutoff of 8 mg/ml were 4.3% +/- 3.1% vs. 4.3% +/- 4.2%, respectively; p = 0.8465. There was no correlation between post-BD FEV(1) increment and PC(20) values in patients with positive MCT test for the above-mentioned cutoff levels (correlation coefficient r = 0.1645, p = 0.6289; and r = 0.2417, p = 0.4051, respectively).

CONCLUSIONS

In adults with suspected asthma who have normal spirometry, the response to BD cannot be used to predict BHR.

Can bronchodilator response predict bronchial response to methacholine in preschool coughers?

The aim of the present study was to determine the relationship between bronchodilator response, assessed by interrupter resistance (Rint), and bronchial reactivity in preschool children with chronic cough. Thirty-eight children coughers (median age 5.0 years, range 2.8-6.4) were tested. Bronchodilator response was recorded within 4 months before methacholine challenge. Response to the latter was assessed using transcutaneous partial pressure of oxygen and Rint. Children were considered responders if a 20% fall in transcutaneous partial pressure of oxygen occurred during the bronchial challenge. Bronchodilator response was not different between responders (n = 24) and nonresponders (n = 14) [median (range) -0.11 (-0.44-0.09) vs. -0.08 (-0.21-0.10) kPa L(-1) sec; respectively]. However, none of the nonresponders had a bronchodilator response larger than -0.21 kPa L(-1) sec, this cutoff had a 100% positive and a 44% negative predictive value to predict a positive methacholine challenge. The relationship between bronchodilator response and bronchial methacholine responsiveness reached the limit of significance (P = 0.048). Furthermore, the magnitude of the bronchodilator response was correlated to the level of methacholine-induced level of bronchoconstriction (P = 0.01), and to the postchallenge bronchodilation (P = 0.04), all values expressed as % predicted. Moreover, the postbronchodilator Rint value obtained with preceding methacholine challenge was lower than the postbronchodilator value without preceding methacholine challenge in 71.4% (10/14) of the nonresponders and in only 33.3% (8/24) of the responders. Conclusions in preschool coughers bronchodilator response, assessed by the interrupter technique, was correlated to the bronchial responsiveness to methacholine. Non responders had a bronchodilator response not larger than -0.21 kPa L(-1) sec.

Spirometry in an unselected group of 6-year-old children: the DARC birth cohort study

This study presents reference equations for spirometric parameters in 6-year-old children and evaluates the ability of spirometry to discriminate healthy children from children with asthma. Baseline spirometry and respiratory symptoms were assessed in 404 children participating in a longitudinal birth cohort study. Children with known asthma, possible asthma and a control group also performed bronchodilator measurements. At least two acceptable flow-volume curves at baseline were obtained by 368/404 children (91%). The two best values for FEV1 and FVC were within 5% of each other in 88% and 83% of children, respectively. Linear regression analyses for 242 children included in the reference population demonstrated height to be the main predictor of all spirometric indices except FEV1/FVC. FEV1, FEV75, and FVC correlated reasonably to anthropometric data in contrast to flow parameters. Gender differences were found for FEV1, FVC, and FEV75, but not for flow parameters. Asthma was diagnosed in 25/404 children. Baseline lung function in healthy children and children with asthma overlapped, although asthmatic children could be discriminated to some extent. Bronchodilator tests showed a difference in Delta FEV1(mean) between healthy children and children with asthma (3.1% vs. 6.1%, P < 0.05). At a cut-off point of Delta FEV1 = 7.8%, bronchodilator tests had a sensitivity of 46% and a specificity of 92% for current asthma. Spirometry including bronchodilator measurements was demonstrated to be feasible in 6-year-old children and reference values were determined. Spirometry aids the diagnosis of asthma in young children, but knowledge on sensitivity and specificity of these measurements is a prerequisite.

Value of the bronchodilator response in assessing controller naïve asthmatic children

OBJECTIVE

To define the bronchodilator response (BDR) cutoff point that best identified asthma to determine the frequency of abnormal spirometry results across severity.

STUDY DESIGN

Controller naïve children were evaluated with clinical criteria alone to establish a diagnosis of asthma and severity classification, then compared with the BDR, which was calculated as the percent change from the initial forced expiratory volume in 1 second. Receiver operator characteristic analysis determined the cutoff point for asthma diagnosis that gave the best combination of sensitivity and specificity.

RESULTS

Children with asthma (n = 346) and 51 children without asthma, aged 4 to 17 years, who met entry criteria for spirometry were identified. The mean BDR in asthmatics was 8.6% (95% CI, 7.5-9.8), compared with 2.2% (95% CI, 0.2-4.3) for non-asthmatics (P < .001). A BDR > or = 9% best differentiated these populations with a sensitivity rate of 42.5% and a specificity rate of 86.3%. Abnormal spirometry results, defined as a BDR > or = 9%, a forced expiratory volume in 1 second < 80% predicted, or both, ranged from 44.4% for mild intermittent bronchial asthma to 57.0% for severe persistent bronchial asthma.

CONCLUSION

Spirometric criteria that include BDR can potentially identify children who have clinically mild asthma and might benefit from controller therapy.

Fine particles and meteorological conditions are associated with lung function in children with asthma living near two power plants

Fine particles are thought to pose a risk to health, especially for vulnerable groups such as children with asthma. These children are also known to be affected by meteorological and seasonal changes. We assessed the association between air pollution and lung function via peak expiratory flow (PEF), controlling for seasonal changes, meteorological conditions and personal physiological, clinical and sociodemographic measurements, in a panel of schoolchildren with asthma living near two power plants in Israel. Two hundred and eighty-five children with confirmed asthma performed PEF tests and completed a respiratory symptoms diary twice a day. Particulate matter <10 microm in diameter (PM10), particulate matter <2.5 microm in diameter (PM2.5) and meteorological conditions were measured at six fixed stations. Data were analysed using time series analysis-generalized linear model and generalized estimating equations. The models were built under the assumption that any health outcome belongs to a multivariate hierarchical system and depends on meteorological, geophysical and sociocultural variables and pollution factors. No significant differences were found in the demographic (age, gender, mean parental education level, parental smoking habits, place of birth and housing density), physiological (body mass index) and clinical factors (illness severity) between the communities participating in the study. A significant direct effect of PM2.5 on the PEF was found in Ashdod (P=0.000). In Sderot, this effect was through an interaction between PM10 and the sequential day of the year (P=0.000). The main conclusion of this study is that children with asthma are at risk from air pollution and geophysical conditions. Policy makers should take these results into consideration when setting thresholds for environmental protection.

The relationship between asthma and obesity in children: is it real or a case of over diagnosis?

OBJECTIVE

To determine whether obesity among children is associated with an increased incidence of asthma.

DESIGN AND METHOD

Five thousand nine hundred eighty-four children participated in a lung health study in the Ashkelon region, Israel. A lung health questionnaire was completed and they underwent spirometry. Body mass index (BMI) was then calculated for each child.

RESULTS

Three hundred two children (5.05%) were above the 95th percentile for BMI and considered obese. Obese children tended to wheeze more than the non-obese children 14.5% vs. 10.5%, respectively (p<0.038). Asthma (physician diagnosis) was diagnosed more often among obese children than non-obese 7.2% vs. 3.9%, respectively (p<0.008). Inhaler use was more prevalent among obese children than non-obese 15.9% vs. 8.8%, respectively (p<0.001). Bronchial hyperreactivity was significantly greater among the non-obese asthmatic children compared with their obese counterparts, 352 (51.4%) vs. 10 (27.8%), respectively (p<0.001). Chest symptoms and asthma were more frequent in obese than non-obese boys.

CONCLUSION

Asthma, wheezing, and inhaler use were more common in obese children than in non-obese children. Symptoms were more prevalent among obese boys. Increasing BMI among children is a risk factor for asthma, which may in reality be obesity-related chest symptoms that mimic asthma.

Exhaled nitric oxide corresponds with office evaluation of asthma control

Exhaled NO (ENO) has been studied as a noninvasive marker of airway inflammation, and has been shown to be elevated in asthma patients. The aim of this study was to investigate whether ENO measurements differ significantly between groups of asthmatic children with different disease control and to compare ENO measurements with the clinical assessment of asthma control. Seventy-three children between 5-18 years old with a diagnosis of asthma were recruited. ENO was measured online during a slow vital capacity maneuver. The mean of three plateau NO levels was used for analysis. Baseline and postbronchodilator spirometry were performed. The assessment of disease control was based on the frequency of use of beta2-agonists, occurrence of day- and nighttime asthma symptoms, and spirometry results. Twenty-one children (group 1) had good asthma control. In 31 patients (group 2), asthma control was acceptable. In 21 patients (group 3), asthma was insufficiently controlled. ENO levels were (median (quartiles)): group 1, 11 ppb (9-21); group 2, 15 ppb (11-26); and group 3, 28 ppb (19-33). Measurements were significantly different between all three groups (P = 0.009, Kruskal-Wallis), between groups 1 and 3 (P = 0.01, Mann-Whitney U test), and between groups 2 and 3 (P = 0.01, Mann-Whitney-U test). The same was true for reversibility testing. We found significantly different ENO levels between a group of pediatric asthma patients with insufficient and good/sufficient control, as defined by clinical assessment. These results suggest that ENO measurements may be useful for monitoring asthma patients.

Outcome in adulthood of asymptomatic airway hyperresponsiveness in childhood: a longitudinal population study

The clinical outcome of asymptomatic airway hyperresponsiveness (AHR) first detected in childhood is sparsely reported, with conflicting results. We used a birth cohort of 1,037 children followed to age 26 years to assess the clinical outcome of asymptomatic AHR to methacholine first documented in study members at age 9 years. Of 547 study members who denied wheezing symptoms ever at age 9 years, 41 (7.5%) showed AHR. Forty showed methacholine responsiveness, with a provocation concentration of methacholine that elicited a 20% drop in forced expired volume in 1 sec (PC(20)) < or = 8 mg/mL, and one had baseline airway obstruction with a bronchodilator response exceeding 10%. Of these 41 study members, 18 (44%), 11 (27%), and 4 (10%) maintained AHR in 1, 2, and 3 later assessments, respectively, while 23 (56%) manifested AHR only at age 9. Compared with asymptomatic study members without AHR, those with asymptomatic AHR at age 9 years were more likely to report asthma and wheeze at any subsequent assessment, were more likely to have high IgE levels and eosinophils at ages 11 and 21, and more often demonstrated positive responses to skin allergen testing at ages 13 and 21 years. Persistent AHR at later assessments increased these likelihoods further.In conclusion, asymptomatic children with AHR are more likely to develop asthma and atopy later in life compared with asymptomatic children without AHR. Persistent AHR, even though initially asymptomatic, was associated with an even greater increased risk of development of asthma. We suggest that rather than considering AHR as a marker of asthma, it should be regarded as a parallel pathological process that may lead to subsequent symptoms and clinical evidence of asthma.

Risk factors for airway remodeling in asthma manifested by a low postbronchodilator FEV1/vital capacity ratio: a longitudinal population study from childhood to adulthood

Airway remodeling may lead to irreversible loss of lung function in asthma. The impact of childhood asthma, airway responsiveness, atopy, and smoking on airway remodeling was investigated in a birth cohort studied longitudinally to age 26. A low postbronchodilator ratio of forced exhaled volume in 1 second (FEV1) to vital capacity (VC) at age 18 or 26 was used as a marker of airway remodeling. "Normal" study members with no history of asthma ever, no wheezing in the last year, and no smoking ever were used to determine sex- and age-specific reference values for this ratio. The lower limit of normal was defined as the mean ratio minus 1.96 standard deviation, delimiting the 2.5% of the normal population with the lowest FEV1/VC ratio. A low postbronchodilator FEV1/VC ratio was found in 7.4% and 6.4% of study members at ages 18 and age 26 and 4.6% at both assessments. Lung function was low throughout childhood in those with a consistently low postbronchodilator FEV1/VC ratio at both ages. Those with consistently low postbronchodilator ratios also showed a greater decline in the prebronchodilator FEV1/VC ratio from ages 9 to 26 compared with those with normal postbronchodilator ratios at both ages (males, -12% versus -6%, p < 0.0001; females, -10.5% versus -5.5%, p < 0.01). Asthma, male sex, airway hyperresponsiveness, and low lung function in childhood were each independently associated with a low postbronchodilator FEV1/VC ratio, which in turn was associated with an accelerated decline in lung function and decreased reversibility. These data suggest that airway remodeling in asthma, as manifested by impaired lung function, begins in childhood and continues into adult life.

Discriminative capacity of bronchodilator response measured with three different lung function techniques in asthmatic and healthy children aged 2 to 5 years

The primary aim of this study was to quantify and compare bronchodilator responsiveness in healthy and asthmatic children aged 2 to 5 yr. The secondary aim of the study was to compare discriminative capacity (i.e., sensitivity, specificity, and predictive values of the reversibility test for the diagnosis of asthma) for each of the lung function tests applied in the study. Specific airway resistance (sRaw) as measured by whole-body plethysmography, respiratory resistance as measured with the interrupter technique (Rint), and respiratory resistance and reactance at 5 Hz (Rrs5, Xrs5, respectively) as measured with the impulse oscillation technique were assessed before and 20 min after inhalation of terbutaline from a pressurized metered-dose inhaler via a metal spacer by 92 children (37 healthy controls and 55 asthmatic subjects). The study of healthy children followed a randomized, double-blind, crossover design, whereas the study of asthmatic children was open. Baseline lung function was significantly decreased in asthmatic children as compared with healthy control subjects as reflected by all techniques used in the study. sRaw, Rint, and Rrs5, but not Xrs5, improved significantly with terbutaline as compared with placebo in healthy control subjects. Lung function improved to a significantly greater extent in asthmatic children than in control subjects as reflected by all methods. sRaw provided the best discriminative power of such a bronchodilator response, with a sensitivity of 66% and specificity of 81% at the cutoff level of a 25% decrease in sRaw after bronchodilator administration. In conclusion, bronchodilator response measured by sRaw allows a separation of asthmatic from healthy young children. This may help define asthma in this clinically difficult-to-manage group of young wheezy children. The sensitivity and specificity of the other methods used in the study were less than those of sRaw.

Primary ciliary dyskinesia: evolution of pulmonary function

Pulmonary function tests were obtained in 11 patients with primary ciliary dyskinesia. Their mean age was 15 years (range 6-32). Their pulmonary function was obstructive, with a vital capacity (mean+/-SD) of 75%+/-20% predicted, a forced expiratory volume in 1s (FEV1) of 63%+/-20% predicted and a raised residual volume of 169%+/-50% predicted. After inhalation of 200 microg of salbutamol the mean change in FEV1 was + 13.2%+/-9.6% of the baseline value. In the 10 oldest patients, lung function had been measured at regular intervals during 3 20 years. Interestingly, during childhood and adolescence the evolution was not unfavourable: vital capacity increased by 8%+/-20% and FEV1 remained stable (mean change 0.3%+/-12%). Only 2 patients had an unfavourable evolution.

CONCLUSION

At time of diagnosis, patients with primary ciliary dyskinesia have partially reversible obstructive airway disease. During regular follow up and therapy, there is no evidence of a further decline in lung function. Patients with associated immunodeficiency or important damage at the start of therapy may have a worse prognosis.

Sheepskins and bedding in childhood, and the risk of development of bronchial asthma

BACKGROUND

Sheepskin bedding might increase house dust mite exposure and so explain some of the increasing prevalence of severity of childhood asthma.

METHODS

Relationships between use of different types of bedding, and diagnoses of asthma, symptoms of wheezing, skin prick test evidence of house dust mite sensitivity, and airway responsiveness to methacholine, were examined retrospectively in a birth cohort of children followed longitudinally to age 15 years.

RESULTS

In the whole cohort, no associations were identified to suggest a causal relationship between use of any type of bedding and development of features of asthma. Although not an a priori hypothesis, we noted that among children with a family history of atopic disease, those who were house dust mite sensitive were more likely to have used an innerspring mattress (29.6% vs 10.2% who had not used an innerspring mattress, p = 0.005).

CONCLUSION

In this subgroup, increased airway responsiveness and mite sensitivity were significantly associated with use of innerspring mattresses, although whether this is a causal or secondary association is not certain. Use of a sheepskin in the bed in early childhood was not an additional risk factor for the development of asthma.

Airway response to a bronchodilator in healthy parents of infants with bronchiolitis

In order to assess the role of genetic factors and environmental influences in bronchial responsiveness, we studied the airway response to an inhaled bronchodilator in 66 nonasthmatic parents (age, 30.9 +/- 5.9 years) of infants with bronchiolitis (group 1). It was a placebo-controlled double-blind study. A control group (group 2) of healthy parents of infants who did not have bronchiolitis also were investigated with the test of bronchodilator response. All subjects showed normal expiratory airflow and lung volumes (forced vital capacity [FVC], forced expiratory volume in 1 s [FEV1], and mean forced expiratory flow during the middle half of FVC [FEF25-75%] > 80 percent of predicted) at baseline forced expiratory maneuver. In 16 (24.2 percent) subjects of group 1, there was significant increase in at least one parameter after salbutamol administration, but not after placebo inhalation, with respect to baseline levels. Furthermore, no significant changes in FVC, FEV1, or FEF25-75% values were found in group 2. In conclusion, this study confirms that parents of infants with bronchiolitis have an enhanced airway responsiveness, greater than control parents. Further studies are needed to assess whether one may infer the outcome of infants with bronchiolitis from this characteristic in their parents.

The effect of high doses of inhaled salbutamol and ipratropium bromide in patients with stable cystic fibrosis

The effect of large doses of salbutamol (S) and ipratropium bromide (IB) were tested in a double-blind, randomized, crossover study. Nine patients with cystic fibrosis (CF), aged 12.8 +/- 2 years (mean +/- SE), were studied for 8 h on 2 separate days. Pulmonary function tests (PFTs) included spirometry (FEV1), lung volumes (FRC), and airway resistance (Raw) measured by body plethysmography. Heart rate (HR) and oxygen saturation (SaO2) were measured before each test. On 1 day patients received S 200 micrograms, S 400 micrograms, and IB 80 micrograms, by inhalation at 45-min interval (sequence A). On the other day, the sequence was IB 80 micrograms, S 200 micrograms, and S 400 micrograms (sequence B). The PFTs were obtained at baseline, 45 min after each inhalation, and 4 and 8 h after baseline measurements. Baseline PFTs (mean +/- SE) were not significantly different on the 2 study days (FEV1, 1.48 +/- 0.1 vs 1.42 +/- 0.1 L; FRC, 2.77 +/- 0.6 vs 2.87 +/- 0.6 L; Raw, 4.04 +/- 0.2 vs 4.00 +/- 0.3 cm H2O/L/s). The FEV1 and Raw improved from baseline after each inhalation, and at 4 and 8 h during both days (p < 0.05). Forty-five minutes after S 200 micrograms, plus S 400 micrograms, FEV1, FRC, and Raw were not significantly different compared with the values 45 min after IB 80 micrograms, plus S 200 micrograms (1.67 +/- 0.1 vs 1.63 +/- 0.1 L; 2.81 +/- 0.6 vs 2.65 +/- 0.5 L; and 2.98 +/- 0.2 vs 2.66 +/- 0.1 cm H2O/L/s, respectively). The PFTs were not significantly different after maximal doses of IB (80 micrograms) compared with S (600 micrograms). The HR and SaO2 were not significantly different from baseline throughout the study period. These results indicate that both single and sequential therapy have a similar acute bronchodilator effect provided that large doses are used. We speculate that adrenergic and muscarinic pathways are equally important in airflow obstruction in patients with CF.

Response to inhaled bronchodilators and nonspecific airway hyperreactivity in children with cystic fibrosis

We tested the hypothesis that children with CF who have a significant response to bronchodilator (BD) would respond positively to standard methacholine (Mch) challenge. Our objective was to correlate the response to BD with the concentration that produced a 20% fall (PC20) in forced expiratory volume in 1 second (FEV1). We studied 22 patients (12 males), aged 10.5 +/- 0.7 years (mean +/- SE), with a Shwachman-Kulczycki score 82 +/- 2.6 and baseline FEV1 of 80 +/- 4.5% predicted. Baseline expiratory flows, static lung volumes, and airway resistance were measured before and 30 min after inhaled salbutamol. On a separate day, within 2 weeks, a Mch challenge was given, with doubling concentrations from 0.03 to 8.0 mg/mL. A positive challenge was defined as a PC20 less than or equal to 2.0 mg/mL, and a positive response to BD as a greater than 6% of FEV1 increase. Mch challenge yielded 17 responders (R) with a PC20 of 0.5 +/- 0.1 mg/mL, and 5 nonresponders (NR) with a PC20 of 8.8 +/- 2.9 mg/mL. Baseline FEV1 was 77 +/- 5.3% predicted in R compared to 89 +/- 6.3% in NR (P = less than 0.001). History of springtime rhinitis was positive in 9/17 R and 2/5 NR. No significant correlation was found between baseline FEV1 and PC20, or between change in FEV1 post-BD and PC20. A greater than 6% increase in FEV1 was seen in 14/17 R (83% sensitivity) and in none of the 5 NR (100% specificity). In R, 8/17 patients had baseline FEV1 less than 80% predicted, compared to 1/5 in NR.(ABSTRACT TRUNCATED AT 250 WORDS)

Acute bronchodilator response to a combination of beta-adrenergic and anticholinergic agents in patients with cystic fibrosis

Patients with cystic fibrosis had a better acute bronchodilator response to albuterol and ipratropium bromide than to either drug alone. Further studies of long-term efficacy and safety seem justified.