Baseline and post-bronchodilator interrupter resistance and spirometry in asthmatic children

In children unable to perform reliable spirometry, the interrupter resistance (R_int) technique for assessing respiratory resistance is easy to perform. However, few data are available on the possibility to use R_int as a surrogate for spirometry. We aimed at comparing R_int and spirometry at baseline and after bronchodilator administration in a large population of asthmatic children. We collected retrospectively R_int and spirometry results measured in 695 children [median age 7.8 (range 4.8–13.9) years] referred to our lab for routine assessment of asthma disease. Correlations between R_int and spirometry were studied using data expressed as z‐scores. Receiver operator characteristic curves for the baseline R_int value (z‐score) and the bronchodilator effect (percentage predicted value and z‐score) were generated to assess diagnostic performance. At baseline, the relationship between raw values of R_int and FEV₁ was not linear. Despite a highly significant inverse correlation between R_int and all of the spirometry indices (FEV₁, FVC, FEV₁/FVC, FEF_25–75%; P < 0.0001), R_int could detect baseline obstruction (FEV₁ z‐score ≤ ?2) with only 42% sensitivity and 95% specificity. Post‐bronchodilator changes in R_int and FEV₁ were inversely correlated (rhô = ?0.50, P < 0.0001), and R_int (≥35% predicted value decrease) detected FEV₁ reversibility (>12% baseline increase) with 70% sensitivity and 69% specificity (AUC = 0.79). R_int measurements fitted a one‐compartment model that explained the relationship between flows and airway resistance. We found that R_int had poor sensitivity to detect baseline obstruction, but fairly good sensitivity and specificity to detect reversibility. However, in order to implement asthma guidelines for children unable to produce reliable spirometry, bronchodilator response measured by R_int should be systematically studied and further assessed in conjunction with clinical outcomes. Pediatr Pulmonol. 2012. 47:987–993. © 2012 Wiley Periodicals, Inc.     

Response–dose ratio as an index of bronchial responsiveness to hypertonic saline challenge in an epidemiological survey of asthma in Polish children

This epidemiological survey was done to evaluate the bronchial responsiveness (BHR) to a 4.5% hypertonic saline (HS) challenge in 13–14 year-old schoolchildren. BHR was measured by the response–dose ratio in which the response was estimated by the decline of FEV₁ index of BHR (IxFEV₁). Validity of the HS challenge test as a screening test for confirmation of reported asthma symptoms and the diagnosis of asthma was assessed. With a cutoff of 90th percentile of IxFEV₁ in controls, the test sensitivity and specificity for asthma symptoms in the last 12 months was 44% and 90%, respectively. For the diagnosis of asthma the test sensitivity was 67% and specificity 90%. The mean log transform of IxFEV₁ was significantly higher in children with more than three episodes of wheezing in the last 12 months and a diagnosis of asthma than in controls. Moreover, in the group with more than three episodes of asthma in the last 12 months the mean IxFEV₁ was higher in girls than in boys. There was no gender difference in other groups of asthmatic children and controls. In Polish schoolchildren the prevalence of BHR to HS was 12.5% when adjusted to the prevalence of wheezing in the last 12 months. By multiple linear regression analysis, factors associated with BHR were serum levels of total IgE in children and of maternal IgE, as well as children's peripheral blood eosinophil counts. Also, the size of skin reaction to mite and dog allergens correlated with BHR. Pediatr Pulmonol. 1998; 25:375–382. © 1998 Wiley-Liss, Inc.     

Response to Bronchodilators After Exercise Challenge Predicts Bronchial Hyperreactivity

Background. Some subjects with suspected asthma and a negative exercise challenge test (ECT) demonstrate improved expiratory flow rates after administration of bronchodilators (BD) at the end of the ECT (unpublished observation). This study investigated whether this response predicts the presence of bronchial hyperreactivity (BHR). Patients and methods. The study population included 133 young adults (29.4% women) 21.1 ± 4.2 years of age who underwent ECT and a methacholine challenge test (MCT). A receiver-operator-characteristic curve was used to calculate the optimal cutoff level of the response to BD as a predictor of BHR according to MCT. Results. Using a MCT cutoff level of PC₂₀ ≤ 4 mg/mL showed BHR in 12.8% of subjects. Failure to improve FEV₁ by 8% after BD administration predicted the absence of BHR with sensitivity, specificity, and positive and negative predictive values of 76.5%, 68.4%, 25.3%, and 95.5%, respectively. Avoiding MCT in subjects with less than 8% response to BD would have saved 62.5% of the MCTs and would have missed only four (3%) patients with BHR. Conclusions. BD should be administered routinely after ECT, as the response may be used as a simple, inexpensive tool to predict BHR in young patients and may substantially reduce the number of unnecessary MCTs     

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 μ 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 (FEV₁) (PC₂₀) of 4 and 8 mg/mL. Results. Mean (± SD) baseline FEV₁ was 87.8 ± 12% of predicted. After BD administration the mean FEV₁ increased by 4.3 ± 3.9%. The prevalence of BHR was 17.7% and 25.8% for PC₂₀ for PC₂₀ of 4 mg/mL and 8 mg/mL, respectively. The post-BD FEV₁ 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 FEV₁ increment and PC₂₀ 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.     

Exhaled Nitric Oxide and Exercise-Induced Bronchospasm Assessed by FEV1, FEF25 − 75% in Childhood Asthma

The relationship between exhaled nitric oxide (eNO) and bronchial hyperresponsiveness (BHR) should be clarified. The aim of this study was to determine the relationship between eNO and exercise-induced bronchospasm (EIB) by estimation of the each lung parameter in asthmatic children who performed a bicycle ergometer exercise test. Twenty children with asthma were recruited. eNO concentration was examined by the recommended online method. To evaluate BHR, an exercise stress test was performed on a bicycle ergometer. The mean baseline eNO value was significantly correlated with the mean maximum % fall in forced expiratory volume in 1 second (FEV₁), forced expiratory flow between 25% and 75% (FEF25-75%) after exercise (r = 0.53, r = 0.65, respectively). eNO in the EIB-positive group was significantly higher than that in the EIB-negative group by assessing FEV₁, FEF_25?75% (p < 0.005, p = 0.005). We demonstrated that the most important lung parameter assessed the occurrence of EIB by a bicycle ergometer exercise test was not only FEV₁ but FEF_25?75%, which significantly correlated with eNO. This suggests that not only FEV₁ but FEF_25?75% can be used to evaluate the correlations between BHR (EIB) and airway inflammation (eNO) in asthmatic children. A low eNO is useful for a negative predictor for EIB.     

Respiratory system reactance as an indicator of the intrathoracic airway response to methacholine in children

The upper airways may contribute to increases in airway resistance in response to a bronchial challenge, and thus decrease the specificity of such challenge tests to diagnose airway hyperresponsiveness when forced oscillation techniques are used to evaluate changes in respiratory system resistance (R_rs). A concomitent decrease in respiratory system reactance (X_rs) may indicate a change in the intrathoracic airways and/or lung parenchyma, provided that extrathoracic airway wall motion is prevented. To test the value of X_rs in the evaluation of bronchial hyperresponsiveness, we studied the respiratory impedance response to methacholine in 38 children with a history of asthma (aged 6–14.5 years), and compared the results to changes in the forced expiratory volume in one second (FEV₁). R_rs and X_rs were measured by the forced oscillation technique with pseudorandom (11 subjects) or sinusoidal (27 subjects) pressure variations applied around the child's head to minimize upper airway wall motion. Changes in R_rs and in X_rs at 12 Hz (R_rs12, X_rs12) correlated significantly with changes in FEV₁ (P < 0.005). A decrease in FEV₁ ≥20% was observed in 23 subjects. When these 23 subjects were compared with the 15 children who did not show significant changes in FEV₁, the responding group had larger mean ±SEM changes in R_rs (116.0 ± 13.2% vs 60.4 ± 11.4%;, P < 0.006) and in X_rs (−2.1 ± 0.4 hPa · s/L vs −0.9 ± 0.3 hPa·s/L, P < 0.03) than the nonresponders. The receiver operating characteristics (ROC) curve analysis was used to assess the diagnostic value, i.e., specificity and sensitivity, of different levels of change in R_rs and X_rs, with reference to FEV₁. The overall incidence of false results was similar for R_rs and X_rs. The optimum diagnostic value for R_rs was a 70% increase, which corresponded to a sensitivity of 87% and a specificity of 67%. For X_rs the optimum decision level was −1 hPa·s/L, corresponding to a sensitivity of 70% and a specificity of 80%. It is concluded that X_rs may improve the specificity of the forced oscillation technique in interpreting the airway response to methacholine. This may be of particular interest in young children unable to perform forced expirations. Pediatr Pulmonol. 1996;22:7–13. © 1996 Wiley-Liss, Inc.     

Bronchial Responsiveness,Spirometry and Mortality in a Cohort of Adults

Objective. Prospective population studies have reported that pulmonary function, measured by forced expiratory volume in one second (FEV₁), is an independent predictor for mortality. Besides, several studies found that death from all causes is higher in asthmatics than in non-asthmatics. However, none of these studies examined whether bronchial hyperresponsiveness (BHR), one of the key features in asthma, can be used as a predictor for mortality. Thus, the aim of this study was to analyze the association between BHR, FEV_1, and all-cause mortality in a population-based cohort of adults. Methods. Within the cross-sectional survey ECRHS-I Erfurt (1990–1992), 1162 adults aged 20–65 years performed lung function tests, including spirometry and BHR testing by methacholine inhalation up to a cumulative dose of 2 mg. BHR was assessed from the methacholine dose nebulized at ≥ 20% fall of FEV₁. After circa 20 years of follow-up, the association between baseline lung function, BHR, and mortality was investigated. Results. A total of 85 individuals (7.3%) died during a mean follow-up period of 17.4 years (SD = 2.4). FEV₁, but not forced vital capacity (FVC), was a predictor for mortality. In men, BHR increased the mortality risk (OR = 2.6, 95% CI: 1.3–5.3; adjusted for age and BMI). Additional adjustment for asthma did not change the results (OR = 2.4, 95% CI: 1.2–5.0). However, after an additional adjustment for pack years of cigarette smoking or airway obstruction, the association was not statistically significant anymore (OR = 1.8, 95% CI: 0.8–4.0, OR = 1.9, 95% CI: 0.9–4.3, respectively). Conclusions. BHR was associated with an increased mortality risk in men. Potential explanatory factors for this association are cigarette smoking, chronic obstructive pulmonary disease (COPD), or asthma. Thus, BHR might be an indirect predictor for all-cause mortality. FEV₁ was an independent predictor for all-cause mortality.     

Exhaled Nitric Oxide in Children with Allergic Rhinitis and/or Asthma: A Relationship with Bronchial Hyperreactivity

Background. Nowadays, the measure of the fractional concentration of exhaled nitric oxide (FeNO) enables to assess airway inflammation during an office visit and there is international consensus on this testing methodology. The aim of this study was to evaluate whether FeNO measurement is predictable for bronchial hyperreactivity (BHR) in children with allergic rhinitis, asthma, or both. Methods. Two hundred and eighty children with allergic rhinitis, allergic asthma, or both were evaluated. Bronchial function (FEV₁ and FEF_25–75), BHR (assessed by methacholine challenge), FeNO, and sensitizations were assessed. Results. Bronchial function, BHR, and FeNO were significantly different in the three groups (p < .001). A strong inverse correlation between FeNO and BHR was found in patients with asthma and with asthma and rhinitis (r?=??0.63 and r?=??0.61, respectively). A cutoff of 32 ppb of FeNO was a predictive factor for BHR. Conclusions. This study highlights the relevance of FeNO as possible marker for BHR in allergic children and underlines the close link between upper and lower airways.     

Bronchial hyperresponsiveness in an adult population in Helsinki: decreased FEV1, the main determinant

Introduction: Bronchial hyperresponsiveness (BHR) elevates the risk for development of respiratory symptoms and accelerates the decline in forced expiratory volume in the first second (FEV₁). We thus aimed to assess the prevalence, determinants and quantity of BHR in Helsinki. Objectives: This study involved 292 randomly selected subjects age 26–66 years, women comprising 58%. Methods: Following a structured interview, a spirometry, a bronchodilation test, and a skin‐prick test, we assessed a bronchial challenge test with inhaled histamine using a dosimetric tidal breathing method. Results included the provocative dose inducing a decrease in FEV₁ by 15% (PD₁₅FEV₁) and the dose‐response slope. For statistical risk factor‐analyses, the severity of BHR was considered; PD₁₅ values ≤1.6 mg (BHR) and ≤0.4 mg [moderate or severe BHR (BHR_ms)] served as cut‐off levels. Results: BHR presented in 21.2% and BHR_ms in 6.2% of the subjects. FEV₁ < 80% of predicted [odds ratio (OR) 4.09], airway obstruction (FEV₁/forced vital capacity < 88% of predicted) (OR 4.33) and history of respiratory infection at age <5 (OR 2.65) yielded an increased risk for BHR as ORs in multivariate analysis. For BHR_ms, the determinants were decreased FEV₁ below 80% of predicted (OR 27.18) and airway obstruction (OR 6.16). Respiratory symptoms and asthma medication showed a significant association with BHR. Conclusions: Of the adult population of Helsinki, 21% showed BHR to inhaled histamine. The main determinants were decreased FEV₁ and airway obstruction. Quantitative assessment of BHR by different cut‐off levels provides a tool for characterization of phenotypes of airway disorders in epidemiologic and clinical studies. Please cite this paper as: Juusela M, Pallasaho P, Sarna S, Piirilä P, Lundbäck B and Sovijärvi A. Bronchial hyperresponsiveness in an adult population in Helsinki: decreased FEV₁, the main determinant. Clin Respir J 2013; 7: 34–44.     

Relationship Among Pulmonary Function, Bronchial Hyperresponsiveness, and Atopy in Children with Clinically Stable Asthma

Pulmonary function testing plays a key role in the diagnosis and management of asthma in children. However, the literature does not clearly show whether children with clinically stable asthma have significantly reduced lung function when compared with normal children. We compared the lung function of 242 clinically stable asthmatic children who were initially diagnosed with mild intermittent or mild persistent asthma with the lung function of 100 nonasthmatic controls. The lung function was assessed using FEV₁, FEV₁/FVC, FEF_25–75 and PEF. In addition, we measured bronchial hyperresponsiveness (BHR) using the provocation concentration of methacholine needed to produce a 20% fall in FEV₁. All measures of pulmonary function were significantly decreased in the children with asthma. Pulmonary function was not influenced by atopy, serum IgE, or total eosinophil count (TEC). However, the likelihood ratio for trends revealed a significant association between our pulmonary parameters and the degree of BHR. Children with mild-to-severe BHR had greatly decreased lung function compared with those with normal BHR, the control group. In addition, a direct correlation was found between PC₂₀ and our pulmonary parameters in asthmatic children. However, only atopic children with asthma had a significant correlation between PC₂₀ and TEC. We found children with clinically stable asthma to have pulmonary obstruction, which associated strongly with their degree of BHR.     

The Value of Exhaled Nitric Oxide in Predicting Bronchial Hyperresponsiveness in Children

Reduced attention span and motor skills in children limit the practicability of bronchial provocation tests. To assess exhaled nitric oxide (FeNO) as a surrogate for bronchial hyperresponsiveness (BHR) in children with possible reactive airway disease, FeNO was measured using the single-breath method in 169 successive outpatients 11 ± 5 years of age before lung function testing and subsequent bronchial provocation by exercise (n = 165) and methacholine (n = 134). Baseline forced expiratory volume in 1 second (FEV₁) less than 80% of predicted and/or BHR were seen in 59%. FeNO correlated weakly with PD₂₀ to methacholine (r = ?0.24, p < 0.05), but not with the change in FEV₁ due to exercise-induced bronchoconstriction (EIB) (r = 0.1, p > 0.05). The negative predictive value of FeNO less than 10 ppb for EIB was 94%, but overall accuracy for predicting BHR was low. Measurement of FeNO is not a substitute for bronchial provocation in children.     

Airway Hyperresponsiveness: A Comparative Study of Methacholine and Exercise Challenges in Seasonal Allergic Rhinitis with or without Asthma

Background. Asymptomatic airway hyperreactivity in allergic rhinitis is a risk factor for later development of asthma. Although non-specific bronchial hyperresponsiveness (BHR) has been measured by several stimuli, the most appropriate measurement technique still remains unclear. Objective. To investigate whether an exercise challenge can be used to predict BHR in seasonal allergic rhinitis patients with or without asthma and to compare this bronchial reactivity with a methacholine challenge technique. Methods. Forty-six consecutive patients with seasonal allergic rhinitis only (n = 31) and with both seasonal allergic rhinitis and asthma (n = 15) were included in the study during the pollination period. Subjects underwent first methacholine (mch) and then exercise challenge testing (ECT). There was a 1-week interval between the tests. ECT was performed on a bicycle ergometer. Positive result was defined as a 15% decrease in forced expiratory volume in 1 second (FEV₁) post-exercise. A patient's bronchial reactivity to methacholine was considered as hyperresponsive if PC₂₀ was less than 8 mg/mL. Results. Mch PC₂₀ values were significantly lower in patients with both rhinitis and asthma (p < 0.062). Among the 46 patients, mch PC₂₀ values were significantly different between patients who had positive and negative exercise challenge tests (p = 0.007). All patients with rhinitis alone had a negative ECT and 10 had a positive mch challenge. Change in FEV₁ values after ECT was significantly higher in patients with both rhinitis and asthma compared to those with rhinitis alone (p = 0.009). There was a significant relation between positivity of mch and exercise challenges (p = 0.025). ECT positivity was found to be a significant confounding factor in the diagnosis of asthma (p = 0.001). Specificity and sensitivity values were 100% and 24% for ECT and 68% and 100% for mch, respectively. Conclusion. Exercise challenge presents poor diagnostic value for detecting bronchial responsiveness in individuals with allergic rhinitis alone during the pollen season.     

A MCh Test Pre-post Esophageal Acidification in Detecting GER-related Asthma

The direct effect of gastro-esophageal reflux (GER) on lung function is still debated. Objective. To investigate the role of esophageal acidification in affecting airway response to MCh in GER-related versus atopic asthmatics and to assess specificity and sensitivity of events. Subjects. A total of 56 never-smoking, mild asthmatics: 27 non-atopic asthmatics and acid GER (GER+ve) and 29 atopic asthmatics without any GER (GER–ve). Methods. Each subject performed an MCh challenge in baseline (MCh_b), and 30 minutes after an acid drink (125 mL at pH = 2; MCh_ac), one day apart. PD₂₀FEV₁ MCh_b and MCh_ac were compared by estimating the area under the ROC curve (AU-ROC). Results. GER+ve and GER-ve subjects (well matched in baseline) had a different duration of esophageal acid contact (24-hour monitoring; pH-24h AU₄), and PD₂₀FEV₁ MCh_ac (both p < 0.001). AU-ROC was 86.3% (76% to 97%, 95%CI). Sensitivity and specificity of changes were 82.8% (72.9% to 92.7%, 95%CI) and 85.2% (75.9% to 94.5%, 95%CI), respectively. The difference in MCh threshold that maximized both the sensitivity and specificity level was 100 μ g. Conclusions. The esophageal acidification identified GER-related asthma with a good level of both sensitivity and specificity by enhancing the MCh response only in the presence of acid GER. Data are supporting the effectiveness of this procedure for clinical purposes.     

A multifaceted community-based asthma intervention in Chicago: effects of trigger reduction and self-management education on asthma morbidity

Introduction. In the exercise challenge test (ECT), a drop in forced expiratory volume in the first second (FEV₁) of between 10 and 15% is the determinant variable for a diagnosis of exercise-induced bronchospasm. Hypothesis. The use of FEV₁ plus mean forced expiratory flow between 25% and 75% of the forced vital capacity (FEF_25–75%) may increase the sensitivity of the ECT in asthmatic children. Specific objective. To compare FEV₁ and FEF_25–75% changes in a group of asthmatic and healthy children. Methodology. This was a cross-sectional study. Asthmatics were categorized by their severity (GINA) and after 1 month without controller therapy, an ECT was done under standard protocol. As well, a questionnaire about rhinitis and asthma was conducted with the entire population. ROC curves were used for analysis. Results. A total of 147 children (34 healthy and 113 asthmatics, 18 and 58 males, respectively) were evaluated. Divided into healthy children and intermittent, mild and moderate persistent asthmatics, they had similar average ages (9.4, 9.48, 8.97, and 11.2 years, respectively). Using a 15% fall in FEV₁, we obtained 29% sensitivity and 100% specificity. However, when we used a 10% fall in FEV₁, sensitivity was 47% and specificity was 97%. Adding a 28% fall in FEF_25–75%, sensitivity was 52% and specificity was 94%. Conclusion. This study suggests that test sensitivity can increase by using a lower FEV₁ cut-off (10%) and adding a 28% fall in FEF_25–75%.     

Assessing bronchial responsiveness to hypertonic saline using the stepwise protocol of Phase Two of the International Study of Asthma and Allergies in Childhood (ISAAC II)

Measurement of bronchial responsiveness to hypertonic saline was applied in 22 study centers worldwide as part of Phase Two of the International Study of Asthma and Allergies in Childhood (ISAAC Phase Two). Because the amount of inhaled saline was difficult to standardize during the stepwise protocol with inhalation periods of increasing duration, we evaluated different statistical procedures based on inhalation time in relation to wheeze and current asthma. Data on random samples on 9 to 11-year-old children (n = 1,418) from two German centers were analyzed. The following statistical approaches were evaluated: (1) bronchial hyperreactivity (BHR) defined dichotomously as a fall in FEV1 (forced expiratory volume in 1 s) >or=15%; (2) PT15: the provocation time causing BHR using survival-analyses methods; (3) time-response-slope (continuous) of the individual FEV1-courses calculated by a linear model after comparing different mathematical models. The sensitivity and specificity of BHR versus current asthma were 47% and 87%, respectively. Analyses of the provocation time indicated an increased risk (adjusted hazard-ratio: 4.3; 95% CI: 2.8-6.5) for a fall in FEV1 >or= 15% among children with current asthma in comparison to those without. The time-response-slope differed markedly between children with and without wheeze and current asthma (P < 0.0001). BHR is meaningful and relatively easy to use, but has low sensitivity. Time-response-slopes utilize the available information from the stepwise protocol better than BHR and survival-analysis based on PT15. Response parameters based on inhalation time discriminate well between children with and without asthma and will be compared in the analyses of ISAAC Phase Two data.     

Oscillometric and spirometric bronchodilator response in preschool children with and without asthma

BACKGROUND:

Bronchodilator responses (BDR) are routinely used in the diagnosis and management of asthma; however, their acceptability and repeatability have not been evaluated using quality control criteria for preschool children.

OBJECTIVES:

To compare conventional spirometry with an impulse oscillometry system (IOS) in healthy and asthmatic preschool children.

METHODS:

Data from 30 asthmatic children and 29 controls (two to six years of age) who underwent IOS and spirometry before and after salbutamol administration were analyzed.

RESULTS:

Stable asthmatic subjects significantly differed versus controls in their spirometry-assessed BDR (forced expiratory volume in 1 s [FEV₁], forced vital capacity and forced expiratory flow at 25% to 75% of forced vital capacity) as well as their IOS-assessed BDR (respiratory resistance at 5 Hz [Rrs₅], respiratory reactance at 5 Hz and area under the reactance curve). However, comparisons based on the area under the ROC curve for ΔFEV₁ % initial versus ΔRrs₅ % initial were 0.82 (95% CI 0.71 to 0.93) and 0.75 (95% CI 0.62 to 0.87), respectively. Moreover, the sensitivity and specificity for ΔFEV₁ ≥9% were 0.53 and 0.93, respectively. Importantly, sensitivity increased to 0.63 when either ΔFEV₁ ≥9% or ΔRrs₅ ≥29% was considered as an additional criterion for the diagnosis of asthma.

CONCLUSION:

The accuracy of asthma diagnosis in preschool children may be increased by combining spirometry with IOS when measuring BDR.     

Analysis of factors associated with bronchial hyperreactivity to methacholine in bronchiectasis

Nonspecific bronchial hyperreactivity (BHR) has been reported to occur in patients with bronchiectasis. To evaluate this further, we studied 77 patients with stable bronchiectasis (noncystic fibrosis) with special reference to the prevalence of BHR to methacholine (MCh), and its relation to lung function, sputum characteristics, concommitant asthma, and atopy. The concentration of MCh required to produce a fall of 20% in forced expiratory volume in 1 s (FEV₁), PC₂₀, was determined by Wright’s nebulization tidal breathing method. BHR defined by a PC₂₀ ≤ 8 mg/ml was found in 21 of 47 (45%) subjects who underwent bronchial challenge. Presence of BHR was positively associated with low baseline spirometric values, diagnosis of asthma, long duration of disease, and elevated total IgE on univariant analysis, and was significantly related to FEV₁/forced vital capacity (FVC) ratio and asthma on multiple regression analysis. Ten of the 21 hyperreactive subjects did not have clinical asthma, whereas all 11 of 22 subjects with clinical asthma who underwent bronchial challenge were hyperreactive. Among those with BHR, there was a positive correlation between PC₂₀ and baseline FEV₁. When patients were further classified into asthmatic and nonasthmatic subjects, a positive correlation between PC₂₀ and FEV₁ was seen only in those without asthma. Frequency of infective episodes and inflammatory score of sputum assessed by average daily volume, purulence, and leukocyte count did not differ significantly in the groups with and without BHR. These results suggest that BHR in patients with bronchiectasis is associated with coexistent asthma and worse spriometric values, and not with the severity of bronchial sepsis. An erratum to this article is available at .     

Effect of Aging on the Relationship between Asthma Severity and Bronchial Hyperresponsiveness in Children with Asthma

An association between asthma and bronchial hyperresponsiveness (BHR) has been demonstrated. It is possible that the relationship between asthma severity and BHR in children with asthma is different in infants and in adolescents. The aim of this study is therefore to evaluate the effect of aging on the relationship between the severity of asthma and BHR in children with asthma.

We measured BHR in 386 subjects ranging from 2 to 20 years of age. The subjects consisted of 323 children with asthma (boys : girls = 193 : 130, mean age 9.7 years) and 63 age-matched controls (boys : girls = 25 : 38, mean age 8.2 years). BHR was measured using the methacholine inhalation challenge by measuring the transcutaneous oxygen pressure (tcPO₂) in children less than 6 years of age (Dmin-PO₂) and by measuring the respiratory resistance (Rrs) in children 6 years of age and older (Dmin-Rrs). Throughout the whole age range, both the Dmin-PO₂ and Dmin-Rrs in each asthma severity group were higher than those in the controls. In the asthmatics aged 2–5 years, the Dmin-PO₂ levels in the mild asthma group were higher than those in the moderate and severe asthma groups (p < 0.001, p < 0.001, respectively), and the Dmin-PO₂ levels in the moderate asthma group were also higher than those in the severe asthma group. This tendency was also found in the age ranges of 6–9 years and 10–13 years. In the asthmatics aged 14–20 years, the Dmin-Rrs levels were not significantly different among the three groups.

Taken together, these data show that aging has an effect on the relationship between the severity of asthma and BHR during childhood and that BHR may not be the sole determinant for the severity of asthma in adolescence.     

Acute Bronchodilator Response Has Limited Value in Differentiating Bronchial Asthma from COPD

Background. Acute responsiveness to inhaled bronchodilators is often used to differentiate between bronchial asthma and chronic obstructive pulmonary disease (COPD). The response can be expressed in terms of a change in FEV₁ and FVC in several ways—as absolute change, change as percent of baseline value, or as percent of predicted value with different thresholds for a positive test. A comprehensive evaluation of the diagnostic value of these different methods of expressing the acute bronchodilator response has not been carried out. Methodology. Response to inhaled salbutamol was measured by spirometry in 200 asthmatics and 154 patients with COPD. The sensitivity, specificity, and positive and negative predictive values of different methods of expressing responsiveness were calculated. Receiver operative characteristic curves were obtained. Results. None of the expressions of response gave a clear-cut separation between the two diseases. A ΔFEV₁≥ 0.2 L gave the most satisfactory combination of sensitivity (73%) and specificity (80%) and the highest positive (82%) and negative predictive values (69%) for diagnosing asthma. These values were superior to those obtained for the ERS or the ATS criteria for reversibility (ΔFEV₁%predicted ≥ 9% and ΔFEV₁ of ≥ than 12% and 0.2 L over the baseline, respectively), which had almost similar diagnostic characteristics. This was confirmed by the area under curve of the ROC plots. Expressions of response in terms of changes in FVC were unsatisfactory in separating the two diseases. Conclusions. It was concluded that the test of acute bronchodilator responsiveness has limited diagnostic value in separating asthma and COPD.     

Evaluation of the interrupter technique for the use of assessing airway obstruction in children

The purpose of this study was to determine if the interrupter technique, a noninvasive method for measuring airflow resistance, could be used to assess airway obstruction in children. In 107 children (74 with asthma, 12 with cystic fibrosis, and 21 without lung disease) conductance (mostly of airways) measured with the interrupter technique (G_int) was correlated with both forced expiratory volume in 1 second (FEV₁) and the forced expired flow rate between 25% and 75% of vital capacity (FEF_25–75. In addition, 17 children with significant airway obstruction due to asthma also had airway resistance measured by body plethysmography (R_aw) before and after treatment. Resistance and conductance measurements made with the interrupter technique were subdivided into inspiratory (R_int-insp, G_int-insp) and expiratory (R_int-exp G_int-exp) values. In the 107 children, a high degree of linear correlation was found between G_int-exsp and FEV₁ for G_int-insp, r = 0.77 (P < 0.001), and for r = 0.76 (P < 0.001). There was also good linear correlation between Gin, and FEF_25–75 for r = 0.70 (P < 0.001), and for G_int-insp, r = 0.67 (P < 0.001). In the 17 asthmatic children who were tested before and after treatment of their airway obstruction, R_int correlated highly with R_aw; for R_int-exp, r = 0.91 (P < 0.001), and for R_int-insp, r = 0.83 (P < 0.001). The pre- to posttreatment changes in R, and R_aw were similar. We conclude that the interrupter technique can be used to assess changes in airway obstruction, but normal values must be established and further investigation is required before the complete extent of its clinical utility will be known. Pediatr Pulmonol. 1994; 17:211–217. © 1994 Wiley-Liss, Inc.