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.     

Relationship between bronchial hyperresponsiveness and development of asthma in children with chronic cough

To evaluate the relationship between bronchial hyperresponsiveness (BHR) and the development of asthma in children with chronic cough, we performed methacholine inhalation challenges and transcutaneous oxygen pressure (tcPO2) measurements in 92 children with chronic cough aged from 1-13 years (55 boys and 37 girls; mean, 5.3 years) and followed them for > or = 10 years. Forty-four age-matched children with asthma (24 males and 20 females; mean, 6.5 years) and 44 age-matched children without cough or asthma served as controls (18 males and 26 females; mean, 4.6 years). Consecutive doubling doses of methacholine were inhaled until a 10% decrease in tcPO2 from baseline was observed. The cumulative dose of methacholine at the inflection point of the tcPO2 record (Dmin-PO2) was considered to represent hyperresponsiveness to inhaled methacholine. After 10 years or more of follow-up, 60 of the 92 subjects with cough answered our questionnaire, and 27/60 had been diagnosed with asthma. There was a statistical difference in Dmin-PO2 between the children who presented with chronic cough originally and who developed asthma (asthma-developed group) and those who did not develop asthma (asthma-free group). There was no difference in the value of Dmin-PO2 between the asthma-developed group and the asthma group, or between the asthma-free group and the age-matched control group. Among the children with chronic cough, there was no difference in Dmin-PO2 between girls and boys, either in the asthma-developed group or in the asthma-group. We conclude that 45% of the children with a chronic cough in early life developed asthma, and that BHR in children with chronic cough during the childhood period is a strong risk factor for the development of asthma.     

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.     

Effect of Age on Bronchial Reactivity in Children with Asthma

In contrast to an abundance of data concerning age-related changes of bronchial sensitivity, the relationship between age and rapidity of bronchoconstriction (bronchial reactivity) remains unclear. We studied age and bronchial reactivity in children with asthma. Enrolled in this study were 511 asthmatic subjects and 115 age-matched control subjects 1 to 16 years of age. Bronchial reactivity was represented by the slope of the methacholine transcutaneous oxygen pressure dose-response curve (SPO₂) in younger children and the slope of the respiratory resistance dose-response curve (SRrs) in older children. Overall, SPO₂ and SRrs were higher in asthmatic than control subjects. SPO₂ increased significantly from 1 to 6 years in asthmatic subjects, reaching a plateau after age 7. This age-related change in SPO₂ also was seen in controls. SRrs in asthmatic subjects decreased after age 13, while SRrs in controls showed no significant change between age 7 and 16. Age-related change in bronchial reactivity occurs during childhood, possibly reflecting early changes in airway smooth muscle maturity and later changes in airway wall rigidity.     

Effect of Age on Bronchial Reactivity in Children with Asthma

In contrast to an abundance of data concerning age-related changes of bronchial sensitivity, the relationship between age and rapidity of bronchoconstriction (bronchial reactivity) remains unclear. We studied age and bronchial reactivity in children with asthma. Enrolled in this study were 511 asthmatic subjects and 115 age-matched control subjects 1 to 16 years of age. Bronchial reactivity was represented by the slope of the methacholine transcutaneous oxygen pressure dose-response curve (SPO₂) in younger children and the slope of the respiratory resistance dose-response curve (SRrs) in older children. Overall, SPO₂ and SRrs were higher in asthmatic than control subjects. SPO₂ increased significantly from 1 to 6 years in asthmatic subjects, reaching a plateau after age 7. This age-related change in SPO₂ also was seen in controls. SRrs in asthmatic subjects decreased after age 13, while SRrs in controls showed no significant change between age 7 and 16. Age-related change in bronchial reactivity occurs during childhood, possibly reflecting early changes in airway smooth muscle maturity and later changes in airway wall rigidity.     

Determinants of bronchial responsiveness to methacholine at school age in twin pairs

The methacholine inhalation challenge test (MIC) was used to evaluate bronchial responsiveness in 67 children who were the products of multiple pregnancies when they were 7-15 years old. At birth, 30 (45%) infants had intrauterine growth retardation (IUGR; birth weight <2 SD below normal birth weight, or birth weight difference >1.3 SD between twin-pairs), and 59 (88%) were born before 37 weeks of gestation. None of the children had doctor-diagnosed asthma. The provocative dose of methacholine causing a 20% fall in Wright's peak expiratory flow (WPEF) (PD20) was below 1,000 microg in 10 (15%) children, and they were classified as MIC responders. There were no differences in perinatal or neonatal factors between MIC responders and nonresponders; in particular, MIC responses did not differ between IUGR infants, and children with appropriate growth for gestational age (AGA) at birth. There were seven discordant pairs in which one child was a MIC responder and the other was not; 5 responders were IUGR, and 2 were AGA children (ns). Respiratory tract infections after the neonatal period were equally common in IUGR and AGA children. However, these infections were associated with later bronchial hyperresponsiveness. Doctor-diagnosed respiratory infections, numbers of antibiotic courses, episodes of otitis media, and the need for adenoidectomy, tonsillectomy, and tympanostomy were more common in MIC responders than in nonresponders. We conclude that IUGR was not associated with subsequent bronchial hyperresponsiveness in twin pairs assessed by the MIC test. A significant relationship was seen between bronchial hyperresponsiveness and infections after the neonatal period.     

Airway hyperresponsiveness: the usefulness of airway hyperresponsiveness testing in epidemiology,in diagnosing asthma and in the assessment of asthma severity

The present PhD thesis was conducted at the Respiratory Research Unit at the Pulmonary Department L in Bispebjerg Hospital, Copenhagen, Denmark and describes airway hyperresponsiveness in asthma patients in four studies. The first study concerned risk factors for the development of asthma in young adults in a 12‐year prospective follow‐up study of a random population sample of 291 children and adolescents from Copenhagen, who were followed up from the age of 7–17 years (1986) until the age of 19–29 years (1998). During follow‐up, 16.1% developed asthma, and in these subjects, the most important predictor of asthma development was airway hyperresponsiveness to histamine at baseline. Airway hyperresponsiveness is associated with more severe asthma and a poorer prognosis in terms of more exacerbations and less chance of remission of the disease. The second study described the relation between airway hyper‐responsiveness to methacholine and the quality of life in 691 asthma patients: In asthma patients with airway hyperresponsiveness to methacholine, the quality of life measured with a validated questionnaire (Junipers Asthma Quality of Life Questionnaire) was significantly reduced compared to asthma patients who did not respond to bronchial provocation with methacholine. Airway hyperresponsiveness is not uncommonly observed in non‐asthmatics, and the response to bronchial provocation with methacholine is therefore relatively non‐specific. The mannitol test is a relatively new bronchial provocation test that acts indirectly on the smooth airway muscle cells through the release of mediators from inflammatory cells in the airways; the mannitol could consequently be a more specific test compared with methacholine. The third study showed that out of 16 non‐asthmatics with airway hyperresponsiveness to methacholine, 15 did not respond to bronchial provocation with mannitol Because of the mechanism of action of mannitol, it seems plausible that the response to mannitol is more closely correlated to airway inflammation in asthma compared with the response to methacholine. The fourth study showed that in 53 adult asthma patients, who did not receive treatment with inhaled steroids, there was a positive correlation between the degree of airway inflammation and the degree of airway responsiveness to mannitol as well as to methacholine. The mannitol does, however, have the advantage of being a faster and simpler test to perform, requiring no additional equipment apart from a spirometer. Conclusions: Airway hyperresponsiveness in children and in adolescents without asthma predicts asthma development in adulthood. Asthma patients with airway hyperresponsiveness to methacholine have a poorer quality of life as well as more severe disease and a poorer prognosis compared with asthma patients without airway hyperresponsiveness. Bronchial provocation with mannitol as well as with methacholine were useful for evaluating the severity of asthma and the degree of airway inflammation, and accordingly for determining the need for steroid statement. The mannitol test does, however, have practical advantages over the methacholine test that make it preferable for clinical use.     

Evaluation of nasal impedance using the forced oscillation technique in infants

By applying oscillations to the respiratory system through a rigid face mask, the infant-adapted Lándsér forced oscillation technique measures impedance of the total respiratory system including the nose, at frequencies from 4 to 52 Hz. The present study was aimed at evaluating nasal impedance in infants from consecutive forced oscillation measurements through both nostrils and each nostril separately, using a simple electrical model. In 30 asthmatic infants with varying degrees of nasal obstruction, aged 1-16 months, calculated nasal resistance (Rn) at 24 Hz ranged from 1 to 16 cm H2O.L-1.s. The ratio of Rn to total respiratory system resistance varied between 1 and 48% (mean: 16%). In seven non-asthmatic infants, aged 0-12 months, Rn was between 1 and 11 cm H2O.L-1.s. Nasal patency (evaluated clinically) was correlated with the calculated Rn (P less than 0.05). Rn showed almost no frequency dependence between 24 and 48 Hz as demonstrated by a mean slope of -0.09 +/- 0.08 cm H2O.s2/L for the asthmatic and of -0.08 +/- 0.07 for the non-asthmatic infants. In seven of the asthmatic infants the differences between two Rn determinations at a 45 min interval ranged from -1.7 to 3.8 cm H2O.L-1.s-1 at 24 Hz and from -3.6 to 1.0 at 48 Hz. Changes in Rn did not correlate with changes in total respiratory system resistance (P greater than 0.05). In conclusion, nasal impedance can be approximated from three consecutive measurements through both nostrils and through each nostril separately.     

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.     

脉冲振荡技术在支气管哮喘治疗效果评价中的临床应用

目的探讨脉冲振荡(IOS)技术对哮喘患儿治疗效果的评价作用。方法采用德国JAEGER公司生产肺功能仪对30例哮喘急性发作期患儿前后分别进行IOS和常规肺通气功能检查,哮喘患儿按照2008年哮喘指南给予正规治疗达到临床缓解后,再次测试30例哮喘患儿的IOS和常规通气功能检查,对比IOS和常规肺通气功能检查的结果并进行相关性分析。结果哮喘患儿临床缓解期的常规肺通气功能指标:FEV1、FEF50、FEF75、MMEF75/25较急性发作期的肺功能指标明显好转,差异具有统计学意义(P0.05),并且IOS指标Z5、R5、X5、Rp较急性发作期的肺功能指标明显降低,差异具有统计学意义(P0.05);进行相关性分析显示:Z5、R5与FEV1成负相关,X5与FEF25、FEF50成正相关。结论 IOS可以用于儿童哮喘治疗效果监测,是一种简便、需要配合程度低、无创的方法,值得在哮喘管理中推广应用。     

Current and future use of the mannitol bronchial challenge in everyday clinical practice

Objectives: Asthma is a disease associated with inflammation, airway hyperresponsiveness (AHR) and airflow limitation. Clinical diagnosis and management of asthma often relies on assessment of lung function and symptom control, but these factors do not always correlate well with underlying inflammation. Bronchial challenge tests (BCTs) assess AHR, and can be used to assist in the diagnosis and management of asthma. Data Source: Data presented at the symposium ‘Use of inhaled mannitol for assessing airways disease’ organised by the Allied Respiratory Professionals Assembly (9) of the European Respiratory Society (ERS) at the ERS Congress, Berlin 2008. Results: Indirect challenge tests such as exercise testing, hypertonic saline or adenosine 5′‐monophosphate (AMP) are more specific though less sensitive than direct challenge tests (such as methacholine) for identifying patients with active asthma. Indirect BCTs may be used to diagnose exercise‐induced bronchoconstriction or AHR consistent with active asthma, to evaluate AHR that will respond to treatment with anti‐inflammatory drugs and to determine the effectiveness and optimal dosing of such therapy. An ideal indirect challenge test should be standardised and reproducible, and the test result should correlate with the degree of airway inflammation. The mannitol BCT provides a standardised and rapid point‐of‐need test to identify currently active asthma, and is clinically useful in the identification of patients with asthma who are likely to benefit from inhaled corticosteroid therapy. Conclusion: In the future, mannitol BCT may be added to lung function and symptom assessment to aid in the everyday management of asthma. Please cite this paper as: Porsbjerg C, Backer V, Joos G, Kerstjens HAM and Rodriguez‐Roisin R. Current and future use of the mannitol bronchial challenge in everyday clinical practice. The Clinical Respiratory Journal 2009; 3: 189–197.     

Detection of changes in respiratory mechanics due to increasing degrees of airway obstruction in asthma by the forced oscillation technique

Forced expiratory airflows and volumes are often used to assess the airway obstruction in asthmatics. However, forced maneuvers may change bronchial tone and modify airway patency. The aim of this study was to determine whether the Forced Oscillation Technique (FOT), which does not require forced manoeuvres, may be useful to describe the changes in respiratory mechanics in progressive asthma. This study involved 25 healthy and 84 asthmatics, including patients with normal spirometric exam (NE), mild moderate and severe obstruction. Resistive data were interpreted using the respiratory system resistance extrapolated at 0 Hz (R0), the mean respiratory resistance (Rm), and the resistance/frequency slope (S). Reactance data were interpreted by its mean values (Xm), the dynamic compliance (Crs,dyn), and resonant frequency (fr). Receiver operating characteristics curves were used to determine the sensitivity (Se) and specificity (Sp) of FOT parameters in identifying asthma. There were not statistically significant differences between the control and NE groups. Comparing the control and mild groups, significant increases of R0 (P<0.0007), Rm (P<0.003), and S (P<0.003) were observed. In reactive parameters, a significant reduction in Crs,dyn (P<0.04) was observed, while Xm and fr presented significant increases (P<0.0007 and P<0.006, respectively). Comparison between mild and moderate groups showed non-significant modifications in all of the parameters, except for Xm (P<0.02). In the late stages (moderate to severe obstruction), all of the resistive parameters, as well as the reactive ones Xm (P<0.007) and Crs,dyn (P<0.03), presented statistically significant modifications. Among the studied parameters, the effects of airway obstruction in asthma seem to be well described by R0, Rm, S and Xm, which were in close agreement with physiological fundamentals. The best parameters for detecting asthma were R0 (Se=81%, Sp=76%), S (Se=78%, Sp=72%) and Xm (Se=81%, Sp=80%). In conclusion, the results of this study suggest that the FOT can be proposed as an alternative method for the assessment of the respiratory mechanics in asthmatic patients, representing a promising solution to the problem of effort dependence.     

Toll样受体4与支气管哮喘气道高反应

气道高反应性是支气管哮喘的基本特征.气道高反应的机制目前尚未完全阐明.当前支气管哮喘的治疗亦不能有效地抑制气道高反应性和气道重塑.近来发现,Toll样受体是一种属于Ⅰ型跨膜蛋白的天然免疫模式识别受体.TLR4通过调控气道炎症,促进气道平滑肌增生,参与气道重塑等方式参与气道高反应性过程.本文主要探讨TLR4与在支气管哮喘...     

支气管哮喘变应原检测及脱敏治疗的临床应用价值

目的 研究吸入性变应原与支气管哮喘的关系及脱敏疗法治疗支气管哮喘的临床应用价值。方法 应用吸入性变应原对支气管哮喘患者进行皮内试验明确过敏原,并根据检查结果的分级以相应的初始浓度进行脱敏治疗。结果 205例资料完整的患者中,一种变应原阳性率100％,两种以上变应原阳性率89．1％。经1～3年的脱敏治疗后,临床症状控制良好,且治疗时间越长,效果越好。结论 对吸入性变应原阳性的哮喘患者采用脱敏治疗有较好疗效。     

Toll样受体4与支气管哮喘气道高反应

气道高反应性是支气管哮喘的基本特征.气道高反应的机制目前尚未完全阐明.当前支气管哮喘的治疗亦不能有效地抑制气道高反应性和气道重塑.近来发现,Toll样受体是一种属于I型跨膜蛋白的天然免疫模式识别受体.TLR4通过调控气道炎症,促进气道平滑肌增生,参与气道重塑等方式参与气道高反应性过程.本文主要探讨TLR4与在支气管哮喘...     

Differences in the effect of allergen avoidance on bronchial hyperresponsiveness as measured by methacholine,adenosine 5′-monophosphate,and exercise in asthmatic children

Asthma is now considered as an inflammatory airway disease. There is evidence that allergen avoidance reduces clinical symptoms in atopic asthma. We investigated the effect of a month's stay in the hypoallergenic environment of Davos, Switzerland (1560 m) which is relatively free of house dust mite (HDM) on changes in bronchial hyperresponsiveness (BHR), using the challenge tests of adenosine 5′ monophosphate (AMP), exercise and methacholine to test for BHR. Thirteen asthmatic children with an allergy to HDM participated in the study. We measured BHR on admission to the Davos Asthma Center and after 1 month in the house dust-free environment. The medications used by the patients at the time of admission were kept unchanged during this month. No significant difference in BHR was found to methacholine challenge after a 1-month stay at high altitude (P > 0.05). By contrast, the response to AMP was significantly different as indicated by displacement of the dose-response curve to the right by 2.15 doubling concentrations (P = 0.005). We also observed a significant difference in response to exercise (P = 0.03). These results indicate that a month's stay in a hypoallergenic environment caused a reduction in BHR to AMP and exercise, but not to methacholine. In addition, the results support the concept of differences in trigger mechanisms for BHR, and that responses to a methacholine challenge are not the same as responses to an exercise challenge. The observed reduction in BHR in asthmatic children to the indirect bronchial stimuli of AMP and exercise suggest reduced airway inflammation following avoidance of house dust aeroallergens. AMP and exercise challenges may therefore be better indicators of asthmatic airway inflammation than the direct stimulus of methacholine. Pediatr Pulmonol. 1996; 22:147–153. © 1996 Wiley-Liss, Inc.     

Predictive value of respiratory symptoms and bronchial hyperresponsiveness to diagnose asthma in New Zealand

Respiratory symptoms are often used as the only diagnostic criteria for asthma in epidemiological surveys and the clinical diagnosis of asthma relies primarily on a detailed history. The aim of this study is to predict the diagnostic value of 11 different respiratory symptoms to diagnose asthma, and to determine if bronchial hyperresponsiveness (BHR) improves the predictive value of these respiratory symptoms. A random sample of 1257 subjects aged 20-44 years old in 3 different areas of New Zealand were selected between March 1991 and December 1992 to answer the European Community Respiratory Health Survey questionnaire on respiratory symptoms. Of these, 784 underwent bronchial challenge with methacholine. The prevalence of current doctor diagnosed asthma (DDA) defined as asthma confirmed by a physician and an asthma attack in the last 12 months was 8.3%. Wheezing with dyspnoea is the single best predictor of diagnosed asthma with a sensitivity of 82%, a specificity of 90% and a Youden's index of 0.72. Wheezing alone is more sensitive (94%) but less specific (76%), with a Youden's index of 0.70. The addition of BHR to asthma symptoms decreases sensitivity and increases specificity with a small increase in Youden's index to 0.75. In New Zealand adults, a history of wheezing with BHR best predicts a diagnosis of asthma but wheezing alone or with dyspnoea are the two best symptoms for predicting asthma.     

支气管哮喘、咳嗽变异性哮喘及急性支气管炎气道反应性特点及意义

目的探讨支气管哮喘、咳嗽变异性哮喘及急性支气管炎气道反应性特点,以便为临床诊断提供依据。方法采用日本产ＡＳＴＯＧＡＰＨＴＣＫ６０００ＣＶ气道反应测定仪,以乙酰甲胆碱为气道激发剂,观察６０例支气管哮喘、５８例咳嗽变异性哮喘及３７例急性支气管炎患者气道反应性变化。结果支气管哮喘和咳嗽变异性哮喘病人气道激发试验均为阳性,哮喘病人的气道反应阈值（Ｄｍｉｎ）低于咳嗽变异性哮喘病人（Ｐ＜００５）。急性支气管炎病人中,气道激发试验３３例阴性,占８９％,４例阳性,占１１％。４例阳性急性支气管炎患者的气道反应性曲线与哮喘组及咳嗽变异性哮喘组明显不同,其Ｄｍｉｎ也显著高于哮喘组（Ｐ＜００１）及咳嗽变异性哮喘组（Ｐ＜００５）。结论气道反应性测定对于不同类型哮喘及急性支气管炎的鉴别和指导治疗具有很好的临床应用价值。