Influence of baseline lung function on exercise-induced response in childhood asthma

The dependence of bronchial reactivity to exercise on baseline lung function was studied in 84 asthmatic children aged 7-16 years. The percentage fall in PEF values after a standard exercise running test was 8.4 +/- 8.6% in the 39 children with an attack rate of less than 10 per year and 29.6 +/- 23.2% in the 45 children with an attack rate of 10 or more per year (p less than 0.001). A significant negative correlation (r = -0.46, p less than 0.001) was found for pre-exercise MMEF and other sensitive tests of airway calibre with the response to exercise, but no such correlation was found between baseline PEF or SGaw values and the exercise response. These results show that bronchial hyperreactivity to exercise is dependent on residual airway obstruction, but a wide variety of reactivity can occur. If the baseline flow-values are less than three standard deviations below the mean reference, however, a clinically significant response to exercise can be predicted.     

Influence of Baseline Lung Function on Exercise-Induced Response in Childhood Asthma

ABSTRACT. The dependence of bronchial reactivity to exercise on baseline lung function was studied in 84 asthmatic children aged 7–16 years. The percentage fall in PEF values after a standard exercise running test was 8.4± 8.6 % in the 39 children with an attack rate of less than 10 per year and 29.6±23.3% in the 45 children with an attack rate of 10 or more per year (p<0.001). A significant negative correlation (r=-0.46, p<0.001) was found for pre-exercise MMEF and other sensitive tests of airway calibre with the response to exercise, but no such correlation was found between baseline PEF or SG_aw values and the exercise response. These results show that bronchial hyperreactivity to exercise is dependent on residual airway obstruction, but a wide variety of reactivity can occur. If the baseline flow-values are less than three standard deviations below the mean reference, however, a clinically significant response to exercise can be predicted.     

常规肺通气功能检测在儿童支气管哮喘诊疗中的作用

目的 通过对比支气管哮喘(哮喘)患儿规范化治疗前后肺功能指标的变化,探讨其大小呼吸道功能改变及改变时间段.通过对比哮喘患儿吸入支气管扩张剂前后肺功能变化,明确哮喘患儿对支气管扩张剂的反应及呼吸道狭窄、呼吸道阻塞的可逆性.方法 采用肺功能测定系统对25例哮喘患儿分别于哮喘急性发作期、正规治疗后缓解期3个月、6个月、1 a行常规肺通气功能测定,比较各期实测值与预测值;并从中选出10例患儿于急性发作期行支气管舒张试验,比较支气管扩张剂雾化吸入前后其肺功能指标变化. 结果 哮喘患儿急性发作期用力肺活量(FVC)、一秒钟用力呼气量(FEV1)、1秒率(FEV 1.0%)、最大呼气流量(PEF)、25%用力呼气肺活量(FEF25)、FEF50、FEF75、中段呼气流速(MMEF75/25)等实测值均较预测值降低,治疗3个月FVC、FEV1等大呼吸道功能指标恢复,治疗1 a、FEF50、FEF75、MMEF75/25等小呼吸道功能指标恢复.哮喘患儿支气管扩张剂雾化吸入后大呼吸道功能指标FEV1、PEF及小呼吸道功能指标FEF50、FEF75、MMEF75/25等均较雾化前恢复.结论 哮喘患儿的肺功能指标在急性期和缓解期存在特异性动态变化,肺功能检测在儿童哮喘的诊断、疗效及病情判断方面具有良好的作用.     

Pathogenesis of asthma.

Asthma is the most common chronic lower respiratory tract condition in children. Thus, it is imperative that physicians caring for asthmatic patients understand the pathophysiology of asthma and its implications for optimal therapeutic management. A precise understanding of asthma pathophysiology has been impeded due to the fact that a universally acceptable definition for asthma has been difficult to formulate. Clinicians treating asthmatic patients should be aware that the airway obstruction present in these individuals is the result of multiple interrelated factors. Although bronchial smooth muscle spasm can be effectively treated producing rapid symptomatic relief, other factors contributing to airway obstruction, such as airway inflammation and edema, need to be a major focus of therapeutic strategies for more chronic management. While the concepts of reversibility and hyperresponsiveness have been appreciated for some time, the idea that asthma should be viewed as an inflammatory lung disease (or syndrome) has only recently received appropriate emphasis. In this regard, the late phase asthmatic response has provided a convenient model to study the biochemical and cellular interactions that contribute to the pathogenesis of asthma. Further, these responses will aid in the analysis of the potential beneficial effects of various pharmaceuticals as they undergo development and testing for use in asthmatic patients.     

Home recording of peak expiratory flow rates and perception of asthma

Fourteen asthmatic children, aged 7.9 to 18.0 years (mean, 11.3 years), recorded peak expiratory flow rates three times a day at home for four weeks in an attempt to improve perception of their airway obstruction. Pulmonary function tests were performed and a subjective severity score was recorded before and after this period. The accuracy of the parents' perceptions of their child's airway obstruction was also assessed. These children were unable to accurately predict their degree of airway obstruction, and no improvement in prediction was seen following the learning period. Parents' perceptions of the child's airway obstruction were also inaccurate. Recording of peak expiratory flow rate at home did not improve the child's perception of his asthma. Rational management of troublesome asthma requires the use of an inexpensive peak flowmeter to provide continual objective measurements of lung function.     

Lung distensibility and airway function in asthmatic children

Lung distensibility and airway mechanics were evaluated in 24 asthmatic children and adolescents, ages between 7 and 21 years, by quasi-static pressure-volume curves and by the static recoil-lung conductance relationship. The measurements were obtained by the step-wise inflation technique and the pressure-volume curves were analyzed by a new sigmoid exponential curve-fitting model of the form: VL = Vm + [VM/(1 + be-K . PstL)], where VL is lung volume, PstL is static recoil pressure, VM and Vm are the upper and lower asymptotes, and K and b are shape constants. The shape constant K serves as index for lung distensibility, whereas the slope of theta of the static recoil-lung conductance plot represents the flow-resistive behavior of the airways. The combined evaluation of these two parameters (K and theta) shows that some asthmatic children have a very high lung distensibility and normal airway function, whereas others have nearly normal lung elasticity but grossly reduced airway distensibility. Sigmoid exponential analysis of static pressure-volume curves and an evaluation of the static recoil-lung conductance relationship in asthmatic children enable a distinction of these two types of functional derangements. Increased pulmonary distensibility consistent with an increase of alveolar air space seems to indicate an involvement of tissue elements. In contrast, decreased airway distensibility indicates a defect in the conducting airways. Sympathomimetics not only have a positive effect on airway mechanics, but seem to increase lung distensibility both in patients with hyperinflation and to an even greater degree in patients whose lungs are already too compliant.     

Detection of exercise-induced bronchospasm in sixth-grade students: impact of health education]

Underdiagnosis of asthma is frequent in children and may be improved by the development of school-based health programs. MATERIAL AND METHODS: We developed an educational program in 11-year-old schoolchildren who participated in a screening test for exercise-induced asthma (EIA). All children were given an asthma questionnaire before and after two educational sessions. RESULTS: Mean score for asthma knowledge quiz increased from 63 to 85% (p < 0.001). Thirty-six children (3.7%) were initially considered as asthmatic and showed better responses than non-asthmatic children. Peak expiratory flow (PEF) was measured before and after an outside running exercise. A fall in PEF of at least 15% was considered an abnormal result. Seventy-height children (8%) had a decrease in PEF, including 65 children initially not recognized as asthmatic. For these latter, a medical evaluation was recommended to parents. Only 28 of these children gave informations on follow-up: 19 had lung function tests, two received a treatment without preliminary function test, and seven had neither lung function test nor treatment. Among the children who realized lung function tests, five had criteria for airway obstruction at baseline, and ten had significant bronchial hyperreactivity. CONCLUSIONS: However, a new screening test revealed that only a small minority of children initially not recognized as asthmatic but having decreased their PEF, were consequently considered as asthmatic by their practitioner, even in case of positive lung function test.     

FeNO与儿童哮喘关系的研究进展

支气管哮喘是一种异质性疾病,以气道高反应性、气道慢性炎症为特征,常伴有可逆性气流受限。目前儿童哮喘诊断的实验室检测方法主要以肺通气功能检测为主,由于儿童的不配合性,学龄前儿童肺通气功能检测具有挑战性。肺功能检测是瞬时指标,受患儿理解能力、精神因素等影响。肺功能检测不能评估气道炎症的严重程度。近年来一种无创、简单、客观评价气道炎症指标呼出气一氧化氮 （FeNO）逐渐在儿童中应用增多。该综述就FeNO的产生、实验参考值界定及其在不同年龄哮喘儿童的诊断、治疗、预测评估中的作用研究进展进行阐述。     

不同体重指数的哮喘患儿规范化激素治疗后肺功能变化

目的：研究不同体重指数（BMI）的哮喘患儿经吸入糖皮质激素（ICS）治疗后肺功能的改善情况。方法：157例哮喘患儿根据BMI分为肥胖组（46例）、超重组（50例）和体重正常组（61例）,检测所有患儿治疗前及规范化ICS治疗1年后,大气道通气功能指标1秒用力呼气容积（FEV1）、用力肺活量（FVC）及小气道通气功能指标用力呼气25%流量（MEF25）、用力呼气50%流量（MEF50）。结果：治疗前各组患儿行肺功能激发试验,雾化吸入乙酰甲胆碱后肥胖组FVC%、FEV1%、MEF25%及MEF50%下降率均明显高于体重正常组（均P<0.01）;雾化吸入沙丁胺醇后肥胖组FEV1%、MEF25%和MEF50%以及超重组MEF25%和MEF50%改善率均明显低于体重正常组（均P<0.05）。ICS治疗1年后,与治疗前相比,体重正常组FVC%、FEV1%均明显升高,而肥胖组和超重组仅FVC%升高。结论：肥胖能够增加哮喘患儿对乙酰甲胆碱敏感性,而抑制对沙丁胺醇反应性;规律ICS治疗能改善正常体重哮喘患儿大气道通气功能,对小气道通气功能影响较小;肥胖能够抑制ICS对哮喘患儿肺功能的改善作用。     

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??Abstract?? Objective Toinvestigatethe correlation among exhalednitric oxide??lung function and Asthma Control Test inasthmatic childrenand the clinicalsignificance. Methods A total of 136 cases of asthmatic children aged 5 to 15 years old were recruited from Shengjing Hospital of China Medical University.The fraction of exhaled nitric oxide?? lung function and ACTscore were measured??and the correlation among them was analyzed. Results Negative correlation was found between FeNOand ACT??r= -0.251??P<0.005??.Negative correlation was found between FeNOandFEV1/FVC of lung function??r=-0.206??P<0.05????but not FEV1or PEF.Positive correlation was found betweenACT scoreandFEV1/FVC of lung function ??r=0.242??P<0.01???? but not FEV1or PEF. Conclusion For all subjects??FeNO is negatively correlated with ACT score and FEV1/FVC.ACT is positively correlated with FEV1/FVC.When the subjects are grouped??the three don’t have stable correlations.FeNO is a good biomarker to evaluate the airway inflammation of asthmatic children.ACT score evaluates the level of asthma control in children.Lung function evaluates airway obstruction.FeNO??lung function andACTare different measurements that evaluate asthma in different ways.None of them can be used instead of another in clinical practice??and they are complementary.Combinedapplicationscan effectivelyimprove the diagnosis??treatment and asthmacontrol inasthmatic children.     

哮喘儿童呼出气一氧化氮与肺功能及哮喘控制测试相关性研究

目的 探讨哮喘儿童呼出气一氧化氮（FeNO）水平与肺功能、哮喘控制测试（ACT）三者间的相关性及其在哮喘病情评估中的临床意义。方法 以2011年5月至2012年1月于中国医科大学附属盛京医院小儿哮喘门诊就诊的136例5～15岁哮喘儿童为研究对象,分别测定其FeNO水平、肺功能和ACT评分,分析三者间是否存在相关性。结果 FeNO水平与ACT评分水平呈负相关（r=-0.251,P＜0.005）。FeNO水平与肺功能FEV1/FVC（第1秒用力呼气容积/用力肺活量）呈负相关（r=-0.206,P＜0.05）,与FEV1及PEF不相关。ACT评分与肺功能FEV1/FVC呈正相关（r=0.242,P＜0.01）,与FEV1及PEF不相关。结论 针对所有研究对象,哮喘儿童FeNO水平与ACT评分呈负相关,与FEV1/FVC呈负相关, ACT与肺功能FEV1/FVC呈正相关,然而分组研究后,三者不具备稳定的相关性。FeNO评估哮喘儿童气道炎症,ACT评估哮喘患儿疾病控制水平,肺功能评价哮喘患儿气道阻塞情况,三者是从儿童哮喘的不同方面进行评估,互为补充,均具有重要临床意义,共同应用可提高儿童哮喘控制及诊治水平。     

布地奈德溶液雾化吸入治疗对喘息性支气管炎患儿呼吸道阻力的影响

目的研究布地奈德雾化溶液吸入治疗对喘息性支气管炎患儿呼吸道阻力（AR）的影响。方法喘息性支气管炎患儿56例随机分为A组（常规＋布地奈德雾化溶液吸入治疗）和B组（常规治疗）,同时选取同期保健门诊同年龄组正常幼儿30例为对照组。应用Microloop肺功能仪加载的MicroRint传感器分别对各组儿童治疗前后的AR进行监测。结果喘息性支气管炎患儿急性期与对照组相比,AR明显增高（P〈0.01）;治疗2周后,A、B组AR均显著降低（Pa〈0.001）;但A组AR降低程度更明显,与对照组相比无明显差异;B组AR仍高于对照组。结论喘息性支气管炎患儿急性期AR明显升高;加用布地奈德雾化溶液吸入治疗可迅速减低患儿AR,缩短病程。     

The effects of antenatal smoking on lung function and respiratory symptoms in infants and children

We highlight evidence demonstrating antenatal smoking exposure is an important risk factor for increased respiratory symptoms and lung function abnormalities in infants and children. Epidemiological studies have demonstrated an excess both of wheezing in the first two years after birth and asthma and persistent wheezing in older children. Lung function testing in children exposed to antenatal smoking has demonstrated a reduction in airway function. Antenatal exposure of nicotine to animal models results in pulmonary hypoplasia, fewer but larger alveoli and altered airway morphology. Pulmonary function testing, however, has not demonstrated that infant lung volume is affected by antenatal smoking exposure, other than due to the expected effect of smoking on somatic growth, but there is an adverse effect on airway development. There is no evidence that antenatal smoking exposure increases bronchial hyperreactivity, rather it may be associated with a diminished response to both bronchoconstrictors and bronchodilators in infants.     

Inhaled budesonide reduces lung hyperinflation in children with asthma

Previous studies have shown that asthmatics have hyperinflation as defined by larger total lung capacity. The present study was set up in order to document changes in asthma clinic, airway calibre, airway reactivity and lung volumes after budesonide treatment. After a 2-week run-in period, 28 children with moderate persistent asthma were treated in a double-blind manner either with budesonide (0. 4 mg/day) or placebo for 8 weeks and, thereafter, all patients were treated with open-label budesonide for a further 20 weeks. Symptoms, bronchodilator requirements and airway calibre improved significantly after 8 weeks of treatment ( p < 0. 05 for each) and prolonged treatment did not cause any further improvement. Reduction in hyperreactivity was apparent only after 20–28 weeks of treatment. Total lung capacity decreased along with budesonide treatment in both groups suggesting that early introduction of an inhaled corticosteroid may be useful in the prevention of asthma-related remodelling of the lung and thoracic cage.     

Chronic lung disease of prematurity and respiratory outcome at eight years of age

AIM: The study aimed to determine the respiratory outcome of children who had chronic lung disease of prematurity (CLD) compared with a preterm control group of children at school age. METHODS: Fifty-two preterm infants with CLD born between 26 and 33 weeks gestation were assessed regarding respiratory illness with 47 having lung function testing. Information regarding respiratory illness was obtained from 52 children in the birthweight-matched control group of whom 45 had lung function testing. The results were compared between the CLD and control groups. RESULTS: There was no difference in respiratory symptomatology between CLD groups and control preterm infants. On lung function testing, a significantly lower mean forced expiratory flow at 25-75% of vital capacity was identified compared with the preterm controls (P=0.024). This significant difference did not persist after bronchodilator therapy. There was no evidence of increased air trapping or bronchial hyper-reactivity in the CLD children compared with the controls. CONCLUSION: Lung function in CLD children is largely normal in comparison with preterm controls, apart from some evidence of reversible small airway obstruction. Respiratory symptomatology is not increased in chronic disease children in comparison with control preterm children.     

Early airway infection,inflammation, and lung function in cystic fibrosis

Aims: To determine the relation between lower airway infection and inflammation, respiratory symptoms, and lung function in infants and young children with cystic fibrosis (CF). Methods: A prospective study of children with CF aged younger than 3 years, diagnosed by a newborn screening programme. All were clinically stable and had testing as outpatients. Subjects underwent bronchial lavage (BL) and lung function testing by the raised volume rapid thoracoabdominal compression technique under general anaesthesia. BL fluid was cultured and analysed for neutrophil count, interleukin 8, and neutrophil elastase. Lung function was assessed by forced expiratory volume in 0.5, 0.75, and 1 second. Results: Thirty six children with CF were tested on 54 occasions. Lower airway infection shown by BL was associated with a 10% reduction in FEV_0.5 compared with subjects without infection. No relation was identified between airway inflammation and lung function. Daily moist cough within the week before testing was reported on 20/54 occasions, but in only seven (35%) was infection detected. Independent of either infection status or airway inflammation, those with daily cough had lower lung function than those without respiratory symptoms at the time of BL (mean adjusted FEV_0.5 195 ml and 236 ml respectively). Conclusions: In young children with CF, both respiratory symptoms and airway infection have independent, additive effects on lung function, unrelated to airway inflammation. Further studies are needed to understand the mechanisms of airway obstruction in these young patients.     

Early airway infection, inflammation, and lung function in cystic fibrosis.

AIMS: To determine the relation between lower airway infection and inflammation, respiratory symptoms, and lung function in infants and young children with cystic fibrosis (CF). METHODS: A prospective study of children with CF aged younger than 3 years, diagnosed by a newborn screening programme. All were clinically stable and had testing as outpatients. Subjects underwent bronchial lavage (BL) and lung function testing by the raised volume rapid thoracoabdominal compression technique under general anaesthesia. BL fluid was cultured and analysed for neutrophil count, interleukin 8, and neutrophil elastase. Lung function was assessed by forced expiratory volume in 0.5, 0.75, and 1 second. RESULTS: Thirty six children with CF were tested on 54 occasions. Lower airway infection shown by BL was associated with a 10% reduction in FEV(0.5) compared with subjects without infection. No relation was identified between airway inflammation and lung function. Daily moist cough within the week before testing was reported on 20/54 occasions, but in only seven (35%) was infection detected. Independent of either infection status or airway inflammation, those with daily cough had lower lung function than those without respiratory symptoms at the time of BL (mean adjusted FEV(0.5) 195 ml and 236 ml respectively). CONCLUSIONS: In young children with CF, both respiratory symptoms and airway infection have independent, additive effects on lung function, unrelated to airway inflammation. Further studies are needed to understand the mechanisms of airway obstruction in these young patients.     

Does remodelling of the airway wall precede asthma?

Bronchial asthma is very common in childhood but the occurrence of wheeze with viral infections makes asthma difficult to diagnose in the pre-school child. Longitudinal studies suggest that there is a loss of airway function associated with early childhood asthma. Extrapolating from adult disease and the few tissue-based studies of children, this would appear to be related to abnormal postnatal development or remodelling of the airway walls. This appears to be associated with persistent airway inflammation without clinical evidence of airways obstruction. Abnormally thickened airways may be the mechanism underlying both bronchial hyper-responsiveness and fixed loss of respiratory function. The challenges for the future are to identify those children among the pre-school wheezers who will become asthmatic and to construct trials of therapies that may potentially prevent the development of clinical asthma or ameliorate the associated loss of airway function.     

Pathogenesis of bronchiectasis

Non-cystic fibrosis bronchiectasis is a heterogeneous condition and its pathogenesis is still not well defined. A combination of a defect in host defense and bacterial infection allows microbial colonization of the airways resulting in chronic inflammation and lung damage. An ongoing cycle of infection and inflammation may be established. Typically, the walls of the small airway are infiltrated by inflammatory cells causing obstruction whilst mediators, such as proteases released predominantly by neutrophils, damage the large airways resulting in bronchial dilatation. Adjacent parenchyma is also involved in the inflammation. Lung function testing generally demonstrates mild to moderate airflow obstruction that progresses over time. There are a large number of different aetiologic factors associated with bronchiectasis. A variety of different microbial pathogens is involved and they change as disease progresses.