Validation of a Single Concentration Methacholine Inhalation Provocation Test (SCIPT) in Children

A new method to assess bronchial hyperresponsiveness (BHR) using a single concentration methacholine has already been validated in adults with asthma. Because the geometrical dimensions of the airways in children are different, the results from studies in adults cannot be extrapolated to children. In this study, we validated the single concentration methacholine inhalation provocation test (SCIPT) in children. Twenty-two children performed three methacholine inhalation challenge tests in random order. Two challenges were performed according to the SCIPT: doubling doses (0.03–1.8 mg; maximal cumulated dose 3.6 mg) were administered with an Aerosol Provocation System (Masterscope, Jaeger). The third challenge was performed according to a standard dosimeter method (SDM): doubling doses (0.002–1.8 mg; maximal cumulative dose 3.5 mg) were administered with a DeVillbiss 646 nebulizer. The degree of BHR is expressed as a PD₂₀. A difference of < 1.5 dose step was assumed to be due to intraindividual variation. We found an intraclass correlation of 0.91 between both tests according to the SCIPT and of 0.80 between the SCIPT and SDM. We found, according to the method of Bland and Altman, good agreement when comparing these two challenge tests. The single concentration inhalation provocation test is reproducible and shows good agreement with a standard dosimeter method to test bronchial responsiveness in children.     

Cold air as a bronchial provocation technique. Reproducibility and comparison with histamine and methacholine inhalation

Bronchial provocation testing with cold air was carried out on 36 asthmatic and 13 normal subjects in order to assess the reproducibility and clinical relevance of the technique as a test of airways reactivity. Sixteen subjects underwent repeat testing after an interval of two to three weeks. Using a least squares linear regression analysis, the technique was highly reproducible, with a correlation of r = 0.93 (p less than 0.001). The 21 asthmatic subjects who had exercise-provoked symptoms required a significantly lower level of ventilation of cold air to produce a 35 percent drop in specific airways conductance (PD35) than did those who had no exercise-induced asthma (33.9 L min-1 vs 45.8 L min-1; p less than 0.02). Subjects requiring no regular treatment for their asthma had a geometric mean PD35 of 62.6 L min-1, significantly higher than those requiring inhaled therapy (44.9 L min-1; p less than 0.005). Subjects requiring oral in addition to inhaled treatment had the lowest PD35 (23.6 L min-1; p less than 0.02). Atopic status did not appear to influence the response. There was a strong correlation between the PD35 to cold air and to histamine (r = 0.92; p less than 0.001) and between the PD35 to cold air and to methacholine (r = 0.86; p less than 0.001). The three techniques of assessing bronchial reactivity were equally successful in separating the normal and asthmatic groups. The results indicate that cold air provocation may be reliably and reproducibly used to assess bronchial reactivity. The use of a naturally-occurring stimulus of asthma in all subjects has great potential as an investigational technique.     

婴幼儿乙酰甲胆碱支气管激发试验临床应用

目的评价采用乙酰甲胆碱（methacholine，Mch）对婴幼儿进行支气管激发试验（bronehial provocation test，BPrr）的安全性。方法选取喘息性疾病病儿47例（喘息组）、慢性咳嗽病儿45例（慢性咳嗽组）和正常婴幼儿10例（正常组），分为3组，用Mch进行BPT，试验中观察病儿呼吸、心率、咳嗽、哮鸣音等指标。结果喘息、慢性咳嗽及正常组BPT阳性率分别为89．4％，77％，0％喘息及慢性咳嗽组中出现一过性呼气性哮鸣音的病儿分别为55．3％，44．4％，出现咳嗽的病儿为23．4％，22％，呼吸频率〉60次／min有3例，心率〉140次／min的4例，Sa02〈0．80的2例，且均未出现面色青紫、呼吸窘迫及严重哮喘发作。结论Mch在婴幼儿BPT临床应用中耐受性好、未出现任何严重不良反应，可安全应用。     

Effect of inhaled ipratropium bromide on methacholine and exercise provocation in asthmatic children

To determine whether doses of ipratropium bromide (IB) greater than those usually administered by aerosol (75-250 micrograms) give a greater degree of protection from exercise-induced asthma (EIA) in children, 12 patients with chronic asthma, ages 7-13 yr, were challenged with methacholine and exercise after inhalation of saline or 125, 250, 500, and 750 micrograms of IB on different days. A small and similar bronchodilation (mean increase over baseline: 5.26%) was observed 60 min after the administration of each dose of IB. IB prevented the bronchoconstriction caused by methacholine in all doses we used without statistically significant differences between them. All doses gave an all-or-none protection from EIA. Mean percent fall in FEV1 after exercise was 36.8, 18.3, 23.7, 27.1, and 23.2 following inhalation of saline or 125, 250, 500, or 750 micrograms of IB, respectively. The degree of protection from EIA was not correlated with the bronchodilation caused by IB. We suggest that muscarinic mechanisms are only partly responsible for the pathogenesis of EIA in children. Their importance varies among subjects and also may be variable in the same subject. Alternative mechanisms may be responsible for bronchoconstriction.     

肉桂醛咳嗽激发试验方法的建立及评价

目的 探讨肉桂醛咳嗽激发试验的方法.方法 采用吸气触发的定量吸入,对35名健康志愿者及25例咳嗽患者行肉桂醛咳嗽激发试验.受试者初步吸入雾化浓度倍增（50,100,200,400,800 mmol/L）的肉桂醛溶液,记录测试期间咳嗽次数.诱发产生≥2和≥5次咳嗽的浓度（C2,C5）,用比对数值lg C2和lg C5来判断咳嗽反应的敏感性,并测定受试者前、后肺功能.结果 所有受试者中仅1名出现轻微不适,有恶心感.两组受试者咳嗽激发前、后肺通气指标FEV1、FVC、FEV1/FVC,{[（3.35±0.53） L,（3.35±0.52）L],[（2.76±0.82） L,（2.71±0.73）L]},{[（3.72±0.70） L,（3.71±0.71）L],[（3.30±0.78） L,（3.29±0.76）L]},{[（90.6±5.42）％,（90.9±4.92）％],[（83.6±4.45）％,（82.4＋5.04）％]},差异无统计学意义（P值均＞0.05）.咳嗽敏感性lg C2和lg C5值分别为[2.48±0.43,2.72±0.35].结合本实验实际吸入浓度,估计肉桂醛咳嗽敏感性正常参考值C2≥200 mmol/L,C5≥400 mmol/L.咳嗽敏感性lg C2和lg C5与性别差异有统计学意义（P＜0.05）.结论定量吸入肉桂醛咳嗽激发试验,对正常咳嗽敏感性的建立有参考意义.     

辣椒素咳嗽激发试验方法的建立及其安全性评价

目的探讨辣椒素咳嗽激发试验的方法并评价其安全性。方法采用吸气触发的定量吸入装置,对60名健康志愿者(A组)、11例上呼吸道感染患者(B组)、10例胃-食管反流性咳嗽患者(C组)以及10例支气管哮喘(简称哮喘)患者(D组)行辣椒素咳嗽激发试验。所有受试者逐步吸入雾化浓度倍增(1.95、3.90、7.80、15.6、31.2、62.5、125、250、500、1 000μm ol/L)的辣椒素溶液,测试期间记录咳嗽次数。将诱发产生≥5次咳嗽的最低浓度(C5)作为咳嗽阈值,以对数值lg C5判断咳嗽反射的敏感性。在咳嗽激发前、后进行常规肺通气功能以及多频脉冲振荡呼吸阻力测定。结果全部受试者中仅6例出现轻微不适,其中1例有烧灼感、2例恶心和3例声嘶。咳嗽激发前A、B、C、D组患者第一秒用力呼气容积(FEV1)、呼吸总阻抗(Zrs)分别为(3.6±0.5)L、(2.6±0.8)mm Hg.L-1.s-1、(3.7±0.7)L、(2.5±0.5)mm Hg.L-1.s-1、(2.7±0.8)L、(2.7±0.8)mm Hg.L-1.s-1、(2.1±0.8)L,(3.3±1.5)mm Hg.L-1.s-1,经激发后分别为(3.6±0.5)L、(2.7±0.7)mm Hg.L-1.s-1、(3.7±0.8)L、(2.6±0.3)mm Hg.L-1.s-1、(2.6±0.7)L、(2.7±0.7)mm Hg.L-1.s-1、(2.1±0.8)L、(3.7±2.0)mm Hg.L-1.s-1,各组激发前、后FEV1、Zrs比较差异均无统计学意义(P均>0.05)。A、B、C、D组的咳嗽敏感性lg C5分别为2.45±0.46、2.51±0.20、1.52±0.70、2.34±0.56,其中C组与A、B、D组比较差异有统计学意义(P均<0.01);而A、B、D组间比较差异无统计学意义(P均>0.05)。结论定量吸入辣椒素咳嗽激发试验安全、可行,可在临床上用于咳嗽敏感性的测定。     

Modification of the methacholine inhalation test and its epidemiologic use in polyurethane workers

The dosimeter method of administering doubling cumulative doses of methacholine to measure bronchial responsiveness was standardized to control for the effects of a number of potential influencing variables. The aerodynamic mass median diameter of the challenge aerosol produced from a DeVilbiss 646 nebulizer proved to be 1.2 mu, and the mean output per inhalation 8.9 microliters. Each challenge dose comprised 5 inhalations. Cumulative doses ranged from 0.3 methacholine inhalation units (1 unit = 1 inhalation of aerosol from a 1-mg/ml solution of methacholine, i.e., 8.9 micrograms methacholine) to a possible 640 units, the maximum that was considered reasonable to avoid the risk of unacceptable systemic effects. Responsiveness was expressed as the dose provoking a 20% decline (PD20) in FEV1. Modifications in this full protocol were introduced to facilitate epidemiologic investigations. Physician assessments coupled with baseline measurements of ventilatory function allowed starting at higher dosages for persons with low probability of hyperresponsiveness, thereby shortening the time required for testing to an average of 38 min. In a validation study of 20 persons using both the full and modified protocols, no significant differences were detected between measured PD20 values (geometric means Full versus Modified, 14.83 versus 14.88; r = 0.99). The modified protocol was used to measure bronchial responsiveness in 254 workers exposed to toluene diisocyanate. It proved to be safe and acceptable. Sixty-four workers (25.2%) were found to be reactors. The frequency distribution of the PD20 values exhibited a steadily increasing trend, consistent with a unimodal distribution.     

Randomized double-blind study (third place blinded) to examine the effectiveness and side effects of methacholine in the nonspecific bronchial provocation test

Softly and effectiveness of methacholine for the diagnosis of non-specific bronchial hyperresponsiveness [BHR] were tested in a third place blinded study. 61 patients suspected to suffer from BHR took part. 56 subjects provided complete data and were included in the study. 27 participants were challenged with methacholine 0.33% (verum) and 29 patients received NaCl 0.9% (placebo). The challenge was applied as 5-step-test using a storage bag. The doses were elevated by doubling the aerosol volume. A positive test result was assumed when basal specific airway resistance (sRt) reduplicated and simultaneously 2.0 (kPa*s) was attained. Ten out of 27 subjects in the verum group (33.3%) had a positive test result whereas in the placebo group only one subject showed a reaction (3.5%). A statistically significant association between the change of sRt and the cumulative methacholine dose was confirmed in the verum group (p < 0.002), whereas this effect could not be observed in patients challenged with placebo (p = 0.20). Side effects did not occur. We conclude that inhalative challenge with methacholine 0.33% applied as a 5-step-test is suitable to objectify BHR. The substantial benefit of the applied test scheme is the short range of time in which the challenge can be performed (approximately 20 min) and that dilution series of the test substance (methacholine 0.33%) are not required.     

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

Fifty children (27 females, 23 males) ages 6-15 years who were referred for evaluation of suspected asthma had baseline FEV1 and FEF25-75 of greater than or equal to 80% and FEF50 greater than or equal to 70% of predicted values. All had these tests repeated on the same day, after inhaling salbutamol. On a subsequent day PC-20 (methacholine) was determined as an index of bronchial hyperreactivity (BH). Fourteen age-matched healthy children (6 females, 8 males) were studied in a similar manner. There was no significant relationship between the PC20 and the change in FEF25-75 or FEF50 following salbutamol. There was a negative correlation between the initial FEV1 (% predicted) and the percent change in FEV1 following salbutamol (P less than 0.01). An increase in FEV1 of greater than 6% occurred in 7/12 (58.3%) patients with PC20 less than or equal to 0.25 mg/mL (Group I); in 7/24 (29.2%) patients with PC20 = 0.26-2.0 mg/mL (Group II); in only 1/14 (7.1%) patients with PC20 greater than 2.1 mg/mL (Group III) and in none of those asymptomatic (control) children with PC20 greater than 8.0 mg/mL (Group IV). All subjects who had a change in FEV1 greater than 6% after salbutamol had a PC20 less than 8 mg/mL and this test detected the majority of patients with severe BH. However, although the sensitivity of the test was 100%, the predictive value was only 36%. We conclude that in the presence of a normal baseline FEV1 a change of greater than 6% following salbutamol inhalation is indicative of bronchial hyperreactivity.     

支气管激发和舒张试验测试对哮喘患者呼出气一氧化氮的影响及意义

目的:研究乙酰甲胆碱(Mch)支气管激发试验和沙丁胺醇支气管舒张试验对哮喘患者呼出气一氧化氮(FeNO)的影响及意义。方法:选取2011年6月至2015年8月,我院呼吸内科门诊收治的98例哮喘患者作为研究对象。基于患者第1秒用力呼气容积/用力肺活量(EFV1/FVC)值以及配合程度,随机分为Mch支气管激发试验组(激发试验组)和沙丁胺醇支气管舒张试验组(舒张试验组),两组均49例。激发试验组患者通过Astograph Jupiter-21进行Mch激发试验;舒张试验组患者通过Jaeger肺功能仪进行沙丁胺醇舒张试验。比较患者试验前FeNO(Pre-FeNO)以及试验完成后5minFeNO(PostFeNO)的差异。结果:激发试验组患者Post-FeNO为24.08±2.35(ppb),显著低于Pre-FeNO的28.07±1.34(ppb)(t=1.354,P=0.026),其中支气管激发试验阳性患者Pre-FeNO值与Post-FeNO值具差异有统计学意义(t=3.246,P=0.017),而阴性患者差异无统计学意义(t=0.857,P=0.076);舒张试验组患者Pre-FeNO为36.83±2.46(ppb),Post-FeNO为34.69±2.16(ppb),试验前后比较差异无统计学意义(t=0.769,P=0.125)。结论:沙丁胺醇支气管舒张试验对患者FeNO仅有轻微的影响,但Mch支气管激发试验会显著降低哮喘患者FeNO值,因此临床应用Mch支气管激发试验诊断哮喘时应特别谨慎。     

Intrasubject between-day variability of PD20 methacholine assessed by the dosimeter inhalation test

The intrasubject between-day variability of the methacholine inhalation test (MIT) was estimated in a group of 30 patients (15 males, mean age 29 yr), representative of a wide range of degrees of nonspecific bronchial responsiveness (from normal to severely increased). In each patient, an MIT with the dosimeter method was carried out on three separate occasions within one week, keeping as constant as possible both the technical and patient-related factors (FEV1 within +/- 5 percent, no recent airway inflammation) and independently from operator-related factors (three tests, three different operators blinded with regard to previous MIT results). On each occasion, twofold increasing doses of methacholine were given from 6.25 to 3,200 micrograms as cumulative doses, at five-minute intervals by means of a dosimeter Me.far MB3 (nebulization time 0.8 +/- 0.2s, output 5 +/- 0.2 microliters/puff). The FEV1 was measured initially and 1.5 and 3 minutes after each inhalation. The test was continued until either a fall of 20 percent or more in FEV1 was obtained or the last dose was reached. The results were expressed in terms of PD20, ie, the dose of methacholine producing a 20 percent fall in FEV1. Under these carefully controlled conditions, the 95 percent confidence intervals (as based on a single determination) corresponded to +/- 0.22 on a log10 scale or, in a more meaningful way, +/- 1.66 fold-difference in PD20 from one visit to the other.     

Effect of deep inhalations after a bronchial methacholine provocation in asthmatic and non-asthmatic subjects

Deep inhalations cause a transient relaxation of the peripheral airways smooth muscles in non-asthmatic subjects. It has been claimed that the airway response to deep inhalations may be different in asthmatic subjects in whom deep inhalations should rather cause bronchoconstriction. The aim of the present study was to find out whether deep inhalations discriminate between asthmatic and non-asthmatic subjects with pre-constricted airways, using a methacholine provocation test protocol with deep inhalations following the last dose of methacholine. In 164 adults, a methacholine provocation was performed. Directly after the FEV1 measurement at the highest metacholine concentration, the subjects took one deep breath and another three deep inhalations 20 s later. One minute after the inhalation of the highest concentration FEV1 was measured twice. Thirty-three asthmatics PD20FEV1 = 0.24 mg (0.13-0.39) (median, 25-75th 75th percentiles) and 131 non-asthmatics PD20FEV1 = 2.05 mg (0.72-10.1) participated. The mean maximal decrease in FEV1 after the provocation test was 36% in the asthmatics and 27% in the non-asthmatics. Corresponding values after the deep inhalations were 18% in the asthmatics and 12% in the non-asthmatics. In conclusion, deep inhalations attenuate the methacholine-induced bronchoconstriction in both asthmatic and non-asthmatic subjects. Thus, the effect of deep inhalations did not discriminate between asthmatic and non-asthmatic subjects.     

Exhaled nitric oxide following leukotriene E(4) and methacholine inhalation in patients with asthma

Nitric oxide (NO) is a molecular gas that can be recovered in higher levels from the exhaled gas of subjects with asthma than from subjects without asthma. However, the precise mechanisms responsible of promoting increased fraction of expired nitric oxide (FE(NO)) in asthma are unknown. As leukotriene antagonism has been shown to reduce FE(NO) in patients with asthma, we hypothesized that leukotrienes mediate the increased FE(NO) encountered in this condition. Furthermore, because leukotriene antagonism stabilizes serum eosinophil markers during reductions in inhaled corticosteroid doses, and FE(NO) has been shown to correlate with sputum eosinophils in asthma, we reasoned that the effect of leukotrienes on FE(NO) might be mediated by eosinophils recruited to the airway by leukotrienes. To test this hypothesis, we performed methacholine and leukotriene (LT) E(4) bronchoprovocation challenges in 16 subjects with atopic asthma and measured FE(NO) and sputum differential counts before and after bronchoprovocation. We then compared FE(NO) in the seven subjects who developed increased sputum eosinophils following LTE(4) inhalation with values measured after methacholine inhalation in these seven subjects. Following LTE(4) inhalation, eosinophils rose from 4.01 +/- 0.89% pre-LTE(4) to 8.33 +/- 1.52% post-LTE(4). The mean change in sputum eosinophils from baseline after LTE(4) inhalation was larger than that after methacholine inhalation (+4.31 +/- 1.25% versus -1.14 +/- 0.93%). After LTE(4) inhalation, FE(NO) levels did not differ from prechallenge baseline or from levels following methacholine inhalation (ANOVA p > 0.05). These data indicate that neither LTE(4) nor recruitment of eosinophils into the airway by LTE(4) is a sufficient stimulus to acutely increase FE(NO) in subjects with asthma.     

An assessment of methacholine inhalation tests in elderly asthmatics

We have assessed the feasibility and value of measuring nonspecific bronchial responsiveness to methacholine in investigation of asthma in the elderly. Results from duplicated tests in 20 subjects aged 65-82 years were expressed as dose provoking a 20% decrement in 1 second forced expiratory volume (PD20.FEV1) or peak expiratory flow (PD20.PEF). Repeatability for PD20.FEV1 was satisfactory but less good than in younger subjects, 95% confidence limits being 0.39-2.57 and 0.52-1.91, respectively, x initial PD20. For PD20.PEF, confidence limits were wider (0.26-3.91 x initial PD20) but multiple PEF measurements were better tolerated than those of FEV1, which commonly caused fatigue and dizziness. PD20.FEV1 and PD20.PEF correlated closely (r = 0.95, P less than 0.0001) and both predicted bronchodilatation following a 6-week course of inhaled corticosteroid and beta agonist. This was not predicted by the response to a single dose of beta agonist. We conclude that measurement of bronchial responsiveness is feasible and clinically valuable in elderly subjects.     

Changes in the highest frequency of breath sounds without wheezing during methacholine inhalation challenge in children

A breath sound analyser was used to detect bronchoconstriction without wheezing during methacholine inhalation challenge in children. The highest frequency of inspiratory breath sounds increased significantly during bronchoconstriction and decreased after inhalation of a bronchodilator. The highest frequency of inspiratory breaths sounds was correlated with bronchial reactivity. Background and objective: It is difficult for clinicians to identify changes in breath sounds caused by bronchoconstriction when wheezing is not audible. A breath sound analyser can identify changes in the frequency of breath sounds caused by bronchoconstriction. The present study aimed to identify the changes in the frequency of breath sounds during bronchoconstriction and bronchodilatation using a breath sound analyser. Methods: Thirty‐six children (8.2 ± 3.7 years; males : females, 22 : 14) underwent spirometry, methacholine inhalation challenge and breath sound analysis. Methacholine inhalation challenge was performed and baseline respiratory resistance, minimum dose of methacholine (bronchial sensitivity) and speed of bronchoconstriction in response to methacholine (Sm: bronchial reactivity) were calculated. The highest frequency of inspiratory breath sounds (HFI), the highest frequency of expiratory breath sounds (HFE) and the percentage change in HFI and HFE were determined. The HFI and HFE were compared before methacholine inhalation (pre‐HFI and pre‐HFE), when respiratory resistance reached double the baseline value (max HFI and max HFE), and after bronchodilator inhalation (post‐HFI and post‐HFE). Results: Breath sounds increased during methacholine‐induced bronchoconstriction. Max HFI was significantly greater than pre‐HFI (P < 0.001), and decreased to the basal level after bronchodilator inhalation. Post‐HFI was significantly lower than max HFI (P < 0.001). HFI and HFE were also significantly changed (P < 0.001). The percentage change in HFI showed a significant correlation with the speed of bronchoconstriction in response to methacholine (P = 0.007). Conclusions: Methacholine‐induced bronchoconstriction significantly increased HFI, and the increase in HFI was correlated with bronchial reactivity.     

A protocol for performing reproducible methacholine inhalation tests in children with moderate to severe asthma

Reproducibility of methacholine inhalation tests (MIT) over a 2-wk period has been established in adult populations, but similar studies demonstrating reproducibility in children are lacking. We set out to establish the reproducibility of MIT in children as a prerequisite for a study of the natural history of airway hyperreactivity in asthmatic children. Most inhalation testing is done in persons with mild asthma because the recommended time interval for the withholding of medications prior to bronchial challenge is poorly tolerated by more labile asthmatics. In order to evaluate asthmatics with more severe disease, we modified a standardized method of methacholine inhalation to include a three-tier pretest medication regimen and investigated the reproducibility of this MIT protocol in 11 children as young as 6 yr of age. The three tiers were designed to keep baseline FEV1 greater than or equal to 70% predicted since diminished baseline airway caliber may affect MIT results. Eight of the 11 children were bronchodilator-dependent, and two of the eight also required inhaled steroids. Eleven children (6 to 13 yr of age) underwent MIT, between December and March, 1 day, 1 wk, and 1 month after an initial test. The PD20FEV1 using cumulative breath units (BU) were compared. The range of PD20FEV1 in the 11 children was 0.27 to 14.4 BU, with nine subjects classified as severe (PD20FEV1 less than 2.5 BU). We found a high degree of reproducibility of MIT. The interest correlation coefficient (r) was 0.98 after 1 day, 0.95 after 1 wk, and 0.96 after 1 month.(ABSTRACT TRUNCATED AT 250 WORDS)     

Investigation on the protective value of breathing masks in farmer's lung using an inhalation provocation test

Six subjects with farmer's lung underwent double inhalation challenge tests, each lasting 60 min, using natural antigen exposure. Subjects underwent the tests first without and then with protection by a particle-filtering half mask. Our purpose was to determine whether and to what extent the use of such masks reduced or prevented symptoms in affected patients. Clinical assessment included general and pulmonary symptoms, HR, temperature, WBC count, R, ITGV, VC, TLC, PO2, DCO, and chest x-ray film. The unprotected challenge provoked late responses characteristic of extrinsic allergic alveolitis. In the challenge using the mask, all six patients reported to be completely free of symptoms. Compared with the test without a mask, a statistically significant reduction in the rise of temperature, WBCs, HR, R, TLC, and PO2 was observed. Compared with the initial values, a statistically significant reduced increase of temperature and leukocytes was demonstrated in the test using the mask. Pulmonary and systemic alterations were significantly reduced but not completely prevented by the application of the particle-filtering half mask.