Methacholine challenges in the management of young children

Methacholine bronchial challenges (MBCs) have been used as an important diagnostic and management tool for physicians who treat children with chronic asthma. Despite this, children less than 5 years of age present significant diagnostic and management questions that can not easily be answered because of their inability to perform standard spirometry, and thus methacholine bronchial challenges. The present study was designed to evaluate with methacholine bronchial challenge small children (between 2 and 6 years of age) with the diagnosis of or a suspected diagnosis of asthma, utilizing a new method of evaluating airflow in small children through sound analysis, Computer Digitized Airway Phonopneumography (CDAP). There were 23 children in the study between the ages of 2 and 6 years with suspected asthma who could not perform pulmonary function tests. A control group consisting of 12 subjects between the ages of 8 and 38 years of age with a history of chronic cough and/or wheezing who could perform pulmonary function tests was also studied. Of the 12 patients over the age of 8 who had MBC, 11 of them had positive challenges with a fall in FEV1 of 19% or greater. The percent change in sound intensity levels from baseline range from 232% to 396% of baseline. There was greater than 200% change in mean intensity levels with a concentration of methacholine that produced a 19% fall in FEV1 in all of the eleven patients. For one individual who had a negative MBC there was only a 16% change in pulmonary function at 25 mg of methacholine with essentially no change in sound intensity level from baseline.(ABSTRACT TRUNCATED AT 250 WORDS)     

The diagnostic role of the methacholine inhalation challenge in adult patients with chronic persistent cough]

Chronic persistent cough (CPC) is a common medical problem. We determined the value of the methacholine inhalation challenge (MIC) in the evaluation of CPC. We also sought other clinical factors that affect MIC. Patients were selected for the study if 1) CPC was the only presenting symptom, 2) a current roentgenogram did not contribute to the diagnosis, and 3) spirometry revealed a normal FEV1. We measured the minimum dose of methacholine (bronchial sensitivity, Dmin) by the "Asthograph" method. We determined the correlation between log Dmin and demographic and clinical variables, i.e. age, %FVC, %FEV1, FEV1%, %V50, %V25, eosinophil count in peripheral blood, and serum IgE level. The causes of CPC in 51 patients (20 men and 31 women, mean age 41 years) were cough-variant asthma in 29 patients, postinfectious persistent cough in 13 patients, atopic cough in 6 patients, and others in 3 patients. Log Dmin significantly but weakly correlated with %V25 (4 = 0.31, p = 0.02). The sensitivity and specificity of Dmin (< 10 units) in diagnosing cough-variant asthma was 93% and 87%, respectively. Demographic or clinical variables other than Dmin were not useful for the diagnosis of cough-variant asthma. We conclude that MIC is useful for the differential diagnosis of CPC while the usefulness is limited in some cases.     

Chronic cough, sinusitis, and hyperreactive airways in children: an often overlooked association

Ten patients, aged 7 to 16 years, were prospectively evaluated for chronic cough of more than 4 months duration. All patients denied wheezing, but in addition to cough complained of chronic obstructive nasal symptoms. Sinus roentgenograms were consistent with sinusitis in 7/10 patients. Methacholine bronchial provocation was positive in 6/9 patients. The patients were recalled for a 2-year follow-up evaluation. Of seven follow-up patients, bronchial asthma had developed in three, two patients had chronic cough and exercise-induced bronchospasm, and two patients had chronic cough without wheezing. Methacholine bronchial provocation was positive in 6/6 patients. Sinus roentgenograms were compatible with sinusitis in 4/7 patients. Chronic cough in some children may be a complaint of diffuse hyperreactive airways complicated by sinusitis. In some of the children the clinical course evolved into a diffuse respiratory tract disorder including chronic obstructive eosinophilic rhinitis, recurrent or chronic sinusitis and bronchial asthma. An IgE-mediated mechanism usually could not be shown in the pathogenesis.     

Inflammation and functional outcome in diisocyanate-induced asthma after cessation of exposure

Background:  The clinical outcome of diisocyanate-induced asthma has been found to be poor despite cessation of exposure. Our aim was to study the outcome of diisocyanate-induced asthma after initiation of inhaled steroid treatment at a mean period of 7 months (range 2–60 months) after cessation of exposure by following up lung function and bronchial inflammation.
Methods:  Bronchoscopy was performed on 17 patients 2 days after a positive inhalation challenge test, after which budesonide 1600 μg a day was started. Bronchoscopy, spirometry, and histamine challenge tests were repeated at 6 months and on average 3 years. The results were also compared with those obtained from 15 healthy control subjects.
Results:  Nonspecific bronchial hyperreactivity diminished significantly ( P  = 0.006); however, forced expiratory volume in 1 s (FEV1) and forced vital capacity (FVC) values decreased, with a median yearly reduction of FEV1 of 79 ml. The count of mast cells in bronchial mucosa decreased ( P  = 0.012) and that of macrophages increased ( P  = 0.001). Interleukin-4 level in mucosa was during the first year significantly higher than in controls but its level decreased in the follow-up. Interleukin-6, interleukin-15, and tumour necrosis factor alpha messenger-RNA levels were significantly higher in hyperreactive patients than in nonhyperreactive patients at the end of the follow-up.
Conclusion:  Our results indicate that inflammation may persist in diisocyanate-induced asthma despite inhaled steroid medication. However, TH2-type inflammation diminished. Persistent nonspecific bronchial hyperreactivity was associated with proinflammatory acting cytokines produced mainly by macrophages. Considering the poor prognosis of the disease the findings could be utilized to develop the follow-up and treatment of diisocyanate-induced asthma.     

Grading severity and treatment requirements to control symptoms in asthmatic children and their relationship with airway hyperreactivity to methacholine

Airway hyperreactivity has been proposed to be an important determinant of severity of asthma and medication needs to control symptoms in adults. In this study we tried to determine if this relationship existed in childhood asthma. One hundred and forty-five asthmatic children aged 6 to 19 years with a positive methacholine (MCH) challenge test and a baseline forced expiratory volume in one second (FEV1) of 56% to 118% predicted were studied. The MCH concentration required to decrease the FEV1 from baseline by 20% (PC20) ranged from 0.1 to 20 mg/mL (geometric mean = 1.85 mg/mL). Asthma symptoms in this population before the study ranged from 2 months to 14 years. They were followed for a mean of 10 months after the MCH challenge and then grouped into four groups according to overall severity of symptoms and treatment needed to control symptoms. The first grade was comprised of patients with intermittent symptoms only, with a respiratory tract infection (URTI), and no medication; grade 2 symptoms were severe enough to require intermittent bronchodilators (BD); grade 3 symptoms were severe enough to require daily BD; and grade 4 symptoms were severe enough to require daily BD and steroids. Geometric means PC20 were significantly different among the four groups when they were analyzed by ANOVA P less than .01. There was, however, marked overlap between the individual levels of PC20 among the four groups. There was no significant difference in mean FEV1, age, sex, or duration of symptoms among the four groups. There was no significant correlation between baseline FEV1 and the degree of airway hyperreactivity.(ABSTRACT TRUNCATED AT 250 WORDS)     

Effect of hyperoxia on bronchial response to inhaled methacholine

Bronchial reactivity to methacholine (MCH) under normoxic and hyperoxic conditions was studied in a double-blind controlled study in 10 normal subjects and nine asthmatic patients. The normal volunteers were challenged while breathing dry, 21% and 100% O2, and the maximal percent falls in forced expired volume in is (FEV1) following inhalation of the highest concentration of MCH (64 mg/ml) were 8 +/- 5% and 9 +/- 8%, respectively; P = NS. The asthmatic patients had their MCH challenge breathing the same gas composition and the provocative concentrations that caused a 20% fall in FEV1 (PC20) were 0.18 mg/ml (range 0.06-5.73) and 0.25 mg/ml (range 0.07-8.49), respectively, which were statistically not significantly different. We conclude that in humans, 100% O2 does not affect bronchial reactivity to MCH.     

Eosinophilic airway inflammation in nasal polyposis.

BACKGROUND: Asthma and asymptomatic bronchial hyperresponsiveness (BHR) are frequent findings in patients with nasal polyposis (NP). OBJECTIVE: To elucidate mechanisms responsible for the development of BHR, we initiated a prospective study of bronchial inflammation as assessed by bronchial lavage (BL) and bronchial biopsy specimens in 35 patients with noninfectious NP. METHODS: BHR was determined with methacholine provocation testing. Differential cell count, ECP, and histamine and tryptase levels were determined in BLs. Pathologic examination of bronchial biopsy specimens was performed with May-Grünwald-Giemsa stain to assess the number of lymphocytes. Indirect immunoenzymatic methods were used to identify eosinophils and mast cells. RESULTS: Fourteen patients did not exhibit BHR (group A); 7 patients had asymptomatic BHR (group B); and 14 patients had BHR associated with asthma (group C). Patients of group C tended to have a longer duration of nasal symptoms than those of groups A and B. FEV1 (L) was significantly lower in group C than in groups A and B. The number and percentage of eosinophils were significantly higher in BLs in groups B and C than in group A (P <. 05). Patients of groups B and C had a significantly higher number of eosinophils in bronchial submucosa (14.0 +/- 1.5/mm2 and 19.0 +/- 1. 9/mm2, respectively) than patients of group A (0.1 +/- 0.1/mm2). The number of lymphocytes was also higher in groups B and C than in group A. FEV1 (percent of predicted value) and eosinophil number within bronchial mucosa correlated negatively. CONCLUSION: Our results demonstrate that patients with NP and asymptomatic BHR had an eosinophilic bronchial inflammation similar to that observed in asthmatic patients with NP, whereas patients with NP without BHR do not feature eosinophilic lower airways inflammation. The clinical relevance of these results requires careful follow-up to determine whether eosinophilic inflammation in these patients precedes and is responsible for the development of obvious asthma.     

Passive cigarette smoke-challenge studies: increase in bronchial hyperreactivity.

Degree and duration of bronchial hyperreactivity (BHR) after environmental tobacco smoke (ETS) inhalation was assessed in 31 smoke-sensitive subjects with asthma who exhibited lower airway symptoms on ETS exposure (group I) and 39 smoke-sensitive subjects without asthma who manifested only upper airway symptoms on cigarette-smoke exposure (group II). Subjects were challenged with ETS for 4 hours in a static-test chamber. The atmosphere was continuously monitored for airborne particulate levels (800 cpm), total suspended particulates (1266 +/- 283 micrograms/m3), and airborne nicotine levels (226 +/- 49 micrograms/m2). Methacholine challenges were performed before and serially after cigarette-smoke exposure, and the provocative dose causing a 20% fall in FEV1 was determined. Five of the 31 smoke-sensitive subjects with asthma and none of the smoke-sensitive subjects without asthma reacted to cigarette-smoke challenge (greater than or equal to 20% fall from baseline FEV1). Thirty-two percent (10/31) of the subjects with asthma demonstrated increased BHR at 6 hours, 29% (9/31) at 24 hours, and 13% (4/31) up to day 14 after ETS challenge. Of the subjects without asthma, 18% (7/39) demonstrated increased BHR at 6 hours, 10% (4/39) at 24 hours, and 8% (3/39) at 3 weeks. These studies demonstrated an increase in BHR after cigarette-smoke challenge in a number of study subjects (although they were clinically asymptomatic) and suggest that prolonged subclinical airway inflammation can occur in the absence of demonstrable change in airway caliber on exposure to ETS.     

Longitudinal decline in pulmonary function in atopic cough and cough variant asthma

OBJECTIVE: Cough variant asthma and atopic cough are different clinical manifestations of eosinophilic airway inflammation presenting with isolated chronic non-productive cough. The aim of this study was to examine the longitudinal change in pulmonary function in cough variant asthma and atopic cough. METHODS: Longitudinal change in FEV1 was prospectively examined in 20 patients with cough variant asthma, 14 patients with atopic cough and 271 asymptomatic healthy subjects. All were lifetime non-smokers. Of the 20 cough variant asthma patients, 13 were taking long-term inhaled corticosteroid therapy (ICS) (beclomethasone dipropionate 615 +/- 58 micro g/day) and the other seven were not. Spirometry was taken at first visit, after cough was almost completely relieved on therapy, and at least once every year for 5 or more years afterwards. RESULTS: The slope of longitudinal change in FEV1 was not significantly different among cough variant asthma patients (- 0.029 +/- 0.007/year), atopic cough patients (- 0.021 +/- 0.022/year) and asymptomatic subjects (- 0.028 +/- 0.002 L/year). In patients with cough variant asthma, the slope in patients not taking inhaled corticosteroids (ICS) was 0.032 +/- 0.007 L/year, which was not significantly different from that in patients taking ICS (- 0.027 +/- 0.010 L/year). CONCLUSION: Pulmonary function decline is not greater in cough variant asthma than atopic cough and the normal population, and long-term ICS has no effect on the decline in cough variant asthma.     

Bronchial hyperresponsiveness in children with atopic rhinitis: a 7-year follow-up

BACKGROUND: A high prevalence of bronchial hyperresponsiveness (BHR) was found in atopic subjects with rhinitis. Those subjects may be at higher risk for developing bronchial asthma. We evaluated, in a 7-year follow-up, BHR and atopy in a homogeneous population of nonasthmatic children with allergic rhinitis (AR), and their role in asthma development. METHODS: Twenty-eight children (6-15 years) with AR were studied. At enrollment (T(0)), skin tests, total serum IgE assay, peak expiratory flow (PEF) monitoring and methacholine (Mch) bronchial challenge were performed. BHR was computed as the Mch dose causing a 20% forced expiratory volume (FEV)(1) fall (PD(20)FEV(1)) and as dose-response slope (D(RS)). Subjects were reassessed after 7 years (T(1)) using the same criteria. RESULTS: At T(0), 13 children (46%), showing a PD(20)FEV(1) <1526 microg of Mch, had BHR (Mch+), although PEF variability (PEFv) was within normal limits. None of the children with negative methacholine test developed bronchial asthma after 7 years. Of the 13 Mch+, only two reported asthma symptoms after 7 years. No significant change was seen in the other parameters of atopy considered. CONCLUSION: Children with allergic rhinitis present a high prevalence of BHR. Nevertheless, their PEFv is normal and the rate of asthma development low.     

Allergy immunotherapy as an early intervention in patients with child-onset atopic asthma

BACKGROUND: In patients with bronchial asthma an effective treatment is required at early stages of the disease to prevent irreversible structural changes of the airways. The objective of this study was to evaluate the beneficial effects of our routine immunotherapy as an early intervention on FEV1 in patients with child-onset atopic asthma. METHODS: Beneficial effects of successful immunotherapy on FEV1 were analyzed retrospectively in 43 unselected patients who received our routine standard subcutaneous immunotherapy with periodic FEV1 measurements and became asymptomatic. RESULTS: Although there was no significant correlation between the duration of asthma symptoms prior to immunotherapy and the changes in FEV1 before and after immunotherapy in 43 unselected patients, there was a significant inverse correlation between these two parameters in 23 patients whose asthma duration was less than 20 years. As the FEV1 increased after immunotherapy in all 14 patients whose asthma duration was less than 5 years, the 43 patients were divided into a group 1 including these 14 patients and a group 2 including 29 patients whose asthma duration was more than 5 years. The FEV1 decreased in 7 of the 29 asymptomatic patients in group 2. There was no difference in the initial FEV1 between the two groups, but the final FEV1 and the mean of the average increase in FEV1 per year by immunotherapy were significantly higher in group 1 than in group 2. CONCLUSIONS: Immunotherapy should be started as early as possible at the youngest age in order to increase a beneficial effect of successful immunotherapy on FEV1 improvement.     

Cough sensitivity and extrathoracic airway responsiveness to inhaled capsaicin in chronic cough patients

Enhanced cough response has been frequently observed in chronic cough. Recently, extrathoracic airway constriction to inhaled histamine was demonstrated in some chronic cough patients. However, relation between extrathoracic airway hyperresponsiveness (EAHR) and cough sensitivity determined by capsaicin inhalation is unclear in each etiological entity of chronic cough. Seventy-seven patients, with dry cough persisting for 3 or more weeks, normal spirometry and chest radiography, and 15 controls, underwent methacholine bronchial provocation test and capsaicin cough provocation test. Elicited cough number and flow-volume curve was examined after inhalation of capsaicin to evaluate cough sensitivity and EAHR. Thirty-three patients, with postnasal drip, showed normal extrathoracic airway responsiveness, and 27 of them showed normal cough sensitivity to capsaicin. Cough sensitivity was enhanced in 14 patients with cough variant asthma (CVA) who showed bronchial hyperresponsiveness; EAHR to inhaled capsaicin was present in 12 of them. The remaining 30 patients were tentatively diagnosed as idiopathic chronic cough (ICC). Eleven ICC patients showed enhanced cough sensitivity and EAHR to inhaled capsaicin while 19 patients showed normal values. These results indicate that cough sensitivity is closely related with extrathoracic airway responsiveness during capsaicin provocation in some chronic cough patients. EAHR and enhanced cough sensitivity to inhaled capsaicin may be a part of mechanism developing chronic cough.     

Inhaled budesonide aerosols in treatment of childhood asthma

Twenty-six children with chronic bronchial asthma, 19 boys and 7 girls, aged between 6 and 16 years with duration of asthma ranging from 1-12 years, were studied by a control, oral prednisolone 5 mg twice a day and inhaled budesonide 200 micrograms twice daily, each for 3 weeks. The clinical efficacy assessed daily by day and night symptom scores of cough, wheeze, sleep disturbance, limitation of activity, symptomatic inhaled terbutaline usage, daily morning and afternoon Peak Expiratory Flow Rate (PEFR), and weekly PEFR and Forced Expiratory Volume in 1 second (FEV1) in percent of predict, showed statistically significant improvement during the inhaled budesonide aerosol and oral prednisolone treatment periods in comparison with the control. No side effect was observed during any study periods.     

The effect of sputum induction on spirometry parameters in patients with bronchial asthma

Evaluation of differential cell count and biochemical parameters in sputum seems to be a valuable method in asthma studies. The purpose of the paper was to evaluate the effects of sputum induction alone and after fenoterol and salmeterol premedication, on spirometry in asthma patients. The another aim of the study was to observe the correlation between bronchial hyperreactivity and decreases in FEV1 and MEF50 in asthmatics during sputum induction. The studies were carried out on 20 mild to moderate asthma patients (FEV1 baseline 79 +/- 16% of the predicted values) who inhaled an increasing concentration of hypertonic saline (3%, 4% and 5%), using an ultrasonic nebuliser. The forced expiratory volume in one second and MEF50, as the good indicators of bronchial obturation, were evaluated. During the sputum induction significant decreases in FEV1 and MEF50 were observed, which were proportional to the concentration of NaCl. After inhalation of 3% of NaCl the mean of FEV1 was 87.2 +/- 12.7% of the baseline, after 4%--84.3 +/- 16.9% and 5%--77.4 +/- 19.8%. No significant correlation between bronchial hyperreactivity and the induced decreases in FEV1 and MEF50 were found. Fenoterol and salmeterol fully prevented bronchial obturation during sputum induction.     

Angiotensin converting enzyme (ACE) inhibitor-induced cough in non-smoking hypertensive patients]

The author studied the characteristics of ACE inhibitor-induced cough in 41 non-smoking hypertensive patients. For at least 6 months, 20 patients (10 males and 10 females) were treated with enalapril, and 21 (11 males and 10 females) with aracepril. The results were as follows. 1) ACE inhibitor-induced cough was induced in 7 cases (1 male and 6 females). The incident rate of cough was 17.1%. ACE inhibitor-induced cough was not significantly related to past allergic history or to the beta-adrenergic blocker therapy. The laboratory findings of the cough sufferers--such as eosinophil percent in venous blood, serum GOT and GPT, urea nitrogen, creatinine, renal function (PSP excretion test and creatinine clearance), and pulmonary function (%FVC, FEV1.0% and %V25)--were not significantly different from those of the non-coughers. 2) Inhibitory effects of ipratropium bromide inhalation of ACE inhibitor-induced cough were noted in 83.3% of the patients, but their coughs did not completely disappear. From these findings, the pathogenesis of this cough may be related to be as follows. The cough seems to be related to the release of acetylcholine from vagal nerve terminals or to the stimulation of irritant receptors and vagal reflex. 3) Chronic persistent cough or bronchial asthma did not occur after stopping the treatment with ACE inhibitors. The mean follow-up period was 15.6 months.     

Childhood cough variant asthma and its relationship to classic asthma.

BACKGROUND: In pediatrics, some patients with chronic cough who have no evidence of a causative disease are diagnosed as having cough variant asthma (CVA). The precise prognosis of infants and children with CVA, however, is still unclear. OBJECTIVE: To evaluate the relationship between CVA and classic asthma in childhood. METHODS: To diagnose CVA, we performed a methacholine inhalation challenge with use of a transcutaneous oxygen pressure (tcPO2) monitoring system in 100 children with chronic cough, and 75 children (45 boys and 30 girls; mean age, 5.7 years) were diagnosed as having CVA. These patients underwent follow-up monitoring for more than 3 years to ascertain whether classic asthma developed. For comparison, 53 age-matched children with classic asthma (30 boys and 23 girls; mean age, 5.6 years) and 30 age-matched control subjects (12 boys and 18 girls; mean age, 5.5 years) also participated in this study. Consecutive doses of methacholine were doubled until a 10% decrease in tcPO2 from the baseline was reached. The cumulative dose of methacholine at the inflection point of tcPO2 (Dmin-PO2) was considered to represent the sensitivity of tcPO2 to inhaled methacholine. RESULTS: After 3 years or more of follow-up assessments, 52 of the 75 patients answered our questionnaire. Of the responding patients, 28 had been diagnosed as having classic asthma. A significant difference was noted in the age at onset of CVA between the children in whom classic asthma developed (the asthma-developed group) and those in whom classic asthma did not develop (the asthma-free group). No statistically significant differences in Dmin-PO2 between the asthma-developed group and the asthma-free group or between the girls and the boys, however, were foun CONCLUSIONS: This study showed that 75% of children with chronic cough had CVA, that classic asthma developed in 54% of the children with CVA, and that it is not the severity of bronchial hyperresponsiveness in CVA but the age at onset of CVA that is a risk factor for the development of classic asthma in childhood CVA.     

Asymptomatic bronchial hyperresponsiveness in rhinitis

Methacholine inhalation tests are used to help in the diagnosis of asthma when spirometry is normal. However, the significance of increased methacholine responsiveness in patients with rhinitis and no symptoms of asthma is not known. One possibility is that it is a false positive result; another possibility is that it indicates subclinical asthma. We investigated these possibilities in 25 patients with rhinitis, whose attending physician had not made a diagnosis of asthma, by comparing responsiveness to methacholine expressed as the provocation concentration to cause a fall in FEV1 of 20% (PC20) with responsiveness to the natural stimulus of isocapnic hyperventilation of cold air and the diurnal variation of peak flow rate. Asthma was recognized objectively by variable airflow obstruction documented by one of the latter two tests. The PC20 ranged between 4 and greater than 64 mg/ml. In 10 patients the PC20 was less than 16 mg/ml. Five of these patients had bronchoconstriction in response to hyperventilation, and a further two patients demonstrated increased variability of peak flow rates. Thus, in seven of 10 patients, increased bronchial responsiveness was confirmed by the use of two different methods, although they were asymptomatic, and the increased response to methacholine was not a false positive result. In the remaining three patients the PC20 was borderline increased (8 to 16 mg/ml). The results indicate that methacholine responsiveness in the asthmatic range in patients with rhinitis is associated with variable airflow obstruction and subclinical asthma.     

Comparative cutoff points for adenosine monophosphate and methacholine challenge testing.

BACKGROUND: Current use of the PC20 (provocation concentration that causes a decrease in forced expiratory volume in 1 second of 20%) cutoff point for bronchial challenge precludes its use in patients with more severe airflow obstruction. OBJECTIVE: To evaluate the efficacy and safety of lower cutoff points for adenosine monophosphate (AMP) and methacholine (MCH) bronchial challenge tools to monitor response to treatment in chronic asthma. METHODS: We retrospectively examined data from 5 previously published studies (2 using AMP, 2 using MCH, and 1 with MCH and AMP arms) and recalculated 10% and 15% cutoff points for AMP and MCH. Data were analyzed for correlation of single results and doubling dose shifts after anti-inflammatory treatment intervention. RESULTS: A total of 175 individual MCH challenges and 152 AMP challenges were evaluated. Evaluating the doubling dose shift produced by the addition of anti-inflammatory treatment (inhaled corticosteroids or montelukast) produced the following Pearson correlation coefficients: MCH PD20 (provocation dose that causes a decrease in forced expiratory volume in 1 second of 20%) vs PD15, 0.80; MCH PD20 vs PD10, 0.65; AMP PC20 vs PC15, 0.96; and AMP PC20 vs PC10, 0.84 (P < .001 for all). Subgroup analysis of AMP for before and after inhaled corticosteroids only (n = 41) shows AMP PC20 vs PC15 of 0.92 and AMP PC20 vs PC10 of 0.84 (P < .001 for both). CONCLUSIONS: The 10% and 15% cutoff points strongly predict the 20% cutoff value for AMP and MCH, as do the doubling dose shifts after anti-inflammatory treatment. The lower thresholds are suitable for monitoring response to therapy, and they expose patients to significantly less provocation agent.     

慢性咳嗽患者咳嗽敏感性的影响因素

目的探讨慢性咳嗽患者咳嗽敏感性的影响因素.方法按照慢性咳嗽病因诊断程序,人选并诊断慢性咳嗽患者.通过辣椒素咳嗽激发试验测定慢性咳嗽患者(治疗前)的气道咳嗽敏感性,以最先诱发5次或以上咳嗽的辣椒素溶液浓度(C5)的对数作为咳嗽阈值.分析咳嗽阈值与咳嗽积分、年龄、性别、病程、肺通气功能与诱导痰炎性细胞分类间的相关性.结果入选并获得明确诊断的不同病因慢性咳嗽患者共计150例.单因素相关分析显示,慢性咳嗽患者的咳嗽阈值与日间咳嗽积分、性别、年龄、咳嗽病程及诱导痰嗜酸细胞百分比有相关,r分别为-0.175、-0.305、-0.297、-0.238及0.173,P均<0.05;咳嗽阈值与夜间咳嗽积分、痰中性粒细胞百分比、痰巨噬细胞百分比、痰淋巴细胞百分比及肺通气功能[第1秒用力呼气容积占预计值的百分比(FEV1/pred%)、用力呼气中段流速占预计值的百分比(MMEF/pred%)]均不相关,P均>0.05.多元线性回归分析显示,咳嗽阈值仅与性别、咳嗽病程有关(P均<0.01).结论咳嗽敏感性与咳嗽症状积分反映咳嗽程度的不同特征,性别与咳嗽病程可能影响慢性咳嗽患者的咳嗽敏感性.