The Effect of Thoracosopic Thoracic Sympathetomy on Pulmonary Function and Bronchial Hyperresponsiveness

Background. Endoscopic thoracic sympathectic denervation (ESD) is a procedure used in primary hyperhidrosis and upper extremity ischemia. Bronchial tone is affected by the sympathetic and parasympathetic nervous systems and bronchial asthma is associated with an imbalance between them. The aim of this study was to evaluate the effects of ESD on pulmonary function and bronchial hyperresponsiveness (BHR). Patients and methods. Fifty-eight patients with primary hyperhidrosis (n = 54) or upper limb ischemia (n = 4) were included. Spirometry and bronchial provocation test with methacholine was performed before and 4 weeks after ESD. Results. Forced expiratory volume in 1 second (FEV₁) and forced vital capacity (FVC) were significantly decreased early after ESD (from 4.67 ± 0.84 L and 4.36 ± 0.85 L to 4.12 ± 0.78 L and 3.84 ± 0.82 L, respectively), although no patient complained of an aggravation of respiratory symptoms. Twelve patients (21%) had a positive response to methacholine provocation preoperatively, and all remained positive post surgery. The provocative concentration of methacholine, which brought about a 20% decrease in the FEV₁ in the patients, was not significantly changed after surgery (from 5.1 ± 4.3 to 4.6 ± 4.6). Of 46 patients who had a negative result for methacholine challenge preoperatively, 12 (26%) became positive after surgery. In terms of the level of sympathectomy, T3 sympathectomy significantly increased the ratio of patients exhibiting a positive response to methacholine (from 19% to 34%, respectively) (p < 0.005). Conclusions. Thoracic sympathectomy can adversely affect lung function early after surgery, although the clinical significance is uncertain. It may also exert an influence on the development of bronchial hyperresponsiveness, especially when performed at the T3 level.     

Bronchial hyperresponsiveness in Sjögren’s syndrome — relationship between extraglandular manifestation

Abstract

Our objective was to appraise bronchial hyperresponsiveness in Sjögren’s syndrome (SS) and to analyze the clinical aspects of those patients. Forty-five patients with primary and secondary SS underwent examination with chest X-ray, spirometry and directly writing of the dose-response curve of respiratory resistance (R_rs) during the continuous inhalation of methacholine in stepwise incremental concentrations (astograph). Thirty-one patients (68.9%) had bronchial hyperresponsiveness. Ten out of 12 (83.3%) patients with extraglandular involvement had bronchial hyperresponsiveness. The threshold of the increase of R_rs in SS patients was significantly higher than bronchial asthma. This paper shows that some patients with SS have bronchial hyperresponsiveness; especially in patients with extraglandular involvement, it occurs at a high incidence. In addition, the pattern of the dose-response curve with bronchial hyperresponsiveness in SS was similar to that of chronic bronchitis rather than bronchial asthma in the methacholine inhalation test.     

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

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

Effect of interferon-α on pulmonary function and airway responsiveness in patients with chronic hepatitis C

BackgroundInterferon (IFN)-α is the only approved treatment for chronic hepatitis C. Interstitial pneumonia and, rarely, exacerbation of bronchial asthma have been reported as adverse pulmonary effects of IFN-α treatment. The purpose of the present study was to clarify whether IFN-α treatment affects pulmonary function and airway responsiveness in patients with chronic hepatitis C.MethodsWe studied 17 patients (nine males and eight females; mean age 46 years; range 30–62 years) with chronic active hepatitis C diagnosed by serum tests and liver biopsy. Pulmonary function tests included vital capacity (VC), forced expiratory volume in 1 s (FEV₁), forced expiratory flow in the middle half of the forced vital capacity (FVC_25–75%), total lung capacity and carbon monoxide diffusing capacity of the lung (D_LCO), which was adjusted for hemoglobin concentration. Airway responsiveness was measured by methacholine inhalation challenge and determination of the provocative concentration of methacholine causing a 20% fall in FEV₁ (PC₂₀). These tests were performed before and 3 months after initiation of IFN-α therapy.ResultsNo patient developed interstitial pneumonia, although there was a tendency for the hemoglobin-adjusted D_LCO to decrease. Other pulmonary function test parameters were not affected. Overall, there was no significant change in PC₂₀ (from 15.0 to 11.4 mg/mL). In three patients whose initial PC₂₀ was within the normal range, airway hyperresponsiveness was induced and one patient developed bronchial asthma after IFN-α therapy.ConclusionsThese findings suggest that IFN-α induces airway hyperresponsiveness to methacholine in a few patients with chronic hepatitis C.     

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

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

Bronchial Responsiveness,Spirometry and Mortality in a Cohort of Adults

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

Comparison of airway reactivity induced by cold air and methacholine challenges in asthmatic children

Bronchial responsiveness to isocapnic hyperventilation with cold air (CAH) and to inhaled methacholine (MCH) was compared in 17 children with bronchial asthma. The response to cold air was expressed as the percent drop in FEV₁ from baseline at 4 min. after the challenge (Δ% FEV₁ CAH), and the response to methacholine as the provocative concentration required to reduce the FEV₁ by 20% from baseline (PC₂₀MCH). Both tests were sensitive (94%) for detecting airway hyperreactivity. There was no statistically significant relationship between A% FEV, CAH and the log PC₂₀MCH (r = 0.39; P = 0.12). In clinical practice, methacholine test is easier to perform, but in the research field cold air challenge may be preferable because it avoids potential drug effects. © 1995 Wiley-Liss, Inc.     

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.     

Bronchial hyperresponsiveness is a common feature in patients with chronic urticaria.

BACKGROUND: Chronic urticaria (CU) is a skin disorder characterized by long-lasting release of histamine, and sometimes leukotrienes, from both mast cells and basophils. Although both these substances are potent inductors of contraction of airway smooth muscle, pulmonary function and airway hyperresponsiveness have not been systematically investigated in patients with CU. OBJECTIVE: To assess pulmonary function and airway hyperresponsiveness in patients with CU. METHODS: Twenty-six clinically well-characterized adult patients with CU (M/F 8/18; mean age 47 years) underwent pulmonary function tests and methacholine provocation during a phase of moderate activity of their disease. Twenty-six adult asthmatic patients submitted to methacholine provocation were used as controls. RESULTS: Two patients (8%) had overt asthma on baseline pulmonary function tests. Twenty (77%) patients with a normal baseline pulmonary function showed significant bronchial hyperresponsiveness on methacholine provocation. Altogether, 22/26 (85%) patients had asthma or abnormal bronchial reactivity. Airway hyperresponsiveness was not associated with gender, disease duration, intolerance to NSAID, positive autologous serum skin test or respiratory allergy. On average, asthmatic controls showed a much severer airway hyperresponsiveness than urticaria patients (p < 0.01). CONCLUSION: Patients with CU frequently show bronchial hyperresponsiveness. Prospective studies are needed to assess whether they are at risk for bronchial asthma.     

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

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

Bronchial Hyperreactivity to Methacholine in Atopic Versus Nonatopic Asthmatic Schoolchildren and Preschoolers

Background. Atopy and bronchial hyperreactivity are factors related to severe and unremitting asthma of childhood; however, the prevalence of these factors could be different according to age of the child. Objective. To determine if methacholine bronchial hyperreactivity (BHR) differs between atopic and nonatopic preschoolers and schoolchildren with mild-moderate asthma. Methods. Data obtained from 340 children with diagnosis of asthma or recurrent wheezing, matched by atopic conditions (positive or negative skin prick test) and age, and who underwent a methacholine bronchial challenge test (by spirometry in schoolchildren and by transcutaneous oxygen pressure [TcPo₂] in preschoolers) were reviewed. Results. Among 136 schoolchildren (9.07 ± 2.5 years), the prevalence of positive BHR was significantly higher among atopics than nonatopics (75% versus 48.5%, p = .001, respectively), even after controlling for gender and nutritional status (adjusted odds ratio [aOR] = 3.2129, 95% confidence interval [CI]: 1.5–6.8; p = .002). In addition, atopic schoolchildren had lower PC₂₀ and required a lower threshold dose of methacholine to induce a reaction (0.53 versus 0.82 mg/ml, p = .055 and .5 versus 1 mg/ml, p = .02, respectively) than nonatopics. Nevertheless, basal and predicted forced expiratory volume in one second (FEV₁) were similar between groups. In contrast, among 204 preschoolers (4.74 ± 1.1 years), there were no differences in the prevalence of positive BHR between atopics and nonatopics (74.5% versus 72.5%, p = .75, respectively). Furthermore, basal TcPo₂, a higher fall of TcPo₂ and lower threshold doses of methacholine required for induction as measured by TcPo₂ were similar between the atopic and nonatopic preschoolers. Conclusions. Atopic asthmatic schoolchildren have greater hyperresponsiveness to methacholine than nonatopics (only among those with normal nutritional status). However, atopic and nonatopic asthmatic preschoolers have similar hyperresponsiveness to methacholine. Therefore, factors different from atopy may be responsible for wheeze in younger children.     

Mannitol Challenge Does Not Confirm Bronchial Hyperreactivity in Some Histamine-Responsive Asthmatic Children

Objective. The aim of this study was to compare the usefulness of mannitol provocation test to that of classical histamine challenge in children with PC₂₀FEV₁ histamine lower than 4 mg/ml. Methods. Twenty-two adolescent patients (mean age of 15.4 ± 4.1 years) with established asthma (PC₂₀FEV₁ histamine below 4 mg/ml) were included in this study. Bronchial challenge with mannitol was performed 1–2 days after the test with histamine. Results. The fraction of positive results of mannitol test was markedly lower when compared with the histamine challenge (72.7% vs. 100%, p = .015). The test was discontinued in one case due to severe coughing after inhalation of 315 mg of mannitol. Coughing during inhalation of dry mannitol powder occurred in most patients, although drinking water after subsequent doses alleviated this symptom in nearly all of them. Of note, triboelectrification of the inhaler and capsules was observed during the administration of consecutive mannitol doses, markedly hindering the delivery of this provoking agent. The relative decrease in FEV₁ resulting from bronchial provocation was significantly lower following mannitol delivery when compared with the histamine test (70.3% vs. 81.6% of resting value, p < .001). Significant correlation was not observed between the values of PC₂₀FEV₁ histamine and PD₁₅FEV₁ mannitol levels. Conclusions. Bronchial challenge with mannitol can be used as a screening test in everyday practice, but one cannot exclude bronchial hyperresponsiveness based on its negative results. Moreover, its usefulness is limited by the influence of static on the delivery of sequential mannitol doses and coughing which can be often associated with mannitol inhalation.     

Low Attenuation Area Is Associated with Airflow Limitation and Airway Hyperresponsiveness

Background. Asthma is a chronic inflammatory disorder of the airways characterized by airflow limitation and airway hyperresponsiveness. Lung density indices on quantitative computed tomography (QCT) are assumed to reflect the degree of air trapping originated from airflow limitation in airway diseases. Purpose. The present study investigated the availability of lung density indices on QCT in clinical evaluation of asthma. Methods. Eleven asthmatic patients and 48 healthy control subjects were prospectively evaluated by QCT, pulmonary function testing, and a methacholine challenge test. High-resolution computed tomography scans were performed at full-inspiratory and full-expiratory phases, and percentage of lung field occupied by low attenuation area (LAA%) and mean lung density (MLD) at both inspiratory and expiratory phases were measured. Results. MLD values at inspiratory phase were significantly increased in asthmatic patients compared with those in healthy control subjects. Inspiratory LAA% values were significantly decreased in asthmatics compared with the values in control subjects. On expiratory scans, MLD values of asthmatics were significantly lower than the values of control subjects. Expiratory LAA% values of asthmatics were significantly higher than the values of control subjects. The LAA% in the expiratory phase showed significant negative correlation with forced expiratory volume in 1 second (FEV₁), FEV₁/forced vital capacity, and the provocative dose of methacholine causing a 20% decrease in FEV₁ in asthmatic patients. Conclusion. These results suggest that lung density indices on QCT may be useful for clinical evaluation of asthmatic patients and increased LAA% in the expiratory phase is associated with airflow limitation and airway hyperresponsiveness in asthma.     

Relationships Between Airway Hyperresponsiveness,Inflammation, and Calibre in Asthma

Background  

Previous studies have focused upon the relationship between airway inflammation and hyperresponsiveness with different conclusions. We re-examined the relationship between airway inflammation (FE_NO), hyperresponsiveness to methacholine (AHR), and calibre (FEV₁ % predicted) in mild-to-moderate asthmatics.     

Evaluation of interrupter resistance in methacholine challenge testing in children

Bronchial hyperresponsiveness (BHR) is a key feature of asthma and is assessed using bronchial provocation tests. The primary outcome in such tests (a 20% decrease in forced expiratory volume in 1 sec (FEV₁)) is difficult to measure in young patients. This study evaluated the sensitivity and specificity of the interrupter resistance (R_int) technique, which does not require active patient participation, by comparing it to the primary outcome measure. Methacholine challenge tests were performed in children with a history of moderate asthma and BHR. Mean and individual changes in R_int and FEV₁ were studied. A receiver operating characteristic (ROC) curve was used to describe sensitivity and specificity of R_int. Seventy‐three children (median age: 9.2 years; range: 6.3–13.4 years) participated. There was a significant (P < 0.01) increase in mean R_int with increasing methacholine doses. However, individual changes of R_int showed large fluctuations. There was great overlap in change of R_int between children who did and did not reach the FEV₁ endpoint. A ROC curve showed an area under the curve of 0.65. Because of low sensitivity and specificity, the use of R_int to diagnose BHR in individual patients seems limited. Pediatr Pulmonol. 2011; 46:266–271. © 2011 Wiley‐Liss, Inc.     

组胺、乙酰甲胆碱检测气道高反应性不良反应比较

目的 观察组胺与乙酰甲胆碱检测气道高反应性时所出现的不良反应.方法 采用德国耶格（JAEGER）肺功能仪-支气管激发试验检测系统,对60例处于缓解期（肺功能检测正常）的轻度支气管哮喘患者,分别实施组胺与乙酰甲胆碱（乙酰甲胆碱与组胺）支气管激发试验检测.结果 ①60例支气管哮喘患者检测支气管激发试验,激发剂的选择无论是组胺还是乙酰甲胆碱均提示支气管激发试验阳性,支持存在气道高反应性;②支气管激发试验检测过程可见组胺药物不良反应明显大于乙酰甲胆碱,其不良反应程度与随着吸入药物浓度增大、吸入时间延长而增加.结论 药物支气管激发试验激发剂的选择应首选乙酰甲胆碱,组胺应慎选或不选.     

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.     

组胺、乙酰甲胆碱检测气道高反应性不良反应比较

目的 观察组胺与乙酰甲胆碱检测气道高反应性时所出现的不良反应.方法 采用德国耶格(JAEGER)肺功能仪-支气管激发试验检测系统,对60例处于缓解期(肺功能检测正常)的轻度支气管哮喘患者,分别实施组胺与乙酰甲胆碱(乙酰甲胆碱与组胺)支气管激发试验检测.结果 .①60例支气管哮喘患者检测支气管激发试验,激发剂的选择无论是组胺还是乙酰甲胆碱均提示支气管激发试验阳性,支持存在气道高反应性;②支气管激发试验检测过程可见组胺药物不良反应明显大于乙酰甲胆碱.其不良反应程度与随着吸入药物浓度增大、吸人时间延长而增加.结论 药物支气管激发试验激发剂的选择应首选乙酰甲胆碱,组胺应慎选或不选.     

Bronchial hyperresponsiveness in Sjögren’s syndrome — relationship between extraglandular manifestation

Our objective was to appraise bronchial hyperresponsiveness in Sjögren’s syndrome (SS) and to analyze the clinical aspects of those patients. Forty-five patients with primary and secondary SS underwent examination with chest X-ray, spirometry and directly writing of the dose-response curve of respiratory resistance (R_rs) during the continuous inhalation of methacholine in stepwise incremental concentrations (astograph). Thirty-one patients (68.9%) had bronchial hyperresponsiveness. Ten out of 12 (83.3%) patients with extraglandular involvement had bronchial hyperresponsiveness. The threshold of the increase of R_rs in SS patients was significantly higher than bronchial asthma. This paper shows that some patients with SS have bronchial hyperresponsiveness; especially in patients with extraglandular involvement, it occurs at a high incidence. In addition, the pattern of the dose-response curve with bronchial hyperresponsiveness in SS was similar to that of chronic bronchitis rather than bronchial asthma in the methacholine inhalation test.     

Usefulness of Exhaled Nitric Oxide for Diagnosing Asthma

Rationale. A standard asthma diagnosis is made based on clinical history, reversibility of airway obstruction, and bronchial hyperresponsiveness. Fractional exhaled nitric oxide (FeNO) is a noninvasive airway inflammatory marker that has been suggested as a diagnostic tool for asthma. The aim of this study was to establish a FeNO cut-off value for asthma diagnosis. Methods. One hundred and fourteen consecutive adult patients (mean age 34 ± 13 years) reporting symptoms consistent with asthma, with normal spirometric parameters and a negative bronchodilator test, were included in the study. All underwent a methacholine challenge test following the five-breath dosimeter protocol. FeNO was measured with a portable device (NioxMino, Aerocrine AB, Sweden) just before the methacholine challenge. The sensitivity, specificity, and diagnostic performance of FeNO measurement were calculated. Results. Thirty-five out of the 114 patients (30.7%) were diagnosed with asthma. A positive methacholine challenge was associated with higher FeNO levels and with lower forced expiratory volume in one second (FEV₁) at baseline. No correlation was found between methacholine provocative concentration causing a decrease of 20% in FEV₁ (PC₂₀) and FeNO levels. A receiver-operating characteristic curve was constructed for FeNO levels (area under the curve [AUC]: 0.762; 95% confidence interval [CI]: 0.667-0.857; p < .001). The FeNO cut-off point with maximal specificity and sensitivity for asthma diagnosis was 40 ppb. Conclusions. Patients with confirmed asthma showed higher FeNO levels. A cut-off value of 40 ppb was calculated as the most efficient for asthma diagnosis in our population. The use of FeNO measurement may be a helpful tool to rule out a diagnosis of asthma, especially in patients in whom a methacholine challenge is not feasible or available.