Pulmonary Function Tests in Thunderstorm-associated Respiratory Symptoms: A Cross-sectional Study.

Background: Epidemic thunderstorm asthma is an observed increase in cases of acute bronchospasm following thunderstorms. This study aimed to compare the frequency of obstructive airway disease or bronchial hyperresponsiveness in subjects with thunderstorm-associated respiratory symptoms with subjects with similar symptoms presented at other times. Methods: A cross-sectional study from June to November of 2013 was conducted on subjects with thunderstorm-associated respiratory symptoms living in Ahvaz City, Iran. Thunderstorm-associated subjects were presented with asthmatic symptoms in thunderstorms, and other patients presented with similar symptoms at other times. Baseline spirometry was performed on patients to examine the presence of obstructive airway disease. In all patients with normal spirometry, a provocation test was applied. A comparison of qualitative and quantitative variables was made using the Chi-square and independent t test, respectively. All analyses were carried out using SPSS Statistics Version 22. A P value less than 0.05 was considered statistically significant. Results: Out of 584 subjects, 300 and 284 participants were in thunderstorm-associated and non-thunderstorm-associated groups, respectively. After the final analysis, 87 (30.6%) and 89 (33.3%) of the thunderstorm-associated subjects and non-thunderstorm-associated group, respectively, had pieces of evidence of airflow limitation (P=0.27). Among the patients with normal spirometry, 161 (81.72%) of the thunderstorm-associated patients and 100 (56.17%) patients of the non-thunderstorm-associated symptoms group had a positive methacholine challenge test result (P<0.001). Conclusion: Most of the patients with thunderstorm-associated respiratory symptoms had no obvious evidence of airflow limitation in spirometry.

Is bronchial provocation test positivity associated with blood eosinophil count and cut-off value?

OBJECTIVE: Asthma is characterized by airway hyperresponsiveness due to chronic inflammation in the airways. One of the main cells involved in airway inflammation is eosinophils. In the current study, a bronchial provocation test (BPT) was performed to demonstrate airway hyperresponsiveness. We investigated the relationship between BPT and blood eosinophil count and the cut-off value of blood eosinophil count. PATIENTS AND METHODS: In this study, we retrospectively evaluated the data of 246 patients who visited our immunology and allergy clinic, a tertiary reference center, with asthma symptoms between May 2017 and March 2020 and underwent BPT with methacholine for the diagnosis of asthma. The cases were grouped according to the level of BPT positivity and negativity. RESULTS: Of 246 patients, BPT was positive in 90 (36.6%) and negative in 156 (63.4%). The blood eosinophil measurement of the BPT-positive cases was found to be statistically significantly higher than that of the BPT-negative cases (135 vs. 119 cells/µl, respectively, p=0.029). When BPT is grouped according to positivity levels, there was no statistically significant difference in blood eosinophil measurements between subgroups (p=0.174). As a result of the evaluations, the cut-off point obtained for the blood eosinophil count was determined as ≥226 cells/µl. For the blood eosinophil count, for the cut-off value of ≥226 cells/µl, sensitivity was 30.0%, specificity 87.7%, positive predictive value 58.7%, and negative predictive value 68.3%. CONCLUSIONS: This study shows that BPT positivity is associated with blood eosinophil count. The cut-off value (≥226 cells/µl) determined for blood eosinophil count may be helpful when planning BPT and evaluating the diagnosis of asthma.

[Standard technical specifications for methacholine chloride (Methacholine) bronchial challenge test (2023)].

The methacholine challenge test (MCT) is a standard evaluation method of assessing airway hyperresponsiveness (AHR) and its severity, and has significant clinical value in the diagnosis and treatment of bronchial asthma. A consensus working group consisting of experts from the Pulmonary Function and Clinical Respiratory Physiology Committee of the Chinese Association of Chest Physicians, the Task Force for Pulmonary Function of the Chinese Thoracic Society, and the Pulmonary Function Group of Respiratory Branch of the Chinese Geriatric Society jointly developed this consensus. Based on the "Guidelines for Pulmonary Function-Bronchial Provocation Test" published in 2014, the issues encountered in its use, and recent developments, the group has updated the Standard technical specifications of methacholine chloride (methacholine) bronchial challenge test (2023). Through an extensive collection of expert opinions, literature reviews, questionnaire surveys, and multiple rounds of online and offline discussions, the consensus addressed the eleven core issues in MCT's clinical practice, including indications, contraindications, preparation of provocative agents, test procedures and methods, quality control, safety management, interpretation of results, and reporting standards. The aim was to provide clinical pulmonary function practitioners in healthcare institutions with the tools to optimize the use of this technique to guide clinical diagnosis and treatment.Summary of recommendationsQuestion 1: Who is suitable for conducting MCT? What are contraindications for performing MCT?Patients with atypical symptoms and a clinical suspicion of asthma, patients diagnosed with asthma requiring assessment of the severity of airway hyperresponsiveness, individuals with allergic rhinitis who are at risk of developing asthma, patients in need of evaluating the effectiveness of asthma treatment, individuals in occupations with high safety risks due to airway hyperresponsiveness, patients with chronic diseases prone to airway hyperresponsiveness, others requiring assessment of airway reactivity.Absolute contraindications: (1) Patients who are allergic to methacholine (MCh) or other parasympathomimetic drugs, with allergic reactions including rash, itching/swelling (especially of the face, tongue, and throat), severe dizziness, and dyspnea; (2) Patients with a history of life-threatening asthma attacks or those who have required mechanical ventilation for asthma attacks in the past three months; (3) Patients with moderate to severe impairment of baseline pulmonary function [Forced Expiratory Volume in one second (FEV1) less than 60% of the predicted value or FEV1<1.0 L]; (4) Severe urticaria; (5) Other situations inappropriate for forced vital capacity (FVC) measurement, such as myocardial infarction or stroke in the past three months, poorly controlled hypertension, aortic aneurysm, recent eye surgery, or increased intracranial pressure.Relative contraindications: (1) Moderate or more severe impairment of baseline lung function (FEV1%pred<70%), but individuals with FEV1%pred>60% may still be considered for MCT with strict observation and adequate preparation; (2) Experiencing asthma acute exacerbation; (3) Poor cooperation with baseline lung function tests that do not meet quality control requirements; (4) Recent respiratory tract infection (<4 weeks); (5) Pregnant or lactating women; (6) Patients currently using cholinesterase inhibitors (for the treatment of myasthenia gravis); (7) Patients who have previously experienced airway spasm during pulmonary function tests, with a significant decrease in FEV1 even without the inhalation of provocative.Question 2: How to prepare and store the challenge solution for MCT?Before use, the drug must be reconstituted and then diluted into various concentrations for provocation. The dilution concentration and steps for MCh vary depending on the inhalation method and provocation protocol used. It is important to follow specific steps. Typically, a specified amount of diluent is added to the methacholine reagent bottle for reconstitution, and the mixture is shaken until the solution becomes clear. The diluent is usually physiological saline, but saline with phenol (0.4%) can also be used. Phenol can reduce the possibility of bacterial contamination, and its presence does not interfere with the provocation test. After reconstitution, other concentrations of MCh solution are prepared using the same diluent, following the dilution steps, and then stored separately in sterile containers. Preparers should carefully verify and label the concentration and preparation time of the solution and complete a preparation record form. The reconstituted and diluted MCh solution is ready for immediate use without the need for freezing. It can be stored for two weeks if refrigerated (2-8 ℃). The reconstituted solution should not be stored directly in the nebulizer reservoir to prevent crystallization from blocking the capillary opening and affecting aerosol output. The temperature of the solution can affect the production of the nebulizer and cause airway spasms in the subject upon inhaling cold droplets. Thus, refrigerated solutions should be brought to room temperature before use.Question 3: What preparation is required for subjects prior to MCT?(1) Detailed medical history inquiry and exclusion of contraindications.(2) Inquiring about factors and medications that may affect airway reactivity and assessing compliance with medication washout requirements: When the goal is to evaluate the effectiveness of asthma treatment, bronchodilators other than those used for asthma treatment do not need to be discontinued. Antihistamines and cromolyn have no effect on MCT responses, and the effects of a single dose of inhaled corticosteroids and leukotriene modifiers are minimal, thus not requiring cessation before the test. For patients routinely using corticosteroids, whether to discontinue the medication depends on the objective of the test: if assisting in the diagnosis of asthma, differential diagnosis, aiding in step-down therapy for asthma, or exploring the effect of discontinuing anti-inflammatory treatment, corticosteroids should be stopped before the provocation test; if the patient is already diagnosed with asthma and the objective is to observe the level of airway reactivity under controlled medication conditions, then discontinuation is not necessary. Medications such as IgE monoclonal antibodies, IL-4Rα monoclonal antibodies, traditional Chinese medicine, and ethnic medicines may interfere with test results, and clinicians should decide whether to discontinue these based on the specific circumstances.(3) Explaining the test procedure and potential adverse reactions, and obtaining informed consent if necessary.Question 4: What are the methods of the MCT? And which ones are recommended in current clinical practice?Commonly used methods for MCT in clinical practice include the quantitative nebulization method (APS method), Forced Oscillalion method (Astograph method), 2-minute tidal breathing method (Cockcroft method), hand-held quantitative nebulization method (Yan method), and 5-breath method (Chai 5-breath method). The APS method allows for precise dosing of inhaled Methacholine, ensuring accurate and reliable results. The Astograph method, which uses respiratory resistance as an assessment indicator, is easy for subjects to perform and is the simplest operation. These two methods are currently the most commonly used clinical practice in China.Question 5: What are the steps involved in MCT?The MCT consists of the following four steps:(1) Baseline lung function test: After a 15-minute rest period, the subjects assumes a seated position and wear a nose clip for the measurement of pulmonary function indicators [such as FEV1 or respiratory resistance (Rrs)]. FEV1 should be measured at least three times according to spirometer quality control standards, ensuring that the best two measurements differ by less than 150 ml and recording the highest value as the baseline. Usually, if FEV1%pred is below 70%, proceeding with the challenge test is not suitable, and a bronchodilation test should be considered. However, if clinical assessment of airway reactivity is necessary and FEV1%pred is between 60% and 70%, the provocation test may still be conducted under close observation, ensuring the subject's safety. If FEV1%pred is below 60%, it is an absolute contraindication for MCT.(2) Inhalation of diluent and repeat lung function test for control values: the diluent, serving as a control for the inhaled MCh, usually does not significantly impact the subject's lung function. the higher one between baseline value and the post-dilution FEV1 is used as the reference for calculating the rate of FEV1 decline. If post-inhalation FEV1 decreases, there are usually three scenarios: ①If FEV1 decreases by less than 10% compared to the baseline, the test can proceed, continue the test and administer the first dose of MCh. ②If the FEV1 decreases by≥10% and<20%, indicating a heightened airway reactivity to the diluent, proceed with the lowest concentration (dose) of the provoking if FEV1%pred has not yet reached the contraindication criteria for the MCT. if FEV1%pred<60% and the risk of continuing the challenge test is considerable, it is advisable to switch to a bronchodilation test and indicate the change in the test results report. ③If FEV1 decreases by≥20%, it can be directly classified as a positive challenge test, and the test should be discontinued, with bronchodilators administered to alleviate airway obstruction.(3) Inhalation of MCh and repeat lung function test to assess decline: prepare a series of MCh concentrations, starting from the lowest and gradually increasing the inhaled concentration (dose) using different methods. Perform pulmonaryfunction tests at 30 seconds and 90 seconds after completing nebulization, with the number of measurements limited to 3-4 times. A complete Forced Vital Capacity (FVC) measurement is unnecessary during testing; only an acceptable FEV1 measurement is required. The interval between two consecutive concentrations (doses) generally should not exceed 3 minutes. If FEV1 declines by≥10% compared to the control value, reduce the increment of methacholine concentration (dose) and adjust the inhalation protocol accordingly. If FEV1 declines by≥20% or more compared to the control value or if the maximum concentration (amount) has been inhaled, the test should be stopped. After inhaling the MCh, close observation of the subject's response is necessary. If necessary, monitor blood oxygen saturation and auscultate lung breath sounds. The test should be promptly discontinued in case of noticeable clinical symptoms or signs.(4) Inhalation of bronchodilator and repeat lung function test to assess recovery: when the bronchial challenge test shows a positive response (FEV1 decline≥20%) or suspiciously positive, the subject should receive inhaled rapid-acting bronchodilators, such as short-acting beta-agonists (SABA) or short-acting muscarinic antagonists (SAMA). Suppose the subject exhibits obvious symptoms of breathlessness, wheezing, or typical asthma manifestations, and wheezing is audible in the lungs, even if the positive criteria are not met. In that case, the challenge test should be immediately stopped, and rapid-acting bronchodilators should be administered. Taking salbutamol as an example, inhale 200-400 µg (100 µg per puff, 2-4 puffs, as determined by the physician based on the subject's condition). Reassess pulmonary function after 5-10 minutes. If FEV1 recovers to within 10% of the baseline value, the test can be concluded. However, if there is no noticeable improvement (FEV1 decline still≥10%), record the symptoms and signs and repeat the bronchodilation procedure as mentioned earlier. Alternatively, add Ipratropium bromide (SAMA) or further administer nebulized bronchodilators and corticosteroids for intensified treatment while keeping the subject under observation until FEV1 recovers to within 90% of the baseline value before allowing the subject to leave.Question 6: What are the quality control requirements for the APS and Astograph MCT equipment?(1) APS Method Equipment Quality Control: The APS method for MCT uses a nebulizing inhalation device that requires standardized flowmeters, compressed air power source pressure and flow, and nebulizer aerosol output. Specific quality control methods are as follows:a. Flow and volume calibration of the quantitative nebulization device: Connect the flowmeter, an empty nebulization chamber, and a nebulization filter in sequence, attaching the compressed air source to the bottom of the chamber to ensure airtight connections. Then, attach a 3 L calibration syringe to the subject's breathing interface and simulate the flow during nebulization (typically low flow:<2 L/s) to calibrate the flow and volume. If calibration results exceed the acceptable range of the device's technical standards, investigate and address potential issues such as air leaks or increased resistance due to a damp filter, then recalibrate. Cleaning the flowmeter or replacing the filter can change the resistance in the breathing circuit, requiring re-calibration of the flow.b. Testing the compressed air power source: Regularly test the device, connecting the components as mentioned above. Then, block the opening of the nebulization device with a stopper or hand, start the compressed air power source, and test its pressure and flow. If the test results do not meet the technical standards, professional maintenance of the equipment may be required.c. Verification of aerosol output of the nebulization chamber: Regularly verify all nebulization chambers used in provocation tests. Steps include adding a certain amount of saline to the chamber, weighing and recording the chamber's weight (including saline), connecting the nebulizer to the quantitative nebulization device, setting the nebulization time, starting nebulization, then weighing and recording the post-nebulization weight. Calculate the unit time aerosol output using the formula [(weight before nebulization-weight after nebulization)/nebulization time]. Finally, set the nebulization plan for the provocation test based on the aerosol output, considering the MCh concentration, single inhalation nebulization duration, number of nebulization, and cumulative dose to ensure precise dosing of the inhaled MCh.(2) Astograph method equipment quality control: Astograph method equipment for MCT consists of a respiratory resistance monitoring device and a nebulization medication device. Perform zero-point calibration, volume calibration, impedance verification, and nebulization chamber checks daily before tests to ensure the resistance measurement system and nebulization system function properly. Calibration is needed every time the equipment is turned on, and more frequently if there are significant changes in environmental conditions.a. Zero-point calibration: Perform zero-point calibration before testing each subject. Ensure the nebulization chamber is properly installed and plugged with no air leaks.b. Volume calibration: Use a 3 L calibration syringe to calibrate the flow sensor at a low flow rate (approximately 1 L/s).c. Resistance verification: Connect low impedance tubes (1.9-2.2 cmH2O·L-1·s-1) and high impedance tubes (10.2-10.7 cmH2O·L-1·s-1) to the device interface for verification.d. Bypass check: Start the bypass check and record the bypass value; a value>150 ml/s is normal.e. Nebulization chamber check: Check each of the 12 nebulization chambers daily, especially those containing bronchodilators, to ensure normal spraying. The software can control each nebulization chamber to produce spray automatically for a preset duration (e.g., 2 seconds). Observe the formation of water droplets on the chamber walls, indicating normal spraying. If no nebulization occurs, check for incorrect connections or blockages.Question 7: How to set up and select the APS method in MCT?The software program of the aerosol provocation system in the quantitative nebulization method can independently set the nebulizer output, concentration of the methacholine agent, administration time, and number of administrations and combine these parameters to create the challenge test process. In principle, the concentration of the methacholine agent should increase from low to high, and the dose should increase from small to large. According to the standard, a 2-fold or 4-fold incremental challenge process is generally used. In clinical practice, the dose can be simplified for subjects with good baseline lung function and no history of wheezing, such as using a recommended 2-concentration, 5-step method (25 and 50 g/L) and (6.25 and 25 g/L). Suppose FEV1 decreases by more than 10% compared to the baseline during the test to ensure subject safety. In that case, the incremental dose of the methacholine agent can be reduced, and the inhalation program can be adjusted appropriately. If the subject's baseline lung function declines or has recent daytime or nighttime symptoms such as wheezing or chest tightness, a low concentration, low dose incremental process should be selected.Question 8: What are the precautions for the operation process of the Astograph method in MCT?(1) Test equipment: The Astograph method utilizes the forced oscillation technique, applying a sinusoidal oscillating pressure at the mouthpiece during calm breathing. Subjects inhale nebulized MCh of increasing concentrations while continuous monitoring of respiratory resistance (Rrs) plots the changes, assessing airway reactivity and sensitivity. The nebulization system employs jet nebulization technology, comprising a compressed air pump and 12 nebulization cups. The first cup contains saline, cups 2 to 11 contain increasing concentrations of MCh, and the 12th cup contains a bronchodilator solution.(2) Provocation process: Prepare 10 solutions of MCh provocant with gradually increasing concentrations.(3) Operational procedure: The oscillation frequency is usually set to 3 Hz (7 Hz for children) during the test. The subject breathes calmly, inhales saline solution nebulized first, and records the baseline resistance value (if the subject's baseline resistance value is higher than 10 cmH2O·L-1·s-1, the challenge test should not be performed). Then, the subject gradually inhales increasing concentrations of methacholine solution. Each concentration solution is inhaled for 1 minute, and the nebulization system automatically switches to the next concentration for inhalation according to the set time. Each nebulizer cup contains 2-3 ml of solution, the output is 0.15 ml/min, and each concentration is inhaled for 1 minute. The dose-response curve is recorded automatically. Subjects should breathe tidally during the test, avoiding deep breaths and swallowing. Continue until Rrs significantly rises to more than double the baseline value, or if the subject experiences notable respiratory symptoms or other discomfort, such as wheezing in both lungs upon auscultation. At this point, the inhalation of the provocant should be stopped and the subject switchs to inhaling a bronchodilator until Rrs returns to pre-provocation levels. If there is no significant increase in Rrs, stop the test after inhaling the highest concentration of MCh.Question 9: How to interpret the results of the MCT?The method chosen for the MCT determines the specific indicators used for interpretation. The most commonly used indicator is FEV1, although other parameters such as Peak Expiratory Flow (PEF) and Rrs can also be used to assess airway hyperresponsiveness.Qualitative judgment: The test results can be classified as positive, suspiciously positive, or negative, based on a combination of the judgment indicators and changes in the subject's symptoms. If FEV1 decreases by≥20% compared to the baseline value after not completely inhaling at the highest concentration, the result can be judged as positive for Methacholine bronchial challenge test. If the patient has obvious wheezing symptoms or wheezing is heard in both lungs, but the challenge test does not meet the positive criteria (the highest dose/concentration has been inhaled), and FEV1 decreases between 10% and 20% compared to the baseline level, the result can also be judged as positive. If FEV1 decreases between 15% and 20% compared to the baseline value without dyspnea or wheezing attacks, the result can be judged as suspiciously positive. Astograph method: If Rrs rises to 2 times or more of the baseline resistance before reaching the highest inhalation concentration, or if the subject's lungs have wheezing and severe coughing, the challenge test can be judged as positive. Regardless of the result of the Methacholine bronchial challenge test, factors that affect airway reactivity, such as drugs, seasons, climate, diurnal variations, and respiratory tract infections, should be excluded.Quantitative judgment: When using the APS method, the severity of airway hyperresponsiveness can be graded based on PD20-FEV1 or PC20-FEV1. Existing evidence suggests that PD20 shows good consistency when different nebulizers, inhalation times, and starting concentrations of MCh are used for bronchial provocation tests, whereas there is more variability with PC20. Therefore, PD20 is often recommended as the quantitative assessment indicator. The threshold value for PD20 with the APS method is 2.5 mg.The Astograph method often uses the minimum cumulative dose (Dmin value, in Units) to reflect airway sensitivity. Dmin is the minimum cumulative dose of MCh required to produce a linear increase in Rrs. A dose of 1 g/L of the drug concentration inhaled for 1-minute equals 1 unit. It's important to note that with the continuous increase in inhaled provocant concentration, the concept of cumulative dose in the Astograph method should not be directly compared to other methods. Most asthma patients have a Dmin<10 Units, according to Japanese guidelines. The Astograph method, having been used in China for over twenty years, suggests a high likelihood of asthma when Dmin≤6 Units, with a smaller Dmin value indicating a higher probability. When Dmin is between 6 and 10 Units, further differential diagnosis is advised to ascertain whether the condition is asthma.Precautions:A negative methacholine challenge test (MCT) does not entirely rule out asthma. The test may yield negative results due to the following reasons:(1) Prior use of medications that reduce airway responsiveness, such as ß2 agonists, anticholinergic drugs, antihistamines, leukotriene receptor antagonists, theophylline, corticosteroids, etc., and insufficient washout time.(2) Failure to meet quality control standards in terms of pressure, flow rate, particle size, and nebulization volume of the aerosol delivery device.(3) Poor subject cooperation leads to inadequate inhalation of the methacholine agent.(4) Some exercise-induced asthma patients may not be sensitive to direct bronchial challenge tests like the Methacholine challenge and require indirect bronchial challenge tests such as hyperventilation, cold air, or exercise challenge to induce a positive response.(5) A few cases of occupational asthma may only react to specific antigens or sensitizing agents, requiring specific allergen exposure to elicit a positive response.A positive MCT does not necessarily indicate asthma. Other conditions can also present with airway hyperresponsiveness and yield positive results in the challenge test, such as allergic rhinitis, chronic bronchitis, viral upper respiratory infections, allergic alveolitis, tropical eosinophilia, cystic fibrosis, sarcoidosis, bronchiectasis, acute respiratory distress syndrome, post-cardiopulmonary transplant, congestive heart failure, and more. Furthermore, factors like smoking, air pollution, or exercise before the test may also result in a positive bronchial challenge test.Question 10: What are the standardized requirements for the MCT report?The report should include: (1) basic information about the subject; (2) examination data and graphics: present baseline data, measurement data after the last two challenge doses or concentrations in tabular form, and the percentage of actual measured values compared to the baseline; flow-volume curve and volume-time curve before and after challenge test; dose-response curve: showing the threshold for positive challenge; (3) opinions and conclusions of the report: including the operator's opinions, quality rating of the examination, and review opinions of the reviewing physician.Question 11: What are the adverse reactions and safety measures of MCT?During the MCT, the subject needs to repeatedly breathe forcefully and inhale bronchial challenge agents, which may induce or exacerbate bronchospasm and contraction and may even cause life-threatening situations. Medical staff should be fully aware of the indications, contraindications, medication use procedures, and emergency response plans for the MCT.

The diagnostic value of bronchial provocation testing combined with fractional exhaled nitric oxide (FeNO) in children with chest tightness-variant asthma (CTVA).

BACKGROUND: Chest tightness-variant asthma (CTVA) is a novel atypical asthma characterized by chest tightness as the sole or primary symptom. OBJECTIVES: To investigate the value of bronchial provocation testing combined with fractional exhaled nitric oxide (FeNO) in the diagnosis of CTVA in children. METHODS: This study included 95 children aged 6-14 years with chest tightness as the sole symptom, with a duration of symptoms exceeding 4 weeks. All subjects underwent FeNO measurement, pulmonary function testing, and bronchial provocation testing using the Astograph method. Subjects with positive bronchial provocation testing were classified as the CTVA group, while those with negative results served as the non-CTVA control group. RESULTS: The lung function of children in both groups was normal. The FeNO level in the CTVA group was (22.35 ± 9.91) ppb, significantly higher than the control group (14.85 ± 5.63) ppb, with a statistically significant difference (P < 0.05). The value of FeNO in diagnosing CTVA was analyzed using an ROC curve, with an area under the curve of 0.073 (P < 0.05). The optimal cutoff point for diagnosing CTVA using FeNO was determined to be 18.5 ppb, with a sensitivity of 60.3 % and specificity of 77.8 %. There was a negative correlation between FeNO and Dmin as well as PD15 (P = 0.006). CONCLUSION: FeNO can serve as an adjunctive diagnostic tool for CTVA, with the optimal cutoff point for diagnosing CTVA being 18.5 ppb. However, FeNO is not a specific diagnostic marker for CTVA and should be used in conjunction with bronchial provocation testing to enhance its diagnostic value.

MicroRNA Profiling of the Inflammatory Response after Early and Late Asthmatic Reaction.

A high proportion of house dust mite (HDM)-allergic asthmatics suffer from both an early asthmatic reaction (EAR) and a late asthmatic reaction (LAR) which follows it. In these patients, allergic inflammation is more relevant. MiRNAs have been shown to play an important role in the regulation of asthma's pathology. The aim of this study was to analyze the miRNA profile in patients with mild asthma and an HDM allergy after bronchial allergen provocation (BAP). Seventeen patients with EAR/no LAR and 17 patients with EAR plus LAR, determined by a significant fall in FEV1 after BAP, were differentially analyzed. As expected, patients with EAR plus LAR showed a more pronounced allergic inflammation and FEV1 delta drop after 24 h. NGS-miRNA analysis identified the down-regulation of miR-15a-5p, miR-15b-5p, and miR-374a-5p after BAP with the highest significance in patients with EAR plus LAR, which were negatively correlated with eNO and the maximum decrease in FEV1. These miRNAs have shared targets like CCND1, VEGFA, and GSK3B, which are known to be involved in airway remodeling, basement membrane thickening, and Extracellular Matrix deposition. NGS-profiling identified miRNAs involved in the inflammatory response after BAP with HDM extract, which might be useful to predict a LAR.

The role of bronchial challenge test in guiding therapy in preschool children with atypical recurrent respiratory symptoms.

OBJECTIVE: This retrospective observational cohort study aimed to assess the real-life application of bronchial challenge test (BCT) in the management of preschool children presenting with atypical recurrent respiratory symptoms (ARRS). METHODS: We included children aged 0.5-6 years referred to a pediatric-pulmonology clinic who underwent BCT using methacholine or adenosine between 2012 and 2018 due to ARRS. BCT was considered positive based on spirometry results and/or wheezing, desaturation, and tachypnea reactions. We collected data on demographics, BCT results, pre-BCT and post-BCT treatment changes, and 3-6 months post-BCT compliance and symptom control. The primary outcome measure was the change in treatment post-BCT (step-up or step-down). RESULTS: A total of 228 children (55% males) with a mean age of 4.2 ± 0.6 years underwent BCT (52% adenosine-BCT, 48% methacholine-BCT). Children referred for methacholine were significantly younger compared with adenosine (3.6 ± 1.2 vs. 4.2 ± 1.2 years, p < .01). Methacholine and adenosine BCTs were positive in 95% and 61%, respectively. Overall, changes in management were observed in 122 (53.5%) children following BCT, with 83 (36.4%) being stepped up and 37 (17%) being stepped down. Significantly more children in the methacholine group were stepped up compared with the adenosine group (46% vs. 28%, p = .004). During the follow-up assessment, we observed a clinical improvement in 119/162 (73.4%) of the children, with nearly 87% being compliant. CONCLUSION: This study demonstrates the importance of BCT in the management of preschool children presenting to pediatric pulmonary units with ARRS. The change in treatment and subsequent clinical improvement observed highlight the added value of BCT to the pulmonologist.

Relation of changes in PEF and FEV1 in exercise challenge in children.

Decrease in forced expiratory volume in one second (FEV1 ) of 10% or 15% in exercise challenge test is considered diagnostic for asthma, but a decrease of 15% in peak expiratory flow (PEF) is recommended as an alternative. Our aim was to assess the accuracy of different PEF cut-off points in comparison to FEV1 . We retrospectively studied 326 free running exercise challenge tests with spirometry in children 6-16 years old. FEV1 and PEF were measured before and 2, 5, 10 and 15 min after exercise. Receiver operating characteristics (ROC) analysis, sensitivity, specificity, positive and negative predictive values (PPV and NPV) and Ï°-coefficient were used to analyse how decrease in PEF predicts decrease of 10% or 15% in FEV1 . In the ROC analysis, areas under the curve were 0.851 (p < 0.001) and 0.921 (p < 0.001) for PEF decrease to predict a 10% and 15% decrease in FEV1 , respectively. The agreement between changes in PEF and FEV1 varied from slight to substantial (Ï° values of 0.199-0.680) depending on the cut-points. Lower cut-off for decrease in PEF had higher sensitivity and NPV, while higher cut-off values had better specificity and PPV. Decrease of 20% and 25% in PEF seemed to be the best cut-offs for detecting 10% and 15% decrease in FEV1 , respectively. Still, a fifth of the positive findings based on PEF were false. Change in PEF is not a precise predictor of change in FEV1 in exercise test. The currently recommended cut-point of 15% decrease in PEF seems to be too low and leads to high false positive rate.

The link between early childhood lower airway symptoms, airway hyperresponsiveness, and school-age lung function.

BACKGROUND: The role of early airway hyperresponsiveness (AHR) in the lung function of school-age children is currently unclear. OBJECTIVE: To conduct a prospective follow-up study of lung function in schoolchildren with a history of lower airway symptoms and AHR to methacholine in early childhood and to compare the findings to schoolchildren with no previous or current lung diseases. We also explored symptoms and markers of type 2 inflammation. METHODS: In 2004 to 2011, data on atopic markers, lung function, and AHR to methacholine were obtained from 193 symptomatic children under 3 years old. In 2016 to 2018, a follow-up sample of 84 children (median age, 11 years; IQR, 11-12) underwent measurements of atopic parameters, lung function, and AHR to methacholine. Moreover, in 2017 to 2018, 40 controls (median age, 11 years; IQR, 9-12) participated in the study. RESULTS: Schoolchildren with early childhood lower airway symptoms and increased AHR had more frequent blood eosinophilia than their peers without increased AHR and lower prebronchodilator forced expiratory volume in 1 second (FEV1) and FEV1/forced vital capacity Z-scores than those without increased AHR and controls. Post-bronchodilator values were not significantly different between the two AHR groups. Atopy in early childhood (defined as atopic eczema and at least 1 positive skin prick test result) was associated with subsequent lung function and atopic markers, but not AHR. CONCLUSION: In symptomatic young children, increased AHR was associated with subsequent obstructive lung function, which appeared reversible by bronchodilation, and blood eosinophilia, indicative of type 2 inflammation.

Interpretation of Spirometry, Peak Flow, and Provocation Testing for Asthma.

Spirometry plays a crucial role in the diagnosis of asthma. The hallmark spirometry finding of expiratory airflow variability can be demonstrated in several ways including peak airflow and bronchodilator and bronchoprovocation testing. Challenges of overdiagnosis and underdiagnosis underscore the need to consider clinical context while interpreting these tests. A meticulous and multifaceted approach prioritizing objective testing is imperative while diagnosing asthma.

Anticipating undiagnosed asthma in symptomatic adults with normal pre- and post-bronchodilator spirometry: a decision tool for bronchial challenge testing.

BACKGROUND: Some patients with asthma demonstrate normal spirometry and remain undiagnosed without further testing. OBJECTIVE: To determine clinical predictors of asthma in symptomatic adults with normal spirometry, and to generate a tool to help clinicians decide who should undergo bronchial challenge testing (BCT). METHODS: Using random-digit dialling and population-based case-finding, we recruited adults from the community with respiratory symptoms and no previous history of diagnosed lung disease. Participants with normal pre- and post-bronchodilator spirometry subsequently underwent BCT. Asthma was diagnosed in those with symptoms and a methacholine provocative concentration (PC20) of < 8 mg/ml. Sputum and blood eosinophils, and exhaled nitric oxide were measured. Univariate analyses identified potentially predictive variables, which were then used to construct a multivariable logistic regression model to predict asthma. Model sensitivity, specificity, and area under the receiver operating curve (AUC) were calculated. RESULTS: Of 132 symptomatic individuals with normal spirometry, 34 (26%) had asthma. Of those ultimately diagnosed with asthma, 33 (97%) answered 'yes' to a question asking whether they experienced cough, chest tightness or wheezing provoked by exercise or cold air. Other univariate predictors of asthma included female sex, pre-bronchodilator FEV1 percentage predicted, and percent positive change in FEV1 post bronchodilator. A multivariable model containing these predictive variables yielded an AUC of 0.82 (95% CI: 0.72-0.91), a sensitivity of 82%, and a specificity of 66%. The model was used to construct a nomogram to advise clinicians which patients should be prioritized for BCT. CONCLUSIONS: Four readily available patient characteristics demonstrated a high sensitivity and AUC for predicting undiagnosed asthma in symptomatic adults with normal pre- and post-bronchodilator spirometry. These characteristics can potentially help clinicians to decide which individuals with normal spirometry should be investigated with bronchial challenge testing. However, further prospective validation of our decision tool is required.

Severe bronchial hyperresponsiveness along with house dust mite allergy indicates persistence of asthma in young children.

BACKGROUND: Significant risk factors for persistence of asthma later in life are family history of allergies, early allergic sensitization and bronchial hyperresponsiveness (BHR). The evolution of BHR in young children without allergic sensitization and with house dust mite allergy (HDM) was investigated. METHODS: In this retrospective analysis, electronic charts of 4850 young children with asthma and wheezy bronchitis between 2005 and 2018 were reviewed in order to study all patients ≤6 years with BHR assessed by methacholine provocation tests (MCT) at least once (n = 1175). Patients with more than two follow-up measurements were divided in group 1 (no allergic sensitization; n = 110) and group 2 (HDM allergy; n = 88). Additionally, skin prick test, exhaled nitrite oxide (eNO), and asthma treatment were analyzed. RESULTS: Forty-seven patients of group 1 aged median 4.3 years and 48 patients of group 2 aged median 4.7 years showed initially severe BHR <0.1 mg. At follow-up, patients with HDM were more likely to show persistence of severe BHR than non-sensitized patients (severe BHR group 1: n = 5 (10.6%) vs. group 2: n = 21 (43.8%), p < .001). In addition, 89.4% of group 1 had mild to moderate or no BHR, compared to only 56.2% of group 2. There was a significant difference in eN0 (median group 1: 9 ppb vs. group 2: 26 ppb, p < .001), at last follow-up. Age, sex, and asthma therapy had no effect on BHR. CONCLUSION: In young children without sensitization BHR normalizes, whereas HDM allergy indicates a persistence of asthma beyond infancy.

[THE RELATIONSHIP AMONG BRONCHIAL HYPERSENSITIVITY, BRONCHIAL HYPER REACTIVITY, AND BRONCHIAL HYPERRESPONSIVENESS IN ASTOGRAPH].

BACKGROUND: Bronchial hyperresponsiveness testing is useful for diagnosing and predicting the risk of bronchial asthma attacks. The Astograph is a tidal breathing method often used in as bronchial provocation testing in Japan. The minimum methachorine dose (Dmin) indicates bronchial sensitivity and is used mainly as an index of bronchial hyperresponsiveness. However, Dmin does not measured hyperresponsiveness, it cannot be compared directly with PC20 in standard methods using FEV1. METHODS: We investigated the relationship among sensitivity, reactivity, and hyperresponsiveness with the Astograph. We recruited 142 patients with confirmed or suspected bronchial asthma from outpatient clinic at St. Marianna University School of Medicine, Yokohama City Seibu Hospital. We calculated Dmin, SGrs/Grscont, PD35Grs, and PD15Grs compared them as bronchial hyperresponsiveness indices. RESULTS: Subjects had suspected asthma (n=103), or required assessment of asthma remission (n=39). There were significant relationships between logDmin and logPD35Grs (r=0.838, p<0.001), and between parameters and SGrs/Grscont (log PD35Grs r=-0.504, p<0.001, strong, logDmin: r=-0.191, p=0.023, weaker). Among subjects positive for hypersensitivity, (Dmin<10), 38 (36.5%) showed negative hyperresponsiveness (PD35Grs>25). PD15Grs was a strongly and significantly correlated with Dmin and PD35Grs. The ROC curve to detect PD35Grs<25, showed that the cutoff of PD15Grs was 10.7 (AUC 0.983, sensitivity 0.984, specificity 0.905). CONCLUSION: In Astograph, evaluation of bronchial hyperresponsiveness, we focused on relationship differences between sensitivity and reactivity, and hyperresponsiveness. We revealed the usefulness of the PD15Grs evaluation method.

Occupational asthma induced by fish exposure.

Occupational asthma triggered by inhaling fish-derived aerosols is estimated to affect 2-8% of exposed individuals. This primarily affects workers in the fish processing industry. Fishmongers, rarely experience this issue, as recent research found no significant difference in asthma rates compared to a control group. We report the case of a fishmonger who presented with a 1-year history of rhinoconjunctivitis and asthma. The patient attributed these symptoms to his occupational exposure within the fish market environment, which worsened in the cold storage warehouse. Symptoms improved during holidays. Diagnosis involved skin-prick tests, sIgE (ImmunoCAP-specific IgE) measurements, and bronchial challenge tests, confirming occupational asthma from fish bioaerosol exposure. Parvalbumins, common fish proteins, share structural similarities, leading to cross-reactivity in fish allergy sufferers. In this case, sensitivity to rGad c1 (cod parvalbumin) was identified as the primary trigger for the patient's asthma, and responsible for sensitizations observed across various tested fish species.

Exercise-induced bronchoconstriction assessed by a ratio of surface diaphragm EMG to tidal volume.

Exercise-induced bronchoconstriction (EIB) is usually assessed by changes in forced expiratory volume in 1 s (FEV1 ) which is effort dependent. The purpose of this study was to determine whether the diaphragm electromyogram (EMGdi ) recorded from chest wall surface electrodes could be used to reflect changes in airway resistance during an exercise challenge test and to distinguish patients with EIB from those without EIB. Ninety participants with or without asthma history were included in the study. FEV1 was recorded before and 5, 10, 15, and 20 min after exercise. EIB was defined as an FEV1 decline greater than 10% after exercise. A ratio of root mean square of EMGdi to tidal volume (EMGdi /VT ) was used to assess changes in airway resistance. Based on changes in FEV1 , 25 of 90 participants exhibited EIB; the remainder were defined as non-EIB participants. EMGdi /VT in EIB increased by 124% (19%-478%) which was significantly higher than that of 21% (-39% to 134%) in non-EIB participants (p < 0.001). At the optimal cutoff point (54% in EMGdi /VT ), the area under the ROC curve (AUC) for detection of a positive test was 0.92 (p < 0.001) with sensitivity 92% and specificity 88%. EMGdi /VT can be used to assess changes in airway resistance after exercise and could be used to distinguish participants with EIB from those without EIB.

Impact of airway challenges on cardiovascular risk in asthma - a randomized controlled trial.

BACKGROUND: People experiencing asthma exacerbations are at increased risk of cardiovascular events. To better understand the relationship between asthma exacerbations and cardiovascular risk, this randomized case-control, cross-over controlled trial assessed the immediate systemic inflammatory and vascular responses to acutely induced pulmonary inflammation and bronchoconstriction in people with asthma and controls. METHODS: Twenty-six people with asthma and 25 controls underwent three airway challenges (placebo, mannitol, and methacholine) in random order. Markers of cardiovascular risk, including serum C-reactive protein, interleukin-6, and tumor necrosis factor, endothelial function (flow-mediated dilation), microvascular function (blood-flow following reactive hyperemia), and arterial stiffness (pulse wave velocity) were evaluated at baseline and within one hour following each challenge. The systemic responses in a) asthma/control and b) positive airway challenges were analyzed. (ClinicalTrials.gov reg# NCT02630511). RESULTS: Both the mannitol and methacholine challenges resulted in clinically significant reductions in forced expiratory volume in 1 second (FEV1) in asthma (-7.6% and -17.9%, respectively). Following positive challenges, reduction in FEV1 was -27.6% for methacholine and -14.2% for mannitol. No meaningful differences in predictors of cardiovascular risk were observed between airway challenges regardless of bronchoconstrictor response. CONCLUSION: Neither acutely induced bronchoconstriction nor pulmonary inflammation and bronchoconstriction resulted in meaningful changes in systemic inflammatory or vascular function. These findings question whether the increased cardiovascular risk associated with asthma exacerbations is secondary to acute bronchoconstriction or inflammation, and suggest that other factors need to be further evaluated such as the cardiovascular impacts of short-acting inhaled beta-agonists.

Changes in exhaled volatile organic compounds following indirect bronchial challenge in suspected asthma.

BACKGROUND: Inhaled mannitol provokes bronchoconstriction via mediators released during osmotic degranulation of inflammatory cells, and, hence represents a useful diagnostic test for asthma and model for acute attacks. We hypothesised that the mannitol challenge would trigger changes in exhaled volatile organic compounds (VOCs), generating both candidate biomarkers and novel insights into their origin. METHODS: Participants with a clinical diagnosis of asthma, or undergoing investigation for suspected asthma, were recruited. Inhaled mannitol challenges were performed, followed by a sham challenge after 2 weeks in participants with bronchial hyper-responsiveness (BHR). VOCs were collected before and after challenges and analysed using gas chromatography-mass spectrometry. RESULTS: Forty-six patients (mean (SD) age 52 (16) years) completed a mannitol challenge, of which 16 (35%) were positive, and 15 of these completed a sham challenge. Quantities of 16 of 51 identified VOCs changed following mannitol challenge (p<0.05), of which 11 contributed to a multivariate sparse partial least square discriminative analysis model, with a classification error rate of 13.8%. Five of these 16 VOCs also changed (p<0.05) in quantity following the sham challenge, along with four further VOCs. In patients with BHR to mannitol distinct postchallenge VOC signatures were observed compared with post-sham challenge. CONCLUSION: Inhalation of mannitol was associated with changes in breath VOCs, and in people with BHR resulted in a distinct exhaled breath profile when compared with a sham challenge. These differentially expressed VOCs are likely associated with acute airway inflammation and/or bronchoconstriction and merit further investigation as potential biomarkers in asthma.

Force adaptation through the intravenous route in naïve mice.

Aim of the study: Force adaptation is a process whereby the contractile capacity of the airway smooth muscle increases during a sustained contraction (aka tone). Tone also increases the response to a nebulized challenge with methacholine in vivo, presumably through force adaptation. Yet, due to its patchy pattern of deposition, nebulized methacholine often spurs small airway narrowing heterogeneity and closure, two important enhancers of the methacholine response. This raises the possibility that the potentiating effect of tone on the methacholine response is not due to force adaptation but by furthering heterogeneity and closure. Herein, methacholine was delivered homogenously through the intravenous (i.v.) route. Materials and Methods: Female and male BALB/c mice were subjected to one of two i.v. methacholine challenges, each of the same cumulative dose but starting by a 20-min period either with or without tone induced by serial i.v. boluses. Changes in respiratory mechanics were monitored throughout by oscillometry, and the response after the final dose was compared between the two challenges to assess the effect of tone. Results: For the elastance of the respiratory system (Ers), tone potentiated the methacholine response by 64 and 405% in females (37.4 ± 10.7 vs. 61.5 ± 15.1 cmH2O/mL; p = 0.01) and males (33.0 ± 14.3 vs. 166.7 ± 60.6 cmH2O/mL; p = 0.0004), respectively. For the resistance of the respiratory system (Rrs), tone potentiated the methacholine response by 129 and 225% in females (9.7 ± 3.5 vs. 22.2 ± 4.3 cmH2O·s/mL; p = 0.0003) and males (10.7 ± 3.1 vs. 34.7 ± 7.9 cmH2O·s/mL; p < 0.0001), respectively. Conclusions: As previously reported with nebulized challenges, tone increases the response to i.v. methacholine in both sexes; albeit sexual dimorphisms were obvious regarding the relative resistive versus elastic nature of this potentiation. This represents further support that tone increases the lung response to methacholine through force adaptation.

The effect of nose clip on exercise-induced bronchoconstriction in adolescents.

BACKGROUND: Oral breathing is considered to increase hyper-responsiveness of the airways. Data on the need for nose clip (NC) during exercise challenge test (ECT) in children and adolescents is scarce. Ouraim was to evaluate the role of NC during ECT in children and adolescents. METHODS: A prospective, cohort study; children referred for ECT were evaluated on two separate visits, with and without a NC. Demographic, clinical data and measurements of lung functions were recorded. Allergy and asthma control were evaluated by Total Nasal Symptoms Score (TNSS) and Asthma Control Test (ACT) questionnaires. RESULTS: Sixty children and adolescents (mean age 16.7 ± 1.1 years, 38% Female,) performed ECT with NC and 48 (80%) completed visit 2 (ECT without NC), 8.7 ± 7.9 days after visit 1. Following exercise, 29/48 patients (60.4%) with NC had a decline of ≥12% in forced expiratory volume in the first second (FEV1 ) (positive ECT) compared to only 16/48 (33.3%) positive tests without NC (p = 0.0008). Test result was changed in 14 patients from positive ECT (with NC) to negative ECT (no NC) and in only one patient from negative to positive. The use of NC resulted in greater FEV1 decline (median 16.3% predicted, IQR 6.0-19.1% predicted vs. median 4.5% predicted, IQR 1.6-18.4% predicted, p = 0.0001), and better FEV1 increase after bronchodil at or inhalation compared to ECT without NC. Higher TNSS scores did not predict higher probability to positive ECT. CONCLUSIONS: The use of NC during ECT increases detection rate of exercise induced bronchoconstriction during ECT in the pediatric population. These findings strengthen the recommendation of nasal blockage during ECT in children and adolescents.

Disposition of Work-Related Asthma in a Spanish Asthma Cohort: Comparison of Asthma Severity Between Employed and Retired Workers.

BACKGROUND: Exposure to certain agents in the workplace can trigger occupational asthma or work-exacerbated asthma, both of which come under the heading of work-related asthma (WRA). Understanding the burden that WRA represents can help in the management of these patients. OBJECTIVE: To assess the influence of occupation on asthma in real life and analyze the characteristics of patients with WRA included in an asthma cohort. METHODS: This was a prospective multicenter study of a cohort of consecutive patients with asthma. A standardized clinical history was completed. Patients were classified as having WRA or non-WRA. All patients underwent respiratory function tests, FeNO test, and methacholine challenge (methacholine concentration that causes a 20% drop in FEV1) at the beginning of the study. They were classified into two groups, depending on their employment status: employed (group 1) or unemployed (group 2). RESULTS: Of the 480 patients included in the cohort, 82 (17%) received the diagnosis of WRA. Fifty-seven patients (70%) were still working. Mean age (SD) was 46 (10.69) years in group 1 and 57 (9.91) years in group 2 (P < .0001). Significant differences were observed in adherence to treatment (64.9% in group 1 vs 88% in group 2; P = .0354) and in severe asthma exacerbations (35.7% in group 1 vs 0% in group 2; P = .0172). No significant differences were observed in the rest of the variables analyzed. CONCLUSIONS: The burden of WRA in specialized asthma units is not negligible. The absence of differences in the severity of asthma, the treatment administered, alterations in lung function, and the number of exacerbations in those working versus not working may support the idea that advice regarding changing jobs should be customized for individual patients.