Assessment Of Bronchial Hyperresponsiveness Research Articles

Bronchial hyperresponsiveness.

Bronchial hyperresponsiveness (BHR) is often regarded as a 'hallmark' of asthma and bronchoprovocation testing is frequently performed to support a diagnosis of asthma. However, BHR is also found in a spectrum of other lung diseases and can be provoked by a variety of specific stimuli. To review the pathophysiology of BHR, discuss various methods of testing for BHR and describe the epidemiology of BHR in a variety of previously studied populations. We performed a systematic review of references identified using Medline and hand searches of identified articles. Because of space limitations, we have included those reports that seem most representative of the overall BHR literature. BHR can be induced by a variety of stimuli that trigger a number of different but overlapping physiological mechanisms. Bronchoprovocation testing can be performed using a variety of stimuli, various protocols and differing test criteria, yielding results that may be discordant. Elevated rates of BHR have been reported in studies of smokers, chronic obstructive pulmonary disease patients, atopics, athletes, exposed workers and the general population. Due to the prevalence of BHR in a spectrum of clinical patients and working populations, clinicians should be aware that BHR is not specific for asthma. When performed correctly, the greatest clinical value of BHR testing is to rule out suspected asthma in patients in whom testing is negative. Assessment of BHR also provides insights into the pathological mechanisms of airway disease.

Prevalence of over-/misdiagnosis of asthma in patients referred to an allergy clinic

Objective: Increasing asthma incidence may be due to an overall increase in asthma awareness by physicians, potentially resulting in overdiagnosis. One of the unique features of asthma is bronchial hyperresponsiveness, which can be assessed by methacholine bronchial challenge (MBC). Overdiagnosis may result in over- or mistreatment. The aims of this study were to describe the prevalence of the over-/misdiagnosis of asthma and the use of anti-asthmatic drugs in patients with asthma-like symptoms who had not yet undergone a respiratory function assessment to confirm the diagnosis of asthma. Methods: This was a retrospective study analyzing all MBCs performed by our Outpatient Allergy Clinic in a two-year period to confirm/exclude the diagnosis of asthma in patients referred by general practitioners and complaining of asthma-like symptoms. Anti-asthmatic medications used by the patients until the MBC date were recorded. Results: 43.8% of the reviewed MBCs were positive and 37.4% of the patients with a positive MBC were previously taking anti-asthmatic drugs (568.8 ± 76.4 mcg mean beclomethasone equivalents), compared to 51.2% of those patients with a negative MBC (464.8 ± 57.8 mcg). No differences were found in the daily doses of inhaled corticosteroids or other anti-asthmatic drugs, or in the duration of treatment before the assessment of bronchial hyperresponsiveness. Conclusions: A sizeable percentage of subjects who reported physician-diagnosed asthma had a negative MBC. Nevertheless, a greater proportion of negative MBC patients were taking anti-asthmatic drugs compared to those with a confirmed diagnosis of asthma, illustrating that the overdiagnosis of asthma may lead to over- and mistreatment of respiratory symptoms.

Respostas fisiológicas em adolescentes obesos submetidos à broncoprovocação com solução salina hipertônica

INTRODUÇÃO: A hiper-responsividade brônquica é a resposta do aumento dos mecanismos fisiológicos protetores das vias aéreas em indivíduos atópicos e não atópicos. Além disso, a magnitude da hiperresponsividade aérea apresenta influência conforme o grau de obesidade. OBJETIVO: Avaliar as respostas fisiológicas em adolescentes obesos submetidos a hiper-responsividade brônquica a solução salina hipertônica. MATERIAIS E MÉTODOS: Estudo descritivo, transversal e correlacional composto por 15 adolescentes obesos, de ambos os gêneros. O diagnóstico de asma foi realizado por meio de histórico clínico e questionário ISAAC, e a obesidade pelo IMC acima do percentil 95. Utilizou-se o teste de broncoprovocação por solução salina hipertônica para avaliação da hiper-responsividade brônquica, considerando positiva uma diminuição do volume expiratório forçado no primeiro segundo (VEF1) > 15% do valor pré-solução salina e a intensidade da hiper-responsividade brônquica foi calculada pela queda percentual máxima do VEF1 (% Queda máxVEF1). Foram utilizados o teste t independente ou U de Mann-Whitney e a correlação de Spearman rho (p < 0,05). RESULTADOS: Não foram encontradas diferenças significativas entre os asmáticos e não asmáticos para as variáveis antropométricas, espirométricas, lipídicas e hemodinâmicas. Verificaram-se moderadas correlações positivas e diferenças significativas entre o % Queda máxVEF1 com o IMC (p = 0,040) e IMC escore-Z (p = 0,028). Foram detectadas correlações negativas e diferenças significativas para a Queda máxVEF1 e leucócitos (p = 0,005) e para o % Queda máxVEF1 com o sulfato de dehidropiandrosterona (p = 0,032). CONCLUSÃO: Pode-se concluir que os adolescentes obesos submetidos a hiper-responsividade brônquica apresentam alterações espirométricas que estão associadas às inflamações sistêmicas da obesidade.

A scoring algorithm for predicting the presence of adult asthma: a prospective derivation study

Background:To predict the presence of asthma in adult patients with respiratory symptoms, we developed a scoring algorithm using clinical parameters.Methods:We prospectively analysed 566 adult outpatients who visited Kinki University Hospital for the first time with complaints of nonspecific respiratory symptoms. Asthma was comprehensively diagnosed by specialists using symptoms, signs, and objective tools including bronchodilator reversibility and/or the assessment of bronchial hyperresponsiveness (BHR). Multiple logistic regression analysis was performed to categorise patients and determine the accuracy of diagnosing asthma.Results:A scoring algorithm using the symptom-sign score was developed, based on diurnal variation of symptoms (1 point), recurrent episodes (2 points), medical history of allergic diseases (1 point), and wheeze sound (2 points). A score of ≥3 had 35% sensitivity and 97% specificity for discriminating between patients with and without asthma and assigned a high probability of having asthma (accuracy 90%). A score of 1 or 2 points assigned intermediate probability (accuracy 68%). After providing additional data of forced expiratory volume in 1 second/forced vital capacity (FEV1/FVC) ratio <0.7, the post-test probability of having asthma was increased to 93%. A score of 0 points assigned low probability (accuracy 31%). After providing additional data of positive reversibility, the post-test probability of having asthma was increased to 88%.Conclusions:This pragmatic diagnostic algorithm is useful for predicting the presence of adult asthma and for determining the appropriate time for consultation with a pulmonologist.

Predictors for Asthma at Age 7 Years for Low-Income Children Enrolled in the Childhood Asthma Prevention Study

To identify the predictive factors of early childhood wheezing in children of low socioeconomic status. The Childhood Asthma Prevention Study enrolled 177 low-income children (9-24 months old) with frequent wheezing. At age 7 years, presence of asthma was assessed through caregiver reports of physician diagnosis of asthma (CRPDA) and corroborated by assessment of bronchial hyperresponsiveness (BHR). Lung function, inflammatory markers, and asthma symptom severity were compared for children with ±CRPDA, ±BHR, and asthma. Baseline predictors for CRPDA, BHR, and asthma at 7 years of age were examined. Maternal symptom report strongly differentiated children with +CRPDA (49%) despite comparable airflow measurements (P<.0001), and spirometric lung function measurements were different for +BHR (65%) versus -BHR (P<.005). Univariate analyses revealed different baseline predictors of +CRPDA and +BHR for children at age 7 years. Higher levels of maternal psychological resources were associated with +CRPDA, but not +BHR. Only 39% of children with a history of frequent wheezing met the conservative definition of asthma at age 7 years, with the following significant predictors found: low birth weight, baseline symptom severity, and maternal psychological resources. This low-income, multi-ethnic group of wheezing infants represents a unique population of children with distinct characteristics and risks for persistent asthma. Determination of asthma status at 7 years of age required objective measurement of BHR in addition to CRPDA. The association of maternal psychological resources with +CRPDA may represent a previously unrecognized factor in the determination of asthma status among low-income groups.

320 Development of a Questionnaire for the Assessment of Bronchial Hyperresponsiveness in Korea

BackgroundBronchial hyperresponsiveness (BHR) is an important pathophysiological feature of asthma. In addition to the diagnostic significance, BHR is associated with the severity of airway inflammation and BHR- based treatment approaches has been shown to be effective. Nevertheless, challenge tests are time consuming, inconvenient to patients, and are not accessible in every primary care physicians. We aimed to develop a questionnaire for the assessment of BHR in Korean subjects.MethodsFrom the 24 University-affiliated hospitals, we recruited 149 adults between age 20 and 40 years with more than one asthmatic symptom (cough, sputum or dyspnea) and who had bronchial provocation test. A list of 33 symptoms, past history of allergy or smoking and 10 provoking stimuli were selected for the BHR questionnaire. After a methacholine challenge test patients were asked to complete each questionnaire. For each item of questionnaire, diagnostic odds ratios for the presence of BHR were calculated and multiple logistic regression analysis was performed to select final questionnaire items. Receiver operating characteristic (ROC) curve analysis was used to evaluate the sensitivity and specificity of the selected questionnaire items.ResultsMethacholine challenge test was positive in 36 patients (24.2%). Eleven symptoms and 2 provoking stimuli items were statistically significant by the results of diagnostic odds ratio. According to the result of multiple logistic regression analysis, 4 items were finally selected for the significant BHR questionnaire: the presence of wheezing episode, past history of physician-diagnosed asthma, family history of asthma. The psychiatric stress was negatively associated provoking stimuli item for the presence of BHR. The area under the ROC curve was 0.80 (95% CI, 0.72-0.86). Sensitivity was 84.9% (95% CI, 68.1-94.9) and specificity was 65.5% (95% CI, 55.8-74.3).ConclusionsFour BHR questionnaire items including wheezing episode, past history of physician-diagnosed asthma, family history of asthma and psyachiatric stress stimuli were able to assess the presence of BHR in Korean adults.

Healthcare utilisation and cost of care at school age related to home oxygen status during infancy

Aims To determine in prematurely born children who had bronchopulmonary dysplasia (BPD), if respiratory morbidity, lung function, healthcare utilisation and cost of care at school age were influenced by a requirement for supplementary oxygen at home after discharge from the neonatal intensive care unit (NICU). Methods One hundred and sixty children, median gestational age 27 (range 22–31) weeks, cared for on four tertiary neonatal intensive care units were examined. Sixty five of them had received supplementary oxygen when discharged home from the NICU (home oxygen group). A parent completed respiratory questionnaire was administered and lung function measurements (including assessment of bronchial hyper-responsiveness) were undertaken when the children were eight years old. Healthcare utilisation during years five to seven was assessed by examining hospital and general practitioner records to identify all hospital admissions, out-patient and general practitioner attendances and medication prescribed; whether the healthcare utilisation was related to respiratory problems was noted. The cost of care was calculated using the National Scheme of Reference Costs (2003) and medication costs calculated using the British National Formulary prices. Results No child was oxygen dependent at school age. There were no significant differences in cough or wheeze or in the baseline lung function results between the two groups, but there was tendency for more of the home oxygen group to respond to a cold air challenge (p=0.0596). The home oxygen group had more out-patient attendances (p=0.0168), particularly for respiratory related problems (p=0.0032), with greater associated costs of care (p=0.0186, p=0.0030 respectively). In addition, their cost of care for prescriptions (p=0.0409) and total respiratory related cost of care (p=0.0354) were significantly greater that that of the non-home oxygen group. Conclusion Children with BPD who required supplementary oxygen at home after discharge from the NICU have increased healthcare utilisation and associated cost of care at school age. These results emphasise such prematurely born children need ongoing follow up beyond when they cease to require home oxygen.

Development of a questionnaire for the assessment of bronchial hyperresponsiveness

Bronchial hyperresponsiveness (BHR) is a hallmark of asthma. Treatment approaches based on BHR severity have been shown to be effective. However, challenge tests are expensive, inconvenient to patients, time consuming, and not easily accessible to general practitioners. Assessment of BHR by a questionnaire would be advantageous in the diagnosis and management of asthma. To select a set of respiratory symptoms and provoking stimuli related to BHR to compose a reliable Bronchial Hyperresponsiveness Questionnaire (BHQ). A list of 33 symptoms and 68 stimuli were selected by in-depth interviews, focus group discussions with asthma patients, and literature review. After a histamine challenge test patients (n=302) were asked to score each question on a 7-point scale (0=no; 6=severe complaints). Factor analysis was performed to identify clusters of interrelated symptoms associated with PC20-histamine. The sensitivity to detect the presence of BHR was analysed by Receiver Operating Curves (ROC). The correlation between the PC20-score and the scores on the questions was analysed. 15 symptoms and 19 provoking stimuli were ultimately selected for the BHQ. The BHQ was developed according to FDA-approved standards and is a condition-specific questionnaire able to assess the presence of BHR.

The forced oscillation technique in clinical practice: methodology, recommendations and future developments.

The forced oscillation technique (FOT) is a noninvasive method with which to measure respiratory mechanics. FOT employs small-amplitude pressure oscillations superimposed on the normal breathing and therefore has the advantage over conventional lung function techniques that it does not require the performance of respiratory manoeuvres. The present European Respiratory Society Task Force Report describes the basic principle of the technique and gives guidelines for the application and interpretation of FOT as a routine lung function test in the clinical setting, for both adult and paediatric populations. FOT data, especially those measured at the lower frequencies, are sensitive to airway obstruction, but do not discriminate between obstructive and restrictive lung disorders. There is no consensus regarding the sensitivity of FOT for bronchodilation testing in adults. Values of respiratory resistance have proved sensitive to bronchodilation in children, although the reported cutoff levels remain to be confirmed in future studies. Forced oscillation technique is a reliable method in the assessment of bronchial hyperresponsiveness in adults and children. Moreover, in contrast with spirometry where a deep inspiration is needed, forced oscillation technique does not modify the airway smooth muscle tone. Forced oscillation technique has been shown to be as sensitive as spirometry in detecting impairments of lung function due to smoking or exposure to occupational hazards. Together with the minimal requirement for the subject's cooperation, this makes forced oscillation technique an ideal lung function test for epidemiological and field studies. Novel applications of forced oscillation technique in the clinical setting include the monitoring of respiratory mechanics during mechanical ventilation and sleep.

The effect of ribavirin to treat previously healthy infants admitted with acute bronchiolitis on acute and chronic respiratory morbidity

The role of ribavirin in the treatment of acute bronchiolitis is controversial. It has been suggested that the use of ribavirin may be of benefit during the acute illness and may reduce subsequent recurrent respiratory morbidity. This randomized, double-blind, placebo-controlled study was designed to determine whether ribavirin administered during the acute illness would have an influence on respiratory morbidity during both the acute illness and during the following year. Bronchial reactivity 6 months after the acute illness was also assessed. Forty previously well infants with moderately severe acute bronchiolitis were recruited during three winter epidemics. Subjects received study medication for 18 h a day. Management was otherwise unaltered. Subjects were evaluated daily by the investigator and subsequently assessed at 6 weeks, 6 months and 1 year following the acute illness. Assessment of bronchial hyper-responsiveness was assessed at 6 months of age using total body plethysmography and an established ultra-sonically nebulized distilled water challenge.A total of 40 patients (21 ribavirin, 19 placebo) were entered into the study. The two groups did not differ with respect to age, gender or clinical severity on entry to the trial. No significant differences were identified in the rate of clinical improvement over the first 24 h, the time to discharge, bronchial responsiveness at 6 months of age, frequency of significant respiratory symptoms over the first year of life and the frequency of prescribed bronchodilators and inhaled steroids during the year of follow-up.This study was unable to demonstrate any clinical benefit from the use of ribavirin in the acute illness or during subsequent follow-up for 1 year.

Development of Bronchial Hyperresponsiveness During Childhood

Bronchial hyperresponsiveness (BHR) produces the characteristic pathological abnormalities seen in asthma and clearly plays a central role in the pathophysiology of asthma. The presence of BHR has been demonstrated in infants with asthma, as has the possibility of BHR persisting through the childhood period. The level of BHR may not only reflect the state of the airways, as a marker of airway dysfunction, but may also predict the persistent prognosis of the disease. Thus, measurement of BHR may provide important information about the symptoms and lung function in children with asthma. In view of multiple pathophysiological mechanisms, BHR does not seem to have a single cause. Many potential confounding variables, such as age, gender, and genetic status, and some environmental factors, such as allergens, infections, and pollutants, could be responsible for the establishment of childhood BHR. There may be differences between the mechanisms that induce transient BHR and the mechanisms that induce persistent BHR. Also, there may be differences between the causes that induce BHR in the infantile period and the causes that maintain persistent BHR during childhood asthma. There is also disagreement as to the most suitable method to measure BHR in children, especially in infants. The assessment of BHR in young children has not been uniformly successful, and measurements of BHR changes over the childhood period are associated with a number of problems. To resolve these problems, there may be two ways to study childhood BHR. One is to use age-matched specific techniques to clarify the precise BHR in each age group; the other is to use simple techniques that can be performed over the childhood period on a large number of subjects. In studies of infantile respiratory dysfunction the ultimate goal is to establish a simple, noninvasive method by which measurements of respiratory function may be obtained in infants. Further investigations and acceptable methods will be needed to clarify the mechanisms involved in the establishment of asthma throughout the childhood period.

Quantitative bronchial challenge tests with wheat flour dust administered by Spinhaler: Comparison with aqueous wheat flour extract inhalation

Background: Quantitative bronchial challenge tests with flour dust for the diagnosis of bakers' asthma may be performed by inhalation of flour delivered to the patient's respiratory tract by sophisticated equipment. Objective: This study was carried out to assess the diagnostic value of bronchial challenge tests with flour dust inhalation from capsules administered by a Spinhaler (Fisons Inc., Loughborough, U.K.) and to compare this method quantitatively with bronchial challenge tests with a commercially available wheat flour extract. Methods: A highly selected group of 36 bakers with work-related symptoms of rhinitis or asthma were referred to our department, a tertiary referral center, from 1992 to 1995. Thirty-four of the subjects and 10 atopic control subjects were included in this study. After the assessment of bronchial hyperresponsiveness on day 1, subjects were randomized to inhale an aqueous wheat flour extract at concentrations of 0.01, 0.1, 1, 10, and 100 mg/ml by tidal volume breathing for 10 minutes or to inhale wheat flour dust filled in capsules on days 2 and 3. One, two, and four capsules (maximum of 7 cumulative capsules) of flour dust were administered by a Spinhaler. In addition, skin prick tests were performed with a battery of environmental and occupational allergens. Total serum IgE and specific IgE to wheat flour were measured by standard procedures. Results: Seventeen bakers and two control subjects demonstrated a positive skin test response to wheat flour (wheal ≥3 mm). Fifteen bakers demonstrated a fall of 50% or more in specific airway conductance after inhalation of the commercial wheat flour extract, and 11 demonstrated such a fall in specific airway conductance after inhalation of wheat dust. Three control subjects had a positive bronchial challenge response to the extract, but dust inhalation from the capsule did not cause positive bronchial reactions in control subjects. When a 50% fall of specific airway conductance was used as criterion for a positive bronchial provocation test result, sensitivity for the extract or dust inhalation was 0.44 and 0.32, respectively, and specificity was 0.7 and 1.0, respectively. If only subjects with a positive skin test response to wheat flour were considered, sensitivity of both tests was 0.65. With more stringent criteria for the gold standard, there was a trend for a higher sensitivity but a lower specificity of the extract inhalation. Both methods were safe. Conclusion: The validity of bronchial challenge tests with wheat flour dust inhaled from Spinhaler capsules was superior to that of tests done with a commercially available aqueous wheat flour extract. The higher specificity of the Spinhaler method might be an advantage if bronchial challenge tests are used as confirmation tests. (J Allergy Clin Immunol 1997;100:199-207.)

Assessment of bronchial hyperresponsiveness in preschool children: methodological issues.

Assessment of bronchial hyperresponsiveness in preschool children: methodological issues.

Osmotic Challenges in the Assessment of Bronchial Hyperresponsiveness

It is now well recognized that a change in osmolarity of the periciliary fluid is a potent stimulus to airway narrowing and may be a common cause for provoking an attack of asthma. This has led to the use of nonisotonic aerosols to document bronchial hyperresponsiveness in patients with clinical asthma. These aerosols are generated by ultrasonic nebulizers, and the most commonly used are water, hyperosmolar sodium or potassium chloride, and dextrose. An increase in specific airway resistance of 100% or a reduction in FEV1 of 20% is considered as an abnormal response to these aerosols. There are a number of factors that affect the airway response to these aerosols, and these include the osmolarity of the solution and its ionic content and pH. In addition responses may be affected by a previous challenge or medication. It is not known precisely how these aerosols act to induce airway narrowing, but it is not by a direct action on smooth muscle. It is thought that a change in osmolarity of the airways causes the release of inflammatory mediators, which then act to narrow the airways. For this reason challenge by nonisotonic aerosols is different from challenge by histamine and methacholine and may be preferable for the diagnosis of asthma and assessment of its treatment.

Clinical assessment of bronchial hyperresponsiveness due to nonspecific and specific agents

Clinical assessment of bronchial hyperresponsiveness due to nonspecific and specific agents

Clinical Assessment of Bronchial Hyperresponsiveness due to Nonspecific and Specific Agents

Clinical Assessment of Bronchial Hyperresponsiveness due to Nonspecific and Specific Agents