Effects of small airway dysfunction on the clinical expression of asthma: a focus on asthma symptoms and bronchial hyper-responsiveness

BACKGROUND

The small airways are an important site of inflammation in asthma. However, the relation between small airway dysfunction and clinical expression of asthma has hardly been studied.

AIM

To investigate the association of small and large airway dysfunction with asthma symptoms and bronchial hyper-responsiveness (BHR).

METHODS

Fifty-eight patients with asthma were characterized with spirometry, body plethysmography, impulse oscillometry, alveolar and bronchial exhaled nitric oxide, and a methacholine provocation. Symptoms of nocturnal asthma, exercise-related symptoms, BHR symptoms, and respiratory symptoms were assessed with the Asthma Control Questionnaire and Bronchial Hyper-responsiveness Questionnaire. Perception of dyspnea was rated with the Borg score during the provocation test.

RESULTS

Small and large airway dysfunction did not associate with higher scores for nocturnal, exercise-related, or BHR symptoms. Only higher scores on wheezing were significantly associated with higher values of difference between R5 and R20 (R5-R20) (r = 0.367, P < 0.01) and AX (r = 0.354, P < 0.01). Lower FEF25-75% (P = 0.024) and higher R5-R20 (P = 0.003) values were independently associated with more severe BHR to methacholine, but not FEV1 or R20 values. The increase in dyspnea during the methacholine provocation was strongly and independently correlated with the decrease in FEV1 and reactance of the respiratory system at 5 Hertz.

CONCLUSION

Small and large airway dysfunction poorly associate with asthma symptoms in our patients. However, deteriorations in small airway dysfunction are strongly related to an increase in dyspnea during bronchial provocation with methacholine. Small airway dysfunction contributes also independently to the clinical expression of asthma, as reflected by the severity of BHR.

Lung function by impulse oscillometry at age 5-7 years after bronchiolitis at age 0-6 months

BACKGROUND

Viral bronchiolitis in infancy has been associated with increased bronchial reactivity and reduced lung function in later childhood and even in adulthood. However, lung function at preschool age is less studied, mainly due to technical difficulties. The purpose of the study was to evaluate lung function and bronchial reactivity at preschool age in children who were hospitalized for bronchiolitis in early infancy.

SUBJECTS AND METHODS

Airway resistance and reactance, and bronchial reactivity to exercise were studied with impulse oscillometry (IOS) at the mean age of 6.3 years in 103 children hospitalized for bronchiolitis at less than 6 months of age.

RESULTS

In baseline lung-function measurement, resistance (n = 8; 7.8%) or reactance (19; 18.4%) at 5 Hz were pathological in 20% of children compared to Finnish population-based height-adjusted reference values. Increased bronchial reactivity by exercise challenge (5; 4.9%) or bronchodilatation (11; 10.7%) tests was present in 16%. Irreversible changes were revealed in only one case.

CONCLUSIONS

Though reduced lung function and increased airway reactivity were rather common, evidence for persistent lung function reduction was rare, less than 1%, at preschool age in children hospitalized for bronchiolitis caused mainly by respiratory syncytial virus at age less than 6 months.

Perceived exercise limitation in asthma: The role of disease severity, overweight, and physical activity in children

BACKGROUND

Children with asthma may be less physically active than their healthy peers. We aimed to investigate whether perceived exercise limitation (EL) was associated with lung function or bronchial hyper-responsiveness (BHR), socioeconomic factors, prenatal smoking, overweight, allergic disease, asthma severity, or physical activity (PA).

METHODS

The 302 children with asthma from the 10-year examination of the Environment and Childhood Asthma birth cohort study underwent a clinical examination including perceived EL (structured interview of child and parent(s)), measure of overweight (body mass index by sex and age passing through 25 kg/m² or above at 18 years), exercise-induced bronchoconstriction (forced expiratory volume in one-second (FEV₁ ) pre- and post-exercise), methacholine bronchial challenge (severe BHR; provocative dose causing ≥20% decrease in FEV₁ ≤ 1 μmol), and asthma severity score (dose of controller medication and exacerbations last 12 months). Multivariate logistic regression analyses were conducted to assess associations with perceived EL.

RESULTS

In the final model explaining 30.1%, asthma severity score (OR: 1.49, (1.32, 1.67)) and overweight (OR: 2.35 (1.14, 4.82)) only were significantly associated with perceived EL. Excluding asthma severity and allergic disease, severe BHR (OR: 2.82 (1.38, 5.76)) or maximal reduction in FEV₁ post-exercise (OR: 1.48 (1.10, 1.98)) and overweight (OR: 2.15 (1.13, 4.08) and 2.53 (1.27, 5.03)) explained 9.7% and 8.4% of perceived EL, respectively.

CONCLUSIONS

Perceived EL in children with asthma was independently associated with asthma severity and overweight, the latter doubling the probability of perceived EL irrespectively of asthma severity, allergy status, socioeconomic factors, prenatal smoking, or PA.

Isolated small airway reactivity during bronchoprovocation as a mechanism for respiratory symptoms in WTC dust-exposed community members

INTRODUCTION

Small airway dysfunction occurs following WTC dust exposure, but its role in producing symptoms is unclear.

METHODS

Methacholine challenge (MCT) was used to assess the relationship between onset of respiratory symptoms and small airway abnormalities in 166 symptomatic WTC dust-exposed patients. Forced oscillation testing (FOT) and respiratory symptoms were assessed during MCT. FOT parameters included resistance at 5 and 20 Hz (R5 and R20 ) and the R5 minus R20 (R5-20 ).

RESULTS

Baseline spirometry was normal in all (mean FEV1 100 + 13% predicted, mean FEV1 /FVC 80 + 4%). MCT revealed bronchial hyperreactivity by spirometry in 67 patients. An additional 24 patients became symptomatic despite minimal FEV1 change (<5%); symptom onset coincided with increased R5 and R5-20 (P > 0.001 vs. baseline). The dose-response of FOT (reactivity) was greater compared with subjects that remained asymptomatic (P < 0.05).

CONCLUSIONS

FOT during MCT uncovered reactivity in small airways as a mechanism for respiratory symptoms in subjects with inhalational lung injury. Am. J. Ind. Med. 59:767-776, 2016. © 2016 Wiley Periodicals, Inc.

Nocturnal symptoms perceived as asthma are associated with obstructive sleep apnoea risk, but not bronchial hyper-reactivity

BACKGROUND AND OBJECTIVE

Obstructive sleep apnoea (OSA) and asthma are associated, and nocturnal breathing difficulty that is usually identified as asthma-like symptoms can be present in both conditions. We investigated how nocturnal asthma-like symptoms (NAS) and bronchial hyper-reactivity (BHR) contribute to the association between OSA risk and current asthma, which is currently unknown but a clinically important question.

METHODS

We used data from 794 middle-aged participants in a population-based cohort who provided information on OSA risk (defined by a STOP-Bang questionnaire score of at least 3), current asthma and NAS, and underwent methacholine bronchial challenge testing. Using regression models, we examined the association between OSA risk and current asthma-NAS subgroups and investigated any effect modification by BHR.

RESULTS

The participants were aged 50 years (49.8% male). OSA risk was associated with NAS with or without current asthma (odds ratio (OR): 2.6; 95% CI = 1.3-5.0; OR: 4.2; 95% CI = 1.1-16.1, respectively), but not with current asthma in the absence of NAS. BHR was associated with current asthma with or without NAS (OR: 2.9; 95% CI = 1.4-5.9; OR: 3.4; 95% CI = 2.0-7.0, respectively) but not with NAS in the absence of current asthma. The associations between OSA risk and current asthma were neither modified nor mediated by BHR.

CONCLUSION

Our findings suggest that some of the nocturnal symptoms perceived as asthma may be OSA symptoms. Patients with nocturnal asthma symptoms should be considered for possible OSA.

Lung function and bronchial hyper-reactivity from 11 to 18 years in children with bronchiolitis in infancy

BACKGROUND

Various trajectories for lung function and bronchial hyper-reactivity (BHR) from early childhood to adulthood are described, including puberty as a period with excessive lung growth. Bronchiolitis in infancy may be associated with increased risk of developing chronic obstructive pulmonary disease, but the development of respiratory patterns during puberty is poorly characterized for these children. We aimed to study the development and trajectories of lung function and BHR from 11 to 18 years of age in children hospitalized for bronchiolitis in infancy.

METHODS

Infants hospitalized for bronchiolitis at the University Hospitals in Stavanger and Bergen, Norway, during 1997-1998, and an age-matched control group, were included in a longitudinal follow-up study and examined at 11 and 18 years of age with spirometry and methacholine provocation test (MPT). The MPT data were managed as dose-response slope (DRS) in the statistical analyses. Changes in lung function and DRS from 11 to 18 years of age were analyzed by generalized estimating equations, including interaction terms.

RESULTS

z-scores for forced vital capacity (FVC), forced expiratory volume in first second (FEV₁ ), FEV₁ /FVC ratio, and DRS were not different from 11 to 18 years of age in both the post-bronchiolitis and the control group. The trajectories from 11 to 18 years did not differ between the two groups. BHR at age 11 was independently associated with asthma at age 18.

CONCLUSION

Children hospitalized for bronchiolitis had stable predicted lung function and BHR from 11 to 18 years of age. The lung function trajectories were not different from controls.

Subjective responses to sprint interval exercise in adults with and without Exercise-induced bronchoconstriction

OBJECTIVE

Little is known of the subjective response to exercise that involves short "all out" bursts of effort, separated by recovery periods (sprint interval exercise (SPRINT)) among adults with exercise-induced bronchoconstriction (EIBC). The purpose of this study was to compare subjective responses to SPRINT and moderate intensity continuous exercise (MOD) among adults with EIBC, and to compare these responses between adults with EIBC and those without EIBC.

METHODS

Eight adults (22.3 ± 3.0 years) with EIBC, and eight adults (22.3 ± 3.0 years) without EIBC completed a SPRINT (4 × 30 second sprints separated by 4.5 minutes of active recovery) and MOD (20 minutes at 65% peak power output) session in random order. Self-reported affect, perceived breathlessness, and perceived exertion were recorded throughout exercise using validated scales. Enjoyment was assessed following exercise.

RESULTS

Differences between SPRINT and MOD were observed such that affect and perceived breathlessness were worse during the initial stages of SPRINT than MOD; however, differences disappeared by the end of exercise. Enjoyment was similar for SPRINT and MOD in the EIBC group (SPRINT: 72.9 ± 20.0 vs. MOD: 79.5 ± 20.5, p = 0.25), and between groups for SPRINT and MOD.

CONCLUSIONS

Perceived breathlessness may impact affect during the early stages of exercise among those with EIBC. Post-exercise enjoyment appears to be similar between SPRINT and MOD. Future research is needed to better understand the relationship between ventilation patterns, exercise intensity, and enjoyment of exercise among those with EIBC.

Life-threatening asthma attack during prolonged fingolimod treatment: case report

BACKGROUND

Fingolimod (FTY) mediates bronchoconstriction by interacting with sphingosine-1-phosphate receptors. The majority of the reported adverse respiratory events occur during the first weeks of treatment.

CASE PRESENTATION

A 49-year-old woman developed a life-threatening asthma attack after 6 months of continuous FTY treatment. The adverse event required prolonged hospitalization, and the patient recovered without sequelae after FTY interruption. A history of previous airway hyperreactivity and a concurrent viral respiratory infection possibly acted as predisposing factors.

CONCLUSION

This first description of a severe, life-threatening asthma attack during prolonged FTY treatment suggests the need for long-term clinical surveillance, especially in patients with known predisposing factors.

Mechanisms of nasal hyper-reactivity

Hyper-reactivity to non-specific challenges has been considered a hallmark of asthma and is defined as an abnormal responsiveness of the bronchial airways to a variety of provocative agents. The mechanisms underlying hyper-reactivity in the upper and lower airways are not known. By using the nose to study the inflammatory response possible abnormalities can be investigated carefully and pathophysiology of specific airway hyper-reactivities can be better understood. Other factors than merely constriction of the bronchial smooth muscles can cause narrowing of the free lumen to airflow. Functionally different and very distinct mucosal end-organ reactivities may also be increased. If these reactivities can be well assessed, specific airway hyper-reactivity can be defined. In the present report, specific mucosal end-organ hyper-reactivities in the allergic nasal mucosa are presented. Certain widespread hypotheses, such as the role of the eosinophil and the "increased absorption permeability theory", are disputed.

Absence of hyper-responsiveness to methacholine after specific bronchial provocation tests in a worker with hydroxyapatite-induced occupational asthma

Hydroxyapatite is commonly used as a filler to replace amputated bone or as a coating to promote bone ingrowth into prosthetic implants. Many modern implants, such as hip replacements and dental implants, are coated with hydroxyapatite. We report a patient with occupational asthma due to hydroxyapatite, proven by a specific inhalation challenge, who experienced an early asthmatic reaction after exposure to hydroxyapatite, without increased airway responsiveness to methacholine despite an increased eosinophil count in the peripheral blood. A 38-year-old male dental implant worker visited our allergy department for the evaluation of occupational asthma. He had treated dental implant titanium surfaces with hydroxyapatite for 1.5 years. One year after starting his employment, he noticed symptoms of rhinorrhea, paroxysmal cough, and chest tightness. His symptoms were aggravated during and shortly after work and subsided several hours after work. When he stopped working for 2 months because of his chest symptoms, he became asymptomatic. After restarting his work, his symptoms reappeared and were aggravated. A methacholine bronchial challenge test had a negative response. The following day, a specific bronchial provocation test with wheat powder was negative. On the third day, a specific bronchial provocation test with hydroxyapatite powder produced an early asthmatic response. On the fourth day, a methacholine bronchial challenge test was negative. Further studies are needed to evaluate the exact pathogenetic mechanism of hydroxyapatite-induced occupational asthma.

Asthma-like peak flow variability in various lung diseases

BACKGROUND AND OBJECTIVES

Bronchodilator reversibility and diurnal peak flow variability are considered characteristic of asthma patients. Patients with chronic obstructive pulmonary disease (COPD) show poor reversibility. But reversibility and variability in other pulmonary diseases manifesting with airflow obstruction in not known. Therefore, we assessed reversibility and peak flow variability in patients with various lung diseases to recognize the pattern.

MATERIALS AND METHODS

Seventy consecutive patients with a diagnosis of lung diseases manifesting with airflow obstruction were recruited in the study. These included 23 patients with asthma, 11 patients with bronchiectasis, 16 patients with post-tubercular lung disease (PTLD), and 20 patients with COPD. Ten healthy matched control subjects were also selected to pair with asthmatic patients. Bronchodilator reversibility test was done initially and peak expiratory flow rate (PEFR) was measured for a duration of 1 week by patients themselves on a chart that was given to them. The mean amplitude percentage of these records were analyzed.

RESULTS

The mean values of peak flow variability were 14.73% ± 6.1% in asthmatic patients, 11.98% ± 7.5% in patients with bronchiectasis, and 10.54% ± 5.3% in PTLD. The difference in the mean values of peak flow variability between asthma and bronchiectasis, that is, 14.73 (6.1) vs 11.98 (7.5) was not statistically significant (P > 0.05). Forced expiratory volume one second (FEV(1)) reversibility values were 14.77% ± 26.93%, 11.24% ± 20.43%, 10.85% ± 13.02%, 16.83% ± 22.84%, and 5.47% ± 4.99% in asthma, COPD, PTLD, bronchiectasis, and healthy subjects, respectively.

CONCLUSION

Both reversibility and diurnal peak flow variability were higher in patients with various lung diseases compared with normal healthy subjects. Although these are characteristic of asthma, some cases of bronchiectasis and PTLD patients may also manifest asthma-like PEFR variability and reversibility.