Effect of Continuous Positive Airway Pressure on Airway Reactivity in Asthma. A Randomized, Sham-controlled Clinical Trial

Chronic Cough and Obstructive Sleep Apnea

Chronic cough, defined as a cough lasting more than 8 weeks, is a common medical condition occurring in 5% to 10% of the population. Its overlap with another highly prevalent disorder, obstructive sleep apnea (OSA), is therefore not surprising. The relationship between chronic cough and OSA extends beyond this overlap with higher prevalence of OSA in patients with chronic cough than in the general population. The use of continuous positive airway pressure can result in improvement in chronic cough although further studies are needed to understand which patients will experience benefit in their cough from the treatment of comorbid OSA.

Sleep Deficiency, Sleep Apnea, and Chronic Lung Disease

With sleep occupying up to one-third of every adult's life, addressing sleep is essential to overall health. Sleep disturbance and deficiency are common in patients with chronic lung diseases and associated with worse clinical outcomes and poor quality of life. A detailed history incorporating nocturnal respiratory symptoms, symptoms of obstructive sleep apnea (OSA) and restless legs syndrome, symptoms of anxiety and depression, and medications is the first step in identifying and addressing the multiple factors often contributing to sleep deficiency in chronic lung disease. Additional research is needed to better understand the relationship between sleep deficiency and the spectrum of chronic lung diseases.

Asthma and obstructive sleep apnoea in adults and children - an up-to-date review

Obstructive sleep apnoea (OSA) and asthma are two common respiratory disorders in children and adults. Apart from common risk factors, such as obesity, gastroesophageal reflux disease and allergic rhinitis, emerging evidence suggest that the two diseases may complicate the clinical course of each other. On one hand, OSA modifies asthmatic airway inflammation and is associated with poor asthma control. On the other hand, asthma and its medications increase the collapsibility of the upper airways contributing to the development and worsening of OSA. The overnight respiratory symptoms of OSA and asthma are often similar, and an inpatient polysomnography is often necessary for a proper diagnosis, especially in children. Continuous positive pressure, the gold standard treatment for OSA can improve asthma control in patients suffering from both diseases. However, there is limited evidence how anti-asthma medications act in the same patients. Nevertheless, adenotonsillectomy seems to be effective in children with concomitant asthma and OSA. This review summarises the evidence for the bidirectional link between asthma and OSA, focuses on diagnostic and therapeutic challenges and highlights the need for further research.

Airway smooth muscle pathophysiology in asthma

The airway smooth muscle (ASM) cell plays a central role in the pathogenesis of asthma and constitutes an important target for treatment. These cells control muscle tone and thus regulate the opening of the airway lumen and air passage. Evidence indicates that ASM cells participate in the airway hyperresponsiveness as well as the inflammatory and remodeling processes observed in asthmatic subjects. Therapeutic approaches require a comprehensive understanding of the structure and function of the ASM in both the normal and disease states. This review updates current knowledge about ASM and its effects on airway narrowing, remodeling, and inflammation in asthma.

[Obstructive sleep apnea and asthma: Clinical implications]

Obstructive sleep apnea (OSA) and asthma are common respiratory diseases that can coexist in the same patient. Epidemiological and pathophysiological data suggest an independent link between these two diseases. Specially, OSA is frequently associated with non-eosinophilic and with poorly-controlled asthma. Common comorbidities including obesity, gastroesophageal reflux and rhinitis may promote this association. The impact of OSA treatment on the clinical and functional control of asthma has been extensively investigated. Numerous non-randomized studies suggest that continuous positive pressure treatment is likely to improve asthma symptoms, the control of the disease and quality of life in asthmatics with OSA. However, this impact has not been confirmed in the limited randomized trial available. To date, the optimal treatment approach in asthmatics with OSA is the best treatment of each disease separately and the recognition and treatment of comorbidities. When indicated, obesity surgery has a major impact on both diseases.

From sleep medicine to medicine during sleep-a clinical perspective

Objective. In this perspective paper, we aim to highlight the potential of sleep as an auspicious time for diagnosis, management and therapy of non-sleep-specific pathologies.Approach. Sleep has a profound influence on the physiology of body systems and biological processes. Molecular studies have shown circadian-regulated shifts in protein expression patterns across human tissues, further emphasizing the unique functional, behavioral and pharmacokinetic landscape of sleep. Thus, many pathological processes are also expected to exhibit sleep-specific manifestations. Modern advances in biosensor technologies have enabled remote, non-invasive recording of a growing number of physiologic parameters and biomarkers promoting the detection and study of such processes.Main results. Here, we introduce key clinical studies in selected medical fields, which leveraged novel technologies and the advantageous period of sleep to diagnose, monitor and treat pathologies. Studies demonstrate that sleep is an ideal time frame for the collection of long and clean physiological time series data which can then be analyzed using data-driven algorithms such as deep learning.Significance.This new paradigm proposes opportunities to further harness modern technologies to explore human health and disease during sleep and to advance the development of novel clinical applications - from sleep medicine to medicine during sleep.

Continuous positive airway pressure acutely increases exercise duration in children with severe therapy-resistant asthma: a randomized crossover trial

BACKGROUND

Lower exercise tolerance is an important component of asthma and the possible effects of non-invasive ventilation on exercise capacity in individuals with severe therapy-resistant asthma (STRA) are unknown. This study aimed to evaluate the immediate effect of continuous positive airway pressure (CPAP) on exercise tolerance in children with STRA.

METHODS

We performed a controlled, randomized, crossover clinical trial including subjects aged 6 to 18 years old diagnosed with STRA. Clinical, anthropometric and lung function data were collected. The participants in the intervention group (IG) used CPAP (PEEP 10cmH₂O and FiO₂ 0.21) for a period of 40 min. Subjects in the control group (CG) used CPAP with minimum PEEP at 1 cmH₂0 also for 40 min. Afterwards, subjects from both groups underwent cardiopulmonary exercise testing (CPET). After a 15-day washout period, on a subsequent visit, subjects participated in the opposite group to the initial one.

RESULTS

Thirteen subjects with a mean age of 12.30 ± 1.7 years were included. The variables of peak expiratory flow (PEF) and forced expiratory volume in the first second (FEV₁) before using CPAP and after performing CPET did not show significant differences. Regarding CPET results, there was no significant difference (P = 0.59) between groups at peak exercise for oxygen consumption-VO₂ (CG: 33.4 ± 6.3 and IG: 34.5 ± 5.9, mL kg^-1 min^-1). However, the IG (12.4 ± 2.1) presented a total test time (min) significantly (P = 0.01) longer than the CG (11.5 ± 1.3).

CONCLUSION

The results suggest that the use of CPAP before physical exercise increases exercise duration in children and adolescents with STRA.

Asthma and Obstructive Sleep Apnea Overlap: What Has the Evidence Taught Us?

Obstructive sleep apnea (OSA) and asthma are highly prevalent chronic respiratory disorders. Beyond their frequent coexistence arising from their high prevalence and shared risk factors, these disorders feature a reciprocal interaction whereby each disease impacts the severity of the other. Emerging evidence implicates airway and systemic inflammation, neuroimmune interactions, and effects of asthma-controlling medications (corticosteroids) as factors that predispose patients with asthma to OSA. Conversely, undiagnosed or inadequately treated OSA adversely affects asthma control, partly via effects of intermittent hypoxia on airway inflammation and tissue remodeling. In this article, we review multiple lines of recently published evidence supporting this interaction. We provide a set of recommendations for clinicians involved in the care of adults with asthma, and identify critical gaps in our knowledge about this overlap.

Perioperative Implications of Vaping

Over the past 10 - 15 years, there has been a significant increase in the use of electronic cigarettes. These devices are generally used to deliver nicotine through inhalation by aerosolization. While the long-term risk of lung cancer is yet to be known, the chemicals and impurities in the solutions may have other acute and chronic effects on the respiratory system including respiratory failure from adult respiratory distress syndrome. Recent concerns have been raised regarding the potential for significant acute and chronic health care risks of these devices including pneumonitis, airway reactivity and respiratory failure. Given that many of the acute effects are related to the respiratory system, anesthetic care may be required during diagnostic procedures including bronchoscopy to investigate the etiology of acute respiratory symptomatology. We present an adolescent who presented to the operating room for bronchoscopy and bronchoalveolar lavage to investigate the etiology of respiratory involvement following an episode of vaping. The healthcare and end-organ effects of nicotine, tobacco smoke and vaping are discussed, and potential anesthetic implications are presented.

Nocturnal bilevel positive airway pressure for the treatment of asthma

Nocturnal worsening of asthma may be due to reduced lung volumes and fewer sigh breaths, which have been shown to increase airway resistance and bronchoreactivity. We hypothesized that mimicking deep inspiration using nocturnal mechanical support would improve symptoms in patients with asthma. Subjects with asthma underwent usual care and bilevel positive airway pressure (PAP) therapy for 4 weeks, separated by 4 weeks, and methacholine challenge (PC20) and subjective assessments. 13 patients with asthma alone and 8 with asthma + OSA completed the protocol. Change in bronchoreactivity (ratio of Post/Pre PC20) was not significantly different during usual care and bilevel PAP [0.86 (IQR 0.19, 1.82) vs 0.94 (IQR 0.56, 2.5), p = 0.88], nor was the change in Asthma Control Test different: 0.1 ± 2.2 vs. -0.2 ± 2.9, p = 0.79, respectively. Bilevel PAP therapy for four weeks did not improve subjective or objective measures of asthma severity in patients with asthma or those with asthma and OSA, although there was heterogeneity in response.

The Effects of Obesity in Asthma

PURPOSE OF REVIEW

Rising costs and increasing morbidity makes the identification and treatment of high-risk asthma phenotypes important. In this review, we outline the complex relationship between obesity and asthma.

RECENT FINDINGS

Studies have confirmed a bi-directional relationship between obesity and asthma. Pathophysiological factors implicated include genetic risk, the effect of diet and microbiome, and obesity-related cytokines. There have been robust, albeit derived, efforts to phenotype this group with distinct clinical presentations based on age of onset of asthma. Unfortunately, the poor performance of biomarkers and traditional lung function testing has impeded diagnosis, phenotyping, and management of the obese asthma patient. There is also a lack of targeted interventions with weight loss showing some benefits. Obesity increases the prevalence of asthma and is associated with worse outcomes. There are unique research and clinical challenges while managing this group of patients.

Sleep and asthma

PURPOSE OF REVIEW

There is a longstanding recognition of the detrimental effect of poorly controlled asthma on sleep, but recent years have seen a growing interest in how asthma and sleep may interact. This review examines the current evidence of relationships between asthma, sleep and sleep disorders.

RECENT FINDINGS

Poor quality sleep and sleep disturbance is highly prevalent in asthmatic patients, and particularly in those with severe asthma. Impaired sleep quality correlates with worse asthma control and quality of life. Sleep disturbance in asthma may be related to due circadian variation in airway inflammation, but may also be related to specific sleep disorders. Obstructive sleep apnoea (OSA) appears to be significantly more common in asthmatic patients than nonasthmatic patients, and treatment of OSA with continuous positive airway pressure (CPAP) may lead to improved asthma-specific quality of life. Nocturnal CPAP may also be of benefit to asthmatic patients without OSA, potentially because of stretching of airway smooth muscle. Insomnia is also highly prevalent in severe asthma patients, and is associated with a history of poor asthma control and increased healthcare utilization.

SUMMARY

Asthma, sleep and sleep disorders appear to have complex, but significant relationships. Prospective observational and controlled interventional studies are needed to quantify how addressing sleep difficulties may benefit asthma patients.

Effect of CPAP on airway reactivity and airway inflammation in children with moderate-severe asthma

BACKGROUND AND OBJECTIVE

Asthma is characterized by airway hyperreactivity and airway inflammation. We previously demonstrated that adults with mild well-controlled asthma exhibited a marked decrease in airway reactivity (PC20 increased >2-fold) after using nocturnal continuous positive airway pressure (CPAP) for 1 week. If CPAP produces a similar suppression of airway reactivity in children with moderate-severe asthma, who require chronic use of corticosteroids, then this non-pharmacological therapy might provide a beneficial alternative or supplemental therapy in these subjects.

METHODS

Children aged 8-17 years with moderate-severe asthma were treated with 4 weeks of nocturnal CPAP (8-10 cm H2 O) or sham CPAP (<2 cm H2 O). Adherence was monitored with a modem installed in the equipment or by memory cards. Airway reactivity, assessed by methacholine bronchial challenge, was measured prior to and following treatment.

RESULTS

The percentage of subjects adherent to treatment was similar in both groups (19/27 CPAP vs 19/28 sham, ~70%). There was a tendency for PC20 to increase with treatment in both groups (3.0-5.3 mg/mL CPAP vs 3.2 to 4.3 mg/mL sham, P = 0.083); however, the change did not differ significantly between groups (P = 0.569).

CONCLUSION

We found that the 4-week treatment with nocturnal CPAP did not produce a twofold suppression of airway reactivity in children with moderate-severe asthma.

Similar Airway Function after Volitional Hyperpnea in Mild-Moderate Asthmatics and Healthy Controls

BACKGROUND

The beneficial effects of exercise training for asthmatics might relate to repetitive airway stretching. Thus, a training with more pronounced airway stretch using isolated, volitional hyperpnea (HYP) might be similarly or more effective. However, in healthy subjects, a bout of HYP training is known to cause an acute FEV1 decline.

OBJECTIVE

The aim of the present study was therefore to test whether these changes are more pronounced in asthmatics, possibly putting them at risk with HYP training.

METHODS

Nine subjects with mild-moderate asthma (confirmed by mannitol challenge) and 11 healthy subjects performed six 5-min bouts (with 6-min breaks; HYP1) and one 30-min bout (HYP2) of normocapnic HYP at 60% of maximal voluntary ventilation using warm and humid air. FEV1 and airway resistance (R5) were measured before, in breaks (HYP1), and immediately after HYP, and during 60 min of recovery.

RESULTS

In both groups, a significant and similar decrease in FEV1 during HYP1 (asthmatics: -3 ± 3%; healthy subjects: -2 ± 3%), after HYP1 (asthmatics: -2 ± 5%; healthy subjects: -1 ± 4%), and after HYP2 (asthmatics: -4 ± 5%; healthy subjects: -3 ± 3%), and an increase in R5 during and after both HYPs were observed. Maximal changes in FEV1 and R5 did not correlate with baseline lung function or responsiveness to mannitol.

CONCLUSIONS

A bout of HYP does not lead to relevant bronchoconstriction and the observed changes in lung function and airway resistance are neither of the magnitude of clinical relevance, nor do they differ from responses in healthy individuals. Thus, HYP training can safely be tested as an airway-specific exercise training alternative (or add-on) modality to regular aerobic exercise training.

Older age and obesity are associated with increased airway closure in response to methacholine in patients with asthma

BACKGROUND AND OBJECTIVE

The reduction of forced expiratory volume in 1 s (FEV₁ ) in response to methacholine challenge in asthma may reflect two components: airway narrowing, assessed by the change in FEV₁ /forced vital capacity (FVC), and airway closure, assessed by the change in FVC. The purpose of this study was to determine the degree and determinants of airway closure in response to methacholine in a large group of asthmatic patients participating in studies conducted by the American Lung Association-Airways Clinical Research Centers (ALA-ACRC).

METHODS

We used the methacholine challenge data from participants in five studies of the ALA-ACRC to determine the closing index, defined as the contribution of airway closure to the decrease in FEV₁ , and calculated as %ΔFVC/%ΔFEV₁ .

RESULTS

There were a total of 936 participants with asthma, among whom the median closing index was 0.67 relative to that of a published healthy population of 0.54. A higher closing index was associated with increased age (10-year increments) (0.04, 95% CI = 0.02, 0.05, P < 0.005) and obesity (0.07, 95% CI = 0.03, 0.10, P < 0.001). There was no association between the closing index and asthma control.

CONCLUSION

Our findings confirm that airway closure in response to methacholine occurs in a large, diverse population of asthmatic participants, and that increased airway closure is associated with older age and obesity. These findings suggest that therapies targeting airway closure may be important in patients with a high closing index.

Current opinions for the management of asthma associated with ear, nose and throat comorbidities

Ear, nose and throat (ENT) comorbidities are common in patients with asthma and are frequently associated with poorer asthma outcomes. All these comorbidities are "treatable traits" in asthma. Identification and management of these disorders may spare medication usage and contribute to improved asthma control and quality of life, and a decrease in exacerbation rates.This review summarises recent data about the prevalence, clinical impact and treatment effects of ENT comorbidities in asthma including allergic rhinitis, chronic rhinosinusitis with and without nasal polyposis, aspirin-exacerbated respiratory disease, obstructive sleep apnoea and vocal cord dysfunction.Many of these comorbidities are possible to be managed by the pulmonologist, but the collaboration with the ENT specialist is essential for patients with chronic rhinosinusitis or vocal cord dysfunction. Further rigorous research is needed to study the efficacy of comorbidity treatment to improve asthma outcomes, in particular with the development of biotherapies in severe asthma that can also be beneficial in some ENT diseases.

Continuous positive airway pressure for obstructive sleep apnoea does not improve asthma control

BACKGROUND AND OBJECTIVE

Unrecognized obstructive sleep apnoea syndrome (OSAS) may lead to poor asthma control despite optimal therapy. We assessed asthma control, airway responsiveness, daytime sleepiness and health status at baseline and 3 months after continuous positive airway pressure (CPAP) treatment among asthma patients with nocturnal symptoms and OSAS.

METHODS

Patients with nocturnal asthma symptoms despite receiving at least moderate-dose inhaled corticosteroid and long-acting bronchodilators underwent a home sleep study using 'Embletta' portable diagnostic system. Patients with significant OSAS (apnoea-hypopnoea index (AHI) ≥10/h) were randomized to receive either CPAP or conservative treatment for 3 months.

RESULTS

Among 145 patients recruited, 122 underwent sleep study with 41 (33.6%) having AHI ≥10/h. Patients with significant OSAS had higher BMI (27.4 (5.1) vs 25.1 (4.5) kg/m² , P = 0.016), bigger neck circumference (36.6 (3.1) vs 34.8 (3.6) cm, P = 0.006) and lower minimum SaO₂ (80.7 (6.6) vs 87.2 (3.9) %, P < 0.001). Using intention-to-treat analysis among 37 patients with AHI ≥10/h (CPAP group (n = 17) vs control group (n = 20)), there was no significant difference in Asthma Control Test score (CPAP 3.2 (2.7) vs control 2.4 (5.7), P = 0.568) but the CPAP group had a greater improvement in Epworth Sleepiness Scale (-3.0 (4.5) vs 0.5(3.8), P = 0.014), Asthma Quality of Life Questionnaire (0.6 (0.8) vs 0.02 (0.7), P = 0.022) and vitality domain in the SF-36 questionnaire (14.7 (16.8) vs 0.3 (16.2), P = 0.012) after 3 months. Data are presented as mean (SD) unless otherwise stated.

CONCLUSION

A high prevalence of OSAS was found among patients with asthma and snoring. CPAP therapy for 3 months did not enhance asthma control but improved daytime sleepiness, quality of life and vitality.

Performance of the Asthma Impact on Quality of Life Scale (A-IQOLS) in diverse asthma research populations and demographic subgroups

BACKGROUND

The Asthma Impact on Quality of Life Scale (A-IQOLS) assesses the patient-perceived negative effect of asthma on quality of life. Its standard error of measurement is known; it has strong construct, convergent, and divergent validity; and it provides information that is unique among asthma outcome measures.

OBJECTIVE

We sought to characterize the psychometric properties of the A-IQOLS and its suitability for use in demographically and clinically diverse adult asthmatic populations.

METHODS

Data from participants in 5 independent asthma studies, with samples ranging from patients with well-controlled moderate asthma to patients with severe poorly controlled asthma, were pooled to determine the psychometric performance of A-IQOLS scores overall and in multiple demographic, disease status, and study subgroups.

RESULTS

Pooled sample (n = 597) age averaged 45 years; 66% were female, 65% were white, 22% were African American, 11% were Hispanic, and 11% had a high school education or less. The rated importance of its underlying life dimensions and associations between A-IQOLS scores and lung function, symptom, Asthma Control Test, Juniper Mini Asthma Quality of Life Questionnaire, and Marks Asthma Quality of Life Questionnaire scores was very similar, regardless of patients' demographic and clinical characteristics. A-IQOLS scores discriminated among the individual study samples, as well as other patient-reported symptom and functional status measures. Distribution and anchor-based considerations suggest an A-IQOLS minimum clinically important difference in the vicinity of 0.50 and not less than 0.33 scale score units.

CONCLUSIONS

A-IQOLS is valid for research and potentially clinical use in demographically and clinically diverse patients.

Reproducibility of airway luminal size in asthma measured by HRCT

Brown RH, Henderson RJ, Sugar EA, Holbrook JT, Wise RA, on behalf of the American Lung Association Airways Clinical Research Centers. Reproducibility of airway luminal size in asthma measured by HRCT. J Appl Physiol 123: 876-883, 2017. First published July 13, 2017; doi:10.1152/japplphysiol.00307.2017.-High-resolution CT (HRCT) is a well-established imaging technology used to measure lung and airway morphology in vivo. However, there is a surprising lack of studies examining HRCT reproducibility. The CPAP Trial was a multicenter, randomized, three-parallel-arm, sham-controlled 12-wk clinical trial to assess the use of a nocturnal continuous positive airway pressure (CPAP) device on airway reactivity to methacholine. The lack of a treatment effect of CPAP on clinical or HRCT measures provided an opportunity for the current analysis. We assessed the reproducibility of HRCT imaging over 12 wk. Intraclass correlation coefficients (ICCs) were calculated for individual airway segments, individual lung lobes, both lungs, and air trapping. The ICC [95% confidence interval (CI)] for airway luminal size at total lung capacity ranged from 0.95 (0.91, 0.97) to 0.47 (0.27, 0.69). The ICC (95% CI) for airway luminal size at functional residual capacity ranged from 0.91 (0.85, 0.95) to 0.32 (0.11, 0.65). The ICC measurements for airway distensibility index and wall thickness were lower, ranging from poor (0.08) to moderate (0.63) agreement. The ICC for air trapping at functional residual capacity was 0.89 (0.81, 0.94) and varied only modestly by lobe from 0.76 (0.61, 0.87) to 0.95 (0.92, 0.97). In stable well-controlled asthmatic subjects, it is possible to reproducibly image unstimulated airway luminal areas over time, by region, and by size at total lung capacity throughout the lungs. Therefore, any changes in luminal size on repeat CT imaging are more likely due to changes in disease state and less likely due to normal variability.NEW & NOTEWORTHY There is a surprising lack of studies examining the reproducibility of high-resolution CT in asthma. The current study examined reproducibility of airway measurements. In stable well-controlled asthmatic subjects, it is possible to reproducibly image airway luminal areas over time, by region, and by size at total lung capacity throughout the lungs. Therefore, any changes in luminal size on repeat CT imaging are more likely due to changes in disease state and less likely due to normal variability.

Management of Severe Asthma before Referral to the Severe Asthma Specialist

Severe asthma is associated with significant morbidity and can be challenging to assess and control, due to heterogeneity of disease, complexity of diagnosis, and impact of comorbidities. A structured approach to the assessment and management of severe asthma may be helpful to the practicing clinician. First, it is important to confirm a diagnosis of asthma. In patients who are either not responding to treatment, or who require high doses of medication to control symptoms, it is highly possible that disease mimickers or comorbidities are present and can inhibit therapeutic responsiveness. The assessment and management of common comorbidities of asthma may dramatically impact disease control and thus medication requirement. Determining medication adherence and optimizing drug dose and delivery may separate out truly severe asthmatics from those not using medications regularly or properly. Next, although true personalized medicine for severe asthma is not yet realized, for those individuals with severe asthma, phenotypic characteristics of each patient may guide which therapeutic options may be most effective for that patient. Finally, evaluation and management of severe asthma at a referral center can add additional phenotyping, therapeutic, and diagnostic strategies.