Expiratory central airway collapse in stable COPD and during exacerbations

Bronchoscopy for refractory/unexplained cough with mucus

INTRODUCTION

Refractory/unexplained cough (RUCC) is typically associated with throat symptoms and a dry cough. Some patients attending specialist cough clinics however, report sputum production (>1 tablespoon daily) and atypical sensations (urge-to-cough in chest). Bronchoscopy findings in this specific cohort have rarely been described.

AIMS

We aimed to evaluate bronchoscopy, bronchoalveolar lavage (BAL) cell differential and microbiology findings in RUCC with mucus production.

METHODS

We retrospectively reviewed case notes, procedure results and treatment of patients undergoing bronchoscopy for RUCC with more than a tablespoon of sputum daily.

RESULTS

Data were included from 54 patients with RUCC, normal or trivial findings on CT (Computerised Tomography) imaging and no response to guideline-directed treatment of their cough. Most (84%) patients had BAL neutrophilia and excessive dynamic airway collapse (EDAC) was seen in 31%. Treatment strategies in these patients differed to those adopted in typical RUCC associated with a dry cough. Management was influenced or changed in 48/54 (89%) of the patients undergoing bronchoscopy.

CONCLUSIONS

Bronchoscopy provides high diagnostic value in RUCC with mucus production (>1 tbsp daily), identifying specific treatable traits including neutrophilic airway inflammation and EDAC.

Physiotherapy for large airway collapse: an ABC approach

Large airway collapse (LAC) describes the phenomenon of excessive, abnormal, inward movement of the large airways (i.e. trachea and/or main bronchi and/or bronchus intermedius) occurring during the expiratory phase of the respiratory cycle. It is an increasingly well-recognised problem and a prevalent comorbidity in other chronic respiratory conditions (e.g. COPD and asthma). LAC is associated with pervasive respiratory features such as a barking cough, exertional dyspnoea and an increased propensity to lower respiratory tract infection. These symptoms are unpleasant, and patients are often limited in their daily life and their function. The pathophysiology of this condition impairs airway clearance and can cause breathlessness and exercise intolerance, due to a loss of airway patency during expiratory flow. Dysfunctional adaptations to breathing and coughing may further amplify symptoms. This article provides, for the first time, clinically focused physiotherapeutic intervention advice based on our understanding of the pathophysiology of LAC, to support conservative management. It uses the available evidence from LAC, transferable evidence from other conditions and knowledge based on clinical experience. It proposes a practical "ABC model" to ensure physiotherapy assessment and treatments are centred around optimising three key clinical areas: Airways, including airway clearance and cough; Breathing, including breathlessness and breathing pattern; and Capacity for exercise, including an assessment of functional exercise ability.

Detection and diagnosis of large airway collapse: a systematic review

Large airway collapse (LAC) is a frequently encountered clinical problem, caused by tracheobronchomalacia +/− excessive dynamic airway collapse, yet there are currently no universally accepted diagnostic criteria. We systematically reviewed studies reporting a diagnostic approach to LAC in healthy adults and patients, to compare diagnostic modalities and criteria used. Electronic databases were searched for relevant studies between 1989 and 2019. Studies that reported a diagnostic approach using computed tomography (CT), magnetic resonance imaging or flexible fibreoptic bronchoscopy were included. Random effects meta-analyses were performed to estimate the prevalence of LAC in healthy subjects and in patients with chronic obstructive airway diseases. We included 41 studies, describing 10 071 subjects (47% female) with a mean±sd age of 59±9 years. Most studies (n=35) reported CT findings, and only three studies reported bronchoscopic findings. The most reported diagnostic criterion was a ≥50% reduction in tracheal or main bronchi calibre at end-expiration on dynamic expiratory CT. Meta-analyses of relevant studies found that 17% (95% CI: 0–61%) of healthy subjects and 27% (95% CI: 11–46%) of patients with chronic airways disease were classified as having LAC, using this threshold. The most reported approach to diagnose LAC utilises CT diagnostics, and at a threshold used by most clinicians (i.e., ≥50%) may classify a considerable proportion of healthy individuals as being abnormal and having LAC in a quarter of patients with chronic airways disease. Future work should focus on establishing more precise diagnostic criteria for LAC, relating this to relevant physiological and disease sequelae.

CT is mostly used to diagnose LAC, and at a threshold used by most clinicians (i.e. ≥50%) that would classify a large proportion of healthy individuals as being abnormal and LAC in a quarter of patients with chronic airway diseaseshttps://bit.ly/3izAuSk

Expiratory central airway collapse and symptoms in smokers

BACKGROUND

The prevalence and clinical impacts of expiratory central airway collapse (ECAC) in smokers remain controversial. Although studies have shown associations of ECAC with airflow limitation and symptoms, others have shown that higher tracheal collapsibility is associated with lower expiratory-to-inspiratory ratio of lung volume (E/I-LV), but not airflow limitation. This study tested whether ECAC of the trachea and main bronchi could occur exclusively in smokers with lower E/I-LV and affect their symptoms independent of emphysema and intrapulmonary airway disease.

METHODS

ECAC was defined as the expiratory-to-inspiratory ratio of cross-sectional lumen area <0.5 for at least one of the three locations, including the trachea, right and left main bronchi on static full-inspiratory, and end-tidal expiratory CT. Symptoms were assessed using the chronic obstructive pulmonary disease (COPD) assessment test (CAT) and modified MRC scale (mMRC).

RESULTS

Out of 241 smokers with and without COPD (n = 189 and 52, respectively), ECAC was found in 21 (9%) smokers. No ECAC was found in smokers with E/I-LV ≥0.75. CAT and mMRC in smokers with ECAC were higher than in non-ECAC smokers with E/I-LV <0.75, but comparable to those in non-ECAC smokers with E/I-LV ≥0.75. In the multivariable analysis of smokers with E/I-LV <0.75, ECAC was associated with increased mMRC and CAT independent of CT-emphysema severity, wall area percent of segmental airways, and forced expiratory volume in 1 s CONCLUSIONS: ECAC is associated with worsening of symptoms independent of emphysema and segmental airway disease in smokers with a lower expiratory-to-inspiratory lung volume ratio.

Differences in airway lumen area between supine and upright computed tomography in patients with chronic obstructive pulmonary disease

BACKGROUND

No clinical studies to date have compared the inspiratory and expiratory airway lumen area between supine and standing positions. Thus, the aims of this study were twofold: (1) to compare inspiratory and expiratory airway lumen area (IAA and EAA, respectively) on computed tomography (CT) among supine and standing positions; and (2) to investigate if IAA and EAA are associated with lung function abnormality in patients with chronic obstructive pulmonary disease (COPD).

METHODS

Forty-eight patients with COPD underwent both low-dose conventional (supine position) and upright CT (standing position) during inspiration and expiration breath-holds and a pulmonary function test (PFT) on the same day. We measured the IAA and EAA in each position.

RESULTS

For the trachea to the third-generation bronchi, the IAA was significantly larger in the standing position than in the supine position (4.1-4.9% increase, all p < 0.05). The EAA of all bronchi was significantly larger in the standing position than in the supine position (9.7-62.5% increases, all p < 0.001). The correlation coefficients of IAA in the standing position and forced expiratory volume in 1 s were slightly higher than those in the supine position. The correlation coefficients of EAA or EAA/IAA in the standing position and residual volume, and the inspiratory capacity/total lung capacity ratio were higher than those in the supine position.

CONCLUSIONS

Airway lumen areas were larger in the standing position than in the supine position. IAAs reflect airway obstruction, and EAAs reflect lung hyperinflation. Upright CT might reveal these abnormalities more precisely. Trial registration University Hospital Medical Information Network (UMIN 000026587), Registered 17 March 2017. URL: https://upload.umin.ac.jp/cgi-open-bin/ctr/ctr_view.cgi?recptno=R000030456 .

A narrative review of electrical impedance tomography in lung diseases with flow limitation and hyperinflation: methodologies and applications

Electrical impedance tomography (EIT) is a functional radiation-free imaging technique that measures regional lung ventilation distribution by calculating the impedance changes in the corresponding regions. The aim of the present review was to summarize the current literature concerning the methodologies and applications of EIT in lung diseases with flow limitation and hyperinflation. PubMed was searched up to May 2020 to identify studies investigating the use of EIT in patients with asthma, bronchiectasis, bronchitis, bronchiolitis, chronic obstructive pulmonary disease, and cystic fibrosis. The extracted data included study design, EIT methodologies, interventions, validation and comparators, population characteristics, and key findings. Of the 44 included studies, seven were related to simulation, animal experimentation, or reconstruction algorithm development with evaluation on patients; 27 studies had the primary objective of validating EIT technique and measures including regional ventilation distribution, regional EIT-spirometry parameters, end-expiratory lung impedance, and regional time constants; and 10 studies had the primary objective of applying EIT to monitor the response to therapeutic interventions, including various ventilation supports, patient repositioning, and airway suctioning. In pediatric and adult patients, EIT has been successfully validated for assessing spatial and temporal ventilation distribution, measuring changes in lung volume and flow, and studying regional respiratory mechanics. EIT has also demonstrated potential as an alternative or supplement to well-established measurement modalities (e.g., conventional pulmonary function testing) to monitor the progression of obstructive lung diseases, although the existing literature lacks prediction values as references and lacks clinical outcome evidence.

Central Airway Collapse, an Underappreciated Cause of Respiratory Morbidity

Dyspnea, cough, sputum production, and recurrent respiratory infections are frequently encountered clinical concerns leading patients to seek medical care. It is not unusual for a well-defined etiology to remain elusive or for the therapeutics of a presumed etiology to be incompletely effective. Either scenario should prompt consideration of central airway pathology as a contributor to clinical manifestations. Over the past decade, recognition of dynamic central airway collapse during respiration associated with multiple respiratory symptoms has become more commonly appreciated. Expiratory central airway collapse may represent the answer to this diagnostic void. Expiratory central airway collapse is an underdiagnosed disorder that can coexist with and mimic asthma, chronic obstructive pulmonary disease, and bronchiectasis. Awareness of expiratory central airway collapse and its spectrum of symptoms is paramount to its recognition. This review includes clear definitions, diagnostics, and therapeutics for this challenging condition. We performed a narrative review through the PubMed (MEDLINE) database using the following MeSH terms: airway collapse, tracheobronchomalacia, tracheomalacia, and bronchomalacia. We include reports from systematic reviews, narrative reviews, clinical trials, and observational studies from 2005 to 2020. Two reviewers evaluated potential references. No systematic reviews were found. A total of 28 references were included into our review. Included studies report experience in the diagnosis and/or treatment of dynamic central airway collapse; case reports and non-English or non-Spanish studies were excluded. We describe the current diagnostic dilemma, highlighting the role of dynamic bronchoscopy and tracheobronchial stent trial; outline the complex therapeutic options (eg, tracheobronchoplasty); and present future directions and challenges.

Quality of life outcomes in tracheobronchomalacia surgery

Tracheobronchomalacia (TBM) is an obstructive airway disease characterized by laxity and redundancy of the posterior membrane of the main airways leading to dynamic airway collapse during exhalation. The gold standard for diagnosis is dynamic computed tomography (DCT) scan and dynamic flexible bronchoscopy (DFB). Patients with complete or near-complete collapse (>90% reduction in cross-sectional area) of the airway are possible candidates for surgical management. Central airway stabilization by tracheobronchoplasty (TBP) effectively corrects malacic airways and has demonstrated significant improvement in objective functional measures, which is often but not uniformly accompanied by equal improvement in health-related quality of life (HRQOL) metrics. This article reviews HRQOL instruments used to report outcomes after TBM surgery.

Thoracic Imaging at Exacerbation of Chronic Obstructive Pulmonary Disease: A Systematic Review

Exacerbations of chronic obstructive pulmonary disease (COPD) are currently diagnosed based on changes in respiratory symptoms. Characterizing the imaging manifestation of exacerbations could be useful for objective diagnosis of exacerbations in the clinic and clinical trials, as well as provide a mechanism for monitoring exacerbation treatment and recovery. In this systematic review, we employed a comprehensive search across three databases (Medline, EMBASE, Web of Science) to identify studies that performed imaging of the thorax at COPD exacerbation. We included 51 from a total of 5,047 articles which met all our inclusion criteria. We used an adapted version of the Modified Newcastle-Ottawa Quality Assessment Scale for cohort studies to assess the quality of the included studies. Conclusions were weighted towards higher-quality articles. We identified a total of 36 thoracic imaging features studied at exacerbation of COPD. Studies were generally heterogeneous in their measurements and focus. Nevertheless, considering studies which performed consecutive imaging at stable state and exacerbation, which scored highest for quality, we identified salient imaging biomarkers of exacerbations. An exacerbation is characterized by airway wall and airway calibre changes, hyperinflation, pulmonary vasoconstriction and imaging features suggestive of pulmonary arterial hypertension. Most information was gained from CT studies. We present the first ever composite imaging signature of COPD exacerbations. While imaging during an exacerbation is comparatively new and not comprehensively studied, it may uncover important insights into the acute pathophysiologic changes in the cardiorespiratory system during exacerbations of COPD, providing objective confirmation of events and a biomarker of recovery and treatment response.

Computed Tomography Imaging for Novel Therapies of Chronic Obstructive Pulmonary Disease

Novel therapeutic options in chronic obstructive pulmonary disease (COPD) require delicate patient selection and thus demand for expert radiologists visually and quantitatively evaluating high-resolution computed tomography (CT) with additional functional acquisitions such as paired inspiratory-expiratory scans or dynamic airway CT. The differentiation between emphysema-dominant and airway-dominant COPD phenotypes by imaging has immediate clinical value for patient management. Assessment of emphysema severity, distribution patterns, and fissure integrity are essential for stratifying patients for different surgical and endoscopic lung volume reduction procedures. This is supported by quantitative software-based postprocessing of CT data sets, which delivers objective emphysema and airway remodelling metrics. However, the significant impact of scanning and reconstruction parameters, as well as intersoftware variability still hamper comparability between sites and studies. In earlier stage COPD imaging, it is less clear as to what extent quantitative CT might impact decision making and therapy follow-up, as emphysema progression is too slow to realistically be useful as a mid-term outcome measure in an individual, and longitudinal data on airway remodelling are still very limited.

In vivo dynamics of the tracheal airway and its influences on respiratory airflows

Respiration is a dynamic process accompanied by morphological changes in the airways. Although deformation of large airways is expected to exacerbate pulmonary disease symptoms by obstructing airflow during increased minute ventilation, its quantitative effects on airflow characteristics remain unclear. Here, we used an exemplar case derived from in vivo dynamic imaging and examined the effects of tracheal deformation on airflow characteristics under different conditions. First, we measured tracheal deformation profiles of a healthy lung using magnetic resonance imaging during forced exhalation, which we simulated to characterize subject-specific airflow patterns. Subsequently, for both inhalation and exhalation, we compared the airflows when the maximal deformation in tracheal cross-sectional area was 0% (rigid), 33% (mild), 50% (moderate), or 75% (severe). We quantified differences in airflow patterns between deformable and rigid airways by computing the correlation coefficients (R) and the root-mean-square of differences (Drms) between their velocity contours. For both inhalation and exhalation, airflow patterns were similar in all branches between the rigid and mild conditions (R > 0.9; Drms < 32%). However, airflow characteristics in the moderate and severe conditions differed markedly from those in the rigid and mild conditions in all lung branches, particularly for inhalation (moderate: R > 0.1, Drms < 76%; severe: R > 0.2, Drms < 96%). Our exemplar case supports the use of a rigid airway assumption to compute flows for mild deformation. For moderate or severe deformation, however, dynamic contraction should be considered, especially during inhalation, to accurately predict airflow and elucidate the underlying pulmonary pathology.

Impact of a homeopathic medication on upper respiratory tract infections in COPD patients: Results of an observational, prospective study (EPOXILO)

BACKGROUND

Chronic obstructive pulmonary disease (COPD) is a progressive lung disorder in which airflow is obstructed. Viral or bacterial upper respiratory tract infections (URTIs) may lead to exacerbations. Homeopathic medication administration to COPD patients during the influenza-exposure period may help to reduce the frequency of common URTIs.

METHODS

This prospective, observational, multicenter study was carried out in Cantabria, Spain. Patients with COPD were divided into two groups: group 1 received conventional treatment + homeopathic medication (diluted and dynamized extract of duck liver and heart; Boiron) (OG); group 2 received conventional treatment only (CG). The primary endpoint was the number of URTIs between the 4-5 months follow up (mean 4.72 ± 0.96) from basal to last visit. Secondary endpoints included the duration of URTIs, number and duration of COPD exacerbations, use of COPD drugs, changes in quality of life (QoL), compliance, and adverse events (AEs).

RESULTS

219 patients were analyzed (OG = 109, CG = 110). There was a significant reduction in mean number of URTIs during the follow-up period in OG compared to CG (0.514 ± 0.722 vs. 1.037 ± 1.519, respectively; p = 0.014). Logistic regression analysis showed a 3.3-times higher probability of suffering ≥2 URTI episodes in CG (p = 0.003, n = 72). OG patients having ≥1 URTI also had a significant reduction in mean URTI duration per episode (3.57 ± 2.44 days OG vs. 5.22 ± 4.17 days CG; p = 0.012). There was no significant difference in mean number of exacerbations, mean duration of exacerbations, or QoL between OG and CG. There was a greater decrease in proportion of patients using corticosteroids for exacerbations between baseline and visit 2 in OG compared to CG (22.1% vs. 7.5% fewer respectively, p = 0.005). Exacerbator phenotype patients had a significant decrease in number of URTIs (0.54 ± 0.72 vs. 1.31 ± 1.81; p = 0.011), and fewer COPD exacerbations (0.9 ± 1.3 vs. 1.5 ± 1.7; p = 0.037) in OG vs. CG, respectively.

CONCLUSIONS

Homeopathic medication use during the influenza-exposure period may have a beneficial impact at reducing URTIs' number and duration in COPD patients and at reducing the number of COPD exacerbations in patients with the exacerbator phenotype. Further studies are needed to confirm the effects observed in this study.

Positive airway pressure devices for the management of breathlessness

PURPOSE OF REVIEW

Breathlessness is a common symptom in many chronic diseases and may be refractory to pharmacotherapy. In this review, we discuss the pathophysiology of breathlessness and the role of positive airway pressure (PAP) devices to ameliorate it.

RECENT FINDINGS

Breathlessness is directly related to neural respiratory drive, which can be modified by addressing the imbalance between respiratory muscle load and capacity. Noninvasive PAP devices have been applied to patients limited by exertional breathless and, as the disease progresses, breathlessness at rest. The application of PAP is focussed on addressing the imbalance in load and capacity, aiming to reduce neural respiratory drive and breathlessness. Indeed, noninvasive bi-level PAP devices have been employed to enhance exercise capacity by enhancing pulmonary mechanics and reduce neural drive in chronic obstructive pulmonary disease (COPD) patients, and reduce breathlessness for patients with progressive neuromuscular disease (NMD) by enhancing respiratory muscle capacity. Novel continuous PAP devices have been used to maintain central airways patency in patients with excessive dynamic airway collapse (EDAC) and target expiratory flow limitation in severe COPD.

SUMMARY

PAP devices can reduce exertional and resting breathlessness by reducing the load on the system and enhancing capacity to reduce neural respiratory drive.