Exertional Dyspnoea in Chronic Respiratory Diseases: From Physiology to Clinical Application

Effect of breathing exercises on patients with interstitial lung disease: A systematic review and meta-analysis

PURPOSE

This study was designed to synthesize the efficacy and safety of breathing exercises in interstitial lung disease (ILD) patients by reviewing the literature and comparing the impact of different control group types, ILD subtypes, breathing exercise action modes or methods, and intervention durations on clinical efficacy.

METHODS

Systematic searches were conducted across 9 electronic databases, including PubMed, to retrieve English and Chinese studies reporting on ILD patients from inception to February 12, 2024. Study selection and data extraction were independently conducted by two researchers. The quality of the included studies was assessed using the Cochrane risk of bias tool. The data were analysed using RevMan 5.4 and STATA 17.0 software.

RESULTS

The search identified 25 studies. Compared to the control group, the breathing exercise group exhibited significantly improved lung function (FVC%pred: MD  =  3.46, 95%CI = 1.04 to 5.88; DLCO%pred: MD = 3.20, 95% CI = 2.91 to 3.48), dyspnoea (MRC or mMRC scale: MD = - 0.50, 95%CI = - 0.77 to - 0.22), exercise capacity (6MWD: MD = 32.65, 95% CI = 14.77 to 50.53), and HRQoL (SGRQ: MD = - 6.53, 95% CI = - 8.72 to - 4.34) in ILD patients. According to the subgroup analysis, significant improvements consistent with the overall results were observed in the control group with usual treatment. Compared with the control group, breathing exercises had varying degrees of improvement in the mixed diagnostic group, known-cause group, and fibrotic group of ILD patients; breathing exercises alone significantly improved DLCO%pred, MRC (or mMRC), and SGRQ; and the improvement in breathing exercises as part of pulmonary rehabilitation (PR) was more notable. Different durations of breathing exercise could promote the efficacy of different aspects of treatment for ILD patients.

CONCLUSIONS

Compared with usual treatment, breathing exercises can improve lung function, exercise capacity, and HRQoL in ILD patients, particularly without high requirements for intervention duration. The efficacy of breathing exercises varies for different ILD subtypes, and incorporating breathing exercises as part of PR can be more beneficial for ILD patients. No studies have shown significant risks for ILD patients engaging in breathing exercises.

Dynamic hyperinflation on exercise and its relationship with lung mechanics at rest in adults with central obesity

This study aimed to evaluate the presence of dynamic hyperinflation (DH) during the Glittre-ADL test (TGlittre) coupled to the dynamic ventilation measurements in people with central obesity (pwCO) and to correlate it with lung mechanics at rest. Sixty-four pwCO underwent TGlittre and the following resting lung function tests: spirometry and impulse oscillometry system (IOS). On TGlittre, 22 participants presented DH at the end of the test (DH group), while 42 did not present DH (NDH group). Body mass index (BMI), waist circumference (WC), and hip circumference (HC) were higher in the DH group than in the NDH group. IOS abnormalities were more common in the DH group compared to the NDH group. TGlittre time significantly correlated with BMI, WC, waist-to-hip ratio (WHR), and neck circumference (NC). Delta inspiratory capacity correlated significantly with WC, HC, NC, and resonance frequency measured by IOS. Thus, pwCO perform worse on TGlittre, and DH is frequent in those with higher anthropometric indices and worse lung mechanics.

Cardiopulmonary exercise testing applied to respiratory medicine: Myths and facts

Cardiopulmonary exercise testing (CPET) remains poorly understood and, consequently, largely underused in respiratory medicine. In addition to a widespread lack of knowledge of integrative physiology, several tenets of CPET interpretation have relevant controversies and limitations which should be appropriately recognized. With the intent to provide a roadmap for the pulmonologist to realistically calibrate their expectations towards CPET, a collection of deeply entrenched beliefs is critically discussed. They include a) the actual role of CPET in uncovering the cause(s) of dyspnoea of unknown origin, b) peak O₂ uptake as the key metric of cardiorespiratory capacity, c) the value of low lactate ("anaerobic") threshold to differentiate cardiocirculatory from respiratory causes of exercise limitation, d) the challenges of interpreting heart rate-based indexes of cardiovascular performance, e) the meaning of peak breathing reserve in dyspnoeic patients, f) the merits and drawbacks of measuring operating lung volumes during exercise, g) how best interpret the metrics of gas exchange inefficiency such as the ventilation-CO₂ output relationship, h) when (and why) measurements of arterial blood gases are required, and i) the advantages of recording submaximal dyspnoea "quantity" and "quality". Based on a conceptual framework that links exertional dyspnoea to "excessive" and/or "restrained" breathing, I outline the approaches to CPET performance and interpretation that proved clinically more helpful in each of these scenarios. CPET to answer clinically relevant questions in pulmonology is a largely uncharted research field: I, therefore, finalize by highlighting some lines of inquiry to improve its diagnostic and prognostic yield.

A mixed-methods pilot study of handheld fan for breathlessness in interstitial lung disease

Dyspnoea is a cardinal symptom of fibrotic interstitial lung disease (ILD), with a lack of proven effective therapies. With emerging evidence of the role of facial and nasal airflow for relieving breathlessness, this pilot study was conducted to examine the feasibility of conducting a clinical trial of a handheld fan (HHF) for dyspnoea management in patients with fibrotic ILD. In this mixed-methods, randomised, assessor-blinded, controlled trial, 30 participants with fibrotic ILD who were dyspnoeic with a modified Medical Research Council Dyspnoea grade ≥ 2 were randomised to a HHF for symptom control or no intervention for 2 weeks. Primary outcomes were trial feasibility, change in Dyspnoea-12 scores at Week 2, and participants’ perspectives on using a HHF for dyspnoea management. Study recruitment was completed within nine months at a single site. Successful assessor blinding was achieved in the fan group [Bang’s Blinding Index − 0.08 (95% CI − 0.45, 0.30)] but not the control group [0.47 (0.12, 0.81)]. There were no significant between-group differences for the change in Dyspnoea-12 or secondary efficacy outcomes. During qualitative interviews, participants reported that using the HHF relieved breathlessness and provided relaxation, despite initial scepticism about its therapeutic benefit. Oxygen-experienced participants described the HHF being easier to use, but not as effective for symptomatic relief, compared to oxygen therapy. Our results confirmed the feasibility of a clinical trial of a HHF in fibrotic ILD. There was a high level of patient acceptance of a HHF for managing dyspnoea, with patients reporting both symptomatic benefits and ease of use.

The clinical value of cardiopulmonary exercise testing in the modern era

Cardiopulmonary exercise testing (CPET) has long been used as diagnostic tool for cardiac diseases. During recent years CPET has been proven to be additionally useful for 1) distinguishing between normal and abnormal responses to exercise; 2) determining peak oxygen uptake and level of disability; 3) identifying factors contributing to dyspnoea and exercise limitation; 4) differentiating between ventilatory (respiratory mechanics and pulmonary gas exchange), cardiovascular, metabolic and peripheral muscle causes of exercise intolerance; 5) identifying anomalies of ventilatory (respiratory mechanics and pulmonary gas exchange), cardiovascular and metabolic systems, as well as peripheral muscle and psychological disorders; 6) screening for coexistent ischaemic heart disease, peripheral vascular disease and arterial hypoxaemia; 7) assisting in planning individualised exercise training; 8) generating prognostic information; and 9) objectively evaluating the impact of therapeutic interventions. As such, CPET is an essential part of patients' clinical assessment. This article belongs to the special series on the "Ventilatory efficiency and its clinical prognostic value in cardiorespiratory disorders", addressed to clinicians, physiologists and researchers, and aims at encouraging them to get acquainted with CPET in order to help and orient the clinical decision concerning individual patients.

MicroPhenoDB Associates Metagenomic Data with Pathogenic Microbes, Microbial Core Genes, and Human Disease Phenotypes

Microbes play important roles in human health and disease. The interaction between microbes and hosts is a reciprocal relationship, which remains largely under-explored. Current computational resources lack manually and consistently curated data to connect metagenomic data to pathogenic microbes, microbial core genes, and disease phenotypes. We developed the MicroPhenoDB database by manually curating and consistently integrating microbe-disease association data. MicroPhenoDB provides 5677 non-redundant associations between 1781 microbes and 542 human disease phenotypes across more than 22 human body sites. MicroPhenoDB also provides 696,934 relationships between 27,277 unique clade-specific core genes and 685 microbes. Disease phenotypes are classified and described using the Experimental Factor Ontology (EFO). A refined score model was developed to prioritize the associations based on evidential metrics. The sequence search option in MicroPhenoDB enables rapid identification of existing pathogenic microbes in samples without running the usual metagenomic data processing and assembly. MicroPhenoDB offers data browsing, searching, and visualization through user-friendly web interfaces and web service application programming interfaces. MicroPhenoDB is the first database platform to detail the relationships between pathogenic microbes, core genes, and disease phenotypes. It will accelerate metagenomic data analysis and assist studies in decoding microbes related to human diseases. MicroPhenoDB is available through http://www.liwzlab.cn/microphenodb and http://lilab2.sysu.edu.cn/microphenodb.

Patterns of Physical Activity Progression in Patients With COPD

INTRODUCTION

Although mean physical activity in COPD patients declines by 400-500steps/day annually, it is unknown whether the natural progression is the same for all patients. We aimed to identify distinct physical activity progression patterns using a hypothesis-free approach and to assess their determinants.

METHODS

We pooled data from two cohorts (usual care arm of Urban Training [NCT01897298] and PROactive initial validation [NCT01388218] studies) measuring physical activity at baseline and 12 months (Dynaport MoveMonitor). We identified clusters (patterns) of physical activity progression (based on levels and changes of steps/day) using k-means, and compared baseline sociodemographic, interpersonal, environmental, clinical and psychological characteristics across patterns.

RESULTS

In 291 COPD patients (mean±SD 68±8 years, 81% male, FEV₁ 59±19%_pred) we identified three distinct physical activity progression patterns: Inactive (n=173 [59%], baseline: 4621±1757 steps/day, 12-month change (Δ): -487±1201 steps/day), ActiveImprovers (n=49 [17%], baseline: 7727±3275 steps/day, Δ:+3378±2203 steps/day) and ActiveDecliners (n=69 [24%], baseline: 11 267±3009 steps/day, Δ: -2217±2085 steps/day). After adjustment in a mixed multinomial logistic regression model using Active Decliners as reference pattern, a lower 6-min walking distance (RRR [95% CI] 0.94 [0.90-0.98] per 10m, P=.001) and a higher mMRC dyspnea score (1.71 [1.12-2.60] per 1 point, P=.012) were independently related with being Inactive. No baseline variable was independently associated with being an Active Improver.

CONCLUSIONS

The natural progression in physical activity over time in COPD patients is heterogeneous. While Inactive patients relate to worse scores for clinical COPD characteristics, Active Improvers and Decliners cannot be predicted at baseline.

Health-related quality of life of patients diagnosed with COPD in Extremadura, Spain: results from an observational study

BACKGROUND

COPD is a high prevalence chronic disease that involves large reductions of health-related quality of life (HRQL) of patients. This study aims to describe the HRQL of patients with COPD in Extremadura (Spain).

METHODS

This is a cross-sectional observational study carried out using a representative sample of patients diagnosed with COPD in Extremadura. The inclusion criteria were patients of legal age, diagnosed with COPD at least 12 months prior to the visit, residing in Extremadura, with electronic medical records available for the 12 months prior to the visit and providing informed consent. The intervention aimed to elicit HRQL indicators obtained from two validated questionnaires: EuroQol - 5 Dimensions - 5 Levels (EQ-5D-5L), and St. George's Respiratory Questionnaire-COPD (SGRQ-C). The main outcome measures were general HRQL (utility and visual analogue scale) and specific quality of life of COPD patients (total score and three component scores: Symptoms, Activity, and Impacts). Stepwise multiple regression analysis was applied to evaluate the association of EQ-5D-5L and SGRQ-C with respect to clinical and sociodemographic characteristics of the patients.

RESULTS

We recruited 386 patients (mean age 71.8 ± 10.3 years, 76.2% males). In the EQ-5D-5L, participants reported greater problems with respect to mobility (56.5%) and pain/discomfort (48.2%). The mean utility was 0.72 ± 0.31, and the SGRQ-C total score was 40.9 ± 25.0. The results of both questionnaires were associated with number of exacerbations in the last 12 months, level of COPD severity, gender, and education level of the patient (p < 0.05).

CONCLUSIONS

The results for both utility and total SGRQ-C score indicate that having suffered exacerbations in the last year, presenting a higher level of severity, being a woman, and having a low education level are related to worse HRQL in patients with COPD.

Bendopnea and Its Clinical Importance in Outpatient Patients with Pulmonary Arterial Hypertension

Purpose

Bendopnea is a recently reported novel symptom in patients with heart failure (HF) defined as shortness of breath when bending forward. It has been demonstrated that bendopnea is associated with advanced symptoms and worse outcomes. The aim of this study was to assess the presence of bendopnea and its clinical importance with regards to functional status, hemodynamic and echocardiographic characteristics in outpatient pulmonary arterial hypertension (PAH) patients.

Methods

We conducted this prospective observational study of 53 patients who were admitted to our PAH clinic for routine control visits. We determined the presence of bendopnea and analyzed hemodynamic parameters, World Heart Organization (WHO) functional class, transcutaneous oxygen saturation, 6-minute walking distance (6-MWD), N-terminal pro-brain natriuretic peptide (NT-proBNP) and right ventricular (RV) function indicators in patients with and without bendopnea.

Results

Bendopnea was present 33.9% of the PAH patients. The mean age was higher in the patients with bendopnea than in those without bendopnea, but the difference was not significant (p = 0.201). The patients with bendopnea had a lower 6-MWD and higher NT-proBNP level (p < 0.001), and worse WHO functional class symptoms (p = 0.010). Mean right atrial pressure, pulmonary artery pressure, and pulmonary vascular resistance were higher in the patients with bendopnea. The patients with bendopnea had a more dilated RV end-diastolic diameter and lower tricuspid annular plane systolic excursion value (p < 0.001 and p = 0.001, respectively).

Conclusions

Bendopnea was associated with worse functional capacity status, hemodynamic characteristics and RV function in our outpatient PAH patients.

Mechanisms, measurement and management of exertional dyspnoea in asthma: Number 5 in the Series "Exertional dyspnoea" Edited by Pierantonio Laveneziana and Piergiuseppe Agostoni

Asthma is a heterogeneous condition, with dyspnoea during exercise affecting individuals to a variable degree. This narrative review explores the mechanisms and measurement of exertional dyspnoea in asthma and summarises the available evidence for the efficacy of various interventions on exertional dyspnoea. Studies on the mechanisms of dyspnoea in asthma have largely utilised direct bronchoprovocation challenges, rather than exercise, which may invoke different physiological mechanisms. Thus, the description of dyspnoea during methacholine challenge can differ from what is experienced during daily activities, including exercise. Dyspnoea perception during exercise is influenced by many interacting variables, such as asthma severity and phenotype, bronchoconstriction, dynamic hyperinflation, respiratory drive and psychological factors. In addition to the intensity of dyspnoea, the qualitative description of dyspnoea may give important clues as to the underlying mechanism and may be an important endpoint for future interventional studies. There is currently little evidence demonstrating whether pharmacological or non-pharmacological interventions specifically improve exertional dyspnoea, which is an important area for future research.