Thoracoabdominal asynchrony: Two methods in healthy, COPD, and interstitial lung disease patients

Understanding Breathlessness Burden and Psychophysiological Correlates in Asthma

BACKGROUND

Breathlessness is a disabling symptom, with complexity that is often under-recognized and undertreated in asthma.

OBJECTIVE

To highlight the burden of breathlessness in people with severe compared with mild-to-moderate asthma and identify psychophysiological correlates of breathlessness.

METHODS

This was a cross-sectional study of people with mild-to-severe asthma, who attended 2 in-person visits to complete a multidimensional assessment. The proportion of people with mild-to-moderate versus severe asthma who reported physically limiting breathlessness (modified Medical Research Council [mMRC] dyspnea score ≥2) was compared. Psychophysiological factors associated with breathlessness in people with asthma were identified via a directed acyclic graph and explored with multivariate logistic regression to predict breathlessness.

RESULTS

A total of 144 participants were included, of whom, 74 (51%) had mild-to-moderate asthma and 70 (49%) severe asthma. Participants were predominantly female (n = 103, 72%) with a median (quartile 1, quartile 3) age of 63.4 (50.5, 69.5) years and body mass index (BMI) of 31.3 (26.2, 36.0) kg/m2. The proportion of people reporting mMRC ≥2 was significantly higher in those with severe- (n = 37, 53%) than those with mild-to-moderate (n = 21, 31%) asthma (P = .013). Dyspnoea-12 Total (8.00 [4.75, 17.00] vs 5.00 [2.00, 11.00], P = .037) score was also significantly higher in the severe asthma group. Significant predictors of physically limiting breathlessness were BMI, asthma control, exercise capacity, and hyperventilation symptoms. Airflow limitation and type 2 inflammation were poor breathlessness predictors.

CONCLUSIONS

Over half of people with severe asthma experience physically limiting breathlessness despite treatment. Targeting psychophysiological factors, or traits, associated with breathlessness may help relieve this distressing symptom, which is of high priority to people with asthma.

Measurement of thoraco-abdominal synchrony using respiratory inductance plethysmography: technical aspects and a proposal to overcome its limitations

BACKGROUND

Thoraco-abdominal asynchrony (TAA) is usually assessed by respiratory inductance plethysmography. The main parameter used for its assessment is the calculation of the phase angle based on Lissajous plots. However, there are some mathematical limitations to its use.

RESEARCH DESIGN AND METHODS

Sequences of five breaths were selected from a) normal subjects, b) COPD patients, both at rest and during exercise, and c) patients with obstructive apnea syndrome. Automated analysis was performed calculating phase angle, loop rotation (clockwise or counterclockwise), global phase delay and loop area. TAA severity was estimated quantitatively and in subgroups.

RESULTS

2290 cycles were analyzed (55% clockwise rotation). Phase angle ranged from -86.90 to + 88.4 degrees, while global phase delay ranged from -179.75 to + 178.54. Despite a good correlation with global phase delay (p < 0.01, ANOVA test), phase angle and loop area were not able to correctly classify breaths with severe deviation and paradoxical movements (p=ns, Bonferroni post hoc test).

CONCLUSIONS

Global phase delay covers the whole spectrum of TAA situations in a single value. It may be a relevant parameter for diagnosis and follow-up of clinical conditions leading to TAA.

CLINICAL TRIAL REGISTRATION

The trial from which the traces were obtained was registered at ClinicalTrials.gov ;(identifier: NCT04597606).

Elastic tape reduces dyspnea and improves health status in the short term in nonobese COPD males: A randomized controlled trial

INTRODUCTION AND OBJECTIVES

The elastic tape (ET) is a novel intervention that acutely improves exercise capacity in laboratory tests; however, its effect on a patient's daily life remains unknown. This randomized controlled trial evaluated the effects of ET on daily life physical activity (DLPA), dyspnea symptoms, health status, and health-related quality of life (HRQoL) in individuals with COPD.

METHODS

Fifty males with moderate to very severe COPD were randomly assigned to an intervention group (ETG, n = 25), receiving ET on the chest wall and abdomen, or a control group (CG, n = 25). The intervention was for 14 days. DLPA (accelerometry; steps per day, and sedentary time), dyspnea symptoms (transition dyspnea index, TDI; and modified Medical Research Council, mMRC), health status (COPD assessment test, CAT), and health-related quality of life (HRQoL, CRQ) were evaluated at baseline and on Day 21 after the intervention.

RESULTS

No change in the DLPA was observed in between-group comparison. CG presented a reduction in step counts after 21days (-707,p <0.05) while ETG. maintained (-114,p > 0.94). However, ET reduced dyspnea symptoms in all TDI domains (functional, task, and effort) and on the mMRC scale after 14 days compared with CG (p < 0.01). Also, the ETG improved CAT score compared to the CG, reaching minimal clinical important difference (MCID) (-4.4 score, p <0.01). The ETG also improved in most CRQ domains reaching MCID after 21 days.

CONCLUSIONS

ET does not modify DLPA but reduces dyspnea and improves health status and HRQoL in nonobese males with moderate to very severe COPD in the short term. This novel and low-cost intervention improves COPD symptoms.

Breathing Pattern Disorders Distinguished from Healthy Breathing Patterns Using Optoelectronic Plethysmography

There is no gold standard diagnostic method for breathing pattern disorders (BPD) which is commonly diagnosed through the exclusion of other pathologies. Optoelectronic plethysmography (OEP) is a 3D motion capture technique that provides a comprehensive noninvasive assessment of chest wall during rest and exercise. The purpose of this study was to determine if OEP can distinguish between active individuals classified with and without BPD at rest and during exercise. Forty-seven individuals with a healthy breathing pattern (HBP) and twenty-six individuals with a BPD performed a submaximal exercise challenge. OEP measured the movement of the chest wall through the calculation of timing, percentage contribution, and phase angle breathing pattern variables. A mixed model repeated measures ANOVA analysed the OEP variables between the groups classified as HBP and BPD at rest, during exercise, and after recovery. At rest, regional contribution variables including ribcage percentage contribution (HBP: 71% and BPD: 69%), abdominal ribcage contribution (HBP: 13% and BPD: 11%), abdomen percentage contribution (HBP: 29% and BPD: 31%), and ribcage and abdomen volume index (HPB: 2.5 and BPD: 2.2) were significantly (p < 0.05) different between groups. During exercise, BPD displayed significantly (p < 0.05) more asynchrony between various thoracic compartments including the ribcage and abdomen phase angle (HBP: -1.9 and BPD: -2.7), pulmonary ribcage and abdomen phase angle (HBP: -0.5 and BPD, 0.5), abdominal ribcage and shoulders phase angle (HBP: -0.3 and BPD: 0.6), and pulmonary ribcage and shoulders phase angle (HBP: 0.2 and BPD: 0.6). Additionally, the novel variables inhale deviation (HBP: 8.8% and BPD: 19.7%) and exhale deviation (HBP: -10.9% and BPD: -17.6%) were also significantly (p < 0.05) different between the groups during high intensity exercise. Regional contribution and phase angles measured via OEP can distinguish BPD from HBP at rest and during exercise. Characteristics of BPD include asynchronous and thoracic dominant breathing patterns that could form part of future objective criteria for the diagnosis of BPD.

Updated Perspectives on the Role of Biomechanics in COPD: Considerations for the Clinician

Patients with chronic obstructive pulmonary disease (COPD) demonstrate extra-pulmonary functional decline such as an increased prevalence of falls. Biomechanics offers insight into functional decline by examining mechanics of abnormal movement patterns. This review discusses biomechanics of functional outcomes, muscle mechanics, and breathing mechanics in patients with COPD as well as future directions and clinical perspectives. Patients with COPD demonstrate changes in their postural sway during quiet standing compared to controls, and these deficits are exacerbated when sensory information (eg, eyes closed) is manipulated. If standing balance is disrupted with a perturbation, patients with COPD are slower to return to baseline and their muscle activity is differential from controls. When walking, patients with COPD appear to adopt a gait pattern that may increase stability (eg, shorter and wider steps, decreased gait speed) in addition to altered gait variability. Biomechanical muscle mechanics (ie, tension, extensibility, elasticity, and irritability) alterations with COPD are not well documented, with relatively few articles investigating these properties. On the other hand, dyssynchronous motion of the abdomen and rib cage while breathing is well documented in patients with COPD. Newer biomechanical technologies have allowed for estimation of regional, compartmental, lung volumes during activity such as exercise, as well as respiratory muscle activation during breathing. Future directions of biomechanical analyses in COPD are trending toward wearable sensors, big data, and cloud computing. Each of these offers unique opportunities as well as challenges. Advanced analytics of sensor data can offer insight into the health of a system by quantifying complexity or fluctuations in patterns of movement, as healthy systems demonstrate flexibility and are thus adaptable to changing conditions. Biomechanics may offer clinical utility in prediction of 30-day readmissions, identifying disease severity, and patient monitoring. Biomechanics is complementary to other assessments, capturing what patients do, as well as their capability.

Measurement of chest wall motion using a motion capture system with the one-pitch phase analysis method

Spirometry is a standard method for assessing lung function. However, its use is challenging in some patients, and it has limitations such as risk of infection and inability to assess regional chest wall motion. A three-dimensional motion capture system using the one-pitch phase analysis (MCO) method can facilitate high precision measurement of moving objects in real-time in a non-contacting manner. In this study, the MCO method was applied to examine thoraco-abdominal (TA) wall motion for assessing pulmonary function. We recruited 48 male participants, and all underwent spirometry and chest wall motion measurement with the MCO method. A significant positive correlation was observed between the vital capacity (Spearman’s ρ = 0.68, p < 0.0001), forced vital capacity (Spearman’s ρ = 0.62, p < 0.0001), and tidal volume (Spearman’s ρ = 0.61, p < 0.0001) of spirometry and the counterpart parameters of MCO method. Moreover, the MCO method could detect regional rib cage and abdomen compartment contributions and could assess TA asynchrony, indicating almost complete synchronous movement (phase angle for each compartment: − 5.05° to 3.86°). These findings suggest that this technique could examine chest wall motion, and may be effective in analyzing chest wall volume changes and pulmonary function.

Reference equations for tidal breathing parameters using structured light plethysmography

Tidal breathing measurements can be used to identify changes in respiratory status. Structured light plethysmography (SLP) is a non-contact tidal breathing measurement technique. Lack of reference equations for SLP parameters makes clinical decision-making difficult. We have developed a set of growth-adjusted reference equations for seven clinically pertinent parameters of respiratory rate (f_R), inspiratory time (t_I), expiratory time (t_E), duty cycle (t_I/total breath time), phase (thoraco-abdominal asynchrony (TAA)), relative thoracic contribution (RTC) and tidal inspiratory/expiratory flow at 50% volume (IE50).

Reference equations were developed based on a cohort of 198 seated healthy subjects (age 2–75 years, height 82–194 cm, 108 males). We adopted the same methodological approach as the Global Lung Function Initiative (GLI) report on spirometric reference equations. 5 min of tidal breathing was recorded per subject. Parameters were summarised with their medians. The supplementary material provided is an integral part of this work and a reference range calculator is provided therein.

We found predicted f_R to decrease with age and height rapidly in the first 20 years and slowly thereafter. Expected t_I, t_E and RTC followed the opposite trend. RTC was 6.7% higher in females. Duty cycle increased with age, peaked at 13 years and decreased thereafter. TAA was high and variable in early life and declined rapidly with age. Predicted IE50 was constant, as it did not correlate with growth.

These reference ranges for seven key measures ensure that clinicians and researchers can identify tidal breathing patterns in disease and better understand and interpret SLP and tidal breathing data.

A set of reference equations for seven key tidal breathing parameters measured using structured light plethysmography (SLP) to help clinicians better understand and interpret SLP data and the value of tidal breathing patternshttps://bit.ly/2Og2H3h

Thoracoabdominal asynchrony associates with exercise intolerance in fibrotic interstitial lung diseases

BACKGROUND AND OBJECTIVE

The precise coordination of respiratory muscles during exercise minimizes work of breathing and avoids exercise intolerance. Fibrotic interstitial lung disease (f-ILD) patients are exercise-intolerant. We assessed whether respiratory muscle incoordination and thoracoabdominal asynchrony (TAA) occur in f-ILD during exercise, and their relationship with pulmonary function and exercise performance.

METHODS

We compared breathing pattern, respiratory mechanics, TAA and respiratory muscle recruitment in 31 f-ILD patients and 31 healthy subjects at rest and during incremental cycle exercise. TAA was defined as phase angle (PhAng) >20°.

RESULTS

During exercise, when compared with controls, f-ILD patients presented increased and early recruitment of inspiratory rib cage muscle (p < 0.05), and an increase in PhAng, indicating TAA. TAA was more frequent in f-ILD patients than in controls, both at 50% of the maximum workload (42.3% vs. 10.7%, p = 0.01) and at the peak (53.8% vs. 23%, p = 0.02). Compared with f-ILD patients without TAA, f-ILD patients with TAA had lower lung volumes (forced vital capacity, p < 0.01), greater dyspnoea (Medical Research Council > 2 in 64.3%, p = 0.02), worse exercise performance (lower maximal work rate % predicted, p = 0.03; lower tidal volume, p = 0.03; greater desaturation and dyspnoea, p < 0.01) and presented higher oesophageal inspiratory pressures with lower gastric inspiratory pressures and higher recruitment of scalene (p < 0.05).

CONCLUSION

Exercise induces TAA and higher recruitment of inspiratory accessory muscle in ILD patients. TAA during exercise occurred in more severely restricted ILD patients and was associated with exertional dyspnoea, desaturation and limited exercise performance.

Advancements in Methods and Camera-Based Sensors for the Quantification of Respiration

Assessment of respiratory function allows early detection of potential disorders in the respiratory system and provides useful information for medical management. There is a wide range of applications for breathing assessment, from measurement systems in a clinical environment to applications involving athletes. Many studies on pulmonary function testing systems and breath monitoring have been conducted over the past few decades, and their results have the potential to broadly impact clinical practice. However, most of these works require physical contact with the patient to produce accurate and reliable measures of the respiratory function. There is still a significant shortcoming of non-contact measuring systems in their ability to fit into the clinical environment. The purpose of this paper is to provide a review of the current advances and systems in respiratory function assessment, particularly camera-based systems. A classification of the applicable research works is presented according to their techniques and recorded/quantified respiration parameters. In addition, the current solutions are discussed with regards to their direct applicability in different settings, such as clinical or home settings, highlighting their specific strengths and limitations in the different environments.

The Importance of Respiratory Rate Monitoring: From Healthcare to Sport and Exercise

Respiratory rate is a fundamental vital sign that is sensitive to different pathological conditions (e.g., adverse cardiac events, pneumonia, and clinical deterioration) and stressors, including emotional stress, cognitive load, heat, cold, physical effort, and exercise-induced fatigue. The sensitivity of respiratory rate to these conditions is superior compared to that of most of the other vital signs, and the abundance of suitable technological solutions measuring respiratory rate has important implications for healthcare, occupational settings, and sport. However, respiratory rate is still too often not routinely monitored in these fields of use. This review presents a multidisciplinary approach to respiratory monitoring, with the aim to improve the development and efficacy of respiratory monitoring services. We have identified thirteen monitoring goals where the use of the respiratory rate is invaluable, and for each of them we have described suitable sensors and techniques to monitor respiratory rate in specific measurement scenarios. We have also provided a physiological rationale corroborating the importance of respiratory rate monitoring and an original multidisciplinary framework for the development of respiratory monitoring services. This review is expected to advance the field of respiratory monitoring and favor synergies between different disciplines to accomplish this goal.

Contact-Based Methods for Measuring Respiratory Rate

There is an ever-growing demand for measuring respiratory variables during a variety of applications, including monitoring in clinical and occupational settings, and during sporting activities and exercise. Special attention is devoted to the monitoring of respiratory rate because it is a vital sign, which responds to a variety of stressors. There are different methods for measuring respiratory rate, which can be classed as contact-based or contactless. The present paper provides an overview of the currently available contact-based methods for measuring respiratory rate. For these methods, the sensing element (or part of the instrument containing it) is attached to the subject's body. Methods based upon the recording of respiratory airflow, sounds, air temperature, air humidity, air components, chest wall movements, and modulation of the cardiac activity are presented. Working principles, metrological characteristics, and applications in the respiratory monitoring field are presented to explore potential development and applicability for each method.