Thoracoabdominal Asynchrony Contributes to Exercise Limitation in Mild Asthmatic Subjects

Breathing pattern changes in response to bronchoconstriction in physically active adults

OBJECTIVES

To determine whether Opto-Electronic Plethysmography (OEP) can distinguish Exercise-Induced Bronchoconstriction (EIB) breathing patterns by comparing individuals with and without EIB, and between broncho-constriction and recovery. Breathing pattern was quantified in terms of regional contribution, breathing timing, and the phase between chest sub-compartments which indicates the synchronization in movement of the different sub-compartments.

METHODS

Individuals (n = 47) reporting no respiratory symptoms and no history of any respiratory disease or disorder were assumed to have a healthy breathing pattern. Of 38 participants reporting respiratory symptoms during exercise, and/or a previous diagnosis of asthma or EIB, 10 participants had a positive result to the Eucapnic Voluntary Hyperpnea test, defined as a fall of at least 10% in FEV1 from baseline at two consecutive time points and were classified into the EIB group. OEP data was obtained from 89 markers and an 11-camera motion capture system operating at 100 Hz as follows: pre- and post-EVH challenge, and post-inhaler in participants who experienced a bronchoconstriction, and 2) for the healthy group during tidal breathing.

RESULTS

RCpRCa-Phase (upper versus lower ribcage), RCaS-Phase (lower ribcage versus shoulders), and RCpS-Phase (upper ribcage versus shoulders) differed between bronchoconstriction and rest in athletes with EIB and rest in healthy participants (p < 0.05), in all cases indicating greater asynchrony post-bronchoconstriction, and later movement of the abdominal ribcage (RCa) post-bronchoconstriction. RCpS-Phase was different (p < 0.05) between all conditions (rest, post-bronchoconstriction, and post-inhaler) in EIB.

CONCLUSIONS

OEP can characterize and distinguish EIB-associated breathing patterns compared to rest and individuals without EIB at rest.

Effect of respiratory muscle training in asthma: A systematic review and meta-analysis

BACKGROUND

The last systematic review about respiratory muscle training (RMT) in people with asthma was published almost 10 years ago. Since then, several works have been published.

OBJECTIVE

To review the effect of RMT in people with asthma.

METHODS

We conducted a systematic review of research included up to September 2021 in PubMed/MEDLINE, PEDro, Scopus, Web of Science, CINAHL, LILACS, Cochrane Central Register of Controlled Trials and ClinicalTrials.gov. We included randomized controlled trials and quasi-experimental studies assessing the effect of RMT on respiratory muscle function, rescue medication, asthma-related symptoms, lung function, exercise capacity, healthcare use, health-related quality of life (HRQoL) and adverse effects in people with asthma. Risk of bias and methodological quality were assessed with the Cochrane Risk of Bias assessment tool and the PEDro scale. Meta-analysis was performed whenever possible; otherwise a qualitative approach was followed.

RESULTS

Eleven studies (270 participants) were included, 10 with only adults and were included in the meta-analysis. Inspiratory muscle training (IMT) had beneficial effects on maximal inspiratory pressure (PImax: mean difference [MD] 21.95 cmH₂O [95% confidence interval [CI] 15.05; 28.85]), with no changes in maximal expiratory pressure (MD 14.97 cmH₂O [95%CI -5.65; 35.59]), lung function (forced expiratory volume in 1 sec: MD 0.06 [95%CI -0.14; 0.26] L; force vital capacity: MD 0.39 [95%CI -0.24; 1.02] L) and exercise capacity (standard mean difference [SMD] 1.73 [95%CI -0.61; 4.08]). Subgroup analysis revealed that IMT load >50% PImax and duration >6 weeks were beneficial for exercise capacity. The qualitative analysis suggested that IMT may have benefits on respiratory muscle endurance, rescue medication and exertional dyspnoea, with no adverse effects.

CONCLUSIONS

This systematic review and meta-analysis showed a significant increase in PImax after IMT in adults with asthma and reinforced the relevance of the dose-response principle of training. More evidence is needed to clarify the effect of IMT in respiratory muscle endurance, rescue medication, exercise capacity, healthcare use and HRQoL.

TRIAL REGISTRATION

PROSPERO International Prospective Register of Systematic Reviews CRD42020221939; https://www.crd.york.ac.uk/prospero/display_record.php?RecordID=221939.

Respiratory Inductance Plethysmography to Assess Fatigability during Repetitive Work

Cumulative fatigue during repetitive work is associated with occupational risk and productivity reduction. Usually, subjective measures or muscle activity are used for a cumulative evaluation; however, Industry 4.0 wearables allow overcoming the challenges observed in those methods. Thus, the aim of this study is to analyze alterations in respiratory inductance plethysmography (RIP) to measure the asynchrony between thorax and abdomen walls during repetitive work and its relationship with local fatigue. A total of 22 healthy participants (age: 27.0 ± 8.3 yrs; height: 1.72 ± 0.09 m; mass: 63.4 ± 12.9 kg) were recruited to perform a task that includes grabbing, moving, and placing a box in an upper and lower shelf. This task was repeated for 10 min in three trials with a fatigue protocol between them. Significant main effects were found from Baseline trial to the Fatigue trials (p < 0.001) for both RIP correlation and phase synchrony. Similar results were found for the activation amplitude of agonist muscle (p < 0.001), and to the muscle acting mainly as a joint stabilizer (p < 0.001). The latter showed a significant effect in predicting both RIP correlation and phase synchronization. Both RIP correlation and phase synchronization can be used for an overall fatigue assessment during repetitive work.

Effect of Chest Resistance and Expansion Exercises on Respiratory Muscle Strength, Lung Function, and Thoracic Excursion in Children with a Post-Operative Congenital Diaphragmatic Hernia

BACKGROUND

Congenital diaphragmatic hernia (CDH) is a life-threatening condition with long-term complications including respiratory tract infections, respiratory muscle weakness, and abnormal lung functions. This study was designed to ascertain the effects of chest resistance and chest expansion exercises on respiratory muscle strength, lung function, and chest mobility in children with post-operative CDH.

METHODS

This randomized controlled clinical study was conducted in the outpatient physiotherapy clinic at Prince Sattam bin Abdulaziz University. Thirty-two children with CDH aged 10-14 years between May 2020 and February 2021 were randomly allocated to the study group (n = 16) and the control group (n = 16). The control group underwent a usual chest physiotherapy program; however, the study group underwent a 12-week chest resistance exercise combined with chest expansion exercise in addition to usual chest physiotherapy, with three sessions per week. Respiratory muscle strength, lung function, and thoracic excursion were assessed pre- and post-treatment.

RESULTS

Using the 2 × 2 repeated ANOVA, significant time × group interactions were detected in favor of the study group, FVC (F = 4.82, 95% CI = -15.6 to -0.97, p = 0.005, and η² = 0.16), FEV1 (F = 4.54, 95% CI = -11.99 to -2.8, p ˂ 0.001, and η² = 0.14), PImax (F = 5.12, 95% CI = -15.71 to -5.3, p ˂ 0.001, and η² = 0.15), and thoracic excursion (F = 4.41, 95% CI = -2.04 to -0.16, p = 0.036, and η² = 0.17).

CONCLUSIONS

Concurrent chest resistance and expansion exercises may improve respiratory muscle strength, lung function, and thoracic excursion in children with post-operative CDH. The study findings suggest that concurrent chest and chest expansion exercises be part of an appropriate pulmonary rehabilitation program in children with a history of CDH.

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.

After-Effects of Thixotropic Maneuvers on Chest Wall and Compartmental Operational Volumes of Healthy Subjects Using Optoelectronic Plethysmography

The volumes assessed by optoelectronic plethysmography (OEP) and based on a three-compartmental model provide an accurate breath-by-breath index of expiratory and inspiratory (ribcage muscles and diaphragm) muscle length. Thus, after performing thixotropic maneuvers, OEP may also provide evidence regarding the history-dependent properties of these muscles. We studied the after-effects of different thixotropic conditionings on chest wall (CW) and compartmental operational volumes of 28 healthy subjects (25.5 ± 2.2 years, FVC_%pred 94.8 ± 5.5, and FEV_1%pred 95.5 ± 8.9) using OEP. Conditionings were composed of inspiratory or expiratory contractions performed from total lung capacity (TLC) or residual volume (RV). The study protocol was composed of three consecutive contractions of the same maneuver, with 60 s of spontaneous breathing in between, and after-effects were studied in the first seven respiratory cycles of each contraction. Cumulative effects were also assessed by comparing the after-effects of each thixotropic maneuver. Inspiratory contractions performed from both TLC and RV acutely increased end-inspiratory (EIV) CW volumes (all p < 0.0001), mainly on both upper and lower ribcage compartments (i.e., non-diaphragmatic inspiratory muscles and diaphragm, respectively); while, expiratory contractions from RV decreased CW volumes (p < 0.0001) by reducing the upper ribcage and abdominal volumes (all p < 0.0001). The response of the thixotropic maneuvers did not present a cumulative effect. In healthy, the use of the three-compartmental model through OEP allows a detailed assessment of the diaphragm, inspiratory and expiratory muscle thixotropy. Furthermore, specific conditioning maneuvers led to thixotropy of the inspiratory ribcage, diaphragm, and expiratory muscles.

Highlights from the 2018 European Respiratory Society International Congress: sleep and clinical physiology

The 2018 European Respiratory Society (ERS) International Congress held in Paris, France, served as a platform to discover the latest research on respiratory diseases, the improvement in their treatments and patient care. Specifically, the scientific sessions organised by ERS Assembly 4 provided novel insights into sleep disordered breathing and fresh knowledge in respiratory physiology, stressing its importance to understanding and treating respiratory diseases. This article, divided by session, will summarise the most relevant studies presented at the ERS International Congress. Each session has been written by early career members specialised in the different fields of this interdisciplinary assembly.