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Recently, the interest in the Helmet interface during non-invasive respiratory support (NIRS) has increased due to the COVID-19 pandemic. During NIRS, positive end-expiratory pressure (PEEP) can be given as continuous positive airway pressure (CPAP), which maintains a positive airway pressure throughout the whole respiratory cycle with Helmet as an interface (H-CPAP). The main disadvantage of the H-CPAP is the inability to measure tidal volume (VT). Opto-electronic plethysmography (OEP) is a non-invasive technique that is not sensitive to gas compression/expansion inside the helmet. OEP acquisitions were performed on 28 healthy volunteers (14 females and 14 males) at baseline and during Helmet CPAP. The effect of posture (semi-recumbent vs. prone), flow (50 vs. 60 L/min), and PEEP (0 vs. 5 vs. 10 cmH2O) on the ventilatory and thoracic-abdominal pattern and the operational volumes were investigated. Prone position limited vital capacity, abdominal expansion and chest wall recruitment. A constant flow of 60 L/min reduced the need for the subject to ventilate while having a slight recruitment effect (100 mL) in the semi-recumbent position. A progressive increasing recruitment was found with higher PEEP but limited by the prone position. It is possible to accurately measure tidal volume during H-CPAP to deliver non-invasive ventilatory support using opto-electronic plethysmography during different clinical settings. [ABSTRACT FROM AUTHOR]

Objectives: This study investigates the chest wall motions and estimates respiratory volumes in a patient with scoliosis compared to a healthy person using the optoelectronic plethysmography method in a sitting position. Methods: In this research, a scoliosis patient and a healthy individual comprised two subjects. Each person’s upper, middle, and lower chest movement in a seated position was measured using optoelectronic plethysmography. Results: The changes in respiratory volumes of the middle and lower parts of the chest in patients with scoliosis are more than those of a healthy person during quiet breathing. Moreover, the changes in the upper, middle, and lower parts of the chest in the healthy person are also more than those of the subject with scoliosis during deep breathing. Discussion: Optoelectronic plethysmography is a noninvasive method to evaluate chest wall movements, respiratory system function, and volumes with fewer limitations than other methods of evaluating respiratory function.

Objectives: This study investigates the chest wall motions and estimates respiratory volumes in a patient with scoliosis compared to a healthy person using the optoelectronic plethysmography method in a sitting position. Methods: In this research, a scoliosis patient and a healthy individual comprised two subjects. Each person's upper, middle, and lower chest movement in a seated position was measured using optoelectronic plethysmography. Results: The changes in respiratory volumes of the middle and lower parts of the chest in patients with scoliosis are more than those of a healthy person during quiet breathing. Moreover, the changes in the upper, middle, and lower parts of the chest in the healthy person are also more than those of the subject with scoliosis during deep breathing. Discussion: Optoelectronic plethysmography is a noninvasive method to evaluate chest wall movements, respiratory system function, and volumes with fewer limitations than other methods of evaluating respiratory function. [ABSTRACT FROM AUTHOR]

Background. Accurate measurements of limb volumes are important for clinical reasons. We aimed to assess the reliability and validity of two centimetric and two optoelectronic techniques for limb volume measurements against water volumetry, defined as the gold standard. Methods. Five different measurement methods were executed on the same day for each participant, namely water displacement, fixed-height (circumferences measured every 5 (10) cm for the upper (lower limb) centimetric technique, segmental centimetric technique (circumferences measured according to proportional height), optoelectronic plethysmography (OEP, based on a motion analysis system), and IGOODI Gate body scanner technology (which creates an accurate 3D avatar). Results. A population of 22 (15 lower limbs, 11 upper limbs, 8 unilateral upper limb lymphoedema, and 6 unilateral lower limb lymphoedema) participants was selected. Compared to water displacement, the fixed-height centimetric method, the segmental centimetric method, the OEP, and the IGOODI technique resulted in mean errors of 1.2, 0.86, −16.0, and 0.71%, respectively. The corresponding slopes (and regression coefficients) of the linear regression lines were 1.0002 (0.98), 1.0047 (0.99), 0.874 (0.94) and 0.9966 (0.99). Conclusion. The centimetric methods and the IGOODI system are accurate in measuring limb volume with an error of <2%. It is important to evaluate new objective and reliable techniques to improve diagnostic and follow-up possibilities. [ABSTRACT FROM AUTHOR]

Breathing motion is based on the differential activity of the thoracic, diaphragmatic and abdominal muscles. Muscle contributions differ between rest and exercise conditions and depend on posture and other factors. Traditionally, these changes are investigated on volumetric data using optoelectronic plethysmography (OEP). OEP offers insight into size variations of different chest wall (CW) compartments but does not provide three-dimensional visualization methods of CW breathing kinematics. Here we explore the use of three-dimensional geometric morphometrics to analyse size and shape changes caused by spontaneous breathing motion during quiet (QB), and recovery breathing (REC, immediately after heavy exercise) in two different postures (SIT, sitting on cycle ergometer; STA, standing position). Our findings show that size and shape differ significantly between inspiration and expiration and that differences are greater in REC than in QB. However, this is achieved by stronger expiration in SIT but by greater expiratory and inspiratory movements in STA. Shape analysis suggests that these differences may be attributed to constrained mobility of the shoulder girdle and a minor thoracic spine extension during inspiration owing to position on the ergometer. Breathing motion in STA seems biomechanically less constrained. Geometric morphometrics analyses can provide additional insights into data obtained by OEP.

Respiratory rate monitoring is fundamental in clinical settings, and the accuracy of measurement methods is critical. This study aimed to develop and validate methods for assessing respiratory rate and the duration leof respiratory cycle phases in different body positions using optoelectronic plethysmography (OEP) based on a motion capture video system. Two analysis methods, the summation method and the triangle method were developed. The study focused on determining the optimal number of markers while achieving accuracy in respiratory parameter measurements. The results showed that most analysis methods showed a difference of ≤0.5 breaths per minute, with R2 ≥ 0.94 (p < 0.001) compared to spirometry. The best OEP methods for respiratory rate were the abdominal triangles and the sum of abdominal markers in all body positions. The study explored inspiratory and expiratory durations. The research found that 5–9 markers were sufficient to accurately determine respiratory time components in all body positions, reducing the marker requirements compared to previous studies. This interchangeability of OEP methods with standard spirometry demonstrates the potential of non-invasive methods for the simultaneous assessment of body segment movements, center of pressure dynamics, and respiratory movements. Future research is required to improve the clinical applicability of these methods. [ABSTRACT FROM AUTHOR]

We investigated respiratory muscle strength, diaphragm mobility, lung function, functional capacity, quality of life, body composition, breathing pattern, and chest wall (VT,CW) and compartmental volumes of Mucopolysaccharidosis (MPS) patients and compared these variables with matched healthy individuals. A cross-sectional study with data analyzed separately according to age group. A total of 68 individuals (34 MPS and 34 matched-healthy subjects) were included. Six-minute walking test assessed functional capacity and ultrasound assessed diaphragm mobility during quiet spontaneous breathing (QB). Optoelectronic plethysmography assessed VT,CW and breathing pattern during QB in two different positions: seated and supine (45° trunk inclination). Body composition, lung function, respiratory muscle strength, and functional capacity were reduced in MPS (all p < 0.01). Diaphragm mobility was only reduced in adolescents (p = 0.01) and correlated with body composition and breathing pattern. Upper chest wall compartmental volumes were significantly lower in MPS, while abdominal volume only differed significantly in adolescents. Percentage contribution (%) of upper ribcage compartments to tidal volume was reduced in MPS children, whereas %AB was significantly increased compared with healthy subjects. Lung function, respiratory muscle strength, functional capacity, diaphragm mobility, and quality of life are reduced in MPS compared with matched healthy subjects. VT,CW was mainly reduced due to pulmonary and abdominal ribcage impairment. Reduction in respiratory muscle strength, functional capacity, diaphragm excursion and low lung volumes were found in individuals with Mucopolysaccharidoses (MPS). Chest wall volumes and the upper chest wall compartmental volumes during quiet spontaneous breathing are reduced in MPS. Assessment and monitoring of the respiratory system for individuals with MPS should be performed periodically through standardized assessments to enable identification of changes and early intervention by rehabilitation protocols. This study may provide the necessary basis for carrying out respiratoty rehabilitation protocols that can improving chest wall mechanics with breathing exercise in this group. [ABSTRACT FROM AUTHOR]

The breathing technique is a determining factor for the singer's sound quality and consequently crucial for the choral sound. However, very little is known about possible influences of the conductor's preparatory gesture on the way choral singers inhale before the beginning of a piece (respectively every subsequent phrase). The conducting literature does not discriminate between out- and inward preparatory gestures and even describes them as equivalent, but previous studies suggest that singers assign different types of inhalation to different preparatory gestures. It may therefore be assumed that the type of preparatory gesture has a direct influence on the singer's inhalation and tone production, and the aim of this study is hence to examine possible effects of two contrasting preparatory gestures on the singer's inhalation type and the resulting tone quality. In our within-subjects study design, 18 healthy choral singers (9 male/ 9 female) were recruited to participate in a laboratory experiment. The participants were asked to sing a tone suitable for their voice register in response to different video stimuli. These consisted of two conducting-videos, each showing a different preparatory gesture, and two control conditions with an animated bar and an arrow indicating the desired breathing type. The singers reacted to 10 sets of videos, each set consisting of the four stimuli in randomized order. For evaluation of the breathing behavior and vocal output during the different experimental conditions, chest wall kinematics of upper rib cage, abdominal rib cage and abdomen were measured via 3D motion capture and voice samples were recorded. The obtained data were filtered and compared using the repeated measures analysis of variance and post hoc Tukey test for significant results. The level of significance was set at P < 0.05. The results of the study show significant differences in volume of the abdomen between the two different gestures (F 1,17 = 24.04, η2 = 0.59, P = 0.0001), which can be validated by the two control measurements (F 1,17 = 21.12, η2 = 0.55, P = 0.0002). An outward preparatory gesture evoked an abdominal breathing type while an inward-upward movement led to an inhalation with a higher portion of clavicular breathing. Furthermore, significant differences in timbre and loudness of the produced tone could be observed. The maximum sound pressure level of the outward preparatory gesture was significantly higher than in case of the inward-upward movement (F 1,17 = 20.4, η2 = 0.56, P = 0.0004). In contrast to the existing conducting literature, which does not discriminate between out- and inward preparatory gestures, the results of this study show that the conductor's choice of trajectory direction and form of the preparatory gestures elicit spontaneous, gesture-specific reactions in singers' breathing behavior as well as the corresponding loudness and sound quality. [ABSTRACT FROM AUTHOR]

To compare the effect of unsupported arm elevation (UAE) in different planes on chest wall volumes, thoracoabdominal asynchrony (TAA), ventilatory demands, dyspnea, and arm fatigue in patients with chronic obstructive pulmonary disease (COPD) and healthy subjects. Twenty-one patients with COPD and healthy-matched subjects performed UAE in shoulder flexion, scaption, abduction, and resting. Pulmonary total and regional chest wall volumes (VRCp), abdominal rib cage volume, abdominal volume, TAA, and ventilatory demands during arm positions were measured using optoelectronic plethysmography. In both groups, VRCp and TAA were significantly affected during UAEs compared with the resting position. The healthy subjects had significantly decreased VRCp (L) (p < 0.05) during scaption (0.14 ± 0.07) and abduction (0.15 ± 0.06) than during flexion (0.18 ± 0.07) and no significantly different TAA between UAEs. The COPD group had no significantly different VRCp between UAEs, had significantly increased TAA (p < 0.05) during scaption (31.1°±9.5°) and abduction (32.3°±9.9°) than during flexion (29.7°±9.1°); and had significantly worse VRCp (p = 0.007), TAA (p = 0.0001), ventilatory demands (p < 0.05), dyspnea ((p = 0.03), and arm fatigue (p = 0.002). In patients with COPD, UAE in different planes similarly restricted the upper chest wall volume. Shoulder scaption and abduction significantly impaired TAA, ventilation, dyspnea, and arm fatigue compared with flexion. These results may help to select the appropriate UAE during physical activities. [ABSTRACT FROM AUTHOR]

Respiratory assessment can be carried out by using motion capture systems. A geometrical model is mandatory in order to compute the breathing volume as a function of time from the markers' trajectories. This study describes a novel model to compute volume changes and calculate respiratory parameters by using a motion capture system. The novel method, ie, prism-based method, computes the volume enclosed within the chest by defining 82 prisms from the 89 markers attached to the subject chest. Volumes computed with this method are compared to spirometry volumes and to volumes computed by a conventional method based on the tetrahedron's decomposition of the chest wall and integrated in a commercial motion capture system. Eight healthy volunteers were enrolled and 30 seconds of quiet breathing data collected from each of them. Results show a better agreement between volumes computed by the prism-based method and the spirometry (discrepancy of 2.23%, R² = .94) compared to the agreement between volumes computed by the conventional method and the spirometry (discrepancy of 3.56%, R² = .92). The proposed method also showed better performances in the calculation of respiratory parameters. Our findings open up prospects for the further use of the new method in the breathing assessment via motion capture systems. [ABSTRACT FROM AUTHOR]

• We have shown for the first time that after the trauma, TBPI patients who had not been treated with nerve transfer surgery present a decrease in inspiratory muscle strength, and exercise capacity. • Besides diaphragmatic mobility, reduced volume variation and ventilation asymmetry of the upper ribcage compartment. • It can also be speculated that the use of incentive spirometry may decrease the level of ventilation asymmetry; however, this issue needs further investigation. To investigate the repercussions of traumatic brachial plexus injury (TBPI) on diaphragmatic mobility and exercise capacity, compartmental volume changes, as well as volume contribution of each hemithorax and ventilation asymmetry during different respiratory maneuvers, and compare with healthy individuals. The velocity of shortening of the diaphragm, inspiratory, and expiratory muscles were also assessed. The cross-sectional study was conducted with 40 male individuals (20 with TBPI who have not undergone nerve transfer surgery [mean age 30.1 ± 5.3] and 20 healthy paired by age and body mass index). Only patients with C8-T1 root avulsion were studied. Compartmental and hemithoracic volumes, as well as asymmetry between the affected and unaffected sides were assessed using optoelectronic plethysmography. The 6 minute walking test was performed to evaluate exercise capacity, while diaphragm mobility was assessed during quiet breathing (QB) using an ultrasound device. TBPI patients with mean lesion time of 174 ± 45.24 days showed a decreased pulmonary function, respiratory muscle strength, exercise capacity, and diaphragm mobility (all p <.001) compared with healthy. The pulmonary ribcage compartment of the affected side was the main contributor to the reduction in volume during inspiratory capacity, vital capacity, and inspiratory load imposition (all p <.05). This compartment also exhibited a higher ventilation asymmetry with reduced shortening velocity of the inspiratory ribcage muscles. Compared with healthy, TBPI patients who have not undergone nerve transfer surgery present low exercise capacity and diaphragmatic mobility, as well as reduced volume of the upper ribcage compartment on the affected side that leads to reduced shortening velocity and ventilation asymmetry. [ABSTRACT FROM AUTHOR]

This study aimed to explore novel inertial measurement unit (IMU)-based strategies to estimate respiratory parameters in healthy adults lying on a bed while breathing normally. During the experimental sessions, the kinematics of the chest wall were contemporaneously collected through both a network of 9 IMUs and a set of 45 uniformly distributed reflective markers. All inertial kinematics were analyzed to identify a minimum set of signals and IMUs whose linear combination best matched the tidal volume measured by optoelectronic plethysmography. The resulting models were finally tuned and validated through a leave-one-out cross-validation approach to assess the extent to which they could accurately estimate a set of respiratory parameters related to three trunk compartments. The adopted methodological approach allowed us to identify two different models. The first, referred to as Model 1, relies on the 3D acceleration measured by three IMUs located on the abdominal compartment and on the lower costal margin. The second, referred to as Model 2, relies on only one component of the acceleration measured by two IMUs located on the abdominal compartment. Both models can accurately estimate the respiratory rate (relative error < 1.5%). Conversely, the duration of the respiratory phases and the tidal volume can be more accurately assessed by Model 2 (relative error < 5%) and Model 1 (relative error < 5%), respectively. We further discuss possible approaches to overcome limitations and improve the overall accuracy of the proposed approach. [ABSTRACT FROM AUTHOR]

Total lung capacity is usually measured by a body plethysmograph or helium dilution methods. In this study an alternative approach to obtain total lung capacity of spontaneous breathing subjects is introduced. The device utilises an optoelectronic plethysmograph and a small tube, which measures mouth pressure and allows total lung capacity to be obtained, which differs less than 0.4 L from the total lung capacity of the body plethysmograph. The method shows potential to be a less burdensome method to estimate total lung capacity determination than the body plethysmograph.

Plethysmography is an indispensable component of clinical lung function testing. However, lung volume measurement in the supine position using an optoelectronic system requires the placement of reflective markers on the anterior and lateral torso surface. The conventional method computes breath-by-breath changes in the volume between the markers and the bed, which serves as the reference plane. In contrast, the surface method consists of measuring the volume delineated by the surface area of the marker network at the onset and end of inspiration. We compared these 2 methods to spirometry during spontaneous breathing in 11 healthy volunteers and in 14 patients receiving routine visits for neuromuscular disease. Bland-Altman plots showed that agreement with spirometry was better for the surface method that the conventional method. Our results open up prospects for integrating these methods in the development of new devices. [ABSTRACT FROM AUTHOR]

• Optoelectronic plethysmography (OEP) is used to assess the thoracoabdominal kinematics of healthy individuals. • Chest and abdominal fat excess could compromise the evaluation by OEP. • Thoracoabdominal kinematics of people with obesity, with a BMI of up to 50 kg/m2, can be assessed by OEP. Optoelectronic Plethysmography (OEP) is an effective method for evaluating thoracoabdominal kinematics. However, little is known about the viability and use the OEP in people with obesity. Summarize information on the use and feasibility of OEP in the assessment of thoracoabdominal kinematics in people with obesity. Studies were identified through PubMed, EMBASE, Science Direct, Web of Science and Scopus databases in the February 2021. Six studies met the inclusion criteria. The studies used the OEP to assess abdominal and thoracic mobility in obese people of different BMI, using the default setting. No study reported the impossibility of using OEP in people with obesity. Has been shown that it is possible to use the OEP in people with obesity with a BMI of up to 50 kg/m2. More studies are needed to demonstrate the feasibility of the method in people with a BMI greater than this value. [ABSTRACT FROM AUTHOR]

Phrenic nerve damage may occur as a complication of specific surgical procedures, prolonged mechanical ventilation, or physical trauma. The consequent diaphragmatic paralysis or dysfunction can lead to major complications. The purpose of this study was to elucidate the role of the nondiaphragmatic respiratory muscles during partial or complete diaphragm paralysis induced by unilateral and bilateral phrenic nerve damage at different levels of ventilatory pressure support in an animal model. Ten pigs were instrumented, the phrenic nerve was exposed from the neck, and spontaneous respiration was preserved at three levels of pressure support, namely, high, low, and null, at baseline condition, after left phrenic nerve damage, and after bilateral phrenic nerve damage. Breathing pattern, thoracoabdominal volumes and asynchrony, and pressures were measured at each condition. Physiological breathing was predominantly diaphragmatic and homogeneously distributed between right and left sides. After unilateral damage, the paralyzed hemidiaphragm was passively dragged by the ipsilateral rib cage muscles and the contralateral hemidiaphragm. After bilateral damage, the drive to and the work of breathing of rib cage and abdominal muscles increased, to compensate for diaphragmatic paralysis, ensuing paradoxical thoracoabdominal breathing. Increasing level of pressure support ventilation replaces this muscle group compensation. When the diaphragm is paralyzed (unilaterally and/or bilaterally), there is a coordinated reorganization of nondiaphragmatic respiratory muscles as compensation that might be obscured by high level of pressure support ventilation. Noninvasive thoracoabdominal volume and asynchrony assessment could be useful in phrenic nerve-injured patients to estimate the extent and type of inspiratory muscle dysfunction. [ABSTRACT FROM AUTHOR]

Abstract Background The effects of the Nuss procedure on chest wall motion and spirometry have previously been described; we aimed to describe the effects of removal of the Nuss bar. Methods We studied 9 patients just prior to and 6 weeks after Nuss bar removal. Regional chest volume changes, synchrony of respiratory movement and spirometry were recorded using optoelectronic plethysmography (OEP) and compared. Recordings were performed at rest and exercise during cycle ergometry. Results There were small but statistically significant changes in tidal volumes of the diaphragmatic ribcage compartment during exercise (+ 48 ml, p = 0.038, Cohen’s d = 0.12) and percentage contribution of the diaphragmatic ribcage to total tidal volumes at rest (+ 2.7 percentage points, p = 0.038, Cohen’s d = 0.12). Synchrony of respiratory movements at rest and during exercise was unchanged following Nuss bar removal. There were no significant changes in spirometry and exercise capacity. Conclusions The effects of Nuss bar removal on diaphragmatic ribcage motion are detectable but small and unlikely to be of clinical significance. No change in exercise capacity should be expected after Nuss bar removal. Trial registration Registered at ClinicalTrials.gov, identifier NCT02958683, registered 5th August 2016, first patient enrolled July 2016, retrospectively registered.

Motion tracking of thorax kinematics can be used to determine respiration. However, determining a minimal sensor configuration from 64 candidate sensor locations is associated with high computational costs. Hence, a hierarchical optimization method was proposed to determine the optimal combination of sensors. The hierarchical method was assessed by its ability to quickly determine the sensor combination that will yield optimal modelled tidal volume compared to body plethysmograph measurements. This method was able to find the optimal sensor combinations, in approximately 2% of the estimated time required by an exhaustive search.

Purpose: In healthy humans, postural and respiratory dynamics are intimately linked and a breathing-related postural perturbation is evident in joint kinematics. A cognitive dual-task paradigm that is known to induce both postural and ventilatory disturbances can be used to modulate this multijoint posturo-ventilatory (PV) interaction, particularly in the cervical spine, which supports the head. The objective of this study was to assess this modulation.Methods: With the use of optoelectronic sensors, the breathing profile, articular joint motions of the cervical spine, hip, knees and ankles, and centre of pressure (CoP) displacement were measured in 20 healthy subjects (37 years old [29; 49], 10 females) during natural breathing (NB), a cognitive dual task (COG), and eyes-closed and increased-tidal-volume conditions. The PV interaction in the CoP and joint motions were evaluated by calculating the respiratory emergence (REm).Results: Only the COG condition induced a decrease in the cervical REm (NB: 17.2% [7.8; 37.2]; COG: 4.2% [1.8; 10.0] p = 0.0020) concurrent with no changes in the cervical motion. The CoP REm (NB: 6.2% [3.8; 10.3]; COG: 12.9% [5.8; 20.7] p = 0.0696) and breathing frequency (NB: 16.6 min-1 [13.3; 18.7]; COG: 18.6 min-1 [16.3; 19.4] p = 0.0731) tended to increase, while the CoP (p = 0.0072) and lower joint motion displacements (p < 0.05) increased.Conclusion: This study shows stable cervical spine motion during a cognitive dual task, as well as increased postural perturbations globally and in other joints. The concurrent reduction in the PV interaction at the cervical spine suggests that this "stabilization strategy" is centrally controlled and is achieved by a reduction in the breathing-related postural perturbations at this level. Whether this strategy is a goal for maintaining balance remains to be studied. [ABSTRACT FROM AUTHOR]

• Aging reduces rib cage contribution and increase abdominal contribution. • Aging increases end-inspiratory and end-expiratory chest wall volumes. • Sitting position might benefit patients who present reduced tidal volume. • Posture influences all variables of breathing pattern and chest wall motion, except respiratory rate and duty cycle. • Women present higher thoracic contribution to the tidal volume. We evaluated the effects of posture, sex, and age on breathing pattern and chest wall motion during quiet breathing in healthy participants. Eighty-three participants aged 42.72 (SD = 21.74) years presenting normal pulmonary function were evaluated by optoelectronic plethysmography in the seated, inclined (with 45° of trunk inclination), and supine positions. This method allowed to assess the chest wall in a three dimensional way considering the chest wall as three compartments: pulmonary rib cage, abdominal rib cage and abdomen. Posture influenced all variables of breathing pattern and chest wall motion, except respiratory rate and duty cycle. Chest wall tidal volume and minute ventilation were reduced (p < 0.05) in both sexes from seated to inclined and from seated to supine positions, mainly in males. Moreover, moving from seated to supine position significantly increased the percentage contribution of the abdomen to the tidal volume in both sexes (p < 0.0001). Regarding sex, women showed higher contribution of thoracic compartment compared to men (p = 0.008). Aging provided reductions on rib cage contributions to tidal volume that were compensated by increases of abdomen contributions (p < 0.0001). In addition, increases in end-inspiratory and end-expiratory volumes over the years were observed. The degree of contribution of chest wall compartments is dependent on posture, sex, and age. Therefore, verticalization increases expansion of pulmonary rib cage as well as horizontalization increases abdominal displacement. Women presented higher thoracic contribution to tidal volume than men. Aging reduces rib cage contributions to tidal volume that were compensated by increases of abdomen contributions. [ABSTRACT FROM AUTHOR]

Continuous monitoring of breathing frequency (fB) could foster early prediction of adverse clinical effects and exacerbation of medical conditions. Current solutions are invasive or obtrusive and thus not suitable for prolonged monitoring outside the clinical setting. Previous studies demonstrated the feasibility of deriving fB by measuring inclination changes due to breathing using accelerometers or inertial measurement units (IMU). Nevertheless, few studies faced the problem of motion artifacts that limit the use of IMU-based systems for continuous monitoring. Moreover, few attempts have been made to move towards real portability and wearability of such devices. This paper proposes a wearable IMU-based device that communicates via Bluetooth with a smartphone, uploading data on a web server to allow remote monitoring. Two IMU units are placed on thorax and abdomen to record breathing-related movements, while a third IMU unit records body/trunk motion and is used as reference. The performance of the proposed system was evaluated in terms of long-acquisition-platform reliability showing good performances in terms of duration and data loss amount. The device was preliminarily tested in terms of accuracy in breathing temporal parameter measurement, in static condition, during postural changes, and during slight indoor activities showing favorable comparison against the reference methods (mean error breathing frequency < 5%). Graphical abstract Proof of concept of a wearable, wireless, modular respiratory Holter based on inertial measurement units (IMUS) for the continuous breathing pattern monitoring through the detection of chest wall breathing-related movements. [ABSTRACT FROM AUTHOR]

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 FEV1%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.

Dysfunctional breathing patterns (DBP) can have an impact on an individual’s quality of life and/or exercise performance. Breathing retraining is considered to be the first line of treatment to correct breathing pattern, for example, reducing ribcage versus abdominal movement asynchrony. Optoelectronic plethysmography (OEP) is a non-invasive 3D motion capture technique that measures the movement of the chest wall. The purpose of this study was to investigate if the use of a newly developed real-time OEP phase angle and volume feedback system, as an acute breathing retraining intervention, could result in a greater reduction of phase angle values (i.e., an improvement in movement synchrony) when compared to real-time OEP volume feedback alone. Eighteen individuals with a DBP performed an incremental cycle test with OEP measuring chest wall movement. Participants were randomly assigned to either the control group, which included the volume-based OEP feedback or to the experimental group, which included both the volume-based and phase angle OEP feedback. Participants then repeated the same cycle test using the real-time OEP feedback. The phase angle between the ribcage versus abdomen (RcAbPhase), between the pulmonary ribcage and the combined abdominal ribcage and abdomen (RCpAbPhase), and between the abdomen and the shoulders (AbSPhase) were calculated during both cycle tests. Significant increases in RcAbPhase (pre: −2.89°, post: −1.39°, p < 0.01), RCpAbPhase (pre: −2.00°, post: −0.50°, p < 0.01), and AbSPhase (pre: −2.60°, post: −0.72°, p < 0.01) were found post-intervention in the experimental group. This indicates that the experimental group demonstrated improved synchrony in their breathing pattern and therefore, reverting towards a healthy breathing pattern. This study shows for the first time that dysfunctional breathing patterns can be acutely improved with real-time OEP phase angle feedback and provides interesting insight into the feasibility of using this novel feedback system for breathing pattern retraining in individuals with DBP.

A plethora of physiological and biochemical changes occur during normal pregnancy. The changes in the respiratory system have not been as well elucidated, in part because radioimaging is usually avoided during pregnancy. We aimed to use several noninvasive methods to characterize the adaptation of the respiratory system during the full course of pregnancy in preparation for childbirth. Eighteen otherwise healthy women (32.3 ± 2.8 yr) were recruited during early pregnancy. Spirometry, optoelectronic plethysmography, and ultrasonography were used to study changes in chest wall geometry, breathing pattern, lung and thoraco-abdominal volume variations, and diaphragmatic thickness in the first, second, and third trimesters. A group of nonpregnant women were used as control subjects. During the course of pregnancy, we observed a reorganization of rib cage geometry, in shape but not in volume. Despite the growing uterus, there was no lung restriction (forced vital capacity: 101 ± 15% predicted), but we did observe reduced rib cage expansion. Breathing frequency and diaphragmatic contribution to tidal volume and inspiratory capacity increased. Diaphragm thickness was maintained (1st trimester: 2.7 ± 0.8 mm, 3rd trimester: 2.5 ± 0.9 mm; P = 0.187), possibly indicating a conditioning effect to compensate for the effects of the growing uterus. We conclude that pregnancy preserved lung volumes, abdominal muscles, and the diaphragm at the expense of rib cage muscles. [ABSTRACT FROM AUTHOR]

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 FEV1%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. [ABSTRACT FROM AUTHOR]

Highlights • Volume incentive spirometer is superior to flow incentive spirometer. • Sustained maximal inspiration exercise is equivalent to incentive spirometers. • Sustained maximal inspiration exercise might be a without cost alternative. Abstract Purpose To compare the effects of flow incentive spirometer (FIS), volume incentive spirometer (VIS), and sustained maximal inspiration exercise (SMI) on breathing pattern, chest wall motion, and thoracoabdominal asynchrony. Methods Sixteen healthy adults aged 27.63 ± 5.26 years were evaluated by optoelectronic plethysmography in the supine position with trunk inclination of 45° during quiet breathing and during exercise performance. Results In the comparisons among exercises, VIS promoted a significantly higher inspiratory time and lower mean inspiratory flow compared with FIS. The rating of perceived exertion according to the Borg Scale was significantly higher after the performance of FIS compared with VIS. Regarding asynchrony, none of the exercises caused changes in thoracoabdominal synchrony between the rib cage and abdomen. However, both devices significantly reduced the asynchrony between the pulmonary and abdominal rib cage compared with quiet breathing. Conclusion SMI exercise was equivalent to incentive spirometers and may be an interesting alternative for clinical use in cases in which it is not possible to acquire the devices. [ABSTRACT FROM AUTHOR]

BACKGROUND: Breathing exercises, such as diaphragmatic breathing and pursed-lips breathing, play a role in some individuals with COPD and might be considered for those patients who are unable to exercise. However, in the literature are reports of some adverse effects of diaphragmatic breathing in patients with COPD. Thus, the purpose of this study was to assess the effects of diaphragmatic breathing and diaphragmatic breathing combined with pursed-lips on chest wall kinematics, breathlessness, and chest wall asynchrony in subjects with COPD, and also to assess whether the combination of both exercises reduces the adverse effects of diaphragmatic breathing while maintaining its benefits. METHODS: Seventeen subjects with COPD, mean ± SD, 65 ± 7 y of age, with a history of smoking and clinical stability without hospitalization or symptoms of exacerbation in the past 4 wk, were evaluated. On day 1, participants' characteristics were collected, and they learned diaphragmatic breathing and its combination with pursed-lips breathing. On day 2, the participants were evaluated by optoelectronic plethysmography with the participants in the seated position while performing breathing exercises. RESULTS: Diaphragmatic breathing and diaphragmatic breathing plus pursed-lips breathing promoted a significant increase in chest wall tidal volume and its compartments as well as a reduction in breathing frequency compared with quiet breathing. No significant changes were observed in dyspnea or end-expiratory volume of the chest wall. A significant increase in asynchrony (inspiratory-expiratory phase ratio) was observed during diaphragmatic breathing and diaphragmatic breathing plus pursed-lips breathing compared with quiet breathing, with no differences observed between the exercises. CONCLUSIONS: Despite the increase in asynchrony, both breathing exercises were able to improve chest wall volumes without affecting dyspnea. The combination of exercises maintained the benefits but did not reduce the adverse effects of diaphragmatic breathing. [ABSTRACT FROM AUTHOR]

Continuous respiratory monitoring is important to assess adequate ventilation. We present a fiber optic-based smart textile for respiratory monitoring able to work during Magnetic Resonance (MR) examinations. The system is based on the conversion of chest wall movements into strain of two fiber Bragg grating (FBG) sensors, placed on the upper thorax (UT). FBGs are glued on the textile by an adhesive silicon rubber. To increase the system sensitivity, the FBGs positioning was led by preliminary experiments performed using an optoelectronic system: FBGs placed on the chest surface experienced the largest strain during breathing. System performances, in terms of respiratory period (TR), duration of inspiratory (TI) and expiratory (TE) phases, as well as left and right UT volumes, were assessed on four healthy volunteers. The comparison of results obtained by the proposed system and an optoelectronic plethysmography highlights the high accuracy in the estimation of TR, TI, and TE: Bland-Altman analysis shows mean of difference values lower than 0.045 s, 0.33 s, and 0.35 s for TR, TI, and TE, respectively. The mean difference of UT volumes between the two systems is about 8.3%. The promising results foster further development of the system to allow routine use during MR examinations.Continuous respiratory monitoring is important to assess adequate ventilation. We present a fiber optic-based smart textile for respiratory monitoring able to work during Magnetic Resonance (MR) examinations. The system is based on the conversion of chest wall movements into strain of two fiber Bragg grating (FBG) sensors, placed on the upper thorax (UT). FBGs are glued on the textile by an adhesive silicon rubber. To increase the system sensitivity, the FBGs positioning was led by preliminary experiments performed using an optoelectronic system: FBGs placed on the chest surface experienced the largest strain during breathing. System performances, in terms of respiratory period (TR), duration of inspiratory (TI) and expiratory (TE) phases, as well as left and right UT volumes, were assessed on four healthy volunteers. The comparison of results obtained by the proposed system and an optoelectronic plethysmography highlights the high accuracy in the estimation of TR, TI, and TE: Bland-Altman analysis shows mean of difference values lower than 0.045 s, 0.33 s, and 0.35 s for TR, TI, and TE, respectively. The mean difference of UT volumes between the two systems is about 8.3%. The promising results foster further development of the system to allow routine use during MR examinations.

Highlights • Inspiratory loaded breathing (ILB) modifies chest wall volumes in patients with heart failure (HF). • ILB associated with diaphragmatic breathing (ILB di) increases abdominal volume in these patients. • Chest wall tidal volume and breathing pattern variables are similar between ILB and ILB di. Abstract Background Some inspiratory muscle training protocols for patients with heart failure report the request of diaphragmatic breathing during inspiratory loaded breathing. However, it is unclear whether this condition modifies the chest wall volumes. Objective The primary purpose was to evaluate chest wall volumes during inspiratory loaded breathing as well as during inspiratory loaded breathing associated with diaphragmatic breathing in patients with heart failure. Methods Sixteen men with heart failure functional class I to III, aged 50(SD = 7) years were evaluated. Volumes of the pulmonary rib cage, abdominal rib cage and abdomen, as well as other breathing pattern variables, were assessed by optoelectronic plethysmography during quiet breathing, inspiratory loaded breathing, and inspiratory loaded breathing associated with diaphragmatic breathing. Results Chest wall tidal volume significantly increased from quiet breathing 0.53(SD = 0.14)L to inspiratory loaded breathing 1.33(SD = 0.48)L and to inspiratory loaded breathing associated with diaphragmatic breathing 1.36(SD = 0.48)L. A significant volume variation was observed on the three compartments (p < 0.05 for all). During inspiratory loaded breathing associated with diaphragmatic breathing, patients showed increased abdominal volume compared to quiet breathing [0.28(SD = 0.05) to 0.83(SD = 0.47)L, p < 0.001]; as well as from inspiratory loaded breathing [0.63(SD = 0.23) to 0.83(SD = 0.47)L, p = 0.044]. No significant changes were observed between the two inspiratory loaded breathing conditions on the percentages of the contribution of each chest wall compartment for the tidal volume, respiratory rate, minute ventilation, and duty cycle. Conclusion When inspiratory loaded breathing was associated with diaphragmatic breathing, a higher volume in the abdominal compartment was obtained without significant changes in other breathing pattern variables. [ABSTRACT FROM AUTHOR]

Patients with Parkinson’s disease often exhibit respiratory disorders and there are no Respiratory Therapy protocols which are suggested as interventions in Parkinson’s patients. The aim of this study is to evaluate the effects of Breathing-Stacking (BS) and incentive spirometer (IS) techniques in volume variations of the chest wall in patients with Parkinson’s Disease (PD). 14 patients with mild-moderate PD were included in this randomized cross-over study. Volume variations of the chest wall were assessed before, immediately after, then 15 and 30 min after BS and IS performance by optoelectronic plethysmography. Tidal volume (VT) and minute ventilation (MV) significantly increased after BS and IS techniques (p < 0.05). There was greater involvement of pulmonary and abdominal compartments after IS. The results suggest that these re-expansion techniques can be performed to immediately improve volume. [ABSTRACT FROM AUTHOR]

Individuals post-stroke may present restrictive ventilatory pattern generated from changes in the functionality of respiratory system due to muscle spasticity and contractures. Objective was to assess the acute effects after respiratory muscle stretching on the ventilatory pattern and volume distribution of the chest wall in stroke subjects. Ten volunteers with right hemiparesis after stroke and a mean age of 60 ± 5.7 years were randomised into the following interventions: respiratory muscle stretching and at rest (control). The ventilatory pattern and chest wall volume distribution were evaluated through optoelectronic plethysmography before and immediately after each intervention. Respiratory muscle stretching promoted a significant acute increase of 120 mL in tidal volume, with an increase in minute ventilation, mean inspiratory flow and mean expiratory flow compared with the control group. Pulmonary ribcage increased 50 mL after stretching, with 30 mL of contribution to the right pulmonary rib cage (hemiparetic side) in comparison to the control group. Respiratory muscle stretching in patients with right hemiparesis post-stroke demonstrated that acute effects improve the expansion of the respiratory system during tidal breathing. Clinical Trial Registration : NCT02416349 (URL: https://clinicaltrials.gov/ct2/show/ NCT02416349 ). [ABSTRACT FROM AUTHOR]

BACKGROUND: Duchenne muscular dystrophy (DMD) is characterized by progressive degeneration, wasting, and weakness of skeletal musculature, including respiratory muscles. Cough is also compromised with disease progression. Among cough-augmentation techniques, mechanical insufflation-exsufflation (MI-E) has demonstrated several clinical benefits in patients with chronic airway secretion obstruction and muscular weakness. In clinical practice, the use of MI-E in DMD patients is also suggested when they are stable with no airway infections. However, there is a paucity of studies that consider the effect of MI-E specifically on stable DMD patients who have adapted to the use of MI-E. METHODS: Twenty subjects with DMD with no active upper airway or lung infections, who used MI-E device regularly at home, were enrolled. They received a single MI-E treatment consisting of 5 cycles of 5 insufflations-exsufflations with their customary settings. Volume variations during quiet breathing, vital capacity, and cough before and after treatment were measured with optoelectronic plethysmography (OEP). RESULTS: A decrease in breathing frequency (P = .001) and the rapid shallow breathing index emerged (P = .007), while cough peak flow (Spirometer P = .86, OEP P = .58), vital capacity (Spirometer P = .78, OEP total chest wall P = .57), and end-expiratory volumes (Total chest wall P = .97, Ribcage P = .14, Abdomen P = .10) were not affected by the treatment. An increment of the chest wall volume variation during the expiratory cough phase was identified (P = .001), particularly due to an increase in abdominal expansion (P = .005). CONCLUSIONS: A single treatment of MI-E in subjects with stable DMD already adapted to the device can provide beneficial changes in breathing pattern through a significant decrease in breathing frequency and rapid shallow breathing. These findings suggest an improvement in short-term dyspnea, although there were no changes in lung-volume recruitment or unassisted cough peak flow. [ABSTRACT FROM AUTHOR]

Breathing parameters can be measured by motion capture systems by placing photo-reflective markers on the chest wall. A computational model is mandatory to compute the breathing volume and to calculate temporal and kinematical features by the gathered markers trajectories. Despite different methods based on different geometrical approaches can be adopted to compute volumes, no information about their differences in the respiratory evaluation are available. This study investigated the performances of four methods (conventional, prism-based, convex hull with boundary condition, based on Delaunay triangulation) using an optoelectronic motion capture system, on twelve healthy participants during 30 s of breathing. Temporal trends of volume traces, tidal volume values, and breathing durations were compared between methods and spirometry (used as reference instrument). Additionally, thoraco-abdominal motion patterns were compared between methods by analysing the compartmental contributions and their variability. Results shows comparable similarities between the volume traces obtained using spirometry, prism-based and conventional methods. Prism-based and convex hull with boundary condition methods show lower bias in tidal volumes estimation up to 0.06 L, compared to the conventional and Delaunay triangulation methods. Prism-based method shows maximum differences of 30 mL in the comparison of compartmental contributions to the total volume, by resulting in a maximum deviation of 1.6% in the percentage contribution analysis. In conclusion, our finding demonstrated the accuracy of the non-invasive MoCap-based breathing analysis with the prism-based method tested. Data provided in this study will lead researchers and clinicians in the computational method choice for temporal and volumetric breathing analysis. [ABSTRACT FROM PUBLISHER]

This study evaluated the immediate effects of respiratory muscle stretching on chest wall kinematics and electromyographic activity in COPD patients. 28 patients with COPD were randomized into two groups: 14 to the treatment group (TG) and 14 to the control group (CG). The TG underwent a stretching protocol of the rib cage muscles, while the CG remained at rest under similar conditions. After a single session, TG increased the tidal volume of the pulmonary rib cage (Vrcp) (p = 0.020) and tidal volume of abdominal rib cage (Vrca) (p = 0.043) variations and their percentages in relation to the thoracic wall, Vrcp% (p = 0.044) and Vrca% (p = 0.022). Also, TG decreased the end-expiratory Vrcp (p = 0.013) and the end-inspiratory Vrcp (p = 0.011) variations. In addition, there was a reduction in respiratory rate (RR) (p = 0.011) and minute volume (MV) (p = 0.035), as well as an increase in expiratory time (Te) (p = 0.026). There was also an immediate reduction in sternocleidomastoid (p = 0.043) and upper trapezium (p = 0.034) muscle electrical activity. Then, the study supports the use of stretching to improve COPD chest wall mobility with positive effects on chest wall mechanics, on volume distribution and electromyography. [ABSTRACT FROM AUTHOR]

Optoelectronic plethysmography (OEP) is a noninvasive method for assessing lung volume variations and the contributions of different anatomical compartments of the chest wall (CW) through measurements of the motion of markers attached to the CW surface. The present study proposes a new method for analyzing the local CW kinematics from OEP measurements based on the kinematics of triangular Cosserat point elements (TCPEs). 52 reflective markers were placed on the anterior CW to create a mesh of 78 triangles according to an anatomical model. Each triangle was characterized by a TCPE and its kinematics was described using four time-variant scalar TCPE parameters. The total CW volume ( $$V_{\text{TCW}}$$ ) and the contributions of its six compartments were also estimated, using the same markers. The method was evaluated using measurements of ten healthy subjects, nine patients with Pompe disease, and ten patients with Duchenne muscular dystrophy (DMD), during spontaneous breathing (SB) and vital capacity maneuvers (VC) in the supine position. TCPE parameters and compartmental volumes were compared with $$V_{\text{TCW}}$$ by computing the phase angles $$\theta$$ (for SB) and the correlation r (for VC) between them. Analysis of $$\theta$$ and r of the outward translation parameter $$P_{\text{T}}$$ of each TCPE revealed that for healthy subjects it provided similar results to those obtained by compartmental volumes, whereas for the neuromuscular patients the TCPE method was capable of detecting local asynchronous and paradoxical movements also in cases where they were undistinguished by volumes. Therefore, the TCPE approach provides additional information to OEP that may enhance its clinical evaluation capabilities. [ABSTRACT FROM AUTHOR]

Background: Optoelectronic plethysmography (OEP) is a non-invasive motion capture method to measure chest wall movements and estimate lung volumes. Objectives: To provide an overview of the clinical findings and research applications of OEP in the assessment of breathing mechanics across populations of healthy and diseased individuals. Methods: A bibliographic research was performed with the terms "opto-electronic plethysmography," "optoelectronic plethysmography," and "optoelectronic plethysmograph" in 50 digital library and bibliographic search databases resulting in the selection of 170 studies. Results: OEP has been extensively employed in studies looking at chest wall kinematics and volume changes in chest wall compartments in healthy subjects in relation to age, gender, weight, posture, and different physiological conditions. In infants, OEP has been demonstrated to be a tool to assess disease severity and the response to pharmacological interventions. In chronic obstructive pulmonary disease patients, OEP has been used to test if patients can dynamically hyperinflate or deflate their lungs during exercise. In neuromuscular patients, respiratory muscle strength and chest kinematics have been analyzed. A widespread application of OEP is in tailoring post-operative pulmonary rehabilitation as well as in monitoring volume increases and muscle contributions during exercise. Conclusions: OEP is an accurate and validated method of measuring lung volumes and chest wall movements. OEP is an appropriate alternative method to monitor and analyze respiratory patterns in children, adults, and patients with respiratory diseases. OEP may be used in the future to contribute to improvements in the therapeutic strategies for respiratory conditions. [ABSTRACT FROM AUTHOR]

Breathing frequency (fB) is an important vital sign that—if appropriately monitored—may help to predict clinical adverse events. Inertial sensors open the door to the development of low-cost, wearable, and easy-to-use breathing-monitoring systems. The present paper proposes a new posture-independent processing algorithm for breath-by-breath extraction of breathing temporal parameters from chest-wall inclination change signals measured using inertial measurement units. An important step of the processing algorithm is dimension reduction (DR) that allows the extraction of a single respiratory signal starting from 4-component quaternion data. Three different DR methods are proposed and compared in terms of accuracy of breathing temporal parameter estimation, in a group of healthy subjects, considering different breathing patterns and different postures; optoelectronic plethysmography was used as reference system. In this study, we found that the method based on PCA-fusion of the four quaternion components provided the best fB estimation performance in terms of mean absolute errors ( 0.963) and Bland–Altman Analysis, outperforming the other two methods, based on the selection of a single quaternion component, identified on the basis of spectral analysis; particularly, in supine position, results provided by PCA-based method were even better than those obtained with the ideal quaternion component, determined a posteriori as the one providing the minimum estimation error. The proposed algorithm and system were able to successfully reconstruct the respiration-induced movement, and to accurately determine the respiratory rate in an automatic, position-independent manner.

There has been a lack of studies that have used both three-dimensional analysis and imaging tools concurrently to describe lung volume changes and breathing pattern in subjects in the supine position. The purpose of this study was to investigate the correlation between volume changes estimated by optoelectronic plethysmography (OEP) and diaphragmatic excursion (DE) measured by ultrasonography of healthy adults in the supine position. Methods: Twelve healthy male subjects (age, 25.08 ± 6.35 years) were recruited and asked to perform tidal and deep breathing in the supine position. The volume changes during chest wall motion were quantified from OEP analysis—this was done for the upper thorax (UT), lower thorax (LT), and abdominal (AB) compartment. Lung volume was measured synchronously via the mouth piece of an electrospirometer. The right diaphragmatic movement was measured by ultrasonography. Results: Linear regression showed that all three compartments (VUT, VLT and VAB) in the inspiratory phase were correlated highly with DE during tidal and deep breathing. However, multiple linear regression analysis showed that the VAB contributed 94–95% of the variance when performing either tidal or deep breathing. A predicted equation for diaphragmatic movement during deep breathing was DE = 0.052 + 0.294VAB. Conclusion: The movement of VAB can be used as an index of DE among the normal population in the supine position. Its application in patients requires further study.

Purpose: We reasoned that the application of positive pressure through air stacking (AS) technique could cause gas compression and the absolute lung volumes could be estimated. The aim of this study was to estimate the amount of gas compression (ΔV comp) during AS in healthy subjects positioned at 45° trunk inclination and verify if the simultaneous measurements of chest wall volume changes (ΔV CW), by optoelectronic plethysmography, and changes in lung volume (ΔV ao), by pneumotachograph, combined with pressure variation at the airways opening (ΔP ao) during AS are able to provide reliable data on absolute lung volumes.Methods: Twenty healthy subjects (mean age 23.5 ± 3.8 years) were studied during a protocol that included slow vital capacity and AS maneuvers. V comp was calculated by subtracting ΔV ao and ΔV CW occurring during AS and total lung capacity (TLC) was estimated by applying Boyle-Mariote's law using V comp and ΔP ao.Results: During AS, 0.140 ± 0.050 L of gas was compressed with an average ΔP ao of 21.78 ± 6.18 cmH2O. No significant differences between the estimated TLC (-0.03 ± 3.0% difference, p = 0.6020), estimated FRC (-2.0 ± 12.4% difference, p = 0.5172), measured IC (1.2 ± 11.2% difference, p = 0.7627) and predicted values were found.Conclusion: During AS, a significant gas compression occurs and absolute lung volumes can be estimated by simultaneous measurements of ΔV CW, ΔV ao and ΔP ao. [ABSTRACT FROM AUTHOR]

Background: Following diaphragmatic plication for unilateral paralysis, the effect on global chest wall function are unknown. Our hypothesis was that chest wall function would improve in both sides of the chest after plication of the paralysed side.Case Presentation: Using Optoelectronic Plethysmography, total and regional chest wall volumes were measured in one patient before and after left diaphragmatic plication. Volumes were recorded at quiet breathing. Respiratory capacity improved during quiet breathing when measured before and 6 months after surgery. These improvements occur at the abdominal-rib cage level in both operated and contralateral. Prior to surgery the abdominal rib cage motion was out of phase to the upper rib cage and abdominal compartment in both sides of the chest. Synchrony of all three compartments was restored after plication.Conclusion: This physiological study is the first published data in humans to show improvement in chest wall motion both in operated and contralateral side following diaphragmatic plication for unilateral paralysis. [ABSTRACT FROM AUTHOR]

The improvement of care in patients with Duchenne Muscular Dystrophy (DMD), especially the introduction of home mechanical ventilation, corticosteroid therapy, and early cardiologic therapy, allowed an increase of life expectancy, till their 30s or 40s. However, respiratory complications remain one of the major causes of morbidity and mortality with respiratory muscle fatigue, mucus plugging, atelectasis, pneumonia, and respiratory failure. Monitoring of respiratory muscle function and the timely use of lung volume recruitment, assisted coughing, nocturnally assisted ventilation, and subsequent daytime ventilation are essential in the management. Respiratory parameters are important not only in the evaluation of the natural evolution of the disease and setting specific treatments but are becoming increasingly relevant as outcome measures in these areas of gene and gene-modulating therapies. Herein, we present the natural history of respiratory muscle decline in DMD, the role played on it by steroid therapy, and other treatments in curing and slowing the natural course of the disease. We also demonstrate how multidisciplinary and multi-instrumental approaches are essential for an optimal assessment. [ABSTRACT FROM AUTHOR]