Diaphragm: Pathophysiology and Ultrasound Imaging in Neuromuscular Disorders

Prediction of cough effectiveness in amyotrophic lateral sclerosis patients assessed by ultrasuond of the diaphragm during the cough expiration phase

Assessing cough effectiveness, using Cough Peak Flow, is crucial for patients with Neuromuscular Diseases, such as Amyotrophic Lateral Sclerosis. Impaired cough function can contribute to respiratory decline and failure. The goal of the study is to determine the correlation between diaphragmatic excursion and cough expiratory phase, potentially utilizing ultrasonographic indices to estimate Cough Peak Flow in these patients. Twenty-two patients were enrolled in this study. The upward displacement of the diaphragm was measured with ultrasonography during voluntary cough expiration and Cough Peak Flow was simultaneously measured. A multivariable linear regression model was built to quantify the association between Cough Peak Flow and diaphragm expiratory excursion. There is significative relationship between Cough Peak Flow and diaphragm excursion with a Pearson's r coefficient of 0.86 observed in the patients group. Multiple linear regression analysis for Cough Peak Flow (Adjusted R2 = 0.86) revealed significant associations between Cough Peak Flow and expiratory excursion (adjusted β-coefficient: 64.78, 95 %, CI: 51.50-78.07, p<0.001) and sex (adjusted β-coefficient: -69.06; 95 % CI: -109.98 to -28.15, p=0.001). Our results predict the cough effectiveness by using M-mode diaphragmatic sonography with a potentially significant impact on therapeutic choices.

Diaphragm Ultrasound in Different Clinical Scenarios: A Review with a Focus on Older Patients

Diaphragm muscle dysfunction is increasingly recognized as a fundamental marker of several age-related diseases and conditions including chronic obstructive pulmonary disease, heart failure and critical illness with respiratory failure. In older individuals with physical frailty and sarcopenia, the loss of muscle mass and function may also involve the diaphragm, contributing to respiratory dysfunction. Ultrasound has recently emerged as a feasible and reliable strategy to visualize diaphragm structure and function. In particular, it can help to predict the timing of extubation in patients undergoing mechanical ventilation in intensive care units (ICUs). Ultrasonographic evaluation of diaphragmatic function is relatively cheap, safe and quick and can provide useful information for real-time monitoring of respiratory function. In this review, we aim to present the current state of scientific evidence on the usefulness of ultrasound in the assessment of diaphragm dysfunction in different clinical settings, with a particular focus on older patients. We highlight the importance of the qualitative information gathered by ultrasound to assess the integrity, excursion, thickness and thickening of the diaphragm. The implementation of bedside diaphragm ultrasound could be useful for improving the quality and appropriateness of care, especially in older subjects with sarcopenia who experience acute respiratory failure, not only in the ICU setting.

Chest Dynamic MRI as Early Biomarker of Respiratory Impairment in Amyotrophic Lateral Sclerosis Patients: A Pilot Study

Background: Amyotrophic lateral sclerosis (ALS) is a neuromuscular progressive disorder characterized by limb and bulbar muscle wasting and weakness. A total of 30% of patients present a bulbar onset, while 70% have a spinal outbreak. Respiratory involvement represents one of the worst prognostic factors, and its early identification is fundamental for the early starting of non-invasive ventilation and for the stratification of patients. Due to the lack of biomarkers of early respiratory impairment, we aimed to evaluate the role of chest dynamic MRI in ALS patients. Methods: We enrolled 15 ALS patients and 11 healthy controls. We assessed the revised ALS functional rating scale, spirometry, and chest dynamic MRI. Data were analyzed by using the Mann-Whitney U test and Cox regression analysis. Results: We observed a statistically significant difference in both respiratory parameters and pulmonary measurements at MRI between ALS patients and healthy controls. Moreover, we found a close relationship between pulmonary measurements at MRI and respiratory parameters, which was statistically significant after multivariate analysis. A sub-group analysis including ALS patients without respiratory symptoms and with normal spirometry values revealed the superiority of chest dynamic MRI measurements in detecting signs of early respiratory impairment. Conclusions: Our data suggest the usefulness of chest dynamic MRI, a fast and economically affordable examination, in the evaluation of early respiratory impairment in ALS patients.

Quantifying Normal Diaphragmatic Motion and Shape and their Developmental Changes via Dynamic MRI

Background

The diaphragm is a critical structure in respiratory function, yet in-vivo quantitative description of its motion available in the literature is limited.

Research Question

How to quantitatively describe regional hemi-diaphragmatic motion and curvature via free-breathing dynamic magnetic resonance imaging (dMRI)?

Study Design and Methods

In this prospective cohort study we gathered dMRI images of 177 normal children and segmented hemi-diaphragm domes in end-inspiration and end-expiration phases of the constructed 4D image. We selected 25 points uniformly located on each 3D hemi-diaphragm surface. Based on the motion and local shape of hemi-diaphragm at these points, we computed the velocities and sagittal and coronal curvatures in 13 regions on each hemi-diaphragm surface and analyzed the change in these properties with age and gender.

Results

Our cohort consisted of 94 Females, 6-20 years (12.09 + 3.73), and 83 Males, 6-20 years (11.88 + 3.57). We observed velocity range: ∼2mm/s to ∼13mm/s; Curvature range -Sagittal: ∼3m -1 to ∼27m -1 ; Coronal: ∼6m -1 to ∼20m -1 . There was no significant difference in velocity between genders, although the pattern of change in velocity with age was different for the two groups. Strong correlations in velocity were observed between homologous regions of right and left hemi-diaphragms. There was no significant difference in curvatures between genders or change in curvatures with age.

Interpretation

Regional motion/curvature of the 3D diaphragmatic surface can be estimated using free-breathing dynamic MRI. Our analysis sheds light on here-to-fore unknown matters such as how the pediatric 3D hemi-diaphragm motion/shape varies regionally, between right and left hemi-diaphragms, between genders, and with age.

Effectiveness of abdominal sandbag training in enhancing diaphragm muscle function and exercise tolerance in patients with chronic respiratory failure

BACKGROUND

Chronic respiratory failure is a common cause of ventilator dependence in the intensive care unit (ICU). The causes of chronic respiratory failure include primary disease or complications, such as ICU-acquired weakness. Traditional practice requires patients to remain immobile and bedridden; however, recent evidence suggests that early adequate exercise promotes recovery without increasing risks. In this study, we explored the efficacy of planned progressive abdominal sandbag training in promoting the successful withdrawal of patients with chronic respiratory failure from mechanical ventilation.

METHODS

This study was conducted between April 2019 and November 2020. Patients were recruited and divided into two groups: abdominal sandbag training group and control group (no training). The training group participated in a 3-month daily pulmonary rehabilitation program, which involved a 30-min session of progressive sandbag loading on the upper abdomen as a form of diaphragmatic resistant exercise. The pressure support level of the ventilator was adjusted to maintain a tidal volume of 8 mL/kg. To investigate the effect of abdominal sandbag training on patients with chronic respiratory failure, we compared tidal volume, shallow breathing index, maximum respiratory pressure, and diaphragm characteristics between the training and control groups.

RESULTS

This study included 31 patients; of them, 17 (54.8 %) received abdominal sandbag training and 14 (45.2 %) did not. No significant between-group difference was found in baseline characteristics. Compared with the control group, the training group exhibited considerable improvements in ventilation-related parameters (p < 0.001): the tidal volume markedly increased (p = 0.012), rapid shallow breathing index declined (p = 0.016), and maximum respiratory pressure increased (p < 0.001) in the training group. The diaphragm motion value (p = 0.048) and diaphragm thickness (p = 0.041) were greater in the training group than in the control group. Nine patients (52.9 %) in the training group were removed from the ventilator compared with 1 (7.1 %) in the control group (p = 0.008).

CONCLUSIONS

Abdominal sandbag training may be beneficial for patients dependent on a ventilator. The training improves the function of the diaphragm muscle, thereby increasing tidal volume and reducing the respiratory rate and rapid shallow breathing index, thus facilitating withdrawal from ventilation. This training approach may also improve the thickness and motion of the diaphragm and the rate of ventilator detachment.

Assessment of Pulmonary Circulation of Critically Ill Patients Based on Critical Care Ultrasound

Pulmonary circulation is crucial in the human circulatory system, facilitating the oxygenation of blood as it moves from the right heart to the lungs and then to the left heart. However, during critical illness, pulmonary microcirculation can be vulnerable to both intrapulmonary and extrapulmonary injuries. To assess these potential injuries in critically ill patients, critical point-of-care ultrasound can be used to quantitatively and qualitatively evaluate the right atrium, right ventricle, pulmonary artery, lung, pulmonary vein, and left atrium along the direction of blood flow. This assessment is particularly valuable for common ICU diseases such as acute respiratory distress syndrome (ARDS), sepsis, pulmonary hypertension, and cardiogenic pulmonary edema. It has significant potential for diagnosing and treating these conditions in critical care medicine.

Distribution of regional lung function in upright healthy subjects determined by electrical impedance tomography in two chest examination planes

Objective. The variation in pulmonary gas content induced by ventilation is not uniformly distributed in the lungs. The aim of our study was to characterize the differences in spatial distribution of ventilation in two transverse sections of the chest using electrical impedance tomography (EIT).Approach. Twenty adult never-smokers, 10 women and 10 men (mean age ± SD, 31 ± 9 years), were examined in a sitting position with the EIT electrodes placed consecutively in a caudal (6th intercostal space) and a cranial (4th intercostal space) chest location. EIT data were acquired during quiet breathing, slow and forced full expiration manoeuvres. Impedance variations representing tidal volume (VT), vital capacity (VC), forced expiratory volume in 1 s (FEV1) and forced vital capacity (FVC) were calculated at the level of individual image pixels and their spatial distribution was determined using the following EIT measures: the centres of ventilation in ventrodorsal (CoVvd) and right-to-left direction (CoVrl), the dorsal and right fractions of ventilation, the coefficient of variation (CV) and the global inhomogeneity (GI) index.Main results. The sums of pixel ventilation-related impedance variations reproduced reliably the volumetric dissimilarities amongVT, VC, FEV1and FVC, with no significant differences noted between the two examination planes. Significant differences in ventilation distribution were found between the planes during tidal breathing and slow full expiration, mainly regarding the ventrodorsal direction, with higher values of CoVvdand dorsal fraction of ventilation in the caudal plane (p< 0.01). No significant differences in the spatial distribution of FEV1and FVC were detected between the examination planes.Significance. The spatial distribution of ventilation differed between the two examination planes only during the relaxed (quiet breathing and slow VC manoeuvre) but not during the forced ventilation. This effect is attributable to the differences in thoracoabdominal mechanics between these types of ventilation.

High Respiratory and Cardiac Drive Exacerbate Secondary Lung Injury in Patients With Critical Illness

The high respiratory and cardiac drive is essential to the host-organ unregulated response. When a primary disease and an unregulated secondary response are uncontrolled, the patient may present in a high respiratory and cardiac drive state. High respiratory drive can cause damage to the lungs, pulmonary circulation, and diaphragm, while high cardiac drive can lead to fluid leakage and infiltration as well as pulmonary interstitial edema. A "respiratory and cardiac dual high drive" state may be a sign of an unregulated response and can lead to secondary lung injury through the increase of transvascular pressure and pulmonary microcirculation injury. Ultrasound examination of the lung, heart, and diaphragm is important when evaluating the phenotype of high respiratory drive in critically ill patients. Ultrasound assessment can guide sedation, analgesia, and antistress treatment and reduce the risk of high respiratory and cardiac drive-induced lung injury in these patients.

Early detection and assessment of intensive care unit-acquired weakness: a comprehensive review

Intensive care unit-acquired weakness (ICU-AW) is a serious complication in critically ill patients. Therefore, timely and accurate diagnosis and monitoring of ICU-AW are crucial for effectively preventing its associated morbidity and mortality. This article provides a comprehensive review of ICU-AW, focusing on the different methods used for its diagnosis and monitoring. Additionally, it highlights the role of bedside ultrasound in muscle assessment and early detection of ICU-AW. Furthermore, the article explores potential strategies for preventing ICU-AW. Healthcare providers who manage critically ill patients utilize diagnostic approaches such as physical exams, imaging, and assessment tools to identify ICU-AW. However, each method has its own limitations. The diagnosis of ICU-AW needs improvement due to the lack of a consensus on the appropriate approach for its detection. Nevertheless, bedside ultrasound has proven to be the most reliable and cost-effective tool for muscle assessment in the ICU. Combining the Sequential Organ Failure Assessment (SOFA) score, Acute Physiology and Chronic Health Evaluation (APACHE) II score assessment, and ultrasound can be a convenient approach for the early detection of ICU-AW. This approach can facilitate timely intervention and prevent catastrophic consequences. However, further studies are needed to strengthen the evidence.

Ultrasound evaluation of diaphragmatic function in patients with idiopathic pulmonary fibrosis: a retrospective observational study

INTRODUCTION

The diaphragm function assessed by ultrasound has been well-studied in COPD, asthma, and intensive care. However, there are only a few studies on diffuse interstitial lung disease, while dyspnea and quality of life are major issues in the management that may depend on the diaphragm.

METHODS

We retrospectively included idiopathic pulmonary fibrosis (IPF) patients followed in our center (Marseille, France) between January 2020 and February 2023 who underwent diaphragmatic ultrasound. Our objectives were to describe the diaphragmatic function of IPFs compared to healthy controls and to correlate with clinical, functional, and lung density on CT-scan.

RESULTS

24 IPF patients and 157 controls were included. The diaphragmatic amplitude in IPF was increased at rest (median of 2.20 cm vs 1.88 cm on the right, p < 0.007, and 2.30 cm vs 1.91 cm on the left, p < 0.03, in IPF and controls respectively) and decreased in deep breathing (median of 4.85 cm vs 5.45 cm on the right, p < 0.009, and 5.10 cm vs 5.65 cm on the left, p < 0.046, in IPF and controls respectively). Diaphragmatic thickness was significantly reduced at rest on the right side (median of 1.75 mm vs 2.00 mm, p < 0.02, in IPF and controls respectively) and in deep breathing on both sides compared to controls (mean of 3.82 mm vs 4.15 mm on the right, p < 0.02, and 3.53 mm vs 3.94 mm, on the left, p < 0.009, in IPF and controls respectively). Diaphragmatic amplitude in deep breathing was moderate to strongly correlated with FVC, DLCO, and 6MWT and negatively correlated with the dyspnea and lung density on CT scan.

CONCLUSION

The diaphragmatic amplitude and thickness were impaired in IPF compared to controls. Diaphragmatic amplitude is the parameter best correlated with clinical, functional, and lung density criteria. Further studies are needed to determine if diaphragmatic amplitude can be a prognostic factor in IPF.

Effects of usual yoga practice on the diaphragmatic contractility: A cross-sectional controlled study

Objectives

The aim of this study is to observe and compare the effects of regular yoga practice on the main inspiratory muscle, the diaphragm, by analyzing its thickness, excursion, velocity and contraction time, using ultrasound.

Design

A Cross-Sectional Controlled Study.

Participants

80 healthy subjects (40 habitual yoga practitioners and 40 non-practitioners), without previous respiratory pathology participated in this study. During maximum diaphragmatic breathing, the diaphragmatic thickness (at rest and after maximum inspiration), excursion, velocity and contraction time were measured by ultrasound.

Results

in the experimental group, practicing yoga, statistically significant differences (p < 0.001) were observed compared to the control group, not practicing, in the thickness of the diaphragm at rest (0.26 ± 0.02 vs 0.22 ± 0.01 cm); the diaphragmatic thickness in maximum inspiration (0.34 ± 0.03 vs 0.28 ± 0.03 cm); contraction velocity (1.54 ± 0.54 vs 2.23 ± 0.86 cm/s), contraction time (3.28 ± 0.45 vs 2.58 ± 0.49 s) and Borg scale of perceived exertion (1.05 ± 1.6 vs 1.70 ± 1.34), p = 0.05. However, the diaphragmatic excursion was greater in the control group (5.45 ± 1.42 vs 4.87 ± 1.33 cm) with no statistically significant differences (p = 0.06).

Conclusions

the regular practice of yoga improves the parameters of diaphragm thickness, speed and contraction time measured in ultrasound and the sensation of perceived exertion during a maximum inspiration. So it can be considered as another method for training the inspiratory muscles in clinical practice.

Diaphragmatic Ultrasound Advantages in Chronic Obstructive Pulmonary Disease (COPD) Patients: A Systematic Review and Metaanalysis

Background

Diaphragmatic ultrasound is increasingly used to assess patients with Chronic Obstructive Pulmonary Disease (COPD). The present study aims to investigate diaphragmatic dysfunction in COPD patients through a systematic review and meta-analysis.

Methods

In December 2022,The researchers studied four international databases such as Medline/PubMed, ProQuest, ISI/WOS, and Scopus. Joanna Briggs Institute (JBI) checklist was used to review and control the quality of articles.

Results

Finally, 6 articles were included in the analysis. Based on the meta-analysis results, forced expiratory volume (FEV1) was significantly lower in COPD patients compared to the control group (Hedges's g= -2.99, 95 % CI -4.78, -1.19; P =0.001). Forced vital capacity (FVC) was significantly lower in COPD patients compared to the control group (Hedges's g= -1.12, 95 % CI -1.91, - 0.33; P =0.005). COPD patients had significantly lower FEV1/FVC than the control group (Hedges's g= -1.57, 95 % CI -2.33, -0.81; P <0.001).

Conclusion

The present study showed that the diaphragm ultrasound (DUS) method could identify the difference in FEV1, FVC, and FEV1/FVC indices in two groups of COPD patients and healthy people.

Impaired diaphragmatic motility in treatment-naive adult patients with spinal muscular atrophy improved during nusinersen treatment

INTRODUCTION/AIMS

The leading clinical feature of 5q-associated spinal muscular atrophy (SMA) is symmetric, proximal muscle weakness. Muscles involved in ventilation exhibit a specific pattern of denervation: intercostal muscles are severely atrophic, whereas the diaphragm muscle is less affected. The aim of this study was to investigate the involvement of diaphragmatic function by ultrasound imaging in adult patients with SMA and to quantify dynamics of diaphragmatic function during nusinersen treatment.

METHODS

Diaphragmatic thickness, thickening, and excursion during quiet breathing were assessed in 24 adult patients with SMA type 2 and 3 by diaphragm ultrasound imaging before and during nusinersen treatment and were correlated with spirometric parameters.

RESULTS

Diaphragm thickness was not reduced, but increased in a remarkable proportion of patients, whereas diaphragm thickening and excursion were reduced in about 20% to 30% of nusinersen-naive, adult patients with SMA types 2 and 3. During 26 months of nusinersen treatment, diaphragm thickening fraction and excursion improved.

DISCUSSION

Diaphragm ultrasound imaging can provide disease- and treatment-relevant information that is not identified during routine clinical assessments and may therefore be a valuable complementary outcome measure.

Where Are We? The Past, Present and Future of Thoracic Ultrasound

The technique of thoracic ultrasound is living through a progressive rise in clinical routine [...].

Muscle Ultrasound Changes Correlate With Functional Impairment in Spinal Muscular Atrophy

OBJECTIVE

We investigated ultrasound patterns of muscle involvement in different types of spinal muscular atrophy (SMA) and their correlation with functional status to determine the pattern of muscle compromise in patients with SMA and the potential role of ultrasound to evaluate disease progression.

METHODS

We examined muscles (biceps brachii, rectus femoris, diaphragm, intercostals and thoracic multifidus) of 41 patients with SMA (types 1 to 4) and 46 healthy age- and sex-matched control individuals using B-mode ultrasound for gray-scale analysis (GSA), area (biceps brachii and rectus femoris) and diaphragm thickening ratio. Functional scales were applied to patients only. We analyzed ultrasound abnormalities in specific clinical subtypes and correlated findings with functional status.

RESULTS

Compared with controls, patients had reduced muscle area and increased mean GSA for all muscles (p < 0.001), with an established correlation between the increase in GSA and the severity of SMA for biceps brachii, rectus femoris and intercostals (p = 0.03, 0.01 and 0.004 respectively) when using the Hammersmith Functional Motor Scale Expanded. Diaphragm thickening ratio was normal in the majority of patients, and intercostal muscles had higher GSA than diaphragm in relation to the controls.

CONCLUSION

Ultrasound is useful for quantifying muscular changes in SMA and correlates with functional status. Diaphragm thickening ratio can be normal even with severe compromise of respiratory muscles in quantitative analysis, and intercostal muscles were more affected than diaphragm.

Diaphragm thickness by ultrasound in pediatric patients with primary malnutrition

Skeletal muscle atrophy is known to be a marker for nutritional deficiency. The diaphragm is both a skeletal muscle and a respiratory muscle. There is not enough data in the literature about the change in diaphragm thickness (DT) in children with malnutrition. We think that malnutrition may have negative effects on diaphragm thickness. Therefore, in this study, we aimed to compare the diaphragm thicknesses of pediatric patients with primary malnutrition and a healthy control group. The DT of pediatric patients diagnosed with primary malnutrition by a pediatric gastroenterologist was prospectively evaluated by a radiology specialist by ultrasonography (USG). The obtained data were statistically compared with the data of the healthy control group. There was no statistically significant difference between the groups in terms of age and gender (p = 0.244, p = 0.494). We found that right and left diaphragm thicknesses were significantly thinner in the malnourished group than in the healthy control group (p = 0.001, p = 0.009, respectively). We found that right and left diaphragm thicknesses were thinner in those with moderate and severe malnutrition compared to the normal group (p < 0.001, p = 0.003, respectively). We found a significant weak positive correlation between weight and height Z score and right and left diaphragm thickness (respectively, r: 0.297, p < 0.001; r: 0.301, p < 0.001).   Conclusion: Malnutrition is a disease that affects all systems. Our study shows that the DT is thinner in patients with malnutrition. What is Known: •Malnutrition causes skeletal muscle atrophy. What is New: •Diaphragm muscle thickness decreases in malnutrition. •There is a significant positive correlation between diaphragm muscle thickness and height, weight and BMI z scores.

Ultrasound utilization in the diagnosis of diaphragm dysfunction compared to other modalities: A retrospective study

Objectives

Diaphragm is dome-shaped fibro-muscular assembly, composed of central tendon surrounded by peripheral muscle fibers. It plays a significant role in respiration and maintenance of lumber spine stability. Any condition that interferes with diaphragmatic innervation, contractile muscle function or mechanical coupling to chest wall can cause diaphragm dysfunction; which is usually manifests as elevation at chest radiography. Functional imaging with M-mode ultrasonography has been used in assessment of diaphragm kinetics in a variety of normal and pathological conditions. In this study, we evaluate the departmental ultrasound accuracy in diaphragm motion assessment and compare its results with other institutional parameters.

Methods

We retrospectively reviewed the recorded laboratory investigation and chest radiograph of 163 pediatric patients. A total of 131 patients met clinical inclusion criteria for our study, patients under age of 14 years having clinical suspicion of diaphragmatic dysfunction. Patients having neuromuscular blockers, surgical plication, and phrenic nerve pacing were excluded. The mean age was 1.6 (SD 2.6) years and there were 44.3% of male and 55.7% of female patients.

Results

The data demonstrated that ultrasonography is a highly sensitive and specific diagnostic tool compared to X-ray and laboratory investigation and clinical suspicion. The second-best results were obtained by X-ray and less accurate results were obtained by laboratory investigation.

Conclusion

In proper sonographic technique; diaphragmatic ultrasound appears to be a valid and reliable diagnostic too; for diaphragmatic dysfunction. Diaphragm ultrasound may act as an imaging tool guiding rehabilitation success in diaphragmatic dysfunction cases.

Imaging biomarkers in the idiopathic inflammatory myopathies

Idiopathic inflammatory myopathies (IIMs) are a group of acquired muscle diseases with muscle inflammation, weakness, and other extra-muscular manifestations. IIMs can significantly impact the quality of life, and management of IIMs often requires a multi-disciplinary approach. Imaging biomarkers have become an integral part of the management of IIMs. Magnetic resonance imaging (MRI), muscle ultrasound, electrical impedance myography (EIM), and positron emission tomography (PET) are the most widely used imaging technologies in IIMs. They can help make the diagnosis and assess the burden of muscle damage and treatment response. MRI is the most widely used imaging biomarker of IIMs and can assess a large volume of muscle tissue but is limited by availability and cost. Muscle ultrasound and EIM are easy to administer and can even be performed in the clinical setting, but they need further validation. These technologies may complement muscle strength testing and laboratory studies and provide an objective assessment of muscle health in IIMs. Furthermore, this is a rapidly progressing field, and new advances are going to equip care providers with a better objective assessment of IIMS and eventually improve patient management. This review discusses the current state and future direction of imaging biomarkers in IIMs.

The RESISTANT study (Respiratory Muscle Training in Patients with Spinal Muscular Atrophy): study protocol for a randomized controlled trial

BACKGROUND

Spinal Muscular Atrophy (SMA) is characterized by progressive and predominantly proximal and axial muscle atrophy and weakness. Respiratory muscle weakness results in impaired cough with recurrent respiratory tract infections, nocturnal hypoventilation, and may ultimately lead to fatal respiratory failure in the most severely affected patients. Treatment strategies to either slow down the decline or improve respiratory muscle function are wanting.

OBJECTIVE

The aim of this study is to assess the feasibility and efficacy of respiratory muscle training (RMT) in patients with SMA and respiratory muscle weakness.

METHODS

The effect of RMT in patients with SMA, aged ≥ 8 years with respiratory muscle weakness (maximum inspiratory mouth pressure [PImax] ≤ 80 Centimeters of Water Column [cmH2O]), will be investigated with a single blinded randomized sham-controlled trial consisting of a 4-month training period followed by an 8-month open label extension phase.

INTERVENTION

The RMT program will consist of a home-based, individualized training program involving 30-breathing cycles through an inspiratory and expiratory muscle training device. Patients will be instructed to perform 10 training sessions over 5-7 days per week. In the active training group, the inspiratory and expiratory threshold will be adjusted to perceived exertion (measured on a Borg scale). The sham-control group will initially receive RMT at the same frequency but against a constant, non-therapeutic resistance. After four months the sham-control group will undergo the same intervention as the active training group (i.e., delayed intervention). Individual adherence to the RMT protocol will be reviewed every two weeks by telephone/video call with a physiotherapist.

MAIN STUDY PARAMETERS/ENDPOINTS

We hypothesize that the RMT program will be feasible (good adherence and good acceptability) and improve inspiratory muscle strength (primary outcome measure) and expiratory muscle strength (key secondary outcome measure) as well as lung function, patient reported breathing difficulties, respiratory infections, and health related quality of life (additional secondary outcome measures, respectively) in patients with SMA.

DISCUSSION

RMT is expected to have positive effects on respiratory muscle strength in patients with SMA. Integrating RMT with recently introduced genetic therapies for SMA may improve respiratory muscle strength in this patient population.

TRIAL REGISTRATION

Retrospectively registered at clinicaltrial.gov: NCT05632666.

Diaphragmatic Activation Correlated with Lumbar Multifidus Muscles and Thoracolumbar Fascia by B-Mode and M-Mode Ultrasonography in Subjects with and without Non-Specific Low Back Pain: A Pilot Study

Background and Objectives: The diaphragm, the lumbar multifidus muscles, and the thoracolumbar fascia (TLF) execute an important role in the stability of the lumbar spine and their morphology has been modified in subjects with non-specific low back pain (NS-LBP). While it is true that three structures correlate anatomically, the possible functional correlation between them has not been investigated previously in healthy subjects nor in subjects with NS-LBP. The aim of the present study was to examine this functional nexus by means of a comparison based on ultrasonographic parameters of the diaphragm, the lumbar multifidus muscles, and the TLF in subjects with and without NS-LBP. Materials and Methods: A sample of 54 (23 NS-LBP and 31 healthy) subjects were included in the study. The thickness and diaphragmatic excursion at tidal volume (TV) and force volume (FV), the lumbar multifidus muscles thickness at contraction and at rest, and the TLF thickness were evaluated using rehabilitative ultrasound imaging (RUSI) by B-mode and M-mode ultrasonography. The diaphragm thickening capacity was also calculated by thickening fraction (TF) at tidal volume and force volume. Results: There were no significant differences recorded between the activation of the diaphragm and the activation of the lumbar multifidus muscles and TLF for each variable, within both groups. However, there were significant differences recorded between both groups in diaphragm thickness and diaphragm thickening capacity at tidal volume and force volume. Conclusions: Diaphragmatic activation had no functional correlation with the activation of lumbar multifidus muscles and TLF for both groups. Nevertheless, subjects with NS-LBP showed a reduced diaphragm thickness and a lower diaphragm thickening capacity at tidal volume and force volume, compared to healthy subjects.

Effects of C2 hemisection on respiratory and cardiovascular functions in rats

High cervical spinal cord injuries induce permanent neuromotor and autonomic deficits. These injuries impact both central respiratory and cardiovascular functions through modulation of the sympathetic nervous system. So far, cardiovascular studies have focused on models of complete contusion or transection at the lower cervical and thoracic levels and diaphragm activity evaluations using invasive methods. The present study aimed to evaluate the impact of C2 hemisection on different parameters representing vital functions (i.e., respiratory function, cardiovascular, and renal filtration parameters) at the moment of injury and 7 days post-injury in rats. No ventilatory parameters evaluated by plethysmography were impacted during quiet breathing after 7 days post-injury, whereas permanent diaphragm hemiplegia was observed by ultrasound and confirmed by diaphragmatic electromyography in anesthetized rats. Interestingly, the mean arterial pressure was reduced immediately after C2 hemisection, with complete compensation at 7 days post-injury. Renal filtration was unaffected at 7 days post-injury; however, remnant systolic dysfunction characterized by a reduced left ventricular ejection fraction persisted at 7 days post-injury. Taken together, these results demonstrated that following C2 hemisection, diaphragm activity and systolic function are impacted up to 7 days post-injury, whereas the respiratory and cardiovascular systems display vast adaptation to maintain ventilatory parameters and blood pressure homeostasis, with the latter likely sustained by the remaining descending sympathetic inputs spared by the initial injury. A better broad characterization of the physiopathology of high cervical spinal cord injuries covering a longer time period post-injury could be beneficial for understanding evaluations of putative therapeutics to further increase cardiorespiratory recovery.

Respiratory muscle fatigability in patients with spinal muscular atrophy

BACKGROUND

Respiratory failure is a major cause of morbidity and mortality in patients with Spinal Muscular Atrophy (SMA). Lack of endurance, or "fatigability," is an important symptom of SMA. In addition to respiratory muscle weakness, respiratory function in SMA may be affected by Respiratory Muscle Fatigability (RMF).

AIM

The purpose of this study was to explore RMF in patients with SMA.

METHODS

We assessed a Respiratory Endurance Test (RET) in 19 children (median age [years]: 11) and 36 adults (median age [years]: 34) with SMA types 2 and 3. Participants were instructed to breath against an inspiratory threshold load at either 20%, 35%, 45%, 55%, or 70% of their individual maximal inspiratory mouth pressure (PImax). RMF was defined as the inability to complete 60 consecutive breaths. Respiratory fatigability response was determined by change in maximal inspiratory mouth pressure (ΔPImax) and perceived fatigue (∆perceived fatigue).

RESULTS

The probability of RMF during the RET increased by 59%-69% over 60 breaths with every 10% increase in inspiratory threshold load (%PImax). Fatigability response was characterized by a large variability in ΔPImax (-21% to +16%) and a small increase in perceived fatigue (p = 0.041, range 0 to +3).

CONCLUSION AND KEY FINDINGS

Patients with SMA demonstrate a dose-dependent increase in RMF without severe increase in exercise-induced muscle weakness or perceived fatigue. Inspiratory muscle loading in patients with SMA seems feasible and its potential to stabilize or improve respiratory function in patients with SMA needs to be determined in further research.

Abdominal and Pelvic Floor Activity Related to Respiratory Diaphragmatic Activity in Subjects with and without Non-Specific Low Back Pain

One of the advances in physiotherapy in recent years is the exploration and treatment by ultrasound imaging. This technique makes it possible to study the relationship between the musculature of the anterolateral wall of the abdomino-pelvic cavity, the pelvic floor muscles and the diaphragm muscle, among others, and thus understand their implication in non-specific low back pain (LBP) in pathological subjects regarding healthy subjects. Objective: To evaluate by RUSI (rehabilitative ultrasound imaging) the muscular thickness at rest of the abdominal wall, the excursion of the pelvic floor and the respiratory diaphragm, as well as to study their activity. Methodology: Two groups of 46 subjects each were established. The variables studied were: non-specific low back pain, thickness and excursion after tidal and forced breathing, pelvic floor (PF) excursion in a contraction and thickness of the external oblique (EO), internal oblique (IO) and transverse (TA) at rest. Design: Cross-sectional observational study. Results: Good-to-excellent reliability for measurements of diaphragm thickness at both tidal volume (TV) (inspiration: 0.763, expiration: 0.788) and expiration at forced volume (FV) (0.763), and good reliability for inspiration at FV (0.631). A correlation was found between the EO muscle and PF musculature with respect to diaphragmatic thickness at TV, inspiration and expiration, and inspiration at FV, in addition to finding significant differences in all these variables in subjects with LBP. Conclusion: Subjects with LBP have less thickness at rest in the OE muscle, less excursion of the pelvic diaphragm, less diaphragmatic thickness at TV, in inspiration and expiration, and in inspiration to FV.

Diaphragm Dysfunction after Cardiac Surgery: Insights from Ultrasound Imaging during Cardiac Rehabilitation

Diaphragm dysfunction is common after cardiac surgery and can be evaluated with ultrasonography (US). We aimed at assessing with US the incidence of diaphragmatic dysfunction and the impact of cardiovascular rehabilitation (CR) on its recovery. A single-center cohort study was performed. Patients were enrolled after cardiac surgery. The 6-min walking test (6MWT) and diaphragm US were performed at CR admission and after 10 rehabilitative sessions. One hundred eighty-five patients were eligible for final analysis. One hundred thirty-one patients (70.8%) were found to have diaphragm dysfunction (excursion <2 cm). After CR, 68 patients regained normal diaphragmatic function; those with persistent dysfunction had a lower level of functional performance on the 6MWT (metabolic equivalents of tasks: 3.3 vs. 3.6, p = 0.013). The patients who underwent combined surgery (adjusted odds ratio [aOR] = 4.09, p = 0.001) and those with post-operative pneumothorax (aOR = 3.02, p = 0.042) were at increased risk of failure to improve diaphragmatic excursion. US parameters were more powerful tools in predicting diaphragmatic evolution compared with the 6MWT indexes: baseline diaphragm excursion and thickening fraction were associated with complete diaphragmatic functional recovery after CR (aOR = 9.101, p < 0.001, and aOR = 1.058, p = 0.020 respectively). US is a valuable tool for the assessment of post-operative diaphragmatic dysfunction and can identify patients at risk of diaphragmatic recovery failure.

Research Progress on Diaphragm Ultrasound in Chronic Obstructive Pulmonary Disease: A Narrative Review

Chronic obstructive pulmonary disease (COPD) is a common disease of the respiratory system, and its prevalence and mortality remain high. COPD results in continuous impairment of lung function, which severely affects the patient's work and life. In severe cases, there will be acute respiratory failure, which endangers the lives of patients, and respiratory muscle dysfunction is one of the main reasons for this result. As the diaphragm is the most important inspiratory muscle, its dysfunction has a great impact on the deterioration of respiratory function in COPD patients. With the development of ultrasound, more and more studies have found that diaphragm ultrasound can play an important role in the diagnosis and treatment of COPD patients. The main purpose of this article is to review the research progress on diaphragm ultrasound in COPD and briefly introduce diaphragmatic ultrasound examination methods.

Thoracic Excursion Is a Biomarker for Evaluating Respiratory Function in Amyotrophic Lateral Sclerosis

Objective

To evaluate the usefulness of thoracic excursion as a biomarker in patients with amyotrophic lateral sclerosis (ALS).

Methods

We measured the forced the vital capacity (FVC), thoracic excursion, baseline-to-peak diaphragmatic compound muscle action potential (DCMAP) amplitude, diaphragm thickness at full inspiration (DTfi), Medical Research Council (MRC) sum score for muscle strength, and arterial partial pressures of oxygen and carbon dioxide and administered the Amyotrophic Lateral Sclerosis Functional Rating Scale-Revised (ALSFRS-R) and modified Medical Research Council (mMRC) Dyspnea Scale. The test–retest reliability of thoracic excursion was determined.

Results and Conclusions

Thirty-four patients with ALS and 26 age- and sex-matched healthy participants were enrolled. Thoracic excursion measurement had excellent test–retest reliability (intraclass coefficient: 0.974). Thoracic excursion was more strongly correlated with FVC (r = 0.678, p &lt; 0.001) than DCMAP amplitude (r = 0.501, p = 0.003) and DTfi (r = 0.597, p &lt; 0.001). It was also correlated with ALSFRS-R score (r = 0.610, p &lt; 0.001), MRC sum score (r = 0.470, p = 0.005), and mMRC Dyspnea Scale score (r = −0.446, p = 0.008) and was the most sensitive parameter for assessing dyspnea and FVC. Thoracic excursion decreased as FVC declined in the early and late stages, there were no differences in DCMAP amplitude and DTfi between the early and late stages, and ALSFRS-R score and MRC sum score decreased only in the late stage. Thoracic excursion was well correlated with respiratory function and is useful for predicting respiratory and general dysfunction in patients with ALS regardless of stage.

Diaphragm and Phrenic Nerve Ultrasound in COVID-19 Patients and Beyond: Imaging Technique, Findings, and Clinical Applications

The diaphragm, the principle muscle of inspiration, is an under-recognized contributor to respiratory disease. Dysfunction of the diaphragm can occur secondary to lung disease, prolonged ventilation, phrenic nerve injury, neuromuscular disease, and central nervous system pathology. In light of the global pandemic of coronavirus disease 2019 (COVID-19), there has been growing interest in the utility of ultrasound for evaluation of respiratory symptoms including lung and diaphragm sonography. Diaphragm ultrasound can be utilized to diagnose diaphragm dysfunction, assess severity of dysfunction, and monitor disease progression. This article reviews diaphragm and phrenic nerve ultrasound and describes clinical applications in the context of COVID-19.

Regional diaphragm motion analysis via dynamic MRI

Breathing-related movement analysis is important in the study of many disease processes. The analysis of diaphragmatic motion via thoracic imaging in particular is important in a variety of disorders. Compared to computed tomography (CT) and fluoroscopy, dynamic magnetic resonance imaging (dMRI) has several advantages, such as better soft tissue contrast, no ionizing radiation, and greater flexibility in selecting scanning planes. In this paper, we propose a novel method for full diaphragmatic motion analysis via free-breathing dMRI. Firstly, after 4D dMRI image construction in a cohort of 51 normal children, we manually delineated the diaphragm on sagittal plane dMRI images at end-inspiration and end-expiration. Then, 25 points were selected uniformly and homologously on each hemi-diaphragm surface. Based on the inferior-superior displacements of these 25 points between end-expiration (EE) and end-inspiration (EI) time points, we obtained their velocities. We then summarized 13 parameters from these velocities for each hemi-diaphragm to provide a quantitative regional analysis of diaphragmatic motion. We observed that the regional velocities of the right hemi-diaphragm were almost always statistically significantly greater than those of the left hemi-diaphragm in homologous locations. There was a significant difference for sagittal curvatures but not for coronal curvatures between the two hemi-diaphragms. Using this methodology, future larger scale prospective studies may be considered to confirm our findings in the normal state and to quantitatively assess regional diaphragmatic dysfunction when various disease conditions are present.

Diaphragm ultrasound to evaluate the antagonistic effect of sugammadex on rocuronium after liver surgery in patients with different liver Child-Pugh grades: study protocol for a prospective, double-blind, non-randomised controlled trial

INTRODUCTION

The use of muscle relaxants is an indispensable in the general anaesthesia but is prone to accidents, which are often related to residual muscle relaxant. Therefore, how to timely and effectively eliminate the residual effect of muscle relaxants after surgery has become an urgent clinical problem. Rocuronium is a non-depolarising muscle relaxant that is primarily metabolised by the liver. Patients with liver dysfunction can affect the metabolic process of rocuronium, thereby delaying the recovery of muscle relaxation. Sugammadex (SUG) is a novel-specific antagonist of aminosteroidal muscle relaxants, which can effectively antagonise muscle relaxants at different depths. However, whether liver dysfunction affects the antagonistic effect of SUG against rocuronium has not been reported. Therefore, we hypothesise that with the increase of patients' liver Child-Pugh grade, the recovery time of rocuronium antagonised by the same dose of SUG after surgery will be prolonged, and the incidence of muscle relaxation residual will be increased in the short term.

METHODS AND ANALYSIS

This study is a prospective, double-blind, low-intervention, non-randomised controlled clinical trial involving 99 patients with American Society of Anesthesiologists (ASA) Ⅰ-Ⅲ, body mass index 18.5-24.9 kg/m2, who will undergo laparoscopic radical resection of liver cancer under general anaesthesia in the Union Hospital, Tongji Medical College, Huazhong University of Science and Technology. Ultrasonography will be applied to monitor the change rate of diaphragm thickness at different time after extubation to evaluate the occurrence of residual muscle relaxant, which indirectly reflects the dose-effect relationship of SUG antagonising against rocuronium in patients with different liver Child-Pugh grades preoperatively.

ETHICS AND DISSEMINATION

The protocol was reviewed and approved by the Medical Ethics Committee of Union Hospital Affiliated to Tongji Medical College of Huazhong University of Science and Technology (UHCT21012). The findings will be disseminated to the public through peer-reviewed scientific journals.

TRIAL REGISTRATION NUMBER

NCT05028088.

Electrophysiological assessment of respiratory function

While the traditional lung function tests are used to assess lung capacity and pulmonary function, they cannot evaluate respiratory driving function and the integrity of the conduction pathway from the central nervous system to the respiratory motor neuron in the spinal cord and to the diaphragm. The inspiratory trigger is sent from the central nervous system through the phrenic nerve and drives the diaphragm to generate inspiratory movement. Therefore, phrenic nerve stimulation and diaphragmatic electromyography are two fundamental methods to assess respiratory function. There are several useful tools to assess respiratory motor system including electrical or magnetic phrenic nerve stimulation, diaphragmatic needle electromyography, and diaphragmatic ultrasound. By these means, physicians can assess current respiratory status in different neurological diseases that affect respiratory muscles, follow-up of the severity of respiratory impairment, help to predict the chance of successfully weaning from ventilatory support, and confirm clinical diagnoses such as diaphragmatic myoclonus. Although some of these tests require special training, applying these neurophysiological assessments in clinical practice is highly recommended.

Three-dimensional assessment of pharyngeal airway in individuals with myotonic dystrophy type 1

Background/aim

The objectives of this study were to assess pharyngeal airway volume (PAV) in patients with myotonic dystrophy type 1 (DM1) by cone-beam computerized tomography (CBCT) and to evaluate the impact of diaphragm thickness and pulmonary function tests on PAV.

Materials and methods

Thirty DM1 patients (10 female and 20 male; mean age 42.40 ± 12.07) were included in the study. Age and sex-matched thirty patients were participated as control group. In DM1 group pulmonary function tests (PFT) were performed. Independent t-test was used to compare PAV values of patients with DM1 and control group. The Mann–Whitney U test was used to compare the parameters according to sex ( p < 0.05). Pearson and Spearman correlation tests were used to evaluate the relationships between parameters of DM1 patients (p < 0.05). A multiple linear regression analysis was performed to explain the PAV with parameters that showed positive correlation with PAV.

Results

Age of onset and disease duration were 22.37 ± 8.45 and 20.03 ± 12.08, respectively, in patients with DM1. PAV values of control group were significantly lower than DM1 group ( p < 0.001). Forced expiratory volume in 1 s and forced volume vital capacity values were higher in males than females in DM1 group according to sex ( p < 0.001). PAV values were greater in male patients than females of the DM1 group ( p = 0.022). Diaphragm thickness in DM1 group after inspiration and expiration were 2.60 ± 0.65 and 1.94 ± 0.40, respectively. According to the regression analysis, DTai and FVC were significantly explained the PAV.

Conclusion

PAV was higher in DM1 group. There was a significant positive correlation between diaphragm thickness, pulmonary functions, and PAVs of DM1 patients. The amount of the PAV was mostly influenced by DTai and FVC. It is recommended to evaluate the PAV in patients with DM1 because of impaired respiratory functions and pharyngeal muscle involvement.

Respiratory Monitoring at Bedside in COVID-19 Patients

The SARS-CoV-2 (COVID-19) pandemic has forced some reflections to be had surrounding the ventilatory support to be applied to certain types of patients. The model of two phenotypes, set out by Professor Gattinoni and colleagues, suggests that adequate monitoring of respiratory effort may play a key role in the treatment of respiratory failure due to COVID-19. An insufficient control of the patient’s respiratory efforts could lead to an aggravation of lung damage, mainly due to the possibility of generating Patient Self-Inflicted Lung Injury (PSILI) with a consequent aggravation of the pathological picture. Nevertheless, effectively monitoring the patient’s respiratory work, especially in nonintensive settings, is not easy. This article briefly describes some methods that allow the assessment of respiratory effort, such as the use of ultrasound and respiratory tests, which can be performed in nonintensive settings.

The Use of Angle-Independent M-Mode in the Evaluation of Diaphragmatic Excursion: Towards Improved Accuracy

Assessment of diaphragmatic function has been well described in the intensive care setting as well as in emergency medicine and pediatrics. Conventional M-mode evaluation of diaphragmatic excursion is frequently associated with over and under-estimations of diaphragmatic excursion. Angle-independent M-mode allows free rotation and movement of the analysis line to obtain M-mode images in a direction that more accurately reflects diaphragmatic excursion. In order to provide a standardized approach to the evaluation of diaphragmatic excursion with angle-independent M-mode, we propose a landmark-based approach utilizing the spine in order to target the same diaphragmatic segment consistently throughout the diaphragmatic analysis. While the proposed approach is not intended to replace current methods, it may improve accuracy and inter-rater reliability. The relevant background, as well as three patient cases, are presented demonstrating the use of a landmark-based approach in the emergency department. Angle-independent M-mode may provide a more accurate and consistent evaluation of diaphragmatic excursion, an examination that can be used to guide clinical care and anticipate outcomes.

Examination of the diaphragm in obstructive sleep apnea using ultrasound imaging

PURPOSE

The aim of this study was to analyze the effect of obstructive sleep apnea (OSA) on the ultrasound (US) features of the diaphragm and to determine if diaphragmatic US may be a useful screening tool for patients with possible OSA.

METHODS

Patients complaining of snoring were prospectively enrolled for overnight polygraphy using the ApneaLink Air device. Thickness and motion of the diaphragm during tidal and deep inspiration were measured. Logistic regression was used to assess parameters of the diaphragm associated with OSA.

RESULTS

Of 100 patients, 64 were defined as having OSA. Thicknesses of the left and right hemidiaphragms were significantly different between OSA and control groups. Using a combination of diaphragmatic dimensions, diaphragm dilation, age, sex, and BMI, we developed an algorithm that predicted the presence of OSA with 91% sensitivity and 81% specificity.

CONCLUSION

A combination of anthropometric measurements, demographic factors, and US imaging may be useful for screening patients for possible OSA. These findings need to be confirmed in larger sample sizes in different clinical settings.

Ultrasound Evaluation of Diaphragm Force Reserve in Patients with Chronic Obstructive Pulmonary Disease

Rationale: Diaphragm function is a key determinant of dyspnea in chronic obstructive pulmonary disease (COPD); however, it is rarely assessed in clinical practice. Lung hyperinflation can also impair diaphragm function. Ultrasound can assess the activity, function, and force reserve of the diaphragm.Objectives: To compare diaphragm activity, function, and force reserve among patients with COPD and healthy control subjects.Methods: Patients with stable COPD (n = 80) and healthy control subjects (n = 20) were enrolled (97% of them were men). Ultrasound was used to measure the thickening fraction of the diaphragm during tidal breathing and maximum volitional effort. Outcome measures were as follows: 1) the difference in diaphragm force reserve, activity, and function between patients with COPD and control subjects; 2) the correlation between lung volumes and diaphragm force reserve, activity, and function; and 3) the relationship between diaphragm force reserve and the rate of moderate to severe exacerbation of COPD.Results: The tidal thickening fraction of the diaphragm during resting breathing (TFdi-tidal) was higher in patients with COPD than in control subjects (P = 0.002); it was approximately twice as high in patients with severe COPD than in control subjects. Patients with COPD had poorer diaphragm function than control subjects as assessed by the maximal thickening fraction of the diaphragm during Muller maneuver (P < 0.01). Diaphragm force reserve ratio assessed by 1-(tidal thickening fraction of the diagphragm during resting breathing/maximal thickening fraction of the diaphragm) was lower in patients with COPD than in control subjects, and it fell with increasing Global Initiative for Chronic Obstructive Lung Disease stages (P < 0.001); it correlated with inspiratory capacity (r = 0.46) and the body mass index, airflow obstruction, dyspnea, exercise capacity (BODE) index, a multidimensional scoring system (r = -0.49). Patients who developed exacerbation during the following 2 years had less force reserve than patients without exacerbation (P = 0.024).Conclusions: Male patients with COPD have increased diaphragm workload, impaired diaphragm function, and reduced force reserve compared with healthy subjects. Ultrasound assessment of the diaphragm in COPD provides important functional information.Clinical trial registered with the Thai Clinical Trials Registry (TCTR20160411001). Registered 31 April 5, 2016.

Point-of-care lung and diaphragm ultrasound in a patient with spinal muscular atrophy with respiratory distress type 1

Spinal muscular atrophy with respiratory distress type 1 (SMARD1, OMIM #604,320), is a rare autosomal recessive disease resulting from degeneration of motor neurons in the anterior horns, which leads irreversible diaphragmatic palsy and progressive distal symmetrical muscular weakness. Respiratory distress is the main symptom and is severe, rapidly progressive, and frequently requiring invasive ventilation. Despite diaphragm being one of the target organ of the disease, no specific study has been done using ultrasound.We report diaphragm and lung ultrasound findings of a 13-month-old girl affected by SMARD1 (homozygosis c.1540G > A mutation in IGHMPB2 gene) with respiratory failure requiring permanent mechanical ventilation since birth and we discuss the role of diaphragmatic and lung ultrasound in this category of patients and its clinical implications.

Chronic respiratory dysfunction due to diaphragmatic paralysis following penetrating neck trauma: A case report

RATIONALE

Respiratory dysfunction resulting from unilateral diaphragmatic paralysis during neck trauma is very rare in adults. We describe the symptoms, diagnosis and treatment of 1 patient with chronic respiratory insufficiency, in whom the diaphragmatic paralysis was associated with phrenic nerve injury due to penetrating neck trauma.

PATIENT CONCERNS

A 50-year-old worker was admitted because of left penetrating neck trauma. Imaging investigations demonstrated elevation of the left hemidiaphragm and the C5 and C6 roots avulsion. He complained of gradually worsening dyspnea on exertion 2 months later.

DIAGNOSES

The patient was diagnosed with chronic respiratory dysfunction secondary to diaphragmatic paralysis, which caused by phrenic nerve injury.

INTERVENTIONS

A conventional video-assisted thoracoscopic diaphragm plication was performed after failed conservative management.

OUTCOMES

The respiratory status improved markedly, and he did well without recurrence until 2 years' follow-up.

LESSONS

The possibilities of phrenic nerve palsy and diaphragmatic paralysis should not be overlooked during the evaluation of neck trauma.

Diaphragmatic atrophy and dysfunction in critically ill mechanically ventilated children

RATIONALE

The extent of diaphragmatic atrophy and dysfunction in critically ill children from developing countries is not established.

OBJECTIVES

To estimate changes in ultrasound measurements of diaphragmatic thickness over the first week of mechanical ventilation. To assess magnitude and risk factors of diaphragmatic atrophy.

METHODS

In an observational cohort study, children aged 1-18 years, requiring mechanical ventilation were included. Ultrasound measurements of diaphragmatic thickness at end-expiration (DTe) and end-inspiration (DTi), and diaphragmatic thickening fraction (DTF) were performed daily during the first week of admission, and pre- and post-extubation. Diaphragmatic atrophy (%) and atrophy rate (rate of decline in DTe, % per day) were calculated.

MEASUREMENTS AND MAIN RESULTS

Of 55 children (74.6% boys) enrolled, 20 (36.4%) died. Of 35 children with planned extubation, 5 (14.3%) required reintubation. Baseline median (interquartile range [IQR]) DTe, DTi, and DTF were 1.27 mm (1, 1.6), 1.76 mm (1.35, 2.10), and 33.75% (26.90, 44.60), respectively. There was a significant reduction in DTe over the first week of mechanical ventilation (p < .001), median (IQR) diaphragmatic atrophy and atrophy rate of 9.91% (5.26, 17.35) and 2.01% (1.08, 3.04) per day, respectively. Diaphragmatic atrophy rate was lower in pressure targeted ventilation (n = 44; 1.79% [1.03, 2.87]) than volume targeted ventilation (n = 11; 3.10% [1.31, 5.49]), p = .038. There was no difference in diaphragmatic parameters (atrophy rate, and peri-extubation DTe and DTF) in extubation success versus failure.

CONCLUSIONS

The diaphragm undergoes progressive atrophy during the first week of mechanical ventilation in critically ill children. Future studies should evaluate ventilation strategies to reduce the diaphragmatic atrophy.

Long-term benefit of enzyme replacement therapy with alglucosidase alfa in adults with Pompe disease: Prospective analysis from the French Pompe Registry

Despite a wide clinical spectrum, the adult form of Pompe disease is the most common one, and represents more than 90% of diagnosed patients in France. Since the marketing of enzyme replacement therapy (alglucosidase alfa, Myozyme), all reports to date in adults demonstrated an improvement of the walking distance, and a trend toward stabilization of respiratory function, but the majority of these studies were less than 5 years of duration. We report here the findings from 158 treated patients included in the French Pompe Registry, who underwent regular clinical assessments based on commonly used standardized tests (6-minute walking test, MFM scale, sitting vital capacity, MIP and MEP). For longitudinal analyses, the linear mixed effects models were used to assess trends in primary endpoints over time under ERT. A two-phase model better described the changes in distance traveled in the 6-minute walk test and MFM. 6MWT showed an initial significant increase (1.4% ± 0.5/year) followed by a progressive decline (-2.3%/year), with a cut-off point at 2.2 years. A similar pattern was observed in total MFM score (6.6% ± 2.3/year followed by a - 1.1%/year decline after 0.5 years). A single-phase decline with a slope of -0.9 ± 0.1%/year (P < .001) was observed for FVC, and MEP remained stable over the all duration of follow-up. This study provides further evidence that ERT improves walking abilities and likely stabilizes respiratory function in adult patients with Pompe disease, with a ceiling effect for the 6MWT in the first 3 years of treatment.

Assessing the impact of posture on diaphragm morphology and function using an open upright MRI system-A pilot study

PURPOSE

The diaphragm is the most important muscle of respiration. Disorders of the diaphragm can have a deleterious impact on respiratory function. We aimed to evaluate the use of an open-configuration upright low-field MRI system to assess diaphragm morphology and function in patients with bilateral diaphragm weakness (BDW) and chronic obstructive pulmonary disease (COPD) with hyperinflation.

METHOD

The study was approved by the National Research Ethics Committee, and written consent was obtained. We recruited 20 healthy adult volunteers, six subjects with BDW, and five subjects with COPD with hyperinflation. We measured their vital capacity in the upright and supine position, after which they were scanned on the 0.5 T MRI system during 10-s breath-holds at end-expiration and end-inspiration in both positions. We developed and applied image analysis methods to measure the volume under the dome, maximum excursion of hemidiaphragms, and anterior-posterior and left-right extension of the diaphragm.

RESULTS

All participants were able to complete the scanning protocol. The patients found scanning in the upright position more comfortable than the supine position. All differences in the supine inspiratory-expiratory parameters, excluding left-right extension, were significantly smaller in the BDW and COPD groups compared with healthy volunteers. No significant correlation was found between the postural change in diaphragm morphology and vital capacity in either group.

CONCLUSION

Our combined upright-supine MR imaging approach facilitates the assessment of the impact of posture on diaphragm morphology and function in patients with BDW and those with COPD with hyperinflation.

Ultrasound assessment of diaphragmatic function in type 1 spinal muscular atrophy

OBJECTIVE

To investigate ultrasound features of diaphragm motion and function in type 1 spinal muscular atrophy (SMA-1) patients.

DESIGN

Prospective study.

PATIENTS

The study cohort included SMA-1 children younger than 18-year-old. Control subjects included type 2 and type 3 SMA and other neuromuscular disorders younger than 18-year-old.

METHODOLOGY

Diaphragm ultrasound evaluating diaphragmatic excursion, speed of diaphragmatic contraction, duration of the respiratory cycle, inspiratory/expiratory relationship, end-inspiratory and -expiratory thickness, thickening fraction, and pattern of contractility. The interrater reliability for each variable was established by calculation of Cohen's k coefficient.

RESULTS

Twenty-three SMA-1 patients and 12 controls were evaluated. Diaphragm ultrasound values were within normal ranges in all study cohort patients and no difference was found with controls. There was a gradient of diaphragm function with SMA 1.9 subgroup having the best and SMA 1.1 having the worst parameters, particularly in end-inspiratory thickness and diaphragmatic excursion (P = .031 and P = .041, respectively). Seventy-four percent of SMA-1 patients had a dysmotility pattern of diaphragm contraction, mostly represented in SMA 1.9 subgroup (P = .001). This pattern was observed in 92.8% of children on noninvasive ventilation (NIV) for less than 16 hours/d of and in 20% patients with invasive ventilation or NIV for more than 16 hours/d (P = .027). The dysmotility pattern was never observed in the control group. The levels of interobserver agreement were high for "diaphragm irregularities," "inspiratory/expiratory relationship," and "diaphragm thickness," and good for the other variables.

CONCLUSIONS

Ultrasound can be used to evaluate diaphragm function and contractility in SMA-1 children, providing additional information to the clinical examination and functional respiratory tests, describing a characteristic contractility pattern in these patients. Longitudinal studies are needed to understand the impact of diaphragm dysmotility and other parameters on long-term outcome in SMA-1 patients.

Ultrasound assessment of diaphragm function in patients with late-onset Pompe disease

INTRODUCTION

Late-Onset Pompe Disease (LOPD) is characterized by progressive limb-girdle muscle weakness and respiratory dysfunction. Diaphragm is the most impaired muscle in LOPD and its dysfunction cause major respiratory symptoms. The aim of this study was to evaluate the correlation between diaphragm thickness and mobility assessed by ultrasonography and respiratory function and muscle strength tests in patients with LOPD.

METHODS

17 patients with LOPD (9 female, 47 ± 15 years) and 17 age and gender-matched healthy controls underwent spirometry, muscle strength testing, and ultrasound evaluation of diaphragm excursion and thickness.

RESULTS

The following parameters were significantly reduced in LOPD patients versus controls (all p < 0.001): forced vital capacity (FVC) in seated and supine position, maximum inspiratory and expiratory pressure (MIP and MEP), diaphragm excursion, thickness at functional residual capacity (FRC) and total lung capacity (TLC), and thickness fraction (TF). Ultrasound studies of diaphragm thickness at FRC correlated with MIP (r = 0.74; p < 0.0001) and seated FVC(r = 0.73; p < 0.05). Diaphragm thickness at TLC correlated with MIP (r = 0.85; p < 0.0001) and FVC in both seated (r = 0.77; p < 0.0001) and supine position (r = 0.68; p < 0.05). TF correlated significantly with MIP (r = 0.80; p < 0.001), FVC in both seated (r = 0.66; p < 0,005) and supine position (r = 0.61; p < 0.05). Interestingly diaphragm thickness at FRC correlated with disease duration (years) in LOPD patients (r = -0.53; p < 0,05). Ultrasound diaphragm mobility correlated with diaphragm thickness at TLC(r = 0.87; p < 0.0001), FRC (r = 0.84; p < 0.005) and TF (r = 0.73; p < 0.05). Moreover diaphragm mobility correlated with FVC in seated(r = 0.79; p < 0.005) and supine position(r = 0.74; p < 0.05) and MIP (r = 0.81; p < 0.005).

CONCLUSION

Diaphragm ultrasonography is a simple and reproducible technique for manage respiratory dysfunction in LOPD patients.

Thickening fraction as a measure of ultrasonographic diaphragm dysfunction in amyotrophic lateral sclerosis

•

The leading cause of the death in ALS is respiratory failure secondary to diaphragm dysfunction.

•

Three ALS patients with respiratory dysfunction had low phrenic motor nerve action potential.

•

The diaphragm thickening fraction when measured, is low (<15%) in all of them.

Objective

Respiratory failure is the most common cause of death in ALS patients secondary to diaphragmatic dysfunction. Herein, we report three ALS patients, and we sought to determine the diaphragm dysfunction by the measurement of ultrasonographic diaphragmatic thickness fraction (DTf).

Methods

High-resolution linear US probe of 10 MHz (Philips Healthcare EPIQ 7 Ultrasound System Inc.) was used to measure the diaphragm thickness (DT) using B mode at the Zone of Apposition. Phrenic nerve compound muscle action potential measured stimulating the nerve, posterior to the sternocleidomastoid muscle, approximately 3 cm above the clavicle and recording the diaphragm with electrode G1 placed fingerbreadth above the xiphoid process and electrode G2 placed over the anterior costal margin 16 cm from G1.

Results

The diaphragmatic thickening fraction (DTf) measured in these three patients recorded was less than 15%. Diaphragm dysfunction was also suggested by low amplitude of the diaphragmatic compound muscle action potential in each patient.

Conclusion

Diaphragm dysfunction, secondary to lower motor neuron loss, was mirrored by the low amplitude of the diaphragm CMAP in the 3 patient case reports. These cases suggest that a thickening fraction ≤15% is associated with severe diaphragm weakness and risk of respiratory failure.

Significance

Before appropriate data obtained in a population of ALS patients are available, we propose DTf (%) <20% as a possible indicator of diaphragm dysfunction in ALS patients.

Diaphragmatic dysfunction associates with dyspnoea, fatigue, and hiccup in haemodialysis patients: a cross-sectional study

Muscle wasting is associated with increased mortality and morbidity in chronic kidney disease (CKD) patients, especially in the haemodialysis (HD) population. Nevertheless, little is known regarding diaphragm dysfunction in HD patients. We conducted a cross-sectional study at the Institute of Nephrology, Southeast University, involving 103 HD patients and 103 healthy volunteers as normal control. Ultrasonography was used to evaluate diaphragmatic function, including diaphragm thickness and excursion during quiet and deep breathing. HD patients showed lower end-inspiration thickness of the diaphragm at total lung capacity (0.386 ± 0.144 cm vs. 0.439 ± 0.134 cm, p < 0.01) and thickening fraction (TF) (0.838 ± 0.618 vs. 1.127 ± 0.757; p < 0.01) compared to controls. The velocity and excursion of the diaphragm were significantly lower in the HD patients during deep breathing (3.686 ± 1.567 cm/s vs. 4.410 ± 1.720 cm/s, p < 0.01; 5.290 ± 2.048 cm vs. 7.232 ± 2.365 cm; p < 0.05). Changes in diaphragm displacement from quiet breathing to deep breathing (△m) were lower in HD patients than in controls (2.608 ± 1.630 vs. 4.628 ± 2.110 cm; p < 0.01). After multivariate adjustment, diaphragmatic excursion during deep breathing was associated with haemoglobin level (regression coefficient = 0.022; p < 0.01). We also found that the incidence of dyspnoea and hiccup and the fatigue scores, all of which were related to diaphragmatic dysfunction, were significantly higher in HD patients than in controls (all p < 0.01). Improving diaphragm function through targeted therapies may positively impact clinical outcomes in HD patients.

Dynamic respiratory muscle function in late-onset Pompe disease

Maximal inspiratory pressure (PI_MAX) reflects inspiratory weakness in late-onset Pompe disease (LOPD). However, static pressure tests may not reveal specific respiratory muscle adaptations to disruptions in breathing. We hypothesized that dynamic respiratory muscle functional tests reflect distinct ventilatory compensations in LOPD. We evaluated LOPD (n = 7) and healthy controls (CON, n = 7) during pulmonary function tests, inspiratory endurance testing, dynamic kinematic MRI of the thorax, and ventilatory adjustments to single-breath inspiratory loads (inspiratory load compensation, ILC). We observed significantly lower static and dynamic respiratory function in LOPD. PI_MAX, spirometry, endurance time, and maximal diaphragm descent were significantly correlated. During single-breath inspiratory loads, inspiratory time and airflow acceleration increased to preserve volume, and in LOPD, the response magnitudes correlated to maximal chest wall kinematics. The results indicate that changes in diaphragmatic motor function and strength among LOPD subjects could be detected through dynamic respiratory testing. We concluded that neuromuscular function significantly influenced breathing endurance, timing and loading compensations.

Critical Care Management of Acute Spinal Cord Injury-Part II: Intensive Care to Rehabilitation

Spinal cord injury is devastating to those affected due to the loss of motor and sensory function, and, in some cases, cardiovascular collapse, ventilatory failure, and bowel and bladder dysfunction. Primary trauma to the spinal cord is exacerbated by secondary insult from the inflammatory response to injury. Specialized intensive care of patients with acute spinal cord injury involves the management of multiple systems and incorporates evidence-based practices to reduce secondary injury to the spinal cord. Patients greatly benefit from early multidisciplinary rehabilitation for neurologic and functional recovery. Treatment of acute spinal cord injury may soon incorporate novel molecular agents currently undergoing clinical investigation to assist in neuroprotection and neuroregeneration.

Superior Trunk Block

Editor’s Perspective

What We Already Know about This Topic

What This Article Tells Us That Is New

Background

Interscalene nerve blockade remains one of the most commonly used anesthetic and analgesic approaches for shoulder surgery. The high incidence of hemidiaphragmatic paralysis associated with the block, however, precludes its use among patients with compromised pulmonary function. To address this issue, recent studies have investigated phrenic-sparing alternatives that provide analgesia. None, however, have been able to reliably demonstrate surgical anesthesia without significant risk for hemidiaphragmatic paralysis. The utility of the superior trunk block has yet to be studied. The hypothesis was that compared with the interscalene block, the superior trunk block will provide noninferior surgical anesthesia and analgesia while sparing the phrenic nerve.

Methods

This randomized controlled trial included 126 patients undergoing arthroscopic ambulatory shoulder surgery. Patients either received a superior trunk block (n = 63) or an interscalene block (n = 63). The primary outcomes were the incidence of hemidiaphragmatic paralysis and worst pain score in the recovery room. Ultrasound was used to assess for hemidiaphragmatic paralysis. Secondary outcomes included noninvasively measured parameters of respiratory function, opioid consumption, handgrip strength, adverse effects, and patient satisfaction.

Results

The superior trunk group had a significantly lower incidence of hemidiaphragmatic paralysis compared with the interscalene group (3 of 62 [4.8%] vs. 45 of 63 [71.4%]; P &lt; 0.001, adjusted odds ratio 0.02 [95% CI, 0.01, 0.07]), whereas the worst pain scores in the recovery room were noninferior (0 [0, 2] vs. 0 [0, 3]; P = 0.951). The superior trunk group were more satisfied, had unaffected respiratory parameters, and had a lower incidence of hoarseness. No difference in handgrip strength or opioid consumption were detected. Superior trunk block was associated with lower worst pain scores on postoperative day 1.

Conclusions

Compared with the interscalene block, the superior trunk block provides noninferior surgical anesthesia while preserving diaphragmatic function. The superior trunk block may therefore be considered an alternative to traditional interscalene block for shoulder surgery.

Ultrasonographic measurement of the diaphragm thickness in patients with obstructive sleep apnea syndrome

PURPOSE

The aim of this study was to evaluate the diaphragm thickness in patients with obstructive sleep apnea syndrome (OSAS).

METHODS

This prospective study included patients who underwent polysomnography evaluation for the first time with a clinical suspicion of OSAS. All patients underwent polysomnographic evaluation with a 55-channel Alice 6 computerized system (Respironics; Philips, IL). Diaphragm thickness was measured as the distance between the peritoneum and the pleura using electronic calipers with a 7-12-MHz linear probe (PHILIPS EPIQ 5G).

RESULTS

A total of 108 patients (67 males, 41 females) were enrolled in the current study. The mean age of the patients was 48.92 ± 11.47 years. The diaphragm thicknesses were significantly higher in OSAS patients both at end-inspirium and end-expirium compared with the normal group (p < 0.05). No significant difference was observed regarding the change level and thickening ratio (%) (p > 0.05). When the patients were allocated into OSAS subtypes; diaphragm thicknesses at the end of inspirium and expirium on both sides were significantly higher in the severe OSAS group and OSAS+OHS group compared with the other groups of normal, mild OSAS, and moderate OSAS subgroups (p < 0.05 for all). There was no significant difference between the groups regarding the thickening ratio (p > 0.05 for all). There was a positive correlation between the severity of OSAS and diaphragm thickness.

CONCLUSION

Diaphragm thickness seems to be increased in OSAS patients and the thickness correlates with the severity of OSAS. However, the thickness ratio of OSAS patients does not differ from that of normal subjects.

Ultrasonographic evaluation of the diaphragm thickness in patients with multiple sclerosis

BACKGROUND

Diaphragm weakness or dysfunction have been previously reported in multiple sclerosis (MS) patients. The aim of this study was to evaluate diaphragm thickness and thickenning ratio (TR) using ultrasound in MS patients.

METHODS

This prospective study comprised MS patients and a control group. Ultrasound examination was performed using a linear transducer (6-15 MHz). The diaphragm was seen as a hypoechoic structre between the peritoneum and pleura. End-expirium and end-inspirium measurements were obtained. Change levels and TR (%) were calculated. All participants were assessed using the Expanded Distability Status Scale (EDSS) and Fatigue Severity Scale (FSS).

RESULTS

Evaluation was made of 45 MS patients (11 males, 34 females) with a mean age of 37.36±9.0 years and 36 healthy subjects (3 males, 33 females) with a mean age of 35.19±9.3 years. The diaphragm thicknesses were similar at end-expirium (1.86±0.3 vs. 1.83±0.3 mm) and end-inspirium (3.14±0.6 vs. 3.46±0.6 mm). The change level with inspirium (0.90±0.6 vs. 1.31±0.7 mm) and TR (49.77±37.7 vs. 72.30±40.1%) were significantly higher in the control group compared to the values of MS patients. A weak and negative correlation was determined between EDSS and TR values (r=-0.293, p = 0.008), and no significant correlation was observed between the FSS values and diaphragm thickness (p>0.05 for all).

CONCLUSION

Although the diaphragm thickness of MS patients seems to be similar to those of healthy subjects, the change level and TR of MS patients seem to be lower. Furthermore, the change level and TR were found to be associated with EDSS.