Magnetic Resonance Imaging of the Diaphragm: From Normal to Pathologic Findings

The diaphragm is a musculotendinous structure that divides the chest from the abdomen. Its motility, unintentional or voluntary, is crucial for the physiologic respiratory function due to its contribution to lung volume expansion and contraction. Therefore, diaphragmatic dysfunction may cause a respiratory failure without any pathology of the lungs. Different imaging modalities can be employed for diaphragmatic evaluation. Among all, magnetic resonance imaging (MRI) has demonstrated to be the most accurate technique in providing a morphologic and functional assessment of the diaphragm as well as information about the adjacent structures. However, its diagnostic value is still underrated and its performance is often far from the daily clinical practice. Backward, physicians and radiologists should be aware of the undoubted advantages of MRI and confident about the normal or pathologic imaging features, to avoid misdiagnosis.

Diaphragmatic dysfunction in dogs with cervical spinal disorders before and after surgery using fluoroscopy, motion-mode ultrasound and radiography was not different than a group of control dogs

Cervical spinal disorders can lead to life-threatening respiratory complications. Diaphragmatic dysfunction is attributed to spinal cord morbidity secondary to cervical myelopathy or decompressive surgical intervention. The purpose of this observational case-control study was to determine the frequency of diaphragmatic dysfunction in dogs with cervical spinal disorders and a control group, the strength of association between cervical myelopathies and decompressive surgery with diaphragm paresis, and the agreement between and clinical usefulness of fluoroscopy, motion-mode ultrasonography, and radiography for diagnosing diaphragmatic dysfunction. Thirty-five client-owned dogs were recruited with 14 control dogs and 21 test dogs. Dogs were evaluated for the presence of diaphragmatic dysfunction using radiography, M-mode ultrasonography, and fluoroscopy before and after an anesthetic or surgical event. Diaphragmatic dysfunction was observed more frequently in dogs with cervical spinal disease prior to surgery (8/21; 38.1%) compared to control dogs (3/14; 21.4%) but was not statistically significant (P = .30). The occurrence of diaphragmatic dysfunction did not significantly increase following surgical decompression in either group. There was no to slight agreement between all imaging modalities. Most dogs with diaphragmatic dysfunction were asymptomatic. Diaphragmatic dysfunction was not statistically associated with cervical myelopathy or decompressive surgery. Ultrasonography and radiography were not useful diagnostic tests for determining diaphragmatic dysfunction in asymptomatic dogs when compared to fluoroscopy.

Mobility impact and methods of diaphragm monitoring in patients with chronic obstructive pulmonary disease: a systematic review

The objectives of the study were to identify the factors that limit diaphragmatic mobility and evaluate the therapeutic results of the monitoring methods previously used in patients with chronic obstructive pulmonary disease. The PubMed, Web of Science, Scopus, and LILACS databases were used. A gray literature search was conducted with Google scholar. PRISMA was used, and the bias risk analysis adapted from the Cochrane Handbook for clinical trials and, for other studies, the Downs and Black checklist were used. Twenty-five articles were included in the qualitative synthesis analysis on physiotherapeutic techniques and diaphragmatic mobility. Eight clinical trials indicated satisfactory domains, and on the Downs and Black scale, 17 cohort studies were evaluated to have an acceptable score. Different conditions must be observed; for example, for postoperative assessments the supine position is suggested to be the most appropriate position to verify diaphragm excursion, although it has been shown to be associated with difficulty of restriction and matching in samples. Therefore, we identified the need for contemporary adjustments and strategies that used imaging instruments, preferably in the dorsal position. Therapeutic evidence on the association between the instrumental method and diaphragmatic mobility can be controversial. The ultrasound measurements indicated some relevance for different analyses, for pulmonary hyperinflation as well as diaphragm thickness and mobilization, in COPD patients. In particular, the study suggests that the ultrasound technique with B-mode for analysis and M-mode for diaphragmatic excursion be used with a 2 - 5 MHz with the patient in the supine position. However, the methods used to monitor diaphragm excursion should be adapted to the conditions of the patients, and additional investigations of their characteristics should be performed. More selective inclusion criteria and better matching in the samples are very important. In addition, more narrow age, sex and weight categories are important, especially in patients with chronic obstructive pulmonary disease.

Postnatal Ultrasound to Determine the Surgical Strategy for Congenital Diaphragmatic Hernia

OBJECTIVES

To compare defect sizes in congenital diaphragmatic hernia (CDH) measured by postnatal ultrasound (US) between neonates who underwent thoracoscopic surgery and neonates who underwent open surgery and between neonates who underwent primary repair and those who underwent patch repair; additionally, to compare the accuracy of US diagnosis with that of surgical diagnosis for the location of the diaphragmatic hernia and the hernial contents.

METHODS

We included 8 neonates who underwent preoperative US evaluations of CDH. We compared anterior-to-posterior diaphragm defect sizes between thoracoscopic and open surgery approaches and between primary and patch repair by using the Mann-Whitney U test. The diaphragm was divided into 3 segments: anterior, lateral, and posterior. We evaluated the location of the diaphragmatic hernia and the hernial contents.

RESULTS

Four neonates who underwent open surgery had larger diaphragmatic hernias than those who underwent thoracoscopic surgery (mean ± SD, 30.5 ± 5.6 versus 16.3 ± 3.3 mm; P = .030). They were also larger in neonates who underwent patch repair than in those who underwent primary repair (33.0 ± 3.0 versus 17.6 ± 4.2 mm; P = .037). Detection of anterior and lateral diaphragm segments was consistent between US and surgical findings. Three of 4 neonates who underwent open surgery and all 3 neonates who underwent patch repair did not show the lateral segment. The hernial contents were also consistent between US and surgical findings.

CONCLUSIONS

Postnatal US examinations of neonates with CDH could provide surgeons with useful information to determine the surgical approach and repair method. However, since our study cohort was small, further studies are needed with a larger number of neonates with CDH.

Innovative and Contemporary Interventions of Diaphragmatic Disorders

The diaphragm is an inconspicuous fibromuscular septum, and disorders may result in respiratory impairment and morbidity and mortality when untreated. Radiologists need to accurately diagnose diaphragmatic disorders, understand the surgical approaches to diaphragmatic incisions/repairs, and recognize postoperative changes and complications. Diaphragmatic defects violate the boundary between the chest and abdomen, with the risk of herniation and strangulation of abdominal contents. In our surgical practice, patients with diaphragmatic hernias present acutely with incarceration and/or strangulation. Bochdalek hernias are commonly diagnosed in asymptomatic older adults on computed tomography; however, when viscera or a large amount of fat herniates into the chest, surgical intervention is strongly advocated. Morgagni hernias are rare in adults and typically manifest acutely with bowel obstruction. Patients with traumatic diaphragm injury may have an acute, latent, or delayed presentation, and radiologists should be vigilant in inspecting the diaphragm on the initial and all subsequent thoracoabdominal imaging studies. Almost all traumatic diaphragm injury are surgically repaired. Finally, with porous diaphragm syndrome, fluid, air, and tissue from the abdomen may communicate with the pleural space through diaphragmatic fenestrations and result in a catamenial pneumothorax or large pleural effusion. When the underlying disorder cannot be effectively treated, the goal of surgical intervention is to establish the diagnosis, incite pleural adhesions, and close diaphragmatic defects. Diaphragmatic plication may be helpful in patients with eventration or acquired injuries of the phrenic nerve, as it can stabilize the affected diaphragm. Phrenic nerve pacing may improve respiratory function in select patients with high cervical cord injury or central hypoventilation syndrome.

Impact of the crural diaphragm thickness on pulmonary function after lobectomy

Objective

The crural diaphragm is responsible for pulmonary ventilation in the early period after lobectomy. However, the role of its thickness in pulmonary ventilation remains unclear. We investigated the impact of crural diaphragm thickness on pulmonary oxygenation and gas exchange early after lobectomy.

Methods

We enrolled 32 patients with non-small-cell lung cancer who underwent video-assisted thoracoscopic lobectomy. Crural diaphragm thickness was defined as the average of the maximum thicknesses of the right and left crural diaphragm at the level of the median arcuate ligament on computed tomography. Pulmonary oxygenation and gas exchange were evaluated by the ratio of arterial oxygen tension/fraction of inspiratory oxygen and alveolar-arterial oxygen difference on the second postoperative day.

Results

Crural diaphragm thickness of 7.0 ± 1.7 mm was associated with vital capacity. After lobectomy, arterial oxygen tension/fraction of inspiratory oxygen decreased significantly and alveolar-arterial oxygen difference increased significantly. Five patients with oxygen saturation via pulse oximetry ≤92% had a lower arterial oxygen tension/fraction of inspiratory oxygen and higher alveolar-arterial oxygen difference than the others. Crural diaphragm thickness in these patients was less than in the others (5.5 ± 1.9 vs. 7.3 ± 1.5 mm, p = 0.033). In multivariate analysis, crural diaphragm thickness remained an independent factor affecting arterial oxygen tension/fraction of inspiratory oxygen and alveolar-arterial oxygen difference ( p = 0.044, p = 0.049). Crural diaphragm thickness was positively associated with arterial oxygen tension/fraction of inspiratory oxygen and negatively associated with alveolar-arterial oxygen difference.

Conclusion

Crural diaphragm thickness affects pulmonary ventilation early after lobectomy.

Hernia de Bochdalek en adulto: una entidad extremadamente infrecuente

La hernia de Bochdalek es el tipo de hernia diafragmática congénita con menos de 200 reportes en adultos. Los autores presentan uno de estos extraordinarios casos en el Servicio de Cirugía General del Hospital Regional de Alta Especialidad en el estado de Tabasco, México

Usefulness of Ultrasound in Evaluating the Diaphragm in Neonates and Infants With Congenital Diaphragmatic Hernias

This report describes the evaluations of 2 patients with congenital diaphragmatic hernias using ultrasound (US). Identifying the size of the diaphragmatic defect is important when determining the type of surgical repair required. In case 1, the US evaluation of a Bochdalek hernia showed the rim of the anterolateral diaphragm; therefore, thoracoscopic primary repair was performed. In case 2, (Morgagni-Larrey hernia), US revealed the left side of a retrosternal diaphragmatic hernia sac; therefore, thoracoscopic repair from the left thorax was performed. Ultrasound was useful for detecting the location and defect size of the diaphragmatic hernia and determining optimal surgical management.

Assessing Diaphragm Function in Chest Wall and Neuromuscular Diseases

Diaphragm dysfunction is defined as the partial or complete loss of diaphragm muscle contractility. However, because the diaphragm is one of only a few skeletal muscles that is not amenable to direct examination, the tools available for the clinician to assess diaphragm function have been limited. Traditionally, measures of lung volume, inspiratory muscle strength, and radiographic techniques such as fluoroscopy have provided the major method to assess diaphragm function. Measurement of transdiaphragmatic pressure provides the most direct means of evaluating the diaphragm, but this technique is not readily available to clinicians. Diaprhragm ultrasonography is new method that allows for direct examination of the diaphragm.

ACR Appropriateness Criteria® Chronic Dyspnea-Noncardiovascular Origin

Chronic dyspnea may result from a variety of disorders of cardiovascular, pulmonary, gastrointestinal, neuromuscular, systemic, and psychogenic etiology. This article discusses guidelines for the initial imaging of six variants for chronic dyspnea of noncardiovascular origin: (1) Chronic dyspnea of unclear etiology; (2) Chronic dyspnea with suspected chronic obstructive pulmonary disease; (3) Chronic dyspnea with suspected central airways disease; (4) Chronic dyspnea with suspected interstitial lung disease; (5) Chronic dyspnea with suspected disease of the pleura or chest wall; and (6) Chronic dyspnea with suspected diaphragm dysfunction. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment.

Characteristics of the paralysed diaphragm studied by M-mode ultrasonography

BACKGROUND

M-mode ultrasonography might be useful for detecting hemidiaphragm paralysis. The objective of the present study was to describe the motion recorded by M-mode ultrasonography of both diaphragmatic leaves in patients with a pre-established diagnosis of hemidiaphragm paralysis.

METHODS

A study was conducted in 26 patients (18 men, 8 women) with unilateral diaphragmatic paralysis. They were referred to two different rehabilitation centres after thoracic surgery in 23 cases and cardiac interventional procedures in three cases. The pulmonary function tests and the study of the diaphragmatic motion using M-mode ultrasonography were recorded.

RESULTS

The pulmonary function tests showed a restrictive pattern. The M-mode ultrasonography reported either the absence of motion or a weak paradoxical (cranial) displacement (less than 0·5 cm) of the paralysed hemidiaphragm during quiet breathing. A paradoxical motion was recorded in all patients during voluntary sniffing, reaching around -1 cm. During deep breathing, a paradoxical motion at the beginning of the inspiration was observed. Thereafter, a re-establishment of the motion in the craniocaudal direction was recorded. The excursions measured on the healthy side, during quiet breathing and voluntary sniffing, were increased in patients suffering from contralateral hemidiaphragm paralysis, when compared with 170 healthy volunteers.

CONCLUSIONS

To detect diaphragmatic dysfunction in patients at risk, it would be useful to study diaphragmatic motion by M-mode ultrasonography during quiet breathing, voluntary sniffing and deep breathing.

Utility of ultrasound assessment of diaphragmatic function before and after pulmonary rehabilitation in COPD patients

Background

Pulmonary rehabilitation (PR) may improve respiratory symptoms and skeletal muscle strength in patients with COPD. We aimed to evaluate changes in ultrasound (US) measurements of diaphragmatic mobility and thickness after PR in COPD patients and to test its correlation with PR outcomes.

Methods

Twenty-five COPD patients were enrolled and underwent a diaphragm US assessment before and after a 12-week PR program.

Results

We found a correlation between the intraindividual percentage of change in the diaphragmatic length of zone of apposition at functional residual capacity (ΔLzapp%) and the change in 6-minute walking distance (6MWD) after PR (rho=0.49, P=0.02). ΔLzapp% was significantly higher in patients with improved 6MWD and COPD Assessment Test (CAT) score (mean rank=12.03±2.57 vs 6.88±4.37; P=0.02). A ΔLzapp% of ≥10% was able to discriminate among patients with improved 6MWD, with a sensitivity of 83% and a specificity of 74%. The area under the receiver operating characteristic curve for ΔLzapp% was 0.83. A cutoff value of ≥9% of ΔLzapp% had a positive predictive value in discriminating a reduction in ≥2 points of CAT score after PR, with a sensitivity and a specificity of 80% and 62%, respectively.

Conclusion

Diaphragm US assessment represents a useful prognostic marker of PR outcomes in COPD patients.

Unilateral diaphragm paralysis: a dysfunction restricted not just to one hemidiaphragm

Background

Most patients with unilateral diaphragm paralysis (UDP) have unexplained dyspnea, exercise limitations, and reduction in inspiratory muscle capacity. We aimed to evaluate the generation of pressure in each hemidiaphragm separately and its contribution to overall inspiratory strength.

Methods

Twenty-seven patients, 9 in right paralysis group (RP) and 18 in left paralysis group (LP), with forced vital capacity (FVC) < 80% pred, and 20 healthy controls (CG), with forced expiratory volume in 1 s (FEV₁) > 80% pred and FVC > 80% pred, were evaluated for lung function, maximal inspiratory (MIP) and expiratory (MEP) pressure measurements, diaphragm ultrasound, and transdiaphragmatic pressure during magnetic phrenic nerve stimulation (Pdi_Tw).

Results

RP and LP had significant inspiratory muscle weakness compared to controls, detected by MIP (− 57.4 ± 16.9 for RP; − 67.1 ± 28.5 for LP and − 103.1 ± 30.4 cmH₂O for CG) and also by Pdi_TW (5.7 ± 4 for RP; 4.8 ± 2.3 for LP and 15.3 ± 5.7 cmH₂O for CG). The Pdi_Tw was reduced even when the non-paralyzed hemidiaphragm was stimulated, mainly due to the low contribution of gastric pressure (around 30%), regardless of whether the paralysis was in the right or left hemidiaphragm. On the other hand, in CG, esophagic and gastric pressures had similar contribution to the overall Pdi (around 50%). Comparing both paralyzed and non-paralyzed hemidiaphragms, the mobility during quiet and deep breathing, and thickness at functional residual capacity (FRC) and total lung capacity (TLC), were significantly reduced in paralyzed hemidiaphragm. In addition, thickness fraction was extremely diminished when contrasted with the non-paralyzed hemidiaphragm.

Conclusions

In symptomatic patients with UDP, global inspiratory strength is reduced not only due to weakness in the paralyzed hemidiaphragm but also to impairment in the pressure generated by the non-paralyzed hemidiaphragm.

Magnetic resonance imaging of the pediatric mediastinum

The mediastinum, the central anatomical space of the thorax, is divided by anatomical landmarks but not by physical boundaries. The mediastinum is a conduit, a space through which cranial nerves, important nerve branches, the sympathetic chain, vascular structures, and visceral structures, the trachea and esophagus pass. This arrangement allows contiguous extension or communication of disease along facial planes and through potential spaces to and from the head and neck or cervical spine, to and from the superior mediastinum, between superior and inferior mediastinal levels, and between inferior mediastinal spaces into the intra- and retroperitoneal spaces. Magnetic resonance imaging (MRI) of the mediastinum in children poses technical challenges, in particular cardiac and respiratory motion, and diagnostic challenges, including a broad range of tissue types and possible diagnoses. In this paper we review mediastinal anatomy, MRI sequences and protocol choices and include a short discussion of features and MRI findings of some of the congenital and acquired pathologies that are most often encountered in the pediatric mediastinum.

Crus Atrophy: Accuracy of Computed Tomography in Diagnosis of Diaphragmatic Paralysis

PURPOSE

The aim of this study was to measure the association between crus atrophy as depicted by computed tomography (CT) and fluoroscopic diagnosis of hemidiaphragmatic paralysis in patients with suspected diaphragmatic dysfunction.

MATERIALS AND METHODS

A retrospective review of patient data was approved by our institutional review board and was HIPPA-compliant. We reviewed 90 patients who had undergone diaphragmatic fluoroscopy; 72 had CT scans available for measurement of crus thickness at the levels of the celiac and superior mesenteric arteries and the L1 vertebral body. Receiver operating characteristic analysis was used to determine the threshold of crus thinning that best distinguished a paralyzed hemidiaphragm from a nonparalyzed one.

RESULTS

Hemidiaphragmatic paralysis caused significant crus thinning at the celiac artery level (mean±SD, 1.7±0.6 vs. 3.6±1.3 mm, P=0.017, on the right; 1.1±0.4 vs. 3.0±1.4 mm, P=0.001, on the left) and the L1 vertebral level (mean±SD, 1.5±0.7 vs. 4.4±1.6 mm, P=0.018, on the right; 1.5±0.6 vs. 3.6+1.7 mm, P=0.017, on the left). On axial CT, thinning to ≤2.5 mm at the celiac artery level identified paralysis of the hemidiaphragm with a sensitivity of 100% and a specificity of 86% on the right and with a sensitivity of 100% and a specificity of 64% on the left. On coronal CT, thinning to ≤2.5 mm at the L1 vertebral level identified paralysis of the hemidiaphragm with a sensitivity of 100% and a specificity of 88% on the right and with a sensitivity of 100% and a specificity of 77% on the left.

CONCLUSIONS

Atrophy of the crus assessed by CT is a good discriminator of paralyzed versus nonparalyzed hemidiaphragm in patients with suspected diaphragmatic dysfunction.

Mobilidade diafragmática direita e esquerda em indivíduos saudáveis e na doença pulmonar obstrutiva crônica

RESUMO Avaliar o músculo diafragma é importante para verificar suas possíveis alterações ou disfunções. Existem várias formas de avaliar a mobilidade diafragmática, mas poucos estudos que comparam a mobilidade do hemidiafragma direito com o esquerdo. O objetivo deste estudo é avaliar se existem diferenças entre a mobilidade diafragmática das hemicúpulas direita e esquerda em indivíduos saudáveis e em indivíduos com Doença Pulmonar Obstrutiva Crônica (DOCP), bem como comparar a mobilidade diafragmática entre homens e mulheres, e entre pacientes saudáveis e com DPOC. Foram avaliados 40 indivíduos saudáveis e 40 indivíduos com diagnóstico clínico de DPOC. Utilizaram-se os parâmetros antropométricos, cardiopulmonares e avaliação da mobilidade diafragmática pelo método radiográfico. Os dados foram analisados estatisticamente e tratados com análise descritiva (média e desvio-padrão) e análise inferencial. Para comparar a mobilidade das hemicúpulas diafragmáticas direita e esquerda, utilizou-se o teste t pareado. O nível de significância adotado para o tratamento estatístico foi de 5% (p<0,05). Não houve diferença da mobilidade diafragmática tanto do lado direito quanto do lado esquerdo nos indivíduos saudáveis (p=0,45) e nos indivíduos com DPOC (p=0,77), assim como não houve diferenças quando os grupos foram separados por sexo. Foi encontrada uma diferença importante comparando tanto a mobilidade diafragmática do lado direito quanto do lado esquerdo entre indivíduos saudáveis e DPOC (p<0,001). Concluiu-se que a mobilidade diafragmática das hemicúpulas direita e esquerda em indivíduos saudáveis e em indivíduos com DPOC é a mesma. Não há diferença da mobilidade entre homens e mulheres. A mobilidade diafragmática é reduzida em paciente com DPOC.

The breadth of the diaphragm: updates in embryogenesis and role of imaging

The diaphragm is an unique skeletal muscle separating the thoracic and abdominal cavities with a primary function of enabling respiration. When abnormal, whether by congenital or acquired means, the consequences for patients can be severe. Abnormalities that affect the diaphragm are often first detected on chest radiographs as an alteration in position or shape. Cross-sectional imaging studies, primarily CT and occasionally MRI, can depict structural defects, intrinsic and adjacent pathology in greater detail. Fluoroscopy is the primary radiologic means of evaluating diaphragmatic motion, though MRI and ultrasound also are capable of this function. This review provides an update on diaphragm embryogenesis and discusses current imaging of various abnormalities, including the emerging role of three-dimensional printing in planning surgical repair of diaphragmatic derangements.

Diaphragmatic Palsy

The diaphragm is the primary muscle of respiration, and its weakness can lead to respiratory failure. Diaphragmatic palsy can be caused by various causes. Injury to the phrenic nerve during thoracic surgeries is the most common cause for diaphragmatic palsy. Depending on the cause, the symptoms of diaphragmatic palsies vary from completely asymptomatic to disabling dyspnea requiring mechanical ventilation. On pulmonary function tests, there will be a decrease in the maximum respiratory muscle power. Spirometry shows reduced lung functions and a significant drop of lung function in supine position is typical of diaphragmatic palsy. Diaphragmatic movements with respiration can be directly visualized by fluoroscopic examination. Currently, this test is being replaced by bedside thoracic ultrasound examination, looking at the diaphragmic excursion with deep breathing or sniffing. This test is found to be equally efficient, and without risks of ionizing radiation of fluoroscope. Treatment of diaphragmatic palsy depends on the cause. Surgical approach of repair of diaphragm or nonsurgical approach of noninvasive ventilation has been tried with good success. Overall prognosis of diaphragmatic palsy is good, except when it is related to neuromuscular degeneration conditions.

Use of diaphragm thickening fraction combined with rapid shallow breathing index for predicting success of weaning from mechanical ventilator in medical patients

Background

Weaning failure is a crucial hindrance in critically ill patients. Rapid shallow breathing index (RSBI), a well-known weaning index, has some limitations in predicting weaning outcomes. A new weaning index using point-of-care ultrasound with diaphragmic thickening fraction (DTF) has potential benefits for improving weaning success. The aim of this study was to evaluate the efficacy of a combination of DTF and RSBI for predicting successful weaning compared to RSBI alone.

Methods

This prospective study enrolled patients from the medical intensive care unit or ward who were using mechanical ventilation and readied for weaning. Patients underwent a spontaneous breathing trial (SBT) for 1 h, and then, both hemi-diaphragms were visualized in the zone of apposition using a 10-MHz linear probe. Diaphragm thickness was recorded at the end of inspiration and expiration which supposed the lung volume equal to total lung capacity (TLC) and residual volume (RV), respectively, and the DTF was calculated as a percentage from this formula: thickness at TLC minus thickness at RV divided by thickness at RV. In addition, RSBI was calculated at 1 min after SBT. Weaning failure was defined as the inability to maintain spontaneous breathing within 48 h.

Results

Of the 34 patients enrolled, the mean (± SD) age was 66.5 (± 13.5) years. There were 25 patients with weaning success, 9 patients in the weaning failure group. The receiver operating characteristic curves of right and left DTF and the RSBI for the prediction of successful weaning were 0.951, 0.700, and 0.709, respectively. The most accurate cutoff value for prediction of successful weaning was right DTF ≥ 26% (sensitivity of 96%, specificity of 68%, positive predictive value of 89%, negative predictive value of 86%). The combination of right DTF ≥ 26% and RSBI ≤ 105 increased specificity to 78% but slightly decreased sensitivity to 92%. Intra-observer correlation increased sharply to almost 0.9 in the first ten patients and slightly increased after that.

Conclusions

Point-of-care ultrasound to assess diaphragm function has an excellent learning curve and helps physicians determine weaning readiness in critically ill patients. The combination of right DTF and RSBI greatly improved the accuracy for prediction of successful weaning compared to RSBI alone.

Trial registration

Thai Clinical Trials Registry, TCTR20171025001. Retrospectively registered on October 23, 2017.

Respiratory failure because of neuromuscular disease

PURPOSE OF REVIEW

Understanding the mechanisms and abnormalities of respiratory function in neuromuscular disease is critical to supporting the patient and maintaining ventilation in the face of acute or chronic progressive impairment.

RECENT FINDINGS

Retrospective clinical studies reviewing the care of patients with Guillain-Barré syndrome and myasthenia have shown a disturbingly high mortality following step-down from intensive care. This implies high dependency and rehabilitation management is failing despite evidence that delayed improvement can occur with long-term care. A variety of mechanisms of phrenic nerve impairment have been recognized with newer investigation techniques, including EMG and ultrasound. Specific treatment for progressive neuromuscular and muscle disease has been increasingly possible particularly for the treatment of myasthenia, metabolic myopathies, and Duchenne muscular dystrophy. For those conditions without specific treatment, it has been increasingly possible to support ventilation in the domiciliary setting with newer techniques of noninvasive ventilation and better airway clearance. There remained several areas of vigorous debates, including the role for tracheostomy care and the place of respiratory muscle training and phrenic nerve/diaphragm pacing.

SUMMARY

Recent studies and systematic reviews have defined criteria for anticipating, recognizing, and managing ventilatory failure because of acute neuromuscular disease. The care of patients requiring long-term noninvasive ventilatory support for chronic disorders has also evolved. This has resulted in significantly improved survival for patients requiring domiciliary ventilatory support.

Identification of the pericardiacophrenic vein on CT

Background

To evaluate the depictability of pericardiacophrenic veins (PCPV) as landmarks for the location of the phrenic nerves on multi-detector-row computed tomography (MDCT), and to investigate the usefulness of depicting the PCPV to aid differential diagnosis of anterior mediastinal lesions.

Methods

Fifty-six patients with anterior mediastinal lesions (Fifty lesions originated from the thymus, six were of non-thymic origin) were evaluated. Contrast-enhanced CT scans of the chest were performed in all cases before diagnosis, and 22 of these scans were performed with electrocardiographic (ECG) gating. Two chest radiologists assessed the depictability of the PCPV and the positional relationship between the center of each anterior mediastinal lesion and the ipsilateral PCPV.

Results

The use of ECG gating increased the PCPV depiction rate in the lower left part of the mediastinum. The depiction rate of the left PCPV was significantly higher than that of the right PCPV. All 50 tumors of thymic origin and 3 of the 6 tumors of non-thymic origin were located on the medial side of the ipsilateral PCPV. The 3 lesions located on the lateral side of the ipsilateral PCPV were of non-thymic origin (p = 0.0007).

Conclusion

The use of ECG gating during MDCT may improve the depictability of the PCPV in the lower left section of the anterior mediastinum. Solitary anterior mediastinal lesions located on the lateral side of the ipsilateral PCPV are likely to be of non-thymic origin.

Four-Dimensional CT of the Diaphragm in Children: Initial Experience

Objective

To evaluate the technical feasibility of four-dimensional (4D) CT for the functional evaluation of the pediatric diaphragm.

Materials and Methods

In 22 consecutive children (median age 3.5 months, age range 3 days–3 years), 4D CT was performed to assess diaphragm motion. Diaphragm abnormalities were qualitatively evaluated and diaphragm motion was quantitatively measured on 4D CT. Lung density changes between peak inspiration and expiration were measured in the basal lung parenchyma. The diaphragm motions and lung density changes measured on 4D CT were compared between various diaphragm conditions. In 11 of the 22 children, chest sonography was available for comparison.

Results

Four-dimensional CT demonstrated normal diaphragm (n = 8), paralysis (n = 10), eventration (n = 3), and diffusely decreased motion (n = 1). Chest sonography demonstrated normal diaphragm (n = 2), paralysis (n = 6), eventration (n = 2), and right pleural effusion (n = 1). The sonographic findings were concordant with the 4D CT findings in 90.9% (10/11) of the patients. In diaphragm paralysis, the affected diaphragm motion was significantly decreased compared with the contralateral normal diaphragm motion (−1.1 ± 2.2 mm vs. 7.6 ± 3.8 mm, p = 0.005). The normal diaphragms showed significantly greater motion than the paralyzed diaphragms (4.5 ± 2.1 mm vs. −1.1 ± 2.2 mm, p < 0.0001), while the normal diaphragm motion was significantly smaller than the motion of the contralateral normal diaphragm in paralysis (4.5 ± 2.1 mm vs. 7.6 ± 3.8 mm, p = 0.01). Basal lung density change of the affected side was significantly smaller than that of the contralateral side in diaphragm paralysis (89 ± 73 Hounsfield units [HU] vs. 180 ± 71 HU, p = 0.03), while no significant differences were found between the normal diaphragms and the paralyzed diaphragms (136 ± 66 HU vs. 89 ± 73 HU, p = 0.1) or between the normal diaphragms and the contralateral normal diaphragms in paralysis (136 ± 66 HU vs. 180 ± 71 HU, p = 0.1).

Conclusion

The functional evaluation of the pediatric diaphragm is feasible with 4D CT in select children.

The predictive value of serial changes in diaphragm function during the spontaneous breathing trial for weaning outcome: a study protocol

INTRODUCTION

There is a variety of tools being used in clinical practice for the prediction of weaning success from mechanical ventilation. However, their diagnostic performances are less than satisfactory. The purpose of this study is to investigate the value of serial changes in diaphragm function measured by ultrasound during the spontaneous breathing trial (SBT) as a weaning predictor.

METHODS AND ANALYSIS

This is a prospective observational study conducted in a 10-bed medical emergency intensive care unit (EICU) in a university-affiliated hospital. The study will be performed from November 2016 to December 2017. All patients in the EICU who are expected to have mechanical ventilation for more than 48 hours through endotracheal tube are potentially eligible for this study. Patients will be included if they fulfil the criteria for SBT. All enrolled patients will be ventilated with an Evita-4 by using volume assist control mode prior to SBT. Positive end-expiratory pressure (PEEP) will be set to 5 cmH2O and fractional inspired oxygen (FiO2) will be set to a value below 0.5 that guarantees oxygen saturation by pulse oximetry (SpO2) greater than 90%. Enrolled patients will undergo SBT for 2 hours in semirecumbent position. During the SBT, the patients will breathe through the ventilator circuit by using flow triggering (2 L/min) with automatic tube compensation of 100% and 5 cmH2O PEEP. The FiO2 will be set to the same value as used before SBT. If the patients fail to tolerate the SBT, the trial will be discontinued immediately and the ventilation mode will be switched to that used before the trial. Patients who pass the 2-hour SBT will be extubated. Right diaphragm excursion and bilateral diaphragm thickening fraction will be measured by ultrasonography during spontaneous breathing. Images will be obtained immediately prior to the SBT, and at 5, 30, 60, 90 and 120 min after the initiation of SBT. Rapid shallow breathing index will be simultaneously calculated at the bedside by a respiratory nurse.

ETHICS AND DISSEMINATION

The study protocol is approved by the ethics committee of Sir Run Run Shaw Hospital, an affiliate of Zhejiang University, Medical College. The results will be published in a peer-reviewed journal and shared with the worldwide medical community.

TRIAL REGISTRATION NUMBER

ISRCTN42917473; Pre-results.

Time-Resolved Quantitative Analysis of the Diaphragms During Tidal Breathing in a Standing Position Using Dynamic Chest Radiography with a Flat Panel Detector System ("Dynamic X-Ray Phrenicography"): Initial Experience in 172 Volunteers

RATIONALE AND OBJECTIVES

Diaphragmatic motion in a standing position during tidal breathing remains unclear. The purpose of this observational study was to evaluate diaphragmatic motion during tidal breathing in a standing position in a health screening center cohort using dynamic chest radiography in association with participants' demographic characteristics.

MATERIALS AND METHODS

One hundred seventy-two subjects (103 men; aged 56.3 ± 9.8 years) underwent sequential chest radiographs during tidal breathing using dynamic chest radiography with a flat panel detector system. We evaluated the excursions of and peak motion speeds of the diaphragms. Associations between the excursions and participants' demographics (gender, height, weight, body mass index [BMI], smoking history, tidal volume, vital capacity, and forced expiratory volume) were investigated.

RESULTS

The average excursion of the left diaphragm (14.9 ± 4.6 mm, 95% CI 14.2-15.5 mm) was significantly larger than that of the right (11.0 ± 4.0 mm, 95% CI 10.4-11.6 mm) (P <0.001). The peak motion speed of the left diaphragm (inspiratory, 16.6 ± 4.2 mm/s; expiratory, 13.7 ± 4.2 mm/s) was significantly faster than that of the right (inspiratory, 12.4 ± 4.4 mm/s; expiratory, 9.4 ± 3.8 mm/s) (both P <0.001). Both simple and multiple regression models demonstrated that higher BMI and higher tidal volume were associated with increased excursions of the bilateral diaphragm (all P <0.05).

CONCLUSIONS

The average excursions of the diaphragms are 11.0 mm (right) and 14.9 mm (left) during tidal breathing in a standing position. The diaphragmatic motion of the left is significantly larger and faster than that of the right. Higher BMI and tidal volume are associated with increased excursions of the bilateral diaphragm.

Body posture and pulmonary function in mouth and nose breathing children: cross-sectional study

Abstract Introduction: Mouth breathing can lead to changes in body posture and pulmonary function. However, the consequences are still inconclusive and a number of studies are controversial. Objective: Evaluate and correlate spirometric parameters and postural measures in mouth breathing children, and compare them to nose breathers. Methods: two groups of 6 to 12 year-old children were evaluated: mouth breathers (MB, n = 55) and nose breathers (NB, n = 45). Spirometry and body posture analysis using photogrammetry (SAPo 0.68® v) were carried out. The following spirometric measures were evaluated: peak expiratory flow (PEF), forced expiratory volume in 1 second (FEV1), forced vital capacity (FVC), FEV1/FVC ratio (%) and forced expiratory flow between 25% and 75% of FVC (FEF 25-75%). Biophotogrammetric measures analyzed were: horizontal alignment of acromions (HAA) and anterior superior iliac spine (HAASIS), Charpy angle, horizontal alignment of the head (HAH), cervical lordosis (CL), thoracic kyphosis (TK), lumbar lordosis (LL), cervical distance (CD) and lumbar distance (LD). Results: There were no intergroup differences in spirometric and postural variables. Positive and moderate correlations were found between CL and CD measures with PEF, FEV1, FVC and FEF 25-75%, while weak correlations were observed between lumbar lordosis and PEF, FEV1 and FVC. Conclusion: The breathing mode had no influence on postural and respiratory measures. However, greater forward head posture, with smaller cervical lordosis, was related to higher lung volumes and flows in both groups.

Complete eventration of right hemidiaphragm: A rare presentation

Eventration of the diaphragm is a term used to describe an abnormal elevation of part or whole of the hemidiaphragm, where the whole or part of the diaphragm is made up of a thin fibro membranous sheet replacing normal diaphragmatic musculature. Complete and partial eventration both can occur, however, complete eventration of the right hemidiaphragm in an adult female, as presented in this patient, is rarely seen.

Anatomy-based algorithm for automatic segmentation of human diaphragm in noncontrast computed tomography images

In-depth understanding of the diaphragm's anatomy and physiology has been of great interest to the medical community, as it is the most important muscle of the respiratory system. While noncontrast four-dimensional (4-D) computed tomography (CT) imaging provides an interesting opportunity for effective acquisition of anatomical and/or functional information from a single modality, segmenting the diaphragm in such images is very challenging not only because of the diaphragm's lack of image contrast with its surrounding organs but also because of respiration-induced motion artifacts in 4-D CT images. To account for such limitations, we present an automatic segmentation algorithm, which is based on a priori knowledge of diaphragm anatomy. The novelty of the algorithm lies in using the diaphragm's easy-to-segment contacting organs-including the lungs, heart, aorta, and ribcage-to guide the diaphragm's segmentation. Obtained results indicate that average mean distance to the closest point between diaphragms segmented using the proposed technique and corresponding manual segmentation is [Formula: see text], which is favorable. An important feature of the proposed technique is that it is the first algorithm to delineate the entire diaphragm. Such delineation facilitates applications, where the diaphragm boundary conditions are required such as biomechanical modeling for in-depth understanding of the diaphragm physiology.

Seronegative neuromyelitis optica presenting with life-threatening respiratory failure

CONTEXT

Dyspnea has rarely been reported as a presenting symptom in patients with neuromyelitis optica (NMO). We report an unusual case of NMO relapse presenting with rapidly progressive respiratory failure and briefly discuss the possible pathophysiological mechanisms of this potential life-threatening complication of NMO.

FINDINGS

The 58-year-old woman with a history of bilateral optic neuritis presented to the emergency department with rapidly worsening dyspnea. Cervical spine magnetic resonance imaging showed extensive abnormal signal with involvement of the medulla oblongata. Since in our patient chest radiography failed to disclose a diaphragmatic palsy that is commonly observed in patients with phrenic nerve involvement, this acute manifestation of the disease may be attributed to brainstem involvement instead of cervical myelitis.

CONCLUSION/CLINICAL RELEVANCE

Clinicians should be aware of this atypical presentation of NMO, which needs to be promptly recognized and aggressively treated.

Complications associated with radiofrequency ablation of pulmonary veins

OBJECTIVE

Radiofrequency ablation is an efficacious alternative in patients with symptomatic atrial fibrillation who do not respond to or are intolerant to at least one class I or class III antiarrhythmic drug. Although radiofrequency ablation is a safe procedure, complications can occur. Depending on the location, these complications can be classified into those that affect the pulmonary veins themselves, cardiac complications, extracardiac intrathoracic complications, remote complications, and those that result from vascular access. The most common complications are hematomas, arteriovenous fistulas, and pseudoaneurysms at the puncture site. Some complications are benign and transient, such as gastroparesis or diaphragmatic elevation, whereas others are potentially fatal, such as cardiac tamponade.

CONCLUSION

Radiologists must be familiar with the complications that can occur secondary to pulmonary vein ablation to ensure early diagnosis and treatment.

Diaphragm assessment by two dimensional speckle tracking imaging in normal subjects

BACKGROUND

Conventionally, ultrasonographic assessment of diaphragm contractility has involved measuring respiratory changes in diaphragm thickness (thickening fraction) using B-mode or caudal displacement with M-mode. Two-dimensional speckle-tracking has been increasingly used to assess muscle deformation ('strain') in echocardiography. We sought to determine in a pilot study if this technology could be utilized to analyze diaphragmatic contraction.

METHODS

Fifty healthy adult volunteers with normal exercise capacity underwent ultrasound imaging. A linear array transducer was used for the assessment of diaphragm thickness, thickening fraction (TF), and strain in the right anterior axillary line at approximately the ninth intercostal space. A phased array transducer was applied subcostally for the assessment of diaphragm displacement on the right mid-clavicular line. Diaphragmatic images were recorded from the end of expiration through the end of inspiration at 60 % maximal inspiratory capacity. Diaphragm strain was analyzed off-line by speckle tracking imaging. Blinded inter- and intra-rater variability was tested in 10 cases.

RESULTS

Mean right diaphragm thickness at end-expiration (±SD: standard deviation) was 0.24 cm (±0.1), with TF of 45.1 % (±12) at 60 % peak inspiratory effort. Mean right diaphragm caudal displacement was 4.9 cm (±1). Mean right diaphragm strain was -40.3 % (±9). A moderate correlation was seen between longitudinal strain and TF (R(2) 0.44, p < 0.0001). A weak correlation was seen between strain and caudal displacement (R(2) 0.14, p < 0.01), and an even weaker correlation was seen between caudal displacement and TF (R(2) 0.1, p = 0.04). Age, gender, and body mass index were not significantly associated with right diaphragm strain or TF. Although inter- and intra-rater variability was overall good for TF, caudal displacement, and strain (inter-rater R(2); 0.8, 0.9, and 0.7, respectively [p < 0.01], intra-rater R(2); 0.9, 0.7, and 0.9, respectively [p < 0.01]), strain values did have a slightly lower inter-rater repeatability.

CONCLUSIONS

Diaphragmatic strain estimated by speckle tracking imaging was associated with conventional ultrasound measures of diaphragmatic function (TF and caudal displacement). Further clinical studies are warranted to investigate its clinical utility.

Quantification of Diaphragm Mechanics in Pompe Disease Using Dynamic 3D MRI

BACKGROUND

Diaphragm weakness is the main reason for respiratory dysfunction in patients with Pompe disease, a progressive metabolic myopathy affecting respiratory and limb-girdle muscles. Since respiratory failure is the major cause of death among adult patients, early identification of respiratory muscle involvement is necessary to initiate treatment in time and possibly prevent irreversible damage. In this paper we investigate the suitability of dynamic MR imaging in combination with state-of-the-art image analysis methods to assess respiratory muscle weakness.

METHODS

The proposed methodology relies on image registration and lung surface extraction to quantify lung kinematics during breathing. This allows for the extraction of geometry and motion features of the lung that characterize the independent contribution of the diaphragm and the thoracic muscles to the respiratory cycle.

RESULTS

Results in 16 3D+t MRI scans (10 Pompe patients and 6 controls) of a slow expiratory maneuver show that kinematic analysis from dynamic 3D images reveals important additional information about diaphragm mechanics and respiratory muscle involvement when compared to conventional pulmonary function tests. Pompe patients with severely reduced pulmonary function showed severe diaphragm weakness presented by minimal motion of the diaphragm. In patients with moderately reduced pulmonary function, cranial displacement of posterior diaphragm parts was reduced and the diaphragm dome was oriented more horizontally at full inspiration compared to healthy controls.

CONCLUSION

Dynamic 3D MRI provides data for analyzing the contribution of both diaphragm and thoracic muscles independently. The proposed image analysis method has the potential to detect less severe diaphragm weakness and could thus be used to determine the optimal start of treatment in adult patients with Pompe disease in prospect of increased treatment response.

Comparison of tissue distribution, phrenic nerve involvement, and epidural spread in standard- vs low-volume ultrasound-guided interscalene plexus block using contrast magnetic resonance imaging: a randomized, controlled trial

BACKGROUND

Ultrasound guidance allows for the use of much lower volumes of local anaesthetics for nerve blocks, which may be associated with less aberrant spread and fewer complications. This randomized, controlled study used contrast magnetic resonance imaging to view the differential-volume local anaesthetic distribution, and compared analgesic efficacy and respiratory impairment.

METHODS

Thirty patients undergoing shoulder surgery were randomized to receive ultrasound-guided interscalene block by a single, blinded operator with injection of ropivacaine 0.75% (either 20 or 5 ml) plus the contrast dye gadopentetate dimeglumine, followed by magnetic resonance imaging. The primary outcome was epidural spread. Secondary outcomes were central non-epidural spread, contralateral epidural spread, spread to the phrenic nerve, spirometry, ultrasound investigation of the diaphragm, block duration, pain scores during the first 24 h, time to first analgesic consumption, and total analgesic consumption.

RESULTS

All blocks provided fast onset and adequate intra- and postoperative analgesia, with no significant differences in pain scores at any time point. Epidural spread occurred in two subjects of each group (13.3%); however, spread to the intervertebral foramen and phrenic nerve and extensive i.m. local anaesthetic deposition were significantly more frequent in the 20 ml group. Diaphragmatic paralysis occurred twice as frequently (n=8 vs 4), and changes from baseline peak respiratory flow rate were larger [Δ=-2.66 (1.99 sd) vs -1.69 (2.0 sd) l min(-1)] in the 20 ml group.

CONCLUSIONS

This study demonstrates that interscalene block is associated with epidural spread irrespective of injection volume; however, less central (foraminal) and aberrant spread after low-volume injection may be associated with a more favourable risk profile.

CLINICAL TRIAL REGISTRATION

This study was registered with the European Medicines Agency (Eudra-CT number 2013-004219-36) and with the US National Institutes' of Health registry and results base, clinicaltrials.gov (identifier NCT02175069).

Effects of diaphragm stretching on posterior chain muscle kinematics and rib cage and abdominal excursion: a randomized controlled trial

Background

Few studies have explored the effects of stretching techniques on diaphragm and spine kinematics.

Objective

To determine whether the application of diaphragm stretching resulted in changes in posterior chain muscle kinematics and ribcage and abdominal excursion in healthy subjects.

Method

Eighty healthy adults were included in this randomized clinical trial. Participants were randomized into two groups: the experimental group, which received a diaphragmatic stretching technique, or the placebo group, which received a sham-ultrasound procedure. The duration of the technique, the position of participants, and the therapist who applied the technique were the same for both treatments. Participant assessment (cervical range of movement, lumbar flexibility, flexibility of the posterior chain, and rib cage and abdominal excursion) was performed at baseline and immediately after the intervention by a blinded assessor.

Results

The mean between-group difference [95% CI] for the ribcage excursion after technique at xiphoid level was 2.48 [0.97 to 3.99], which shows significant differences in this outcome. The remaining between-group analysis showed significant differences in cervical extension, right and left flexion, flexibility of the posterior chain, and ribcage excursion at xiphoid level (p<0.05) in favor of the experimental group.

Conclusion

Diaphragm stretching generates a significant improvement in cervical extension, right and left cervical flexion, flexibility of the posterior chain, and ribcage excursion at xiphoid level compared to a placebo technique in healthy adults.