Diaphragmatic ultrasound: a review of its methodological aspects and clinical uses

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.

Thoracic manifestations and respiratory function alterations in axial spondyloarthritis and newest possibilities of ultrasound to detect changes in diaphragm-a narrative review

Background and Objective

Axial spondyloarthritis (axSpA) includes thoracic manifestations and changes in respiratory function that require a comprehensive understanding for effective treatment. This review aims to investigate these manifestations and evaluate the role of ultrasound in detecting diaphragmatic changes to provide insights for improved diagnosis and treatment strategies in axSpA patients.

Methods

A systematic search was conducted in Index Medicus and Scopus from 2003 to 2023. Inclusion criteria included primary and secondary publications, with a focus on high-quality evidence such as randomised controlled trials and systematic reviews with or without meta-analysis. Keywords spondyloarthritis, respiratory, chest, thoracic, diaphragm and ultrasound were used in the search. A total of 22 articles were identified after duplicates, and inadequate papers were removed.

Key Content and Findings

The review included the prevalence, classification and extra-articular manifestations of axSpA, highlighting the impact on respiratory function. Thoracic manifestations and the potential impact of pharmacological interventions were detailed, and various conditions affecting respiratory dynamics were discussed. In addition, the utility of ultrasonography in assessing diaphragmatic function was explained and the techniques, parameters and measurements used to assess diaphragmatic movement, muscle thickness and respiratory mobility were described. The results illustrate the changes in diaphragmatic function in axSpA patients and their correlation with disease activity.

Conclusions

This narrative review highlights the intricate relationship between axSpA and respiratory manifestations and emphasises the significant impact on thoracic function and diaphragmatic dynamics. The utility of ultrasound in assessing diaphragmatic function offers a promising avenue for objective evaluation that provides insight into disease activity and potential therapeutic responses. This review emphasises the critical role of early diagnosis and vigilant monitoring, and advocates a multidisciplinary approach that integrates non-pharmacological interventions, particularly tailored physical activity, to maintain and improve respiratory function in axSpA patients. Increased research initiatives and awareness of pulmonary complications in axSpA are essential to optimise medical care and improve treatment outcomes in this patient group.

Diaphragmatic Ultrasound in Children With Asthma Exacerbations

OBJECTIVES

Asthma is a leading cause of pediatric emergency department visits, yet few tools exist to objectively measure asthma severity. Diaphragmatic ultrasound (DUS) is a novel method of assessing respiratory distress; however, data are lacking for children.Our primary aim was to determine if diaphragmatic excursion (DE), diaphragmatic thickening (DT), or diaphragmatic thickening fraction (TF) correlated with asthma severity as determined by the Pediatric Respiratory Assessment Measure (PRAM) score. Secondarily, we examined if these parameters correlated with need for respiratory support and evaluated interrater reliability.

METHODS

We conducted a prospective study of children 5-18 years presenting to a pediatric emergency department with an asthma exacerbation. Diaphragmatic ultrasound was performed by a trained pediatric emergency medicine sonologist in subcostal (DE) and midaxillary (DT). Thickening fraction was calculated from DT values as previously described in literature. To evaluate interrater reliability, a subset of subjects had DUS performed by a second sonologist.

RESULTS

We enrolled 47 subjects for a total of 51 encounters. The mean age was 9.1 ± 3.7 years. Twenty-five (49%) had mild, 24 (47%) had moderate, and 2 (4%) had severe asthma. There was a significant difference in midaxillary DT and TF between children with mild and moderate asthma (P = 0.02; mean difference, 0.2 mm; 95% confidence interval [CI], 0.03-0.4 and P = 0.02; mean difference, 0.11 mm; 95% CI, 0.02-0.2, respectively). No difference was found in subcostal DE (P = 0.43; mean difference, 1.4 mm; 95% CI, -2.1 to 4.8). No association was found between use of positive pressure and DUS parameters. Fourteen encounters had 2 sonologists perform DUS, with strong interrater reliability found for midaxillary DT (Pearson correlation, 0.56) and poor association for subcostal DE (Pearson correlation, 0.18).

CONCLUSIONS

In this pilot study, we conclude that DUS may be helpful in assessing severity of asthma. The midaxillary view assessment for DT and TF had the best correlation with asthma severity and the best interrater reliability. Future studies may benefit from focusing on the midaxillary view for DT and TF.

Point-of-Care Ultrasound to Assess Diaphragmatic Paralysis in Resource-Limited Setting: A Case Series

Diaphragmatic dysfunction can arise from various factors, and Guillain-Barre syndrome, characterized by acute inflammatory polyradiculoneuropathy, is one such cause that may result in respiratory failure due to diaphragmatic paralysis. Prompt recognition and timely intervention, including airway protection and addressing the underlying pathology, are crucial for achieving optimal patient outcomes. Point-of-care ultrasound, specifically utilizing the M-mode function, can be employed for individuals displaying symptoms of diaphragmatic paralysis. This diagnostic approach is uncomplicated an effective tool for serial follow-up. In this context, we present a case series involving three patients with diaphragmatic paralysis in a limited-resource setting.

Evaluation of computed tomography in the diagnosis of ultrasound-proven diaphragm dysfunction

INTRODUCTION

Computed tomography (CT) is routinely employed on the evaluation of dyspnea, yet limited data exist on its assessment of diaphragmatic muscle. This study aimed to determine the capability of CT in identifying structural changes in the diaphragm among patients with ultrasound-confirmed diaphragmatic dysfunction.

METHODS

Diaphragmatic ultrasounds conducted between 2018 and 2021 at our center in Marseille, France, were retrospectively collected. Diaphragmatic pillars were measured on CT scans at the L1 level and the celiac artery. Additionally, the difference in height between the two diaphragmatic domes in both diaphragmatic dysfunction cases and controls was measured and compared.

RESULTS

A total of 65 patients were included, comprising 24 with diaphragmatic paralysis, 13 with diaphragmatic weakness, and 28 controls. In the case group (paralysis and weakness) with left dysfunctions (n = 24), the CT thickness of the pillars at the level of L1 and the celiac artery was significantly thinner compared with controls (2.0 mm vs. 7.4 mm and 1.8 mm vs. 3.1 mm, p < 0.001 respectively). Significantly different values were observed for paralysis (but not weakness) in the right dysfunction subgroup (n = 15) (2.6 mm vs. 7.4 mm and 2.2 mm vs. 3.8 mm, p < 0.001 respectively, for paralysis vs. controls). Regardless of the side of dysfunction, a significant difference in diaphragmatic height was observed between cases and controls (7.70 cm vs. 1.16 cm and 5.51 cm vs. 1.16 cm, p < 0.001 for right and left dysfunctions, respectively). Threshold values determined through ROC curve analyses for height differences between the two diaphragmatic domes, indicative of paralysis or weakness in the right dysfunctions, were 4.44 cm and 3.51 cm, respectively. Similarly for left dysfunctions, the thresholds were 2.70 cm and 2.48 cm, respectively, demonstrating good performance (aera under the curve of 1.00, 1.00, 0.98, and 0.79, respectively).

CONCLUSION

In cases of left diaphragmatic dysfunction, as well as in paralysis associated with right diaphragmatic dysfunction, CT revealed thinner pillars. Additionally, a notable increase in the difference in diaphragmatic height demonstrated a strong potential to identify diaphragmatic dysfunction, with specific threshold values.

The Role of Ultrasonography in the Process of Weaning from Mechanical Ventilation in Critically Ill Patients

Weaning patients from mechanical ventilation (MV) is a complex process that may result in either success or failure. The use of ultrasound at the bedside to assess organs may help to identify the underlying mechanisms that could lead to weaning failure and enable proactive measures to minimize extubation failure. Moreover, ultrasound could be used to accurately identify pulmonary diseases, which may be responsive to respiratory physiotherapy, as well as monitor the effectiveness of physiotherapists' interventions. This article provides a comprehensive review of the role of ultrasonography during the weaning process in critically ill patients.

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.

[Diaphragmatic ultrasonography for the pulmonologist: Technique and clinical use]

INTRODUCTION

Ultrasonography is an emerging tool that helps to assess diaphragmatic function. It is now widely used in ICUs to predict weaning from mechanical ventilation. Ultrasonography is readily available, harmless (no radiation), and repeatable with good interoperator reproducibility. Over the past few years, ultrasonography has seen increasing use in patients with chronic pulmonary pathologies.

STATE OF THE ART

The aim of this review is (1) to describe the ultrasound techniques used to assess diaphragmatic excursion and thickening, (2) to indicate the expected, normal values in healthy patients, and (3) to summarize the main findings and clinical applications in treatment of chronic respiratory disorders.

CONCLUSIONS

Chronic pulmonary diseases are associated with diaphragmatic dysfunction that can be assessed with ultrasound. Diaphragmatic dysfunction is primary in neuromuscular disorders and secondary to respiratory disease in other chronic pulmonary conditions (COPD, ILD). Ultrasound is correlated with the severity of the underlying disease (functional and clinical parameters).

PERSPECTIVES

The prognostic interest of diaphragm ultrasonography remains to be established, after which its utilization should become routine.

Association between abdominal muscle stiffness, diaphragm thickness and peak expiratory flow in younger versus older adults

The present study aimed to evaluate forced expiration based on transverse abdominis (TrA) stiffness by identifying the relationship between TrA stiffness and peak expiratory flow (PEF) in both younger and older adults. We also assessed the relationship between diaphragm thickness and PEF. A total of 31 younger (21.24 ± 2.73 years) and 34 older (71.35 ± 5.26 years) adults were included in the present study. TrA muscle stiffness was measured at rest and during abdominal bracing using shear wave elastography. Diaphragm thickness was measured during deep inspiration and expiration using B-mode ultrasound, and respiratory function was assessed by measuring PEF using a spirometer. We found that TrA stiffness during bracing was significantly lower in older than younger adults (p < 0.05). Similarly, the difference in absolute stiffness of the TrA when bracing versus at rest was significantly lower in older than younger adults (p < 0.05). Additionally, TrA stiffness during bracing was positively associated with PEF in the younger group (r = 0.483), while a very weak correlation was found in the older group (r = 0.172). Similarly, PEF was moderately correlated with diaphragm thickness during expiration as well as during changes between inspiration and expiration in the younger group (r = 0.405 and r = 0.403); however, no significant correlation was found in the older group. These findings of the present study indicate that the variations in PEF between younger and older adults may be due to age-associated changes in the musculoskeletal structure and muscle fibre type.

Ultrasonographic Features of Muscular Weakness and Muscle Wasting in Critically Ill Patients

Muscle wasting begins as soon as in the first week of one's ICU stay and patients with multi-organ failure lose more muscle mass and suffer worse functional impairment as a consequence. Muscle wasting and weakness are mainly characterized by a generalized, bilateral lower limb weakness. However, the impairment of the respiratory and/or oropharyngeal muscles can also be observed with important consequences for one's ability to swallow and cough. Muscle wasting represents the result of the disequilibrium between breakdown and synthesis, with increased protein degradation relative to protein synthesis. It is worth noting that the resulting functional disability can last up to 5 years after discharge, and it has been estimated that up to 50% of patients are not able to return to work during the first year after ICU discharge. In recent years, ultrasound has played an increasing role in the evaluation of muscle. Indeed, ultrasound allows an objective evaluation of the cross-sectional area, the thickness of the muscle, and the echogenicity of the muscle. Furthermore, ultrasound can also estimate the thickening fraction of muscle. The objective of this review is to analyze the current understanding of the pathophysiology of acute skeletal muscle wasting and to describe the ultrasonographic features of normal muscle and muscle weakness.

Validation of a novel point-of-care ultrasound method to assess diaphragmatic excursion

INTRODUCTION

Point-of-care ultrasound can assess diaphragmatic function and rule in or rule out paresis of the diaphragm. While this is a useful bedside tool, established methods have significant limitations. This study explores a new method to assess diaphragmatic motion by measuring the excursion of the uppermost point of the zone of apposition (ZOA) at the mid-axillary line using a high-frequency linear ultrasound probe and compares it with two previously established methods: the assessment of the excursion of the dome of the diaphragm (DOD) and the thickening ratio at the ZOA.

METHODS

This is a single-centre, prospective comparative study on elective surgical patients with normal diaphragmatic function. Following research ethics board approval and patient written consent, 75 elective surgical patients with normal diaphragmatic function were evaluated preoperatively. Three ultrasound methods were compared: (1) assessment of the excursion of the DOD using a curvilinear probe through an abdominal window; (2) assessment of the thickening fraction of the ZOA; and (3) assessment of the excursion of the ZOA. The last two methods performed with a linear probe on the lateral aspect of the chest.

RESULTS

Seventy-five patients were studied. We found that the evaluation of the excursion of the ZOA was more consistently successful (100% bilaterally) than the evaluation of the excursion of the DOD (98.7% and 34.7% on the right and left sides, respectively). The absolute values of the excursion of the ZOA were greater than and well correlated with the values of the DOD.

CONCLUSION

Our preliminary data from this exploratory study suggest that the evaluation of the excursion of the ZOA on the lateral aspect of the chest using a linear probe is consistently successful on both right and left sides. Future studies are needed to establish the distribution of normal values and suggest diagnostic criteria for diaphragmatic paresis or paralysis.

TRIAL REGISTRATION NUMBER

NCT03225508.

Ultrasonographic evaluation of diaphragmatic excursion changes after major laparoscopic surgeries in the Trendelenburg position under general anaesthesia: A prospective observational study

Background and Aims

Laparoscopic surgeries result in increased intra abdominal pressure and cephalad displacement of the diaphragm. The Trendelenburg position can augment these respiratory changes. The primary objective of this study was to compare diaphragmatic excursions before and after a major laparoscopic pelvic surgery under general anaesthesia in the Trendelenburg position using ultrasonography (USG).

Methods

This prospective observational study included 90 patients of either gender, aged 20-60 years, with American Society of Anesthesiologists physical status I/II. M-mode USG was used to assess diaphragm inspiratory amplitude (DIA) before induction of anaesthesia and 10 minutes after tracheal extubation. Factors such as age, gender, body mass index, positive end-expiratory pressure (PEEP), pain, peak airway pressures, duration of pneumoperitoneum, duration and degree of Trendelenburg position and duration of anaesthesia were recorded. Pearson's correlation and multiple linear regression were used to analyse the factors affecting change in DIA (ΔDIA).

Results

The mean difference (95% confidence interval (CI)) of measured DIA was 0.70 (0.598-0.809), P < 0.001. ΔDIA had a weak positive significant correlation with age, anaesthesia duration, pneumoperitoneum, and visual analogue scale (VAS) score 10 minutes after extubation. Multiple linear regression analysis showed 14.86% of the variance in DIA. Age (β = 0.008, P = 0.049), duration of anaesthesia (β = 0.002, P = 0.02) and VAS score 10 minutes after extubation (β = 0.128, P = 0.001) were significant independent predictors.

Conclusion

DIA decreased significantly after pelvic laparoscopic surgeries performed in the Trendelenburg position. Age, duration of anaesthesia and pain after the procedure were significant independent predictors.

Ultrasonographic reliability and repeatability of simultaneous bilateral assessment of diaphragm muscle thickness during normal breathing

Background

The diaphragm is considered the main muscle involved in breathing and also linked to trunk stabilization functions. Up to date, rehabilitative ultrasound imaging (RUSI) has been the most used technique to evaluate unilaterally the transcostal diaphragm thickness. Nevertheless, the inspiratory activity of both hemi-diaphragms is bilaterally performed at the same time, and its simultaneous evaluation with a thoracic orthosis could improve its assessment as well as its re-education with visual biofeedback of both hemi-diaphragms at the same time. The purpose was to evaluate the reliability and repeatability of simultaneous thickness measurements of both hemi-diaphragms bilaterally during normal breathing using a thoracic orthosis that allowed bilateral fixation of both right and left ultrasound probes.

Methods

The study was conducted in 46 healthy subjects, whose diaphragm thickness was measured bilaterally and simultaneously in the anterior axillary line during relaxed breathing with a designed thoracic orthosis and 2 ultrasound tools. Intra-examiner (same examiner), inter-examiner (2 examiners), intra-session (1 hour) and inter-session (1 week) reliability and repeatability between each pair of measurements of diaphragm muscle thickness were analyzed during normal breathing.

Results

Reliability and repeatability for intra-session evaluations using the thoracic orthosis were excellent to evaluate simultaneous thickness of both hemi-diaphragms by bilateral probes fixation (intraclass correlation coefficient =0.919-0.997; standard error of measurement =0.002-0.007 cm; minimum detectable change =0.006-0.020 cm), without systematic errors (P>0.05) between each pair of measurements. Nevertheless, inter-session evaluations varied from good to excellent using the bilateral probes fixation (intraclass correlation coefficient =0.614-0.984; standard error of measurement =0.006-0.028 cm; minimum detectable change =0.017-0.079 cm), although some systematic errors were presented (P<0.05).

Conclusions

Good to excellent reliability and repeatability was shown for simultaneous thickness measurements of both hemi-diaphragms bilaterally during normal breathing. Despite systematic errors were presented for some inter-examiner assessments, the use of the thoracic orthosis that allowed bilateral fixation of ultrasound probes could be recommended for simultaneous hemi-diaphragms breathing re-education by visual biofeedback.

Ultrasonic Evaluation of Diaphragm in Patients with Systemic Sclerosis

The diaphragm is the most important muscle in respiration. Nevertheless, its function is rarely evaluated. Patients with systemic sclerosis (SSc) could be at risk of diaphragmatic dysfunction because of multiple factors. These patients often develop interstitial lung disease (SSc-ILD) and earlier studies have indicated that patients with different ILDs have decreased diaphragmatic mobility on ultrasound (US). This study aimed to evaluate diaphragmatic function in SSc patients using US with regard to the ILD, evaluated with the Warrick score on high-resolution computed tomography (HRCT), and to investigate associations between ultrasonic parameters and dyspnea, lung function, and other important clinical parameters. In this cross-sectional study, we analyzed diaphragm mobility, thickness, lung function, HRCT findings, Modified Medical Research Council (mMRC) dyspnea scale, modified Rodnan skin score (mRSS), autoantibodies, and esophageal diameters on HRCT in patients with SSc. Fifty patients were enrolled in the study. Patients with SSc-ILD had lower diaphragmatic mobility in deep breathing than patients without ILD. The results demonstrated negative correlations between diaphragmatic mobility and mMRC, mRSS, anti-Scl-70 antibodies, esophageal diameters on HRCT, and a positive correlation with lung function. Patients with SSc who experience dyspnea should be evaluated for diaphragmatic dysfunction for accurate symptom phenotyping and personalized pulmonary rehabilitation treatment.

Association of Diaphragm Thickness and Respiratory Muscle Strength With Indices of Sarcopenia

OBJECTIVE

To evaluate the relationship between respiratory muscle strength, diaphragm thickness (DT), and indices of sarcopenia.

METHODS

This study included 45 healthy elderly volunteers (21 male and 24 female) aged 65 years or older. Sarcopenia indices, including hand grip strength (HGS) and body mass index-adjusted appendicular skeletal muscle (ASM/BMI), were measured using a hand grip dynamometer and bioimpedance analysis, respectively. Calf circumference (CC) and gait speed were also measured. Maximal inspiratory pressure (MIP) and maximal expiratory pressure (MEP) were obtained using a spirometer, as a measure of respiratory muscle strength. DT was evaluated through ultrasonography. The association between indices of sarcopenia, respiratory muscle strength, and DT was evaluated using Spearman's rank correlation test, and univariate and multiple regression analysis.

RESULTS

ASM/BMI (r=0.609, p<0.01), CC (r=0.499, p<0.01), HGS (r=0.759, p<0.01), and gait speed (r=0.319, p<0.05) were significantly correlated with DT. In the univariate linear regression analysis, MIP was significantly associated with age (p=0.003), DT (p<0.001), HGS (p=0.002), CC (p=0.013), and gait speed (p=0.026). MEP was significantly associated with sex (p=0.001), BMI (p=0.033), ASM/BMI (p=0.003), DT (p<0.001), HGS (p<0.001), CC (p=0.001) and gait speed (p=0.004). In the multiple linear regression analysis, age (p=0.001), DT (p<0.001), and ASM/BMI (p=0.008) showed significant association with MIP. DT (p<0.001) and gait speed (p=0.050) were associated with MEP.

CONCLUSION

Our findings suggest that respiratory muscle strength is associated with DT and indices of sarcopenia. Further prospective studies with larger sample sizes are needed to confirm these findings.

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.

The ratio of respiratory rate to diaphragm thickening fraction for predicting extubation success

BACKGROUND

Several parameters are used to predict successful extubation but their accuracy varies among studies. We hypothesized that combining conventional and diaphragmatic parameters would be more effective than using just one. Our primary objective was to evaluate the performance of the respiratory rate in relation to the diaphragm thickening fraction (RR/DTF) ratio to predict the success of extubation.

METHODS

We enrolled 130 adult patients who required invasive mechanical ventilation, planned to be extubated, and used a spontaneous breathing trial (SBT) in the intensive care unit from July 2020 to April 2022. We measured the conventional parameters and the diaphragmatic parameters 2 h after SBT. The RR/DTF was calculated by dividing the respiratory rate (RR) by the diaphragm thickening fraction (DTF). The definition of weaning success is successful extubation within 48 h.

RESULTS

Of 130 patients, 8 patients (6.2%) were reintubated within 48 h. The RR/DTF was significantly lower in the successful extubation group than in the extubation failure group (right hemidiaphragm; 0.47 (0.33-0.64) vs 1.1 (0.6-2.32), p < 0.001 and left hemidiaphragm; 0.45 (0.31-0.65) vs 0.78 (0.48-1.75), p < 0.001). The right RR/DTF using a cut-off point at ≤ 0.81 had a sensitivity of 87.7%, a specificity of 75%, and areas under the receiver operating characteristic curve (AUROC) of 0.762 for predicting successful extubation (p = 0.013). The sensitivity, specificity, and AUROC for predicting extubation success of right DTF at a cut-off point of ≥ 26.2% were 84.3%, 62.5%, and 0.775, respectively (p = 0.009).

CONCLUSION

The RR/DTF ratio is a promising tool for predicting extubation outcome. Additionally, using RR/DTF was more reliable than conventional or diaphragmatic parameters alone in predicting extubation success.

Ultrasound assessment of diaphragmatic dysfunction and its improvement with levosimendan in patients with chronic obstructive pulmonary disease

Diaphragmatic Dysfunction (DD) is a clinical condition in which the diaphragm becomes weak or paralyzed, because of muscle strength reduction. It can be due to muscular issues or loss of proper innervation, but, also, to pulmonary hyperinflation or air trapping, such as in Chronic Obstructive Pulmonary Disease (COPD). DD impacts on COPD induced dyspnea, determining its progressive worsening, but levosimendan, an inodilator better known as Ca2+ sensitizer, may limit this phenomenon and diaphragmatic ultrasound assessment can be useful in monitoring its effect. Here, we show the case of a 77-year-old woman admitted to the Emergency department for acute exacerbation of chronic dyspnea in COPD, related to right ventricular failure and DD, which did not respond to medical therapy and non-invasive mechanical ventilation but did experience a favorable outcome after intravenous administration of levosimendan.

Diaphragm Ultrasound in Critically Ill Patients on Mechanical Ventilation—Evolving Concepts

Mechanical ventilation (MV) is a life-saving respiratory support therapy, but MV can lead to diaphragm muscle injury (myotrauma) and induce diaphragmatic dysfunction (DD). DD is relevant because it is highly prevalent and associated with significant adverse outcomes, including prolonged ventilation, weaning failures, and mortality. The main mechanisms involved in the occurrence of myotrauma are associated with inadequate MV support in adapting to the patient’s respiratory effort (over- and under-assistance) and as a result of patient-ventilator asynchrony (PVA). The recognition of these mechanisms associated with myotrauma forced the development of myotrauma prevention strategies (MV with diaphragm protection), mainly based on titration of appropriate levels of inspiratory effort (to avoid over- and under-assistance) and to avoid PVA. Protecting the diaphragm during MV therefore requires the use of tools to monitor diaphragmatic effort and detect PVA. Diaphragm ultrasound is a non-invasive technique that can be used to monitor diaphragm function, to assess PVA, and potentially help to define diaphragmatic effort with protective ventilation. This review aims to provide clinicians with an overview of the relevance of DD and the main mechanisms underlying myotrauma, as well as the most current strategies aimed at minimizing the occurrence of myotrauma with special emphasis on the role of ultrasound in monitoring diaphragm function.

Accuracy of lung and diaphragm ultrasound in predicting successful extubation in extremely preterm infants: A prospective observational study

OBJECTIVE

Chest ultrasound has emerged as a promising tool in predicting extubation readiness in adults and children, yet its utility in preterm infants is lacking. Our aim was to assess the utility of lung ultrasound severity score (LUSS) and diaphragmatic function in predicting extubation readiness in extremely preterm infants.

STUDY DESIGN

In this prospective cohort study, preterm infants < 28 weeks gestational age (GA) who received invasive mechanical ventilation for ≥12 h were enrolled. Chest ultrasound was performed before extubation. The primary outcome was lung ultrasound accuracy for predicting successful extubation at 3 days. Descriptive statistics and logistic regression were done using SPSS version 22.

RESULTS

We enrolled 45 infants, of whom 36 (80%) were successfully extubated. GA and postmenstrual age (PMA) at extubation were significantly higher in the successful group. The LUSS was significantly lower in the successful group compared to failed group (11.9 ± 3.2 vs. 19.1 ± 3.1 p < 0.001). The two groups had no statistically significant difference in diaphragmatic excursion or diaphragmatic thickness fraction. Logistic regression analysis controlling for GA and PMA at extubation showed LUSS was an independent predictor for successful extubation (odd ratio 0.46, 95% confidence interval [0.23-0.9], p = 0.02). The area under the receiver operating characteristic curve was 0.95 (p ˂ 0.001) for LUSS, and a cut-off value of ≥15 had 95% sensitivity and 85% specificity in detecting extubation failure.

CONCLUSION

In extremely preterm infants, lung ultrasound has good accuracy for predicting successful extubation. However, diaphragmatic measurements were not reliable predictors.

Methodological and Clinimetric Evaluation of Inspiratory Respiratory Muscle Ultrasound in the Critical Care Setting: A Systematic Review and Meta-Analysis

OBJECTIVE

Significant variations exist in the use of respiratory muscle ultrasound in intensive care with no society-level consensus on the optimal methodology. This systematic review aims to evaluate, synthesize, and compare the clinimetric properties of different image acquisition and analysis methodologies.

DATA SOURCES

Systematic search of five databases up to November 24, 2021.

STUDY SELECTION

Studies were included if they enrolled at least 50 adult ICU patients, reported respiratory muscle (diaphragm or intercostal) ultrasound measuring either echotexture, muscle thickness, thickening fraction, or excursion, and evaluated at least one clinimetric property. Two independent reviewers assessed titles, abstracts, and full text against eligibility.

DATA EXTRACTION

Study demographics, ultrasound methodologies, and clinimetric data.

DATA SYNTHESIS

Sixty studies, including 5,025 patients, were included with 39 studies contributing to meta-analyses. Most commonly measured was diaphragm thickness (DT) or diaphragm thickening fraction (DTF) using a linear transducer in B-mode, or diaphragm excursion (DE) using a curvilinear transducer in M-mode. There are significant variations in imaging methodology and acquisition across all studies. Inter- and intrarater measurement reliabilities were generally excellent, with the highest reliability reported for DT (ICC, 0.98; 95% CI, 0.94-0.99). Pooled data demonstrated acceptable to excellent accuracy for DT, DTF, and DE to predicting weaning outcome after 48 to 72 hours postextubation (DTF AUC, 0.79; 95% CI, 0.73-0.85). DT imaging was responsive to change over time. Only three eligible studies were available for intercostal muscles. Intercostal thickening fraction was shown to have excellent accuracy of predicting weaning outcome after 48-hour postextubation (AUC, 0.84; 95% CI, 0.78-0.91).

CONCLUSIONS

Diaphragm muscle ultrasound is reliable, valid, and responsive in ICU patients, but significant variation exists in the imaging acquisition and analysis methodologies. Future work should focus on developing standardized protocols for ultrasound imaging and consider further research into the role of intercostal muscle imaging.

Assessment Tools for Pulmonary Involvement in Patients with Ankylosing Spondylitis: Is Diaphragmatic Ultrasonography Correlated to Spirometry?

Objective

Spondyloarthritis (SpA) is a chronic inflammatory rheumatic disease that can lead to spinal ankylosis and consequently, restrictive pulmonary dysfunction. Thus, the present study aimed to assess the accuracy of diaphragm ultrasound compared to spirometry in the screening of restrictive pulmonary disorders in radiographic SpA patients.

Methods

We conducted a cross-sectional study of 50 patients with radiographic SpA, over six months. Sociodemographic data, clinical characteristics of the disease, as well as biological, radiological, and therapeutic data, were collected. Spirometry and diaphragm ultrasound were performed.

Results

The mean age of the study participants (N= 50) was 42.7±11 years [range: 25-66] with male predominance (N= 41). Spirometry showed a restrictive disorder in 32% of cases. The mean chest expansion (CE) value was 3.9±1.81cm [range: 1-9] with a median of 4 cm. A pathological value (<5cm) was observed in 72% of cases. A significant positive correlation was found between the right inspiratory diaphragmatic thickness and forced vital capacity (FVC) (r= 0.36; p = 0.02) and the supine FVC (r=0.29; p = 0.04). The left inspiratory diaphragmatic thickness was correlated with the percentage of the FVC decrease (r= 0.35; p = 0.01) defined as the percentage of difference between FVC and supine FVC. The right expiratory diaphragmatic thickness was associated with the FVC (r=0.32; p = 0.02). A significant positive correlation was found between the CE and the presence of B lines (r=0.32; p = 0.02), but not between the CE and the FVC.

Conclusion

The present study showed that diaphragm ultrasonography is correlated with spirometric findings in radiographic SpA patients. Further studies are required to assess its reliability, specificity, and sensitivity in this pathology.

Ultrasound-guided superficial cervical plexus block combined with clavipectoral fascial plane block or interscalene brachial plexus block in clavicle surgery: a single-centre, double-blind, randomized controlled trial

The sensory innervation of the clavicle is complex, and the best regional block technology for clavicular surgery has yet to be determined. The purpose of this study was to compare the application of ultrasound-guided superficial cervical plexus block combined with clavipectoral fascial plane block verses interscalene brachial plexus block in clavicular surgery. Fifty patients undergoing internal fixation surgery for elective clavicle fractures were randomly divided into two groups (n = 25 for each group): group I and group II. Superficial cervical plexus block combined with clavipectoral fascial plane block was used in group I, and superficial cervical plexus block combined with interscalene brachial plexus block was used in group II. The primary outcome measure was the duration of analgesia. The duration of analgesia in group I was significantly longer than that in group II (P < 0.05). The modified Bromage scale function score in group II was lower than that in group I (P < 0.01). There was no significant difference in the skin acupuncture pain score 30 min after block and visual analog scale (VAS) scores at 6 and 12 h after surgery. However, the 24 h VAS score in group I was lower than that in group II (P < 0.05). The incidence of diaphragmatic paralysis was significantly increased in group II (P < 0.01). Ultrasound-guided superficial cervical plexus block combined with clavipectoral fascial plane block can be used for clavicular surgery. It has a long postoperative analgesia time, can retain the motor function of the involved upper limb and does not cause hemidiaphragmatic paresis.Clinical trial number and registry URL: Clinical Trials.gov; Trial registration number: ChiCTR2000039383; Date of registration: 25 October 2020.

Point-of-care ultrasound for critically-ill patients: A mini-review of key diagnostic features and protocols

Point-of-care ultrasonography (POCUS) for managing critically ill patients is increasingly performed by intensivists or emergency physicians. Results of needs surveys among intensivists reveal emphasis on basic cardiac, lung and abdominal ultrasound, which are the commonest POCUS modalities in the intensive care unit. We therefore aim to describe the key diagnostic features of basic cardiac, lung and abdominal ultrasound as practised by intensivists or emergency physicians in terms of accuracy (sensitivity, specificity), clinical utility and limitations. We also aim to explore POCUS protocols that integrate basic cardiac, lung and abdominal ultrasound, and highlight areas for future research.

Diaphragmatic excursion by ultrasound: reference values for the normal population; a cross-sectional study in Egypt

Background

Measurement of diaphragmatic motion by ultrasound is being utilized in different aspects of clinical practice. Defining reference values of the diaphragmatic excursion is important to identify those with diaphragmatic motion abnormalities. This study aimed to define the normal range of diaphragmatic motion (reference values) by Mmode ultrasound for the normal population.

Methods

Healthy volunteers were included in this study. Those with comorbidities, skeletal deformity, acute or chronic respiratory illness were excluded. Diaphragmatic ultrasound in the supine position was performed using a lowfrequency probe. The B-mode was applied for diaphragmatic identification, and the M-mode was employed for the recording of the amplitude of diaphragm contraction during quiet breathing, deep breathing and sniffing.

Results

The study included 757 healthy subjects [478 men (63.14%) and 279 women (36.86%)] with normal spirometry and negative history of previous or current respiratory illness. Their mean age and BMI were 45.17 ±14.84 years and 29.36±19.68 (kg/m²). The mean right hemidiaphragmatic excursion was 2.32±0.54, 5.54±1.26 and 2.90±0.63 for quiet breathing, deep breathing and sniffing, respectively, while the left hemidiaphragmatic excursion was 2.35±0.54, 5.30±1.21 and 2.97±0.56 cm for quiet breathing, deep breathing and sniffing, respectively. There was a statistically significant difference between right and left diaphragmatic excursion among all studied subjects. The ratio of right to left diaphragmatic excursion during quiet breathing was (1.009±0.19); maximum 181% and minimum 28%. Only 19 cases showed a right to left ratio of less than 50% (5 men and 14 women). The diaphragmatic excursion was higher in males than females. There was a significant difference in diaphragmatic excursion among age groups. Age, sex and BMI significantly affected the diaphragmatic motion.

Conclusions

Diaphragmatic excursion values presented in this study can be used as reference values to detect diaphragmatic dysfunction in clinical practice. Diaphragmatic motion is affected by several factors including age, sex and body mass index.

Effects of Dexmedetomidine on Diaphragm Activity Measured by Ultrasonography in Spontaneously Breathing Patients

Background: Diaphragm movement is well correlated with inspired volume of the lung. Dexmedetomidine (DEX) has less effect on respiratory functions than other sedatives. The objective of this study was to investigate diaphragmatic movement using ultrasound (US) during DEX infusion for sedation in spontaneously breathing patients undergoing unilateral upper limb surgery. Methods: A total of 33 consecutive patients were enrolled in this study. Patients were sedated using DEX with ipsilateral axillary brachial nerve plexus block. Diaphragmatic activity was evaluated using diaphragmatic thickening at end-inspiration (TEI), diaphragmatic thickening at end-expiration (TEE), and diaphragmatic thickening fraction (DTF) measured by diaphragmatic US at three time-points; T0, baseline; T1, after DEX sedation; and T2, after DEX recovery. Supplementary oxygen was applied with a simple mask at 5 L/min. Peripheral oxygen saturation (SpO₂), end tidal CO₂ (EtCO₂), and respiratory rate (RR) were recorded. Results: TEI and TEE showed no significant changes during the study period (P = 0.394 and P = 0.205, respectively). DTF was maintained at both T0 and T1 (P = 1.000). At recovery after DEX infusion discontinued, DTF was increased by 3.85%, although such increase was not statistically significant (T0 vs. T2, P = 0.525). SpO₂ remained above 99% and EtCO₂ remained below 36 mmHg. Desaturation episodes were not observed during the study period. Conclusions: Results of this study showed that DEX sedation did not affect the diaphragmatic movement in situation of decreased RR induced by DEX. This finding implies that DEX-induced sedation does not result in clinically significant respiratory depression.

The Feasibility of Ultrasonographic Diaphragmatic Excursion in Healthy Dogs: Effect of Positioning, Diaphragmatic Location, and Body Weight of Dogs

Diaphragmatic excursion (DE) has been utilized for detecting respiratory related problems in humans. However, several factors should be considered such as the ultrasound technique and factors intrinsic to patients. Nevertheless, knowledge of the effect of these factors on DE in dogs is still lacking. The aim of this study was to evaluate the proper ultrasound technique by varying postures and diaphragmatic locations for DE measurement and to explore intrinsic factors such as diaphragmatic sides, sex, and body weight of dogs on DE. The prospective, analytic, cross-sectional study included 44 healthy dogs; 12 beagles and 32 dogs of other breeds. The experiment was divided into (i) an exploration of the proper ultrasound technique by varying postures (supine, standing, and recumbent in each of the right and left lateral positions), diaphragmatic locations (middle crus and proximal to the last rib), and diaphragmatic sublocations (xiphoid, mid, and proximal rib) for detection of DE and (ii) the evaluation of canine intrinsic factors affecting DE. The results show that the mid-diaphragmatic sublocation in the middle crus area in almost all positions revealed the highest percentage DE detection. However, DEs were revealed to be more accessible in the supine position. There was no significant difference in DE between the right and the left diaphragms or between the sexes of beagle dogs. However, body weight was significantly correlated with the DE among dogs of various sizes. In conclusion, the posture of the dogs and the diaphragmatic location can affect DE evaluation. Neither sex nor diaphragmatic side had an influence, but body weight was revealed as a major factor in DE in dogs.

Diaphragmatic Point-of-Care Ultrasound in COVID-19 Patients in the Emergency Department-A Proof-of-Concept Study

Background: Lung Ultrasound Evaluation (LUS) is usefully applied in the Emergency Department (ED) to patients with suspected or confirmed COVID-19. Diaphragmatic Ultrasound (DUS) may provide additional insight into ventilatory function. This proof-of-concept study aimed to evaluate the feasibility of LUS and DUS in a third level ED during the COVID-19 pandemic. Methods: Adult patients presenting with COVID-19 symptoms were eligible. After the physical examination, both LUS and DUS (i.e., diaphragmatic motion and thickness) were performed. All patients were followed after 30 days to determine their need for ventilation, admission, and/or a new ED evaluation after discharge. The diagnostic accuracies of diaphragm measurements in assessing the risk of the 30-day outcome were calculated as well as the measurements’ usefulness. Bland–Altman plots were used for comparing bedside and off-line diaphragm measurements. Results: 118 patients were enrolled. Median thickness and motion were 1.7 mm (iqr 0.4) and 1.8 cm (iqr 0.7), respectively, with a mean difference of 0.009 mm (95% CI −0.037–0.056 mm) and −0.051 cm (95% CI −0.108–0.006 cm), respectively. The 30-day outcome was associated with an increase in thickness (OR 5.84, 95% CI 0.96–35.4), and a lower motion (OR 0.49, 95% CI 0.2–1.21). Conclusion: DUS seemed to be feasible and reliable in the ED in a population of patients presenting with symptoms related to COVID-19 infection.