Comparison of Diaphragm Thickness Measurements Among Postures Via Ultrasound Imaging

Diaphragmatic ultrasound: approach, emerging evidence, and future perspectives in non-ICU patients

Diaphragmatic dysfunction is an important contributor to hypercapnic respiratory failure, but its presence is often challenging to determine at the bedside. Diaphragm ultrasound provides an opportunity to evaluate the function of the diaphragm noninvasively by evaluating the following parameters that can help define diaphragmatic dysfunction: diaphragm excursion, diaphragm muscle thickness, and thickening fraction. Its evaluation has the potential to assist with diagnosis of respiratory failure, provide prognosis, and assist with patient monitoring and should be considered as part of an internal medicine physician's and emergency physician's skill set. This article provides an overview on how to perform diaphragm ultrasound, review its pitfalls, and discuss the evidence of its use in patients with neuromuscular disorders and chronic obstructive pulmonary disease. Finally, its potential emerging uses in the perioperative setting and for evaluation of acute heart failure are discussed.

Diaphragm excursion and thickness in patients with chronic low back pain with and without lumbar instability

Diaphragm is crucial for respiration and plays a significant role in trunk stabilization, particularly during postural tasks. Several studies have focused primarily on trunk muscles in lumbar instability (LI) patients. However, the role of diaphragm remains underexplored. Therefore, this study aimed to compare diaphragm excursion, diaphragm thickness, and lung function represented by predicted percentage of forced vital capacity (%FVC predicted) during a load-lifting at tidal breathing between CLBP patients with (CLBPLI) and without LI (CLBPNLI). Ninety-six participants with CLBP, aged between 20 and 59 years, were divided into CLBPLI and age-matched CLBPNLI groups based on screening tools and clinical tests. Diaphragm excursion and diaphragm thickness were assessed using real-time ultrasound imaging during load-lifting with tidal breathing. Additionally, lung function was measured using a spirometer. CLBPLI group had significantly decreased total diaphragm excursion (p-value = 0.003) and diaphragm thickness at inspiration (p-value = 0.027) and expiration (p-value = 0.34) compared to CLBPNLI group. There were no differences between the groups in excursions during inspiration and expiration, total thickness, thickness change, and %FVC predicted. Individuals with CLBPLI exhibited decreased diaphragm excursion and diaphragm thickness during inspiration and expiration. Addressing diaphragm training in rehabilitation programs may lead to more effective treatment outcomes for LI patients.

Diaphragm Ultrasonography in Patients Without Symptoms or Signs of Respiratory Impairment

INTRODUCTION/AIMS

We aimed to determine differences in diaphragm thickness by including/excluding pleural and peritoneal membranes, the variability in diaphragm thickness over the apposition zone, and the predictors of diaphragm thickness and excursion measurements.

METHODS

At least 10 male and female subjects were recruited for each decade of life. Spirometry, respiratory muscle strength, and the diaphragm ultrasound (US) measurements were performed. Multivariate linear regression was applied to determine associations between diaphragm US parameters, subject characteristics, spirometry, and respiratory muscle strength.

RESULTS

In 156 subjects (mean 47.8 ± 17.7; 20-80 years of age), a significant difference in diaphragm thickness was found when comparing measurements that included and excluded the pleural and peritoneal membranes (mean 2.3 vs. 1.7 mm; average difference of 35% (95% CI [15.3-60]); p < 0.001), as well as the minimum and maximum diaphragm thicknesses at different locations over the apposition zone (mean 1.4 vs. 2.1 mm; p < 0.001). Adjusting for sex, age, height, sniff nasal inspiratory pressure, and forced vital capacity, a positive association was found between body mass index (BMI) and diaphragm thickness (β =0.024, p < 0.001, partial R 2 = 0.31, 95% CI [0.018, 0.030]); a negative association was found with the thickening ratio (β = -0.013, p = 0.050, partial R 2 = 0.04, 95% CI [-0.024, -0.002]).

DISCUSSION

Caliper placement and the location of measurement over the apposition zone greatly affect diaphragm thickness, which is also associated with BMI. Therefore, a standardized protocol for measuring diaphragmatic thickness and excursion is desirable, and BMI should be considered when interpreting the results.

Comparison of ultrasound and dynamic MRI for the measurement of diaphragmatic excursion: A prospective single-center study

OBJECTIVES

Ultrasound (US) measurements of diaphragmatic excursion (DE) are widely used to provide a non-invasive assessment of the diaphragmatic function at the bedside, especially in intensive care. However, this measurement has never been validated against a less operator-dependent technique such as MRI. Dynamic MRI is the only imaging modality that creates a four-dimensional reconstruction of the diaphragm. The primary objective of this study was to assess the agreement between DE obtained using dynamic MRI with those obtained using ultrasound. The secondary objectives were to define DE thresholds for the diagnosis of DD using MRI and to compare the performance of US and MRI to diagnose DD.

METHODS

Prospective single-center study in which consecutive outpatients referred for a dynamic thoracic MRI were included. This study was conducted at a university hospital in Paris, where there was daily access to ultrasound (US) and extensive expertise in diaphragmatic MRI The DE of each hemi-diaphragm was measured sequentially using ultrasound and MRI in random order, during spontaneous breathing (SB) and forced inspiration (FI) by independent observers blinded to each other. We analyzed the agreement between DE obtained using US and MRI for each hemi-diaphragm.

RESULTS

We enrolled forty-five patients, aged 58 ± 36 years, of which twenty-eight (68%) had a confirmed DD. During SB, the mean bias for DE measurement was -3.8 mm, 95% CI [-7.1; -0.6] for the left hemi-diaphragm, and 1.0 mm, 95% CI [-3.5; 5.5] for the right hemi-diaphragm. Limits of agreement (millimeters) were [-25; 17] on the left side, and [-28; 30] on the right side. MRI threshold values for DE defining dysfunction were 11 mm for quiet SB, and 38 mm for FI. These thresholds had a sensitivity of 77.7% and a specificity of 77.4% during SB, with an AUC of 0.86.

CONCLUSION

US and MRI provide different values for DE, probably because the measurements were not obtained exactly at the same localization. Nevertheless, diagnostic performances of MRI and US to recognize DD appeared comparable.

The Perception of the Diaphragm with Ultrasound: Always There Yet Overlooked?

Diaphragm ultrasound makes it possible to diagnose diaphragmatic atrophy and dysfunction. Important indications include unclear dyspnea; diaphragmatic elevation; assessment of diaphragm dysfunction in pulmonary, neuromuscular and neurovascular diseases; and in critically ill patients before noninvasive and mechanical ventilation and follow-up of diaphragm thickness and function during mechanical ventilation with potential prediction of prolonged weaning. In patients with respiratory insufficiency and potential diaphragm dysfunction, it is possible to objectify the contribution of diaphragm dysfunction. In addition, assessment of diaphragmatic hernias, tumors and diaphragmatic dysfunction in COVID-19 and diaphragmatic ultrasound in sports medicine have been described. This narrative review includes the sonomorphology of the diaphragm, standardization of ultrasonographic investigation with transducer positions and ultrasound techniques, normal findings and diagnostic criteria for pathological findings. The correct sonographic measurement, calculation and evaluation can ultimately influence further therapeutic procedures for the patient suffering from diaphragm dysfunction in various diseases.

Diaphragm dysfunction: how to diagnose and how to treat?

The diaphragm, crucial for respiratory function, is susceptible to dysfunction due to various pathologies that can affect the nervous system, neuromuscular junction or the muscle itself. Diaphragmatic dysfunction presents with symptoms ranging from exertional dyspnoea to respiratory failure, significantly impacting patients' quality of life. Diagnosis involves clinical evaluation complemented by imaging and pulmonary function tests. Chest radiography, fluoroscopy, and ultrasonography are pivotal in assessing diaphragmatic movement and excursion, offering varying sensitivities and specificities based on the type and severity of dysfunction. Ultrasonography emerges as a noninvasive bedside tool with high sensitivity and specificity, measuring diaphragm thickness, thickening fraction, and excursion, and enabling monitoring of disease progression and response to treatment over time. Treatment strategies depend on the underlying aetiology and severity, ranging from conservative management to interventions such as surgical plication or diaphragmatic pacing. Ventilatory support, particularly noninvasive ventilation, plays a pivotal role in treatment, enhancing lung function and patient outcomes across unilateral and bilateral dysfunction. Despite advances in diagnostic techniques, awareness and systematic evaluation of diaphragmatic function remain inconsistent across clinical settings. This review consolidates the current understanding of diaphragmatic dysfunction, highlighting diagnostic modalities and treatment options to facilitate early recognition and management of this entity.

Impact of Diaphragm-Strengthening Core Training on Postural Stability in High-Intensity Squats

This study analyzed the effects of an 8-week diaphragmatic core training program on postural stability during high-intensity squats and examined its efficacy in injury prevention and performance enhancement. Thirty-seven male participants were randomly assigned to three groups: diaphragmatic core training group (DCTG, n = 12), core training group (CTG, n = 13), and control group (CG, n = 12). Outcome measurements included diaphragm thickness, respiratory function (mean and maximal respiratory pressures), and squat postural stability (distance between the sacral and upper body center points, peak trunk extension moment, peak knee flexion moment, and dynamic postural stability index). Compared to both CTG and CG, DCTG demonstrated significantly greater improvements in diaphragm thickness (DCTG: 34.62% increase vs. CTG: 1.36% and CG: 3.62%, p < 0.001), mean respiratory pressure (DCTG: 18.88% vs. CTG: 1.31% and CG: 0.02%, p < 0.001), and maximal respiratory pressure (DCTG: 18.62% vs. CTG: 0.72% and CG: 1.90%, p < 0.001). DCTG also showed superior improvements in postural stability measures, including reductions in the distance between sacral and upper body center points (DCTG: -6.19% vs. CTG: -3.26% and CG: +4.55%, p < 0.05), peak trunk extension moment (DCTG: -15.22% vs. CTG: -5.29% and CG: +19.31%, p < 0.001), and dynamic postural stability index (DCTG: -28.13% vs. CTG: -21.43% and CG: no change, p < 0.001). No significant between-group differences were observed in peak knee flexion moment. Core training incorporating diaphragmatic strengthening was more effective than conventional training in improving postural stability during high-intensity squats. Core training programs, including diaphragmatic strengthening exercises, may contribute to injury prevention and performance enhancement in exercises requiring lumbar stability, such as squats.

The Application of Diaphragm Ultrasound in Chronic Obstructive Pulmonary Disease: A Narrative Review

Chronic Obstructive Pulmonary Disease (COPD) is a prevalent condition that poses a significant burden on individuals and society due to its high morbidity and mortality rates. The diaphragm is the main respiratory muscle, its function has a direct impact on the quality of life and prognosis of COPD patients. This article aims to review the structural measurement and functional evaluation methods through the use of diaphragmatic ultrasound and relevant research on its application in clinical practice for COPD patients. Thus, it serves to provide valuable insights for clinical monitoring of diaphragm function in COPD patients, facilitating early clinical intervention and aiding in the recovery of diaphragm function.

Effect of five different body positions on lung function in stroke patients with tracheotomy

BACKGROUND

In stroke patients with tracheotomy, reduced lung function heightens pulmonary infection risk. Body position can affect lung function; however, its impact in stroke patients with tracheostomy remains unclear.

OBJECTIVE

To investigate the influence of five body positions on pulmonary function in stroke patients with tracheotomy.

METHODS

Pulmonary function was assessed in five body positions (supine, supine 30°, supine 60°, sitting, and prone) in 47 stroke patients who underwent tracheotomy. Diaphragmatic excursion during quiet breathing (DEQ), diaphragmatic thickening fraction during quiet breathing (DTFQ), and diaphragmatic excursion during coughing (DEC) were measured using ultrasound. Peak cough flow (PCF) was measured using an electronic peak flow meter.

RESULTS

Different positions had a significant impact on DEQ, DEC, and PCF in stroke patients with tracheotomy, although not on DTFQ. DEQ showed no significant differences between supine 60°, sitting, and prone positions. Both DEC and PCF reached their maximum values in the sitting position. In the sub-group analysis, DEQ in females did not show significant differences across different positions. Both males and females exhibited significantly higher PCF in the sitting compared to supine position. The lung function of obese patients was significantly better in the sitting than in the supine and supine 30° position. Regardless of the patient's level of consciousness and whether the brainstem was injured, lung function in the sitting position was significantly higher than in the supine position.

CONCLUSIONS

Body posture influences lung function in stroke patients with tracheotomy. Patients should adopt a sitting position to enhance pulmonary function.

Effects of inspiratory muscle training on lung function parameter in swimmers: a systematic review and meta-analysis

Background

This systematic review and meta-analysis aimed to assess the impact of inspiratory muscle training (IMT) on lung function parameters (MIP, MEP, FEV1, and FVC) between both elite and non-elite swimmers.

Methods

We searched for controlled clinical trials (CCT) and prospective longitudinal studies (PLS) in elite and non-elite swimmers following an inspiratory muscle training (IMT) protocol with a standardized device, published between 2012 and 2023. The databases used in the search were PubMed, Science Direct, Scopus, Springer, Cochrane Central Register of Controlled Trials, and Google Scholar. The primary outcome assessed was the impact of IMT on lung function parameters, including MIP, MEP, FEV1, and FVC.

Results

We selected 13 articles involving 277 subjects aged 11-21 years, with 61.4% being male, and 84.6% being elite swimmers. The most commonly used IMT device was the PowerBreathe®, prescribed for 3-12 weeks, 1-2 sessions per day, 3-6 times per week, with 30 repetitions, starting at 50% of MIP and progressing up to 80%. The meta-analysis showed that IMT was associated with a higher MIP (MD = 29.35 cmH2O, 95% CI: 13.04-45.65 cmH2O, p < 0.01) without affecting FEV1 and FVC.

Conclusion

The swimmers that used IMT improved muscle strength, specifically MIP, without changes in MEP, FEV1, and FVC.

Diaphragm Ultrasonography: Reference Values and Influencing Factors for Thickness, Thickening Fraction, and Excursion in the Seated Position

INTRODUCTION

Measurements of diaphragm function by ultrasonography are affected by body position, but reference values in the seated position have not been established for an Asian population. This study aimed to determine reference values for diaphragm thickness, thickening fraction, and dome excursion by ultrasonography and to investigate the effects of sex, height, and body mass index.

METHODS

Diaphragm ultrasonography was performed on 109 seated Japanese volunteers with normal respiratory function who were enrolled between March 2022 and January 2023. Thickness, thickening fraction, and excursion were measured. Reference values and the measurement success rate were calculated. Multivariate analysis adjusted for sex, height, and body mass index was performed.

RESULTS

The measurement success rate was better for thickness than for excursion. The mean (lower limit of normal) values on the right/left sides were as follows. During quiet breathing, thickness at end expiration(mm) was 1.7 (0.9)/1.6 (0.80), thickening fraction(%) was 50 (0.0)/52 (0.0), and excursion(cm) was 1.7 (0.5)/1.9 (0.5). During deep breathing, the thickening fraction was 111 (24)/107 (22), and the excursion was 4.4 (1.7)/4.1 (2.0). In multivariate analysis, body mass index was positively associated with thickness but not with the thickening fraction.

CONCLUSION

The reference values in this study were smaller than those in previous reports from Europe. Considering that thickness is influenced by body mass index, using Western reference values in Asia, where the average body mass index is lower, might not be appropriate. The thickening fraction in deep breathing is unaffected by other items and can be used more universally.

Ultrasound in the Study of Thoracic Diseases: Innovative Aspects

Thoracic ultrasound (TU) has rapidly gained popularity over the past 10 years. This is in part because ultrasound equipment is available in many settings, more training programmes are educating trainees in this technique, and ultrasound can be done rapidly without exposure to radiation. The aim of this review is to present the most interesting and innovative aspects of the use of TU in the study of thoracic diseases. In pleural diseases, TU has been a real revolution. It helps to differentiate between different types of pleural effusions, guides the performance of pleural biopsies when necessary and is more cost-effective under these conditions, and assists in the decision to remove thoracic drainage after talc pleurodesis. With the advent of COVID19, the use of TU has increased for the study of lung involvement. Nowadays it helps in the diagnosis of pneumonias, tumours and interstitial diseases, and its use is becoming more and more widespread in the Pneumology ward. In recent years, TU guided biopsies have been shown to be highly cost-effective, with other advantages such as the absence of radiation and the possibility of being performed at bedside. The use of contrast in ultrasound to increase the cost-effectiveness of these biopsies is very promising. In the study of the mediastinum and peripheral pulmonary nodules, the introduction of echobronchoscopy has brought about a radical change. It is a fully established technique in the study of lung cancer patients. The introduction of elastography may help to further improve its cost-effectiveness. In critically-ill patients, diaphragmatic ultrasound helps in the assessment of withdrawal of mechanical ventilation, and is now an indispensable tool in the management of these patients. In neuromuscular patients, ultrasound is a good predictor of impaired lung function. Currently, in Neuromuscular Disease Units, TU is an indispensable tool. Ultrasound study of the intercostal musculature is also effective in the study of respiratory function, and is widely used in Respiratory Rehabilitation. In Intermediate Care Units, thoracic ultrasound is indispensable for patient management. In these units there are ultrasound protocols for the management of patients with acute dyspnoea that have proven to be very effective.

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.

Update on Lean Body Mass Diagnostic Assessment in Critical Illness

Acute critical illnesses can alter vital functions with profound biological, biochemical, metabolic, and functional modifications. Despite etiology, patient's nutritional status is pivotal to guide metabolic support. The assessment of nutritional status remains complex and not completely elucidated. Loss of lean body mass is a clear marker of malnutrition; however, the question of how to investigate it still remains unanswered. Several tools have been implemented to measure lean body mass, including a computed tomography scan, ultrasound, and bioelectrical impedance analysis, although such methods unfortunately require validation. A lack of uniform bedside measurement tools could impact the nutrition outcome. Metabolic assessment, nutritional status, and nutritional risk have a pivotal role in critical care. Therefore, knowledge about the methods used to assess lean body mass in critical illnesses is increasingly required. The aim of the present review is to update the scientific evidence regarding lean body mass diagnostic assessment in critical illness to provide the diagnostic key points for metabolic and nutritional support.

Anatomical Variation in Diaphragm Thickness Assessed with Ultrasound in Healthy Volunteers

Ultrasonography of the diaphragm in the zone of apposition has become increasingly popular to evaluate muscle thickness and thickening fraction. However, measurements in this anatomical location are frequently hindered by factors that constrain physical accessibility or that alter diaphragm position. Therefore, other anatomical positions at the chest wall for transducer placement are used, but the variability in diaphragm thickness across the dome has not been systematically studied. The aim of this study was to evaluate anatomical variation of diaphragm thickness in 46 healthy volunteers on three ventrodorsal lines and two craniocaudal positions on these three lines. The intraclass correlation coefficient (ICC) for diaphragm thickness in the craniocaudal direction on the mid-axillary line was significantly higher than those on the posterior axillary and midclavicular lines, suggesting it had the lowest variability (ICC_midaxillary = .89, 95% confidence interval [CI]: 0.83-0.93, ICC_{posterior axillary} = 0.74, 95% CI: 0.62-0.85, ICC_{midclavicular} = 0.62, 95% CI: 0.43-0.47, p < 0.05). Average diaphragm thickness was comparable on the posterior axillary and midaxillary lines and substantially larger on the midclavicular line (1.24 mm [1.06-1.47], 1.27 mm [1.10-1.42] and 2.32 [1.97-2.70], p < 0.01). We conclude that the normal diaphragm has a large variability in thickness, especially in the ventrodorsal direction. Variability in craniocaudal position is the lowest at the midaxillary line, which therefore appears to be the preferred site for diaphragm thickness measurement.

Intra-Rater Reliability of Ultrasound Measurements of Diaphragm Thickness and Contractility in Individuals with Nonspecific Chronic Neck Pain

Objective

This study aimed to determine within-day intra-rater reliability of ultrasound measurements of the right and left hemidiaphragm thickness and contractility (quantified by percentage thickness change) in supine position during deep breathing in individuals with nonspecific chronic neck pain.

Methods

Seventeen volunteers (20-55 years of age) participated in this observational study. Bilateral diaphragm muscle thickness and contractility (percentage thickness change) were compared between 2 measurement sessions administered by a radiologist using B-mode real-time ultrasound (30 minutes apart). Intraclass correlation coefficient (ICC [3, 3]) as well as the standard error of measurement (SEM), minimal detectable change (MDC), and the coefficient of variation (CV) were used to determine the intra-rater reliability.

Results

The right and left hemidiaphragm thickness showed good to excellent reliability at the end of deep inspiration (ICC, 0.90; 95% confidence interval [CI], 0.72-0.96; and ICC, 0. 93; 95% CI, 0.81-0.97, respectively) as well as at the end of deep expiration (ICC, 0.91; 95% CI, 0.75-0.96; ICC, 0.91; 95% CI, 0.77-0.97; SEM, 0.19; MDC, 0.54; and CV, 7.84%, respectively) and the percentage thickness change (ICC, 0.83; 95% CI, 0.54-0.94; and ICC, 0.93; 95% CI, 0.82-0.97, respectively).

Conclusion

This study found that diagnostic ultrasound measurements of the right and left hemidiaphragm thickness and contractility in supine position during deep breathing in individuals with nonspecific chronic neck pain was reliable. The SEM, MDC, and CV reported may allow for accurate interpretation of diaphragm assessment in a clinical research setting.

EXpert consensus On Diaphragm UltraSonography in the critically ill (EXODUS): a Delphi consensus statement on the measurement of diaphragm ultrasound-derived parameters in a critical care setting

Background

Diaphragm ultrasonography is rapidly evolving in both critical care and research. Nevertheless, methodologically robust guidelines on its methodology and acquiring expertise do not, or only partially, exist. Therefore, we set out to provide consensus-based statements towards a universal measurement protocol for diaphragm ultrasonography and establish key areas for research.

Methods

To formulate a robust expert consensus statement, between November 2020 and May 2021, a two-round, anonymous and online survey-based Delphi study among experts in the field was performed. Based on the literature review, the following domains were chosen: “Anatomy and physiology”, “Transducer Settings”, “Ventilator Impact”, “Learning and expertise”, “Daily practice” and “Future directions”. Agreement of ≥ 68% (≥ 10 panelists) was needed to reach consensus on a question.

Results

Of 18 panelists invited, 14 agreed to participate in the survey. After two rounds, the survey included 117 questions of which 42 questions were designed to collect arguments and opinions and 75 questions aimed at reaching consensus. Of these, 46 (61%) consensus was reached. In both rounds, the response rate was 100%. Among others, there was agreement on measuring thickness between the pleura and peritoneum, using > 10% decrease in thickness as cut-off for atrophy and using 40 examinations as minimum training to use diaphragm ultrasonography in clinical practice. In addition, key areas for research were established.

Conclusion

This expert consensus statement presents the first set of consensus-based statements on diaphragm ultrasonography methodology. They serve to ensure high-quality and homogenous measurements in daily clinical practice and in research. In addition, important gaps in current knowledge and thereby key areas for research are established.

Trial registration The study was pre-registered on the Open Science Framework with registration digital object identifier https://doi.org/10.17605/OSF.IO/HM8UG.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13054-022-03975-5.

Is sarcopenia a risk factor for reduced diaphragm function following hepatic resection? A study protocol for a prospective observational study

INTRODUCTION

Sarcopenia is associated with reduced pulmonary function in healthy adults, as well as with increased risk of pneumonia following abdominal surgery. Consequentially, postoperative pneumonia prolongs hospital admission, and increases in-hospital mortality following a range of surgical interventions. Little is known about the function of the diaphragm in the context of sarcopenia and wasting disorders or how its function is influenced by abdominal surgery. Liver surgery induces reactive pleural effusion in most patients, compromising postoperative pulmonary function. We hypothesise that both major hepatic resection and sarcopenia have a measurable impact on diaphragm function. Furthermore, we hypothesise that sarcopenia is associated with reduced preoperative diaphragm function, and that patients with reduced preoperative diaphragm function show a greater decline and reduced recovery of diaphragm function following major hepatic resection. The primary goal of this study is to evaluate whether sarcopenic patients have a reduced diaphragm function prior to major liver resection compared with non-sarcopenic patients, and to evaluate whether sarcopenic patients show a greater reduction in respiratory muscle function following major liver resection when compared with non-sarcopenic patients.

METHODS AND ANALYSIS

Transcostal B-mode, M-mode ultrasound and speckle tracking imaging will be used to assess diaphragm function perioperatively in 33 sarcopenic and 33 non-sarcopenic patients undergoing right-sided hemihepatectomy starting 1 day prior to surgery and up to 30 days after surgery. In addition, rectus abdominis and quadriceps femoris muscles thickness will be measured using ultrasound to measure sarcopenia, and pulmonary function will be measured using a hand-held bedside spirometer. Muscle mass will be determined preoperatively using CT-muscle volumetry of abdominal muscle and adipose tissue at the third lumbar vertebra level (L3). Muscle function will be assessed using handgrip strength and physical condition will be measured with a short physical performance battery . A rectus abdominis muscle biopsy will be taken intraoperatively to measure proteolytic and mitochondrial activity as well as inflammation and redox status. Systemic inflammation and sarcopenia biomarkers will be assessed in serum acquired perioperatively.

ETHICS AND DISSEMINATION

This trial is open for recruitment. The protocol was approved by the official Independent Medical Ethical Committee at Uniklinik (Rheinish Westphälische Technische Hochschule (RWTH) Aachen (reference EK309-18) in July 2019. Results will be published via international peer-reviewed journals and the findings of the study will be communicated using a comprehensive dissemination strategy aimed at healthcare professionals and patients.

TRIAL REGISTRATION NUMBER

ClinicalTrials. gov (EK309-18); Pre-results.

Ultrasound Assessment of Diaphragm Thickness and Thickening: Reference Values and Limits of Normality When in a Seated Position

Background: Diagnosing diaphragm dysfunction in the absence of complete paralysis remains difficult. The aim of the present study was to assess the normal values of the thickness and the inspiratory thickening of both hemidiaphragms as measured by ultrasonography in healthy volunteers while in a seated position.

Methods: Healthy volunteers with a normal pulmonary function test were recruited. The diaphragmatic thickness was measured on both sides at the zone of apposition of the diaphragm to the rib cage during quiet breathing at end-expiration, end-inspiration, and after maximal inspiration. The thickening ratio, the thickening fraction, and the thickness at end-inspiration divided by the thickness at deep breathing were determined. The mean values and the lower and upper limits of normal were determined for men and women.

Results: 200 healthy volunteers (100 men and 100 women) were included in the study. The statistical analysis revealed that women had a thinner hemidiaphragm than men on both sides and at the various breathing times studied. The lower limit of normality of the diaphragm thickness measured at end-expiration was estimated to be 1.3 mm in men and 1.1 mm in women, on both sides. The thickening fraction did not differ significantly between men and women. In men, it ranged from 60 to 260% on the left side and from 57 to 200% on the right side. In women, it ranged from 58 to 264% on the left side and from 60 to 229% on the right side. The lower limits of normality of the thickening fraction were determined to be 40 and 39% in men and 39 and 48% in women for the right and left hemidiaphragms, respectively. The upper limit for normal of the mean of both sides of the ratio thickness at end-inspiration divided by the thickness at deep breathing was determined to be 0.78 in women and 0.79 in men.

Conclusion: The normal values of thickness and the indexes of diaphragmatic function should help clinicians with detecting diaphragm atrophy and dysfunction.

NEUROMUSCULAR MECHANISMS AND EFFECTS OF CORE STABILIZATIONS ON TRUNK AND HIP MUSCLE ACTIVITY DURING LIFTING MOVEMENT

While the presence of lumbopelvic-hip stabilization has been provided as an importance component of the intra-abdominal pressure and dynamic spinal stabilization prior to movement, no previous study has investigated the effects in nonsymptomatic adults. This study investigated neuromuscular mechanisms and effects by comparing the natural core stabilization (NCS), abdominal bracing stabilization (ABS), and coordinated core stabilization (CCS) techniques in nonsymptomatic adults during lifting movement. A convenience sample of 40 nonsymptomatic adults (mean [Formula: see text] standard deviation, [Formula: see text]; 27 males, 13 females) were randomized into the NCS, ABS, and CCS techniques during lifting movement. The clinical outcomes included the deep and local (transverse abdominis (TrA), internal oblique (IO), and gluteus maximus (Gmax)) and superficial and global muscle (thoracic erector spinae (TES), lumbar erector spinae (LES), and external oblique (EO)) activation and balance ratios (IO/LES and Gmax/LES) and onset time co-activation ratios (IO/LES and Gmax/LES). One-way repeated-measures analysis of variance (ANOVA) and Bonferroni correction revealed that the IO/LES and Gmax/LES balance and activation ratios were greater in CCS than in NCS and ABS. The onset time co-activation ratio was improved in CCS as compared with NCS and ABS, and ABS dropped equally inversely to NCS. Our results provide novel therapeutic evidence that CCS-based lifting movement is more balanced or coordinated in terms of neuromuscular control than the other techniques and may be used as an alternative exercise for core stabilization.

Diaphragmatic paralysis, respiratory function, and postoperative pain after interscalene brachial plexus block with a reduced dose of 10 ml levobupivacaine 0.25% versus a 20 ml dose in patients undergoing arthroscopic shoulder surgery: study protocol for the randomized controlled double-blind REDOLEV study

BACKGROUND

Arthroscopic shoulder surgery causes severe postoperative pain. An interscalene brachial plexus block provides adequate analgesia, but unintended spread of the local anesthetic administered may result in a phrenic nerve block, usually associated with a nonnegligible incidence of acute hemidiaphragmatic paralysis. The main purpose of this trial will be to analyze the incidence of hemidiaphragmatic paralysis ensuing after interscalene brachial plexus block in patients undergoing arthroscopic shoulder surgery administered a standard volume (20 ml) vs. a low volume (10 ml) of levobupivacaine 0.25%.

METHODS

This will be a prospective double-blind randomized controlled single-center two-arm comparative trial. Forty-eight patients will be included. The primary goal will be to ultrasonographically determine the incidence of hemidiaphragmatic paralysis by calculating the diaphragmatic thickness ratio in each group. The secondary goals will be to compare the two arms in terms of (1) decrease in forced vital capacity and (2) in forced expiratory volume at 1 s by spirometry; (3) decrease in diaphragmatic excursion by ultrasound; (4) 24-h total intravenous morphine consumption; (5) time to first opioid request of a patient-controlled analgesia pump; and (6) postoperative complications.

DISCUSSION

This trial will demonstrate that a low-volume interscalene brachial plexus block decreases hemidiaphragmatic paralysis following arthroscopic shoulder surgery according to spirometry and ultrasound measurements and does not provide inferior postoperative analgesia to the standard volume, as measured by opioid requirements.

TRIAL REGISTRATION

EudraCT and Spanish Trial Register (REec) registration number: 2019-003855-12 (registered on 7 January 2020). ClinicalTrials.gov identification number: NCT04385966 (retrospectively registered on 8 May 2020). Ethics Committee approval: EC19/093 (18 December 2019).

Ultrasound and non-ultrasound imaging techniques in the assessment of diaphragmatic dysfunction

Diaphragm muscle dysfunction is increasingly recognized as an important element of several diseases including neuromuscular disease, chronic obstructive pulmonary disease and diaphragm dysfunction in critically ill patients. Functional evaluation of the diaphragm is challenging. Use of volitional maneuvers to test the diaphragm can be limited by patient effort. Non-volitional tests such as those using neuromuscular stimulation are technically complex, since the muscle itself is relatively inaccessible. As such, there is a growing interest in using imaging techniques to characterize diaphragm muscle dysfunction. Selecting the appropriate imaging technique for a given clinical scenario is a critical step in the evaluation of patients suspected of having diaphragm dysfunction. In this review, we aim to present a detailed analysis of evidence for the use of ultrasound and non-ultrasound imaging techniques in the assessment of diaphragm dysfunction. We highlight the utility of the qualitative information gathered by ultrasound imaging as a means to assess integrity, excursion, thickness, and thickening of the diaphragm. In contrast, quantitative ultrasound analysis of the diaphragm is marred by inherent limitations of this technique, and we provide a detailed examination of these limitations. We evaluate non-ultrasound imaging modalities that apply static techniques (chest radiograph, computerized tomography and magnetic resonance imaging), used to assess muscle position, shape and dimension. We also evaluate non-ultrasound imaging modalities that apply dynamic imaging (fluoroscopy and dynamic magnetic resonance imaging) to assess diaphragm motion. Finally, we critically review the application of each of these techniques in the clinical setting when diaphragm dysfunction is suspected.

Assessment of diaphragmatic function by ultrasonography: Current approach and perspectives

This article reports the various methods used to assess diaphragmatic function by ultrasonography. The excursions of the two hemidiaphragms can be measured using two-dimensional or M-mode ultrasonography, during respiratory maneuvers such as quiet breathing, voluntary sniffing and deep inspiration. On the zone of apposition to the rib cage for both hemidiaphragms, it is possible to measure the thickness on expiration and during deep breathing to assess the percentage of thickening during inspiration. These two approaches make it possible to assess the quality of the diaphragmatic function and the diagnosis of diaphragmatic paralysis or dysfunction. These methods are particularly useful in circumstances where there is a high risk of phrenic nerve injury or in diseases affecting the contractility or the motion of the diaphragm such as neuro-muscular diseases. Recent methods such as speckle tracking imaging and ultrasound shear wave elastography should provide more detailed information for better assessment of diaphragmatic function.

Relationship between the fall in blood pressure in the standing position and diaphragmatic muscle thickness: proof of concept study

BACKGROUND

The diaphragm is an important muscle of respiration, and regulates the intrathoracic pressure. Blood pressure is regulated by the baroreceptor reflex system, and is also affected by intrathoracic pressure. We examined the relationship between the diaphragmatic muscle thickness and the degree of drop in blood pressure in the standing position.

METHODS

We prospectively studied 15 healthy subjects. The diaphragmatic muscle thickness was measured using a B-mode ultrasonic imaging device. The blood pressure before and after standing was measured by a head-up tilt test.

RESULTS

The diastolic blood pressure difference during expiration and inspiration showed a significant correlation with the diaphragmatic muscle thickness (r = 0.578, P = 0.024 and r = 0.518, P = 0.048, respectively).

CONCLUSION

The diaphragmatic muscle thickness was related to the fall in diastolic blood pressure in the standing position. This indicates that adequate diaphragmatic muscle thickness helps to maintain intrathoracic pressure and prevents excessive drop in blood pressure in the standing position.

ERS statement on respiratory muscle testing at rest and during exercise

Assessing respiratory mechanics and muscle function is critical for both clinical practice and research purposes. Several methodological developments over the past two decades have enhanced our understanding of respiratory muscle function and responses to interventions across the spectrum of health and disease. They are especially useful in diagnosing, phenotyping and assessing treatment efficacy in patients with respiratory symptoms and neuromuscular diseases. Considerable research has been undertaken over the past 17 years, since the publication of the previous American Thoracic Society (ATS)/European Respiratory Society (ERS) statement on respiratory muscle testing in 2002. Key advances have been made in the field of mechanics of breathing, respiratory muscle neurophysiology (electromyography, electroencephalography and transcranial magnetic stimulation) and on respiratory muscle imaging (ultrasound, optoelectronic plethysmography and structured light plethysmography). Accordingly, this ERS task force reviewed the field of respiratory muscle testing in health and disease, with particular reference to data obtained since the previous ATS/ERS statement. It summarises the most recent scientific and methodological developments regarding respiratory mechanics and respiratory muscle assessment by addressing the validity, precision, reproducibility, prognostic value and responsiveness to interventions of various methods. A particular emphasis is placed on assessment during exercise, which is a useful condition to stress the respiratory system.

A narrative review of diaphragm ultrasound to predict weaning from mechanical ventilation: where are we and where are we heading?

Background

The use of ultrasound to visualize the diaphragm is well established. Over the last 15 years, certain indices of diaphragm function, namely diaphragm thickness, thickening fraction and excursion have been established for mechanically ventilated patients to track changes in diaphragm size and function over time, to assess and diagnose diaphragmatic dysfunction, and to evaluate if these indices can predict successful liberation from mechanical ventilation. In the last 2 years, three meta-analyses and a systematic review have assessed the usability of diaphragmatic ultrasound to predict successful weaning. Since then, further data have been published on the topic.

Conclusions

The aim of this narrative review is to briefly describe the common methods of diaphragmatic function assessment using ultrasound techniques, before summarizing the major points raised by the recent reviews. A narrative summary of the most recent data will be presented, before concluding with a brief discussion of future research directions in this field.

Diaphragmatic Neurophysiology and Respiratory Markers in ALS

The main reason for short survival in amyotrophic lateral sclerosis (ALS) is involvement of respiratory muscles. Severe compromise of diaphragmatic function due to marked loss of motor units causes poor inspiratory strength leading to symptomatic respiratory fatigue, and hypercapnia and hypoxemia, often firstly detected while sleeping supine. Weakness of expiratory muscles leads to cough weakness and poor bronchial clearance, increasing the risk of respiratory infection. Respiratory tests should therefore encompass inspiratory and expiratory function, and include measurements of blood gases during sleep. Non-volitional tests, such as phrenic nerve stimulation, are particularly convenient for investigating respiratory function in patients unable to perform standard respiratory function tests due to poor cooperation or facial weakness. However, SNIP is a sensitive test when patients with bulbar involvement are able to perform the necessary maneuvers. It is likely that central respiratory regulation is disturbed in some ALS patients, but its evaluation is more complex and not regularly implemented. Practical tests should incorporate tolerability, sensitivity, easy application for regular monitoring, and prognostic value. Impending respiratory failure can cause increased circulating inflammatory markers, but molecular assessment of respiratory distress requires further study. In future, home-monitoring of patients with accessible devices should be developed.

The effect of stabilization exercises on diaphragm muscle thickness and movement in women with low back pain

BACKGROUND

Diaphragm is an important component of spinal stability. In presence of low back pain, there may be some alterations in this muscle like other muscles that are responsible for lumbal stabilization.

OBJECTIVE

This study aims to assess the effects of stabilization exercises on diaphragm muscle thickness and motion along with lumbopelvic stability.

METHODS

Twenty-one women with low back pain participated in the study. Stabilization exercises including motor control training were performed on treatment group (n= 11). In control group (n= 10), strentghening exercises were peformed for back muscles, abdominal muscles and hip muscles. The patients underwent a total of 30 sessions of treatment, 3 days in a week for 10 weeks. The diaphragm muscle thickness and motion was evaluated using ultrasound (US), and lumbopelvic stability was evaluated using lumbopelvic stability tests.

RESULTS

After the treatment, in the treatment group, increase in diaphragm thickness and improvement in lumbopelvic stability were statically significant (p< 0.05). However, there were no significant changes in diaphragm motion in both groups (p> 0.05).

CONCLUSIONS

As a result, stabilization exercises increase diaphragm muscle thickness and improve lumbopelvic stability in women with low back pain. Therefore, stabilization exercises should be considered as a part of the treatment program in low back pain.

Diaphragmatic Ultrasound Correlates with Inspiratory Muscle Strength and Pulmonary Function in Healthy Subjects

Diaphragm ultrasound (DUS) has been used to identify diaphragm dysfunction. However, its correlations with respiratory strength and lung function are unclear, even in healthy patients. A total of 64 healthy patients (30 males) had lung function and inspiratory strength (maximal inspiratory pressure and sniff nasal inspiratory pressure) measured. Gastric and oesophageal pressures were measured in a subgroup (n = 40). DUS was characterized by mobility (quiet breathing [QB] and deep breathing [DB]) and thickness (at functional residual capacity [Th_FRC] and total lung capacity [Th_TLC]). We calculated the thickening fraction (TF). During QB, DUS was similar between sexes. However, during DB, females had lower mobility, thickness and TF than males. Mobility at DB, Th_TLC and TF significantly correlated with lung function and inspiratory strength. These correlations were affected by sex. DUS correlated with inspiratory gastric pressure. In healthy patients, DUS correlated with lung function and inspiratory strength during DB. Significant differences between genders were noticeable when DUS was performed during DB.

Diaphragm Dysfunction: Diagnostic Approaches and Management Strategies

The diaphragm is the main inspiratory muscle, and its dysfunction can lead to significant adverse clinical consequences. The aim of this review is to provide clinicians with an overview of the main causes of uni- and bi-lateral diaphragm dysfunction, explore the clinical and physiological consequences of the disease on lung function, exercise physiology and sleep and review the available diagnostic tools used in the evaluation of diaphragm function. A particular emphasis is placed on the clinical significance of diaphragm weakness in the intensive care unit setting and the use of ultrasound to evaluate diaphragmatic action.