Two-dimensional ultrasound imaging of the diaphragm: quantitative values in normal subjects

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.

Assessment of Respiratory Muscles, Lung Parenchyma, and Cardiac Function by Ultrasound for Predicting Weaning Failure in Critically Ill Adults: A Prospective Observational Study

OBJECTIVES

The parasternal intercostal muscle activity, a marker of accessory muscle usage, is found to correlate inversely with the pressure-generating capacity of the diaphragm and level of support of mechanical ventilation. The primary objective of our study was to determine whether the parasternal intercostal muscle thickening fraction (PMTF) measured by ultrasonography can predict weaning. We also evaluated whether addition of lung ultrasound score and echocardiographic assessment can add on to predicting weaning failure.

METHODS

This prospective observational study conducted in a mixed medical-surgical intensive care unit, included 60 adult patients who were eligible for a spontaneous breathing trial (SBT) after being invasively mechanically ventilated for more than 48 hours. Ultrasound of respiratory muscles, lung parenchyma, and echocardiographic assessment were performed before and after 120 minutes of SBT. Parasternal intercostal muscles were imaged with a high frequency linear probe on the right second intercostal space 5 cm lateral to the sternal margin. PMTF was calculated as (maximum-minimum thickness)/minimum thickness.

RESULTS

Among 60 patients, SBT failure was seen in 11 patients and extubation failed in 8 patients. PMTF (%) was significantly higher in the weaning failure group (13.33 [8.33-19.05]) as compared to patients with successful weaning (6.67 [6.06-11.54]). Diaphragmatic thickening fraction (DTF) correlated inversely to PMTF in patients with weaning failure. A pre-SBT PMTF cut-off of ≥7.7% and post-SBT cut-off of ≥15.38% were good predictors of weaning failure and extubation failure, respectively.

CONCLUSIONS

PMTF has good discriminatory power to predict weaning outcomes (area under the receiver operating characteristic curve: 0.74 [0.59-0.88]). Pre-SBT PMTF had similar power as DTF to predict weaning failure.

Preoperative Diaphragm Muscle Atrophy Increases the Likelihood of Postoperative Pulmonary Complications After Lung Cancer Resection: A Pilot Study

Background/Objectives: Various conditions contribute to the development of postoperative pulmonary complications (PPCs) following thoracic surgery. In this study, the aim was to investigate whether preoperative diaphragm dysfunction is associated with an increased risk of PPCs after lung cancer resection. Methods: We prospectively examined 45 patients scheduled for video-assisted thoracoscopic surgery (VATS) lobectomy or open thoracotomy. Relevant clinical data were retrieved from hospital database records, while diaphragm muscles were assessed using ultrasound. Results: Our results demonstrated that preoperative diaphragm muscle atrophy was significantly associated with a higher risk of developing PPCs compared to patients with normal diaphragm thickness. Diaphragm atrophy was also linked to prolonged hospital stays. Additionally, we observed a moderate correlation between expiratory diaphragm thickness and the number of PPCs. Conclusions: Low diaphragm expiratory thickness is associated with postoperative pulmonary complications after lobectomy for lung cancer. Importantly, unlike other predictive factors such as age, COPD, or smoking, diaphragmatic atrophy is a modifiable risk factor that can potentially be addressed through early therapeutic intervention.

Predictive Value of Diaphragm Muscle Ultrasound for Ventilator Weaning Outcomes After Cervical Spinal Cord Injury: A Retrospective Case Series

OBJECTIVES

Neuromuscular respiratory failure after cervical spinal cord injury (cSCI) can lead to dependence on an invasive mechanical ventilator. Ventilator-free breathing after cSCI is associated with improved morbidity, mortality, and quality of life. We investigated the use of diaphragm muscle ultrasound to predict ventilator weaning outcomes after cSCI.

METHODS

This is a retrospective case series conducted at a university-affiliated freestanding inpatient rehabilitation facility. We identified patients with cSCI who had a tracheostomy and were dependent on an invasive mechanical ventilator at the time of admission to inpatient rehabilitation. A diaphragm muscle ultrasound was performed, which included measurements of the thickness of the diaphragm and a calculation of the thickening ratio (TR), which reflects diaphragm muscle contraction. The primary outcome measure was the need for mechanical ventilation at time of discharge from the inpatient rehabilitation facility. Successful ventilator weaning was defined as either daytime or full 24-hour ventilator-free breathing.

RESULTS

Of the 21 patients enrolled, 11 (52%) were able to wean successfully (partially or fully) from the ventilator. Of the ultrasound measurements that were taken, the TR was the optimal predictor for ventilator weaning outcomes. A threshold of TR ≥ 1.2 as the maximum hemidiaphragm measurement had a sensitivity of 1.0 and specificity of 0.90 for predicting ventilator weaning.

CONCLUSION

Normal diaphragm contractility (TR ≥ 1.2) as determined by diaphragm muscle ultrasound is a strong positive predictor for successful ventilator weaning in patients with cSCI. Utilizing diaphragm ultrasound, rehabilitation physicians can set precision rehabilitation goals regarding ventilator weaning for inpatients with respiratory failure after cSCI, potentially improving both outcomes and quality of life.

Review of Point-of-Care Diaphragmatic Ultrasound in Emergency Medicine: Background, Techniques, Achieving Competency, Research, and Recommendations

ABSTRACT

The diaphragm is the major muscle of inspiration accounting for approximately 70% of the inspired tidal volume. Point-of-care diaphragmatic ultrasound offers the ability to quantitatively assess diaphragmatic function, perform serial evaluations over time, and visualize structures above and below the diaphragm. Although interest in point-of-care ultrasound (POCUS) of the diaphragm is developing in the emergency medicine, assessment of the diaphragm and its function is not recognized as a core application by national organizations or expert guidelines. As a result, it is infrequently performed, and its potential value in research or clinical practice may not be fully appreciated. The purpose of this review is to describe the developmental aspects of the diaphragm as it pertains to POCUS, discuss the POCUS techniques for evaluating diaphragmatic function, address competency acquisition in this POCUS application, summarize relevant research in the ED, and provide a summary of recommendations for further research and clinical utilization of POCUS in diaphragm evaluation.

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.

Phrenic neuropathy etiologies and recovery trajectories in outpatient rehabilitation and neuromuscular medicine clinics: A retrospective analysis

INTRODUCTION/AIMS

Phrenic neuropathy (PhN) impairs diaphragm muscle function, causing a spectrum of breathing disability. PhN etiologies and their natural history are ill-defined. This knowledge gap hinders informed prognosis and management decisions. This study aims to help fill this knowledge gap on PhN etiologies, outcomes, and recovery patterns, especially in the context of nonsurgical clinical practice.

METHODS

This was a retrospective study from two interdisciplinary clinics, physiatry and neurology based. Patients were included if PhN was identified, and other causes of hemi-diaphragm muscle dysfunction excluded. Patients were followed serially at the discretion of the neuromuscular-trained neurologist or physiatrist. Recovery was assessed using pulmonary function tests (PFTs), diaphragm muscle ultrasound (US) thickening ratio, and patient-reported outcomes in patients presenting within 2 years of PhN onset.

RESULTS

We identified 151 patients with PhN. The most common etiologies were idiopathic (27%), associated with cardiothoracic procedure (24%), and intensive care unit (17%). Of these patients, 117 (77%) were evaluated within 2 years of PhN onset. Of patients included in outcome analyses, 64% saw improvement on serial US, 50% on serial PFTs and 79% reported symptomatic improvement at an average of 15, 16, and 17 months, respectively.

DISCUSSION

A clear majority of PhN patients show improvement in diaphragm muscle function, but on average, improvements took 15-17 months depending on the assessment type. These insights are vital for developing tailored treatments and can guide physicians in prognosis and decision-making, especially if more invasive interventions are being considered.

Evaluation and management of dyspnea as the dominant presenting feature in neuromuscular disorders

Dyspnea is a common symptom in neuromuscular disorders and, although multifactorial, it is usually due to respiratory muscle involvement, associated musculoskeletal changes such as scoliosis or, in certain neuromuscular conditions, cardiomyopathy. Clinical history can elicit symptoms such as orthopnea, trepopnea, sleep disruption, dysphagia, weak cough, and difficulty with secretion clearance. The examination is essential to assist with the diagnosis of an underlying neurologic disorder and determine whether dyspnea is from a cardiac or pulmonary origin. Specific attention should be given to possible muscle loss, use of accessory muscles of breathing, difficulty with neck flexion/extension, presence of thoraco-abdominal paradox, conversational dyspnea, cardiac examination, and should include a detailed neurological examination directed at the suspected differential diagnosis. Pulmonary function testing including sitting and supine spirometry, measures of inspiratory and expiratory muscle strength, cough peak flow, sniff nasal inspiratory pressure, pulse oximetry, transcutaneous CO2, and arterial blood gases will help determine the extent of the respiratory muscle involvement, assess for hypercapnic or hypoxemic respiratory failure, and qualify the patient for noninvasive ventilation when appropriate. Additional testing includes dynamic imaging with sniff fluoroscopy or diaphragm ultrasound, and diaphragm electromyography. Polysomnography is indicated for sleep related symptoms that are not otherwise explained. Noninvasive ventilation alleviates dyspnea and nocturnal symptoms, improves quality of life, and prolongs survival. Therapy targeted at neuromuscular disorders may help control the disease or favorably modify its course. For patients who have difficulty with secretion clearance, support of expiratory function with mechanical insufflation-exsufflation, oscillatory devices can reduce the aspiration risk.

Decreased diaphragm moving distance measured by ultrasound speckle tracking reflects poor prognosis in amyotrophic lateral sclerosis

Objective

Decreased cephalocaudal diaphragm movement may indicate respiratory dysfunction in amyotrophic lateral sclerosis (ALS). We aimed to evaluate diaphragm function in ALS using ultrasound speckle tracking, an image-analysis technology that follows similar pixel patterns.

Methods

We developed an offline application that tracks pixel patterns of recorded ultrasound video images using speckle-tracking methods. Ultrasonography of the diaphragm movement during spontaneous quiet respiration was performed on 19 ALS patients and 21 controls to measure the diaphragm moving distance (DMD) in the cephalocaudal direction during a single respiration. We compared respiratory function measures and analyzed the relationship between the clinical profiles and DMD.

Results

DMD was significantly lower in ALS patients than in the control group (0.6 ± 1.4 mm vs 2.2 ± 2.2 mm, p < 0.01) and positively correlated with phrenic nerve compound motor action potential amplitude (R = 0.63, p = 0.01). DMD was negatively correlated with the change in the ALS Functional Rating Scale-Revised scores per month after the exam (R = -0.61, p = 0.02), and those with a larger rate of decline had a significantly lower DMD (p = 0.03).

Conclusions

Diaphragm ultrasound speckle tracking enabled the detection of diaphragm dysfunction in ALS.

Significance

Diaphragm ultrasound speckle tracking may be useful for predicting prognosis.

Diaphragm Assessment by Multimodal Ultrasound Imaging in Healthy Subjects

Background

In recent years, diaphragm ultrasound (DUS) has been used to identify diaphragm dysfunction in the intensive care unit (ICU). However, there are few studies on DUS parameters to evaluate function, normal ranges, and influencing factors in population. The aim of this study is to provide a methodological reference for clinical evaluation of diaphragm function by measuring different DUS parameters in a healthy population.

Methods

A descriptive study was conducted 212 (105 males, 107 females) subjects with normal spirometry underwent ultrasound imaging in this study. The diaphragm contraction and motion related parameters and shear wave velocity (SWV) were measured in the supine position. The effects of gender, age, body mass index (BMI) and lifestyle on diaphragm ultrasound parameters were analyzed.

Results

The diaphragm thickness at end-expiration (DT-exp) was 0.14 ±0.05 cm, the diaphragm thickness at end- inspiration (DT-insp) was 0.29±0.10 cm, with thickening fraction (TF) was 1.11±0.54. The diaphragm excursion (DE) was 1.68±0.37cm and diaphragm velocity was 1.45±0.41 cm/s during calm breathing. During deep breathing, the DE was 5.06±1.40cm and diaphragm velocity was 3.20±1.18 cm/s. The Diaphragm shear modulus-longitudinal view were Mean16.72±4.07kPa, Max25.04±5.58kPa, Min11.06±3.88kPa, SD2.56±0.98. The results of diaphragmatic measurement showed that the DT of males was significantly greater than that of females (P< 0.05), but there was no significant difference in TF. The DT-insp (r=0.155, P= 0.024) and the DT-exp (r=0.252, P=0.000) were positively correlated with age, and the DE during calm breathing was negatively correlated with age (r=-0.218, P= 0.001) and BMI (r=-00.280, P= 0.000). The DE (R=0.371, P=0.000) and velocity (R=0.368, P=0.000) during deep breathing were correlated with lifestyle.

Conclusion

Our study provides normal reference values of the diaphragm and evaluates the influence of gender, age, body mass index and lifestyle on diaphragmatic morphology.

Paradoxical thinning of the diaphragm on ultrasound is a risk factor for requiring non-invasive ventilation in patients with neuromuscular diaphragmatic dysfunction

INTRODUCTION/AIMS

Point-of-care ultrasound of the diaphragm is highly sensitive and specific in the detection of neuromuscular diaphragmatic dysfunction. In some patients with neuromuscular diaphragmatic dysfunction, paradoxical thinning of the diaphragm during inspiration is observed on ultrasound; however, its frequency, electrodiagnostic associations, and prognostic significance remain uncertain.

METHODS

Medical records of patients presenting to two electrodiagnostic laboratories (Mayo Clinic, Rochester, Minnesota and University of Alberta, Edmonton, Alberta) from January 1, 2022 to December 31, 2022, for evaluation of suspected neuromuscular respiratory failure, were reviewed.

RESULTS

214 patients were referred and 19 patients excluded due to incomplete information. Of 195 patients (384 hemidiaphragms), 104 had phrenic neuropathy, 12 had myopathy, and 79 had no evidence of neuromuscular disease affecting the diaphragm. Paradoxical thinning occurred in 31 (27%) patients with neuromuscular diaphragmatic dysfunction and was unilateral in 30, the majority (83%) having normal contralateral ultrasound. Phrenic nerve conduction studies and diaphragm electromyography results did not distinguish patients with paradoxical thinning versus without. Most patients (71%) with paradoxical thinning required non-invasive ventilation (NIV), including 16 with unilateral paradoxical thinning. Paradoxical thinning and BMI ≥30 kg/m2 were risk factors for requiring NIV in multivariable logistic regression analysis, with odds ratios of 2.887 (95% CI:1.166, 7.151) and 2.561 (95% CI: 1.186, 5.532), respectively.

DISCUSSION

Paradoxical thinning of the diaphragm occurs in patients with prominent neuromuscular diaphragmatic dysfunction, most commonly from phrenic neuropathy, and is a significant risk factor for requiring NIV. Unilateral paradoxical thinning is sufficient for needing NIV. BMI ≥30 kg/m2 additionally increases risk of requiring NIV in patients with neuromuscular diaphragmatic dysfunction.

Ultrasonographic Assessment of the Diaphragm

Mechanical ventilation injures not only the lungs but also the diaphragm, resulting in dysfunction associated with poor outcomes. Diaphragm ultrasonography is a noninvasive, cost-effective, and reproducible diagnostic method used to monitor the condition and function of the diaphragm. With advances in ultrasound technology and the expansion of its clinical applications, diaphragm ultrasonography has become increasingly important as a tool to visualize and quantify diaphragmatic morphology and function across multiple medical specialties, including pulmonology, critical care, and rehabilitation medicine. This comprehensive review aims to provide an in-depth analysis of the role and limitations of ultrasonography in assessing the diaphragm, especially among critically ill patients. Furthermore, we discuss a recently published expert consensus and provide a perspective for the future.

Diaphragm and Lung Transplantation

Mutual interactions between the diaphragm and lung transplantation (LTx) are known to exist. Before LTx, many factors can exert notable impact on the diaphragmatic function, such as the underlying respiratory disease, the comorbidities, and the chronic treatments of the patient. In the post-LTx setting, even the surgical procedure itself can cause a stressful trauma to the diaphragm, potentially leading to morphological and functional alterations. Conversely, the diaphragm can significantly influence various aspects of the LTx process, ranging from graft-to-chest cavity size matching to the long-term postoperative respiratory performance of the recipient. Despite this, there are still no standard criteria for evaluating, defining, and managing diaphragmatic dysfunction in the context of LTx to date. This deficiency hampers the accurate assessment of those factors which affect the diaphragm and its reciprocal influence on LTx outcomes. The objective of this narrative review is to delve into the complex role the diaphragm plays in the different stages of LTx and into the modifications of this muscle following surgery.

Ultrasound assessment of diaphragmatic dysfunction in non-critically ill patients: relevant indicators and update

Diaphragm dysfunction (DD) can be classified as mild, resulting in diaphragmatic weakness, or severe, resulting in diaphragmatic paralysis. Various factors such as prolonged mechanical ventilation, surgical trauma, and inflammation can cause diaphragmatic injury, leading to negative outcomes for patients, including extended bed rest and increased risk of pulmonary complications. Therefore, it is crucial to protect and monitor diaphragmatic function. Impaired diaphragmatic function directly impacts ventilation, as the diaphragm is the primary muscle involved in inhalation. Even unilateral DD can cause ventilation abnormalities, which in turn lead to impaired gas exchange, this makes weaning from mechanical ventilation challenging and contributes to a higher incidence of ventilator-induced diaphragm dysfunction and prolonged ICU stays. However, there is insufficient research on DD in non-ICU patients, and DD can occur in all phases of the perioperative period. Furthermore, the current literature lacks standardized ultrasound indicators and diagnostic criteria for assessing diaphragmatic dysfunction. As a result, the full potential of diaphragmatic ultrasound parameters in quickly and accurately assessing diaphragmatic function and guiding diagnostic and therapeutic decisions has not been realized.

Ultrasonographic changes and impact factors of diaphragmatic function in patients with obstructive sleep apnea-hypopnea syndrome

PURPOSE

Diaphragmatic impairment has been reported in obstructive sleep apnea-hypopnea syndrome (OSAHS) patients. However, the risk factors of diaphragmatic dysfunction are unclear. This study was conducted to evaluate the diaphragmatic function and to investigate impact factors of ultrasonographic changes of the diaphragm in OSAHS patients.

METHODS

This cross-sectional study recruited 150 snoring patients. All patients were divided into the control group (AHI < 5/h, n = 20), the mild-to-moderate OSAHS group (5/h ≤ AHI ≤ 30/h, n = 61), and the severe OSAHS group (AHI > 30/h, n = 69). Diaphragmatic thickness at function residual capacity (TFRC) and total lung capacity (TTLC) were measured by two-dimensional ultrasound, and the diaphragmatic excursion during tidal and deep breath was measured by M-mode ultrasound. The diaphragmatic thickening fraction (TF) was calculated. Spearman analysis and multiple linear stepwise regression analysis were conducted to analyze the impact factors of diaphragmatic function.

RESULTS

TFRC in the control group, mild-to-moderate OSAHS group, and severe OSAHS group was 1.23 (1.10, 1.39) mm, 1.60 (1.43, 1.85) mm, and 1.90 (1.70, 2.25) mm; TTLC was 2.75 (2.53, 2.93) mm, 3.25 (2.90, 3.55) mm, and 3.60 (3.33, 3.90) mm, and TF was 119.23% (102.94, 155.97), 96.55% (74.34, 119.11), and 85.29% (60.68,101.22). There were across-group significant differences in TFRC, TTLC, and TF (P < 0.05). The oxygen desaturation index was the influencing factor of TFRC, TTLC, and TF (P < 0.05).

CONCLUSION

The diaphragm is thickened and diaphragmatic contractility is decreased in OSAHS patients. Nocturnal intermittent hypoxia is a risk factor for diaphragmatic hypertrophy and impaired diaphragmatic contractility.

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

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

Diagnosis of hemidiaphragm paralysis: refine ultrasound criteria

Background

Ultrasound has demonstrated its interest in the analysis of diaphragm function in patients with respiratory failure. The criteria used to diagnose hemidiaphragm paralysis are not well defined.

Methods

The aim of this observational retrospective study was to describe the ultrasound findings in 103 patients with diaphragm paralysis, previously diagnosed by conventional methods after various circumstances such as trauma or surgery. The ultrasound study included the recording of excursions of both diaphragmatic domes and the measurement of inspiratory thickening.

Results

On paralyzed hemidiaphragm, thickening was less than 20% in all patients during deep inspiration. Thinning was recorded in 53% of cases. In some cases, the recording of the thickening could be difficult. The study of motion during voluntary sniffing reported a paradoxical excursion in all but one patient. During quiet breathing, an absence of movement or a paradoxical displacement was observed. During deep inspiration, a paradoxical motion at the beginning of inspiration followed by a reestablishment of movement in the cranio-caudal direction was seen in 82% of cases. In some patients, there was a lack of movement followed, after an average delay of 0.4 s, by a cranio-caudal excursion. Finally, in 4 patients no displacement was recorded. Evidence of hyperactivity (increased inspiratory thickening and excursion) of contralateral non-paralyzed hemidiaphragm was observed.

Conclusion

To accurately detect hemidiaphragm paralysis, it would be interesting to combine the ultrasound study of diaphragm excursion and thickening. The different profiles reported by our study must be known to avoid misinterpretation.

Effect of Neurostimulator Usage on Block Success in Costoclavicular Block: A Randomized Controlled Trial

BACKGROUND

The need of a neurostimulator for a successful nerve block was questioned in different block types after ultrasound had become standard.

AIM

To determine the effect of neurostimulator use on block success in the costoclavicular block (CCB).

METHODS

Sixty patients undergoing upper limb surgery were enrolled in the study. Patients using ultrasound and injection pressure manometer were divided as Group USP, and those using ultrasound, injection pressure manometer, and neurostimulator were divided as Group USPN. After block was applied, sensory and motor block levels were measured on a numeric scale. The block was considered successful when the desired score was reached or general anesthesia was not required intraoperatively. The number of successful and unsuccessful blocks for each group was summed up. The successful block rate was compared as the primary objective. Block application time, time to readiness for surgery, the number of needle passes, diaphragm paralysis rate, and complication rate were compared as secondary goals.

RESULTS

Block success rate was 90% (27/30) in Group USP and 96.7% (29/30) in Group USPN. There was no statistical difference in terms of block success rate. Block application time was significantly shorter in Group USP (207.2 ± 32.7 s) when compared to Group USPN (280.9 ± 70.1 s). Other secondary outcomes were similar.

CONCLUSION

Neurostimulator use did not affect block success in the CCB. Neurostimulator utilization prolonged block application time explicitly and did not change the complication rate. Ultrasound and injection pressure manometer are sufficient for a safe and successful CCB.

Imaging of the Diaphragm: A Primer

The diaphragm is a critical musculotendinous structure that contributes to respiratory function. Disorders of the diaphragm are rare and diagnostically challenging. Herein, the author reviews the radiologic options for the assessment of the diaphragm.

Relationship Between Diaphragm Thickness, Thickening Fraction, Dome Excursion, and Respiratory Pressures in Healthy Subjects: An Ultrasound Study

PURPOSE

Diaphragm ultrasonography is used to identify causes of diaphragm dysfunction. However, its correlation with pulmonary function tests, including maximal inspiratory (MIP) and expiratory pressures (MEP), remains unclear. This study investigated this relationship by measuring diaphragm thickness, thickening fraction (TF), and excursion (DE) using ultrasonography, and their relationship to MIP and MEP. It also examined the influence of age, sex, height, and BMI on these measures.

METHODS

We recruited healthy Japanese volunteers and conducted pulmonary function tests and diaphragm ultrasonography in a seated position. Diaphragm ultrasonography was performed during quiet breathing (QB) and deep breathing (DB) to measure the diaphragm thickness, TF, and DE. A multivariate analysis was conducted, adjusting for age, sex, height, and BMI.

RESULTS

Between March 2022 and January 2023, 109 individuals (56 males) were included from three facilities. The mean (standard deviation) MIP and MEP [cmH2O] were 72.2 (24.6) and 96.9 (35.8), respectively. Thickness [mm] at the end of expiration was 1.7 (0.4), TF [%] was 50.0 (25.9) during QB and 110.7 (44.3) during DB, and DE [cm] was 1.7 (0.6) during QB and 4.4 (1.4) during DB. Multivariate analysis revealed that only DE (DB) had a statistically significant relationship with MIP and MEP (p = 0.021, p = 0.008). Sex, age, and BMI had a statistically significant influence on relationships between DE (DB) and MIP (p = 0.008, 0.048, and < 0.001, respectively).

CONCLUSION

In healthy adults, DE (DB) has a relationship with MIP and MEP. Sex, age, and BMI, but not height, are influencing factors on this relationship.

The effect of upper transabdominal plane block on diaphragm thickness in adult patients after laparoscopic cholecystectomy operation

INTRODUCTION

In this prospective and observational study, our objective was to examine the impact of subcostal transversus abdominis plane (SubTAP) block, along with intravenous analgesia techniques, on diaphragm thickness and post-operative pain following laparoscopic cholecystectomy.

PATIENTS AND METHODS

This study examined laparoscopic cholecystectomy patients aged 18-60 years with an American Society of Anesthesiologist score of 1-2. This study divided patients into Group 1 for SubTAP block and Group 2 for intravenous analgesia. This study had 67 patients, at least 30 from each group. Thus, diaphragm thicknesses and Visual Analogue Scale (VAS) values were compared between regional anaesthesia and intravenous analgesia groups.

RESULTS

Pre-operative data showed no statistically significant changes between the groups, although post-extubation inspiratory thickness was closer to baseline in Group 1 patients who received regional block. The groups had different outcomes after extubation and at the post-operative 30th min (P = 0.028 and P = 0.001, respectively). There was also a significant difference in post-operative oxygen saturation and VAS scores (P = 0.001). Our receiver operating characteristic analysis determined that the threshold values for VAS parameters of 2 or 3 were 0.28 cm in inspiration, 0.18 cm in expiration and 1.29 as i/e ratio. Significant discomfort was defined as diaphragm parameter values below these limits.

CONCLUSIONS

We found that the earlier return of diaphragmatic functions to baseline was associated with diaphragm thickness. According to the measurements made in the post-operative care unit, the regional block group effectively prevented the loss of diaphragm function.

Interest of thoracic ultrasound after cardiac surgery or interventional cardiology

Thoracic ultrasound has attracted much interest in detecting pleural effusion or pulmonary consolidation after cardiac surgery. In 2016, Trovato reported, in the World Journal of Cardiology, the interest of using, in addition to echocardiography, thoracic ultrasound. In this editorial, we highlight the value of assessing diaphragm function after cardiac surgery and interventional cardiology procedures. Various factors are able to impair diaphragm function after such interventions. Diaphragm motion may be decreased by chest pain secondary to sternotomy, pleural effusion or impaired muscle function. Hemidiaphragmatic paralysis may be secondary to phrenic nerve damage complicating cardiac surgery or atrial fibrillation ablation. Diagnosis may be delayed. Indeed, respiratory troubles induced by diaphragm dysfunction are frequently attributed to pre-existing heart disease or pulmonary complications secondary to surgery. In addition, elevated hemidiaphragm secondary to diaphragm dysfunction is sometimes not observed on chest X-ray performed in supine position in the intensive care unit. Analysis of diaphragm function by ultrasound during the recovery period appears essential. Both hemidiaphragms can be studied by two complementary ultrasound methods. The mobility of each hemidiaphragms is measured by M-mode ultrasonography. In addition, recording the percentage of inspiratory thickening provides important information about the quality of muscle function. These two approaches make it possible to detect hemidiaphragm paralysis or dysfunction. Such a diagnosis is important because persistent diaphragm dysfunction after cardiac surgery has been shown to be associated with adverse respiratory outcome. Early respiratory physiotherapy is able to improve respiratory function through strengthening of the inspiratory muscles i.e. diaphragm and accessory inspiratory muscles.

Neuromuscular ultrasound: Impact on diagnosis and management

INTRODUCTION/AIM

High-resolution ultrasound (HRUS) is increasingly used in evaluating neuromuscular conditions. Its potential advantages include its ability to discern anatomic information and make specific etiological diagnoses. Although many studies have demonstrated HRUS effectiveness, especially in mononeuropathies, more information is needed to better determine how often and to what extent useful information is obtained; how it influences diagnosis, clinical decision-making, and patient management; and how it is used with electrodiagnostic (EDx) studies.

METHODS

A retrospective cohort study was performed on patients referred for HRUS at a university laboratory during 2021. Demographic information, referral diagnoses, clinical information, HRUS findings, and follow-up patient management were analyzed. For patients who had EDx, results were compared with HRUS. Determinations were made whether HRUS did or did not aid in the diagnosis. For patients in whom HRUS resulted in a diagnosis, determination was made whether it confirmed the diagnosis made clinically or by EDx but did not change management; added additional important information; and/or made a decisive impact on subsequent management.

RESULTS

Five hundred two patients were analyzed, most referred for mononeuropathy, brachial plexopathy, and polyneuropathy. HRUS was abnormal in 81.7% of patients. HRUS added additional useful information in 79.0% and was decisive in management in 62.7%. In patients who also had abnormal EDx, HRUS resulted in decisive management in 49.5%.

DISCUSSION

HRUS is an effective diagnostic tool that frequently adds localizing and structural information that is otherwise not obtainable by clinical and EDx evaluation. In a substantial number of patients selected for HRUS, it is decisive in guiding further management.

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 assessment of diaphragm thickness, contractility, and strain in healthy pediatric patients

BACKGROUND

Ultrasound-based diaphragmatic assessments are becoming more common in pediatric acute care, but baseline pediatric diaphragm thickness and contractility values remain unknown.

METHODS

We conducted a prospective, observational study of healthy children aged <18 years undergoing elective surgery. Diaphragm thickness at end-expiration (Tdi-exp), thickening fraction (DTF) and excursion were measured by ultrasound during spontaneous breathing and during mechanical ventilation. Diaphragm strain and peak strain rate were ascertained post hoc. Measurements were compared across a priori specified age groups (<1 year, 1 to <3, 3 to <6, 6 to <12, and 12 to <18 years) and with versus without mechanical ventilation.

RESULTS

Fifty subjects were evaluated (n = 10 per age group). Baseline mean Tdi-exp was 0.19 ± 0.04 cm, DTF 0.19 ± 0.09, excursion 1.69 ± 0.97 cm, strain -10.3 ± 4.9, peak strain rate -0.48 ± 0.21 s-1 . No significant difference in Tdi-exp or DTF was observed across age groups (p > .05). Diaphragm excursion increased with age (p < .0001). Diaphragm strain was significantly greater in the 12-17-year age group (-14.3 ± 6.4), p = .048, but there were no age-related differences in peak strain rate (p = .08). During mechanical ventilation, there were significant decreases in DTF 0.12 ± 0.04 (p < .0001), excursion 1.08 ± 0.31 cm (p < .0001), strain -4.60 ± 1.93 (p < .0001), and peak strain rate -0.20 ± 0.10 s-1 (p < .0001) while there was no change in Tdi-exp 0.18 ± 0.03 cm (p = .25) when compared to baseline values.

CONCLUSION

Pediatric Tdi-exp, DTF, and diaphragm peak strain rate were similar across age groups. Diaphragm excursion and strain varied across age groups. All measures of diaphragm contractility were diminished during mechanical ventilation.

Maximum abdominal excursion assessment using an abdominal excursion measuring device: Reliability and validity of a new device for simple and quantitative assessment of respiratory function

This study aimed to verify the reliability and validity of abdominal expansion and respiratory function measurements. Forty healthy adult males underwent lung capacity, effort lung capacity, respiratory muscle strength, cough strength, diaphragm ultrasound, and abdominal expansion measurements. Abdominal expansion was measured using a device developed to accurately evaluate abdominal movements and calculate maximum abdominal expansion on the ventral side (AE-max: the difference between maximal abdominal contraction at the same time as maximal-effort expiration and maximal abdominal expansion at the same time as maximal-effort inspiration). Intra- and inter-rater reliabilities of the AE-max measurements were examined, the paired t-test was used for assessing the ratios of the expansion and contraction displacement components in AE-max, and regression analysis was used to obtain equations for predicting maximum inspiratory pressure (MIP) based on AE-max. Both intra- and inter-rater reliabilities were high. Criterion-related validity showed that AE-max was associated with all respiratory function parameters, especially MIP, and a high percentage of expansion displacement. Regression analysis showed that AE-max was significantly associated with MIP. Based on its association with MIP, the large proportion of expansion displacement in AE-max, and the results of the multiple regression analysis, we conclude that AE-max is a helpful measure for estimating MIP.

Ultrasound in the Diagnosis of Non-Expandable Lung: A Prospective Observational Study of M-Mode, B-Mode, and 2D-Shear Wave Elastography

BACKGROUND

Non-expandable lung (NEL) has severe implications for patient symptoms and impaired lung function, as well as crucial implications for the management of malignant pleural effusion (MPE). Indwelling pleural catheters have shown good symptom relief for patients with NEL; hence, identifying patients early in their disease is vital. With the inability of the lung to achieve pleural apposition following thoracentesis and the formation of a hydropneumothorax, traditionally, chest X-ray and clinical symptoms have been used to make the diagnosis following thoracentesis. It is our aim to investigate whether ultrasound measurement of lung movement during respiration can predict NEL before thoracentesis, thereby aiding clinicians in their planning for the optimal treatment of affected patients.

METHODS

A total of 49 patients were consecutively included in a single-centre trial performed at a pleural clinic. Patients underwent protocolled ultrasound assessment pre-thoracentesis with measurements of lung and diaphragm movement and shear wave elastography measurements of the pleura and pleural effusion at the planned site of thoracentesis.

RESULTS

M-mode measurements of lung movement provided the best diagnostic ROC-curve results, with an AUC of 0.81. Internal validity showed good results utilising the calibration belt test and Brier test.

CONCLUSION

M-mode measurement of lung movement shows promise in diagnosing NEL before thoracentesis in patients with known or suspected MPE. A validation cohort is needed to confirm the results.

Electrodiagnostic and ultrasound evaluation of respiratory weakness

Phrenic nerve conduction studies (NCSs) and needle electromyography (EMG) can provide important information on the underlying pathophysiology in patients presenting with unexplained shortness of breath, failure to wean from the ventilator, or consideration of phrenic nerve pacemaker implantation. However, these techniques are often technically challenging, require experience, can lack sensitivity and specificity, and, in the case of diaphragm EMG, involve some degree of risk. Diagnostic high-resolution ultrasound has been introduced in recent years as an adjuvant technique readily available at the bedside that can increase the overall sensitivity and specificity of the neurophysiologic evaluation of respiratory symptoms. Two-dimensional ultrasound in the zone of apposition can identify atrophy and evaluate contractility of the diaphragm, in addition to localizing a safe zone for needle EMG. M-mode ultrasound can identify decreased excursion or paradoxical motion of the diaphragm and can increase the reliability of phrenic NCSs. When used in combination, ultrasound, phrenic NCSs and EMG of the diaphragm can differentiate neuropathic, myopathic, and central disorders, and can offer aid in prognosis that is difficult to arrive at solely from clinical examination. This article will review techniques to successfully perform phrenic NCSs, needle EMG of the diaphragm, and ultrasound of the diaphragm. The discussion will include technical pitfalls and clinical pearls as well as future directions and clinical indications.

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.

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.

Reliability and validity of ultrasonography in evaluating the thickness, excursion, stiffness, and strain rate of respiratory muscles in non-hospitalized individuals: a systematic review

OBJECTIVE

To summarize the reliability and validity of ultrasonography in evaluating the stiffness, excursion, stiffness, or strain rate of diaphragm, intercostals and abdominal muscles in healthy or non-hospitalized individuals.

LITERATURE SEARCH

PubMed, Embase, SPORTDiscus, CINAHL and Cochrane Library were searched from inception to May 30, 2022.

STUDY SELECTION CRITERIA

Case-control, cross-sectional, and longitudinal studies were included if they investigated the reliability or validity of various ultrasonography technologies (e.g., brightness-mode, motion-mode, shear wave elastography) in measuring the thickness, excursion, stiffness, or strain rate of any respiratory muscles.

DATA SYNTHESIS

Relevant data were summarized based on healthy and different patient populations. The methodological quality by different checklist depending on study design. The quality of evidence of each psychometric property was graded by the Grading of Recommendations, Assessment, Development and Evaluations, respectively.

RESULTS

This review included 24 studies with 787 healthy or non-hospitalized individuals (e.g., lower back pain (LBP), adolescent idiopathic scoliosis (AIS), and chronic obstructive pulmonary disease (COPD)). Both inspiratory (diaphragm and intercostal muscles) and expiratory muscles (abdominal muscles) were investigated. Moderate-quality evidence supported sufficient (intra-class correlation coefficient > 0.7) within-day intra-rater reliability of B-mode ultrasonography in measuring right diaphragmatic thickness among people with LBP, sufficient between-day intra-rater reliability of M-mode ultrasonography in measuring right diaphragmatic excursion in non-hospitalized individuals. The quality of evidence for all other measurement properties in various populations was low or very low. High-quality evidence supported sufficient positive correlations between diaphragm excursion and forced expiratory volume in the first second or forced vital capacity (r >  = 0.3) in healthy individuals.

CONCLUSIONS

Despite the reported sufficient reliability and validity of using ultrasonography to assess the thickness, excursion, stiffness, and strain rate of respiratory muscles in non-hospitalized individuals, further large-scale studies are warranted to improve the quality of evidence regarding using ultrasonography for these measurements in clinical practice. Researchers should establish their own reliability before using various types of ultrasonography to evaluate respiratory muscle functions.

TRIAL REGISTRATION

PROSPERO NO. CRD42022322945.

Imaging of the Diaphragm Following Cardiac Surgery: Focus on Ultrasonographic Assessment

Diaphragm dysfunction is a common complication following cardiac surgery. Its clinical impact is variable, ranging from the absence of symptoms to the acute respiratory failure. Post-operative diaphragm dysfunction may negatively affect patients' prognosis delaying the weaning from the mechanical ventilation (MV), extending the time of hospitalization and increasing mortality. Ultrasonography is a valid tool to evaluate diaphragmatic impairment in different settings, like the Intensive Care Unit, to predict successful weaning from the MV, and the Cardiovascular Rehabilitation Unit, to stratify patients in terms of risk of functional recovery failure. The aim of this review is to describe the pathophysiology of post-cardiac surgery diaphragm dysfunction, the techniques used for its diagnosis and the potential applications of diaphragm ultrasound.

The utility of diaphragm ultrasound thickening indices for assessing respiratory decompensation in amyotrophic lateral sclerosis

INTRODUCTION/AIMS

Amyotrophic lateral sclerosis (ALS) leads to diaphragmatic weakness at some point during its course, which is a major cause of respiratory insufficiency. The aim of this study was to evaluate ultrasound-based measures for assessing the diaphragmatic competency and the need for ventilatory support.

METHODS

Twenty-six subjects with ALS and 12 healthy controls were enrolled. All participants underwent B-mode diaphragm ultrasound (DUS). Diaphragm thickness and thickening indices were recorded. In the subjects with ALS, further assessments included functional scales and spirometry. We investigated the diagnostic accuracy of DUS thickening indices in predicting diaphragmatic dysfunction and the correlation between clinical, spirometric, and DUS data.

RESULTS

Significant relationships were found between forced vital capacity and all diaphragmatic thickening indices. Similarly, all diaphragmatic thickening indices correlated with both Milano Torino staging and disease progression rate. Only thickening fraction (TFdi) correlated with score on the revised ALS Functional Rating Scale (r = 0.459, P = .024). TFdi had better accuracy in predicting diaphragmatic dysfunction (area under the curve [AUC] = 0.839, 95% confidence interval [CI] 0.643 to 0.953) and the need for initiation of noninvasive ventilation (NIV) (AUC = 0.989, 95% CI 0.847 to 1.000) compared with the other indices. A TFdi cut-off point of 0.50 was a sensitive threshold to consider NIV.

DISCUSSION

DUS successfully identifies diaphragmatic dysfunction in ALS, being a valuable accessory modality for investigating respiratory symptoms. TFdi was found to be the most useful DUS index, which encourages further investigation.

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.

Evaluation of diaphragm functions with diaphragm ultrasound and pulmonary function tests in individuals with Friedreich's ataxia

Background/aim

It is known that the correlation of pulmonary function tests (PFT) with muscle dysfunction is insufficient. Here, we aimed to evaluate the diaphragm functions in individuals with Friedreich's ataxia (FRDA) and to examine its relationship with respiratory parameters and disease severity.

Materials and methods

This prospective study, conducted between November and December 2022, at Erciyes University, included 14 individuals with genetically confirmed FRDA and an age- and gender-matched healthy control group of eight individuals. We examined pulmonary functions with spirometric methods and evaluated diaphragm excursion, and diaphragm thickness-expiratory (Tde) and - end of inspiration (Tdi) with ultrasonography during calm breathing. Thickening fraction (TF) calculated. Also, we examined PaCO2 at rest. The neurological status of individuals was assessed using the Scale for the Assessment and Rating of Ataxia (SARA).

Results

The mean values of FEV1(lt), FEV1(%), FVC (lt), and FVC (%) were higher in the control group (p; <0.001, 0.013, <0.001, and 0.009, respectively). Also, mean Tdi, Tde, excursion and TF were lower in the FRDA group compared to the control group (p = 0.005, 0.294,0.005, and 0.019, respectively). The mean excursion value was 1.13 ± 0.54cm in the FRDA group and 1.71 ± 0.49cm in the control group. There is a strong, negative, and statistically significant correlation between SARA total score with excursion and TF (r = -0.7432, p = 0.002; r = -0.697, p = 0.008). There is no statistically significant relationship between excursion and BMI, standing-to-supine decrease in FVC, FEV1, and PaCO2. Also, the relationship between maximal inspiratory pressure (PImax) and excursion was moderate.

Conclusion

Diaphragm ultrasound may reveal respiratory dysfunction better than PFT. Diaphragm excursion and TF are associated with disease scores in individuals with FDRA. Further studies are needed regarding the detection of alveolar hypoventilation.

The increase in diaphragm thickness in preterm infants is related to birth weight: a pilot study

Diaphragm ultrasound (DU) has been used in adult and pediatric critical patients in relation to prediction of extubation success or to detect diaphragm dysfunction, but there is a lack of evidence in neonates. Our aim is to study the evolution of diaphragm thickness in preterm infants, as well as related variables. This prospective monocentric observational study included preterm infants born before 32 weeks (PT32). We performed DU to measure right and left inspiratory and expiratory thickness (RIT, LIT, RET, and LET) and calculated the diaphragm-thickening fraction (DTF) in the first 24 h of life and then weekly until 36 weeks postmenstrual age, death, or discharge. Using multilevel mixed-effect regression, we evaluated the influence of time since birth on diaphragm measurements, as well as bronchopulmonary dysplasia (BPD), birth weight (BW), and days of invasive mechanical ventilation (IMV). We included 107 infants, and we performed 519 DUs. All diaphragm thickness increased with time since birth, but the only additional variable that influenced this growth was BW: beta coefficients RIT = 0.00006; RET = 0.00005; LIT = 0.00005; and LET = 0.00004, p < 0.001. Right DTF values remained stable since birth but left DTF increased with time only in infants with BPD.   Conclusion: In our population we found that the higher the BW, the higher diaphragm thicknesses at birth and follow-up. Contrary to the previously published findings in adult and pediatric settings, we were unable to describe a relationship between days of IMV and diaphragm thickness in PT32. The final diagnosis of BPD does not influence this increase either, but it does increase left DTF. What is Known: • Diaphragm thickness and diaphragm thickening fraction have been related to the time on invasive mechanical ventilation in adults and pediatric patients, as well as with extubation failure. • Very few evidence is yet available on the use of diaphragmatic ultrasound in preterm infants. What is New: • Birth weight is the only variable related to diaphragm thickness in preterm infants born before 32 weeks postmenstrual age. • Days of invasive mechanical ventilation do not influence diaphragm increase in thickness in preterm infants.

Prevalence of diaphragm dysfunction in patients with interstitial lung disease (ILD): The role of diaphragmatic ultrasound

BACKGROUND

Diaphragm ultrasound (DUS) has been extensively used in critically ill patients while data on outpatients with interstitial lung disease (ILD) are limited. We hypothesized that diaphragm function, assessed by ultrasound, could be impaired in patients with ILD, considering both Idiopathic Pulmonary Fibrosis (IPF) and Connective Tissue Disease (CTD-ILD), compared to healthy subjects. Moreover, this impairment could impact clinical and functional parameters.

METHODS

All consecutive CTD-ILD and IPF patients followed in our center (March-October 2020) were screened. Diaphragm displacement (DD), inspiratory thickness (Ti), expiratory thickness (Te), thickening fraction (TF), and respiratory functional parameters were collected. The prevalence of diaphragmatic dysfunction (TF <30%) was then recorded.

RESULTS

Eighty-two consecutive patients (41 CTD-ILD, 41 IPF) and 15 age- and sex-matched controls were enrolled. In the overall population, 24 out of 82 (29%) presented diaphragmatic dysfunction. In CTD-ILD, DD and Ti were lower as compared to IPF (p = 0.021 and p = 0.036, respectively); while diaphragmatic dysfunction was more prevalent compared to controls (37% vs 7%, p = 0.043). TF positively correlated to patients' functional parameters in the CTD-ILD group (FVC%pred: p = 0.003; r = 0.45), while not in the IPF group. Diaphragmatic dysfunction was associated with moderate/severe dyspnea in both CTD-ILD and IPF (p = 0.021).

CONCLUSION

The prevalence of diaphragmatic dysfunction was 29% in patients with ILD and was associated with moderate/severe dyspnea. CTD-ILD presented lower DD compared with IPF and a higher prevalence of diaphragmatic dysfunction (TF<30%) compared with controls. TF was associated with lung function only in CTD-ILD patients, suggesting its potential role in the comprehensive patient assessment.

Respiratory Movements at Different Ages

Background and Objectives: The current study aimed to better understand the changes in respiration that occur with aging in men and women to provide accurate recommendations for breathing exercises to improve health. Materials and Methods: A total of 610 healthy subjects, aged 20 to 59, participated in the study. They performed quiet breathing while wearing two respiration belts (Vernier, Beaverton, OR, USA) at the height of the navel and at the xiphoid process to record abdominal motion (AM) and thoracic motion (TM), respectively. Vital capacity, representing maximal inhalation movement, was measured using a spirometer (Xindonghuateng, Beijing, China). After exclusion, 565 subjects (164 men, aged 41 ± 11; 401 women, aged 42 ± 9) were included for statistical analysis using the Kruskal-Wallis U test and stepwise multiple linear regression. Results: Abdominal motion and its contribution to spontaneous breathing were significantly larger for older men, while the contribution of thoracic motion was smaller for older men. There was no significant difference in thoracic motion between the younger and older men. The differences in women's respiratory movements among various ages were mild and negligible. The contribution of thoracic motion to spontaneous breathing in women was larger than in men for those of older ages (40-59 years), but not for those of younger ages (20-39 years). Additionally, men's and women's vital capacities were less in those of older ages, and the men's were larger than the women's. Conclusions: The findings indicate that men's abdominal contribution to spontaneous breathing increased from 20 to 59 years of age due to increased abdominal motion. Women's respiratory movements did not change much with aging. The maximal inhalation movement became smaller with aging for men and women. Healthcare professionals should focus on improving thoracic mobility when addressing health concerns about aging.

Ultrasound assessment of the respiratory system using diaphragm motion-volume indices

Background

Although previous studies have determined limit values of normality for diaphragm excursion and thickening, it would be beneficial to determine the normal diaphragm motion-to-inspired volume ratio that integrates the activity of the diaphragm and the quality of the respiratory system.

Methods

To determine the normal values of selected ultrasound diaphragm motion-volume indices, subjects with normal pulmonary function testing were recruited. Ultrasound examination recorded diaphragm excursion on both sides during quiet breathing and deep inspiration. Diaphragm thickness was also measured. The inspired volumes of the corresponding cycles were systematically recorded using a spirometer. The indices were calculated using the ratio excursion, or percentage of thickening, divided by the corresponding breathing volume. From this corhort, normal values and limit values for normality were determined. These measurements were compared to those performed on the healthy side in patients with hemidiaphragm paralysis because an increase in hemidiaphragm activity has been previously demonstated in such circumstances.

Results

A total of 122 subjects (51 women, 71 men) with normal pulmonary function were included in the study. Statistical analysis revealed that the ratio of excursion, or percentage of thickening, to inspired volume ratio significantly differed between males and females. When the above-mentioned indices using excursion were normalized by body weight, no gender differences were found. The indices differed between normal respiratory function subjects and patients with hemidiaphragm paralysis (27 women, 41 men). On the paralyzed side, the average ratio of the excursion divided by the inspired volume was zero. On the healthy side, the indices using the excursion and the percentage of thickening during quiet breathing or deep inspiration were significantly increased comparedto patients with normal lung function. According to the logistic regression analysis, the most relevant indice appeared to be the ratio of the excursion measured during quiet breathing to the inspired volume.

Conclusion

The normal values of the diaphragm motion-volume indices could be useful to estimate the performance of the respiratory system. Proposed indices appear suitable in a context of hyperactivity.

Inter-Examiner and Intra-Examiner Reliability of Quantitative and Qualitative Ultrasonography Assessment of Peripheral and Respiratory Muscles in Critically Ill Patients

ICU patients are exposed to several factors that can lead to muscle structural and functional changes, and ultrasonography can identify them. Although several studies have analyzed the reliability of muscle ultrasonography assessment, a protocol with more muscle assessments becomes a challenge. The aim of this study was to analyze the inter and intra-examiner reliability of peripheral and respiratory muscle ultrasonography assessment in critically ill patients. The sample size was 10 individuals aged ≥ 18 years who were admitted to the ICU. Practical training of four health professionals from different backgrounds was performed. After training, each examiner acquired three images to assess the thickness and echogenicity of the muscle groups: biceps brachii, forearm flexor group, quadriceps femoris, tibialis anterior and diaphragm. For the reliability analysis, an intraclass correlation coefficient was performed. Six hundred US images were analyzed for muscle thickness and 150 for echogenicity. Excellent intra-examiner reliability for echogenicity (ICC: 0.867-0.973) and inter-examiner reliability for thickness were found in all muscle groups (ICC: 0.778-0.942). For muscle thickness intra-examiner reliability, excellent results were found (ICC: 0.798-0.988), with a "good" correlation in one diaphragm assessment (ICC: 0.718). Excellent inter- and intra-examiner reliability of the thickness assessment and intra-examiner echogenicity of all muscles analyzed were found.

Respiratory muscle ultrasonography evaluation and its clinical application in stroke patients: A review

Background

Respiratory muscle ultrasound is a widely available, highly feasible technique that can be used to study the contribution of the individual respiratory muscles related to respiratory dysfunction. Stroke disrupts multiple functions, and the respiratory function is often significantly decreased in stroke patients.

Method

A search of the MEDLINE, Web of Science, and PubMed databases was conducted. We identified studies measuring respiratory muscles in healthy and patients by ultrasonography. Two reviewers independently extracted and documented data regarding to the criteria. Data were extracted including participant demographics, ultrasonography evaluation protocol, subject population, reference values, etc.

Result

A total of 1954 participants from 39 studies were included. Among them, there were 1,135 participants from 19 studies on diaphragm, 259 participants from 6 studies on extra-diaphragmatic inspiratory muscles, and 560 participants from 14 studies on abdominal expiratory muscles. The ultrasonic evaluation of diaphragm and abdominal expiratory muscle thickness had a relatively typically approach, while, extra-diaphragmatic inspiratory muscles were mainly used in ICU that lack of a consistent paradigm.

Conclusion

Diaphragm and expiratory muscle ultrasound has been widely used in the assessment of respiratory muscle function. On the contrary, there is not enough evidence to assess extra-diaphragmatic inspiratory muscles by ultrasound. In addition, the thickness of the diaphragm on the hemiplegic side was lower than that on the non-hemiplegic side in stroke patients. For internal oblique muscle (IO), rectus abdominis muscle (RA), transversus abdominis muscle (TrA), and external oblique muscle (EO), most studies showed that the thickness on the hemiplegic side was lower than that on the non-hemiplegic side.Clinical Trial Registration: The protocol of this review was registered in the PROSPERO database (CRD42022352901).

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.

Reference values of diaphragmatic dimensions in healthy children aged 0-8 years

Diaphragmatic thickness (Tdi) and diaphragm thickening fraction (dTF) are widely used parameters in ultrasound studies of the diaphragm in mechanically ventilated children, but normal values for healthy children are scarce. We determined reference values of Tdi and dTF using ultrasound in healthy children aged 0-8 years old and assessed their reproducibility. In a prospective, observational cohort, Tdi and dTF were measured on ultrasound images across four age groups comprising at least 30 children per group: group 1 (0-6 months), group 2 (7 months-1 year), group 3 (2-4 years) and group 4 (5-8 years). Ultrasound images of 137 healthy children were included. Mean Tdi at inspiration was 2.07 (SD 0.40), 2.09 (SD 0.40), 1.69 (SD 0.30) and 1.72 (SD 0.30) mm for groups 1, 2, 3 and 4, respectively. Mean Tdi at expiration was 1.64 (SD 0.30), 1.67 (SD 0.30), 1.38 (SD 0.20) and 1.42 (SD 0.20) mm for groups 1, 2, 3 and 4, respectively. Mean Tdi at inspiration and mean Tdi at expiration for groups 1 and 2 were significantly greater than those for groups 3 and 4 (both p < 0.001). Mean dTF was 25.4% (SD 10.4), 25.2% (SD 8.3), 22.8% (SD 10.9) and 21.3% (SD 7.1) for group 1, 2, 3 and 4, respectively. The intraclass correlation coefficients (ICC) representing the level of inter-rater reliability between two examiners performing the ultrasounds was 0.996 (95% CI 0.982-0.999). ICC of the inter-rater reliability between the raters in 11 paired assessments was 0.989 (95% CI 0.973-0.995).   Conclusion: Ultrasound measurements of Tdi and dTF were highly reproducible in healthy children aged 0-8 years.    Trial registration: ClinicalTrials.gov identifier (NCT number): NCT04589910. What is Known: • Diaphragmatic thickness and diaphragm thickening fraction are widely used parameters in ultrasound studies of the diaphragm in mechanically ventilated children, but normal values for healthy children to compare these with are scarce. What is New: • We determined normal values of diaphragmatic thickness and diaphragm thickening fraction using ultrasound in 137 healthy children aged 0-8 years old. The diaphragmatic thickness of infants up to 1 year old was significantly greater than that of children from 2 to 8 years old. Diaphragmatic thickness decreased with an increase in body surface area. These normal values in healthy children can be used to assess changes in respiratory muscle thickness in mechanically ventilated children.

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.

Diaphragmatic Thickness and Excursion in Preterm Infants With Bronchopulmonary Dysplasia Compared With Term or Near Term Infants: A Prospective Observational Study

BACKGROUND

Diaphragmatic atrophy associated with mechanical ventilation is reported in pediatric and adult patients, but a similar association has not been described in preterm infants with bronchopulmonary dysplasia (BPD).

RESEARCH QUESTION

Does BPD impact the diaphragm thickness (DT) and diaphragm excursion (DE) in infants born before 32 weeks' gestation compared with healthy late preterm or term infants?

STUDY DESIGN AND METHODS

In this prospective observational case-control study, DT at end of expiration (DT_exp), DT at end of inspiration (DT_ins), DT fraction (DTF), and DE (DE) were assessed using bedside ultrasound. Two groups were compared: infants with BPD (patients) and healthy, postmenstrual age-matched infants (control participants). To account for variations in body size between groups, diaphragmatic measurements were expressed as a ratio of body surface area (BSA). Statistical analyses were conducted using SAS software version 9.4 (SAS Institute, Inc.).

RESULTS

We enrolled 111 infants, including 56 preterm infants with BPD (mean ± SD study age, 37.7 ± 1.7 weeks) and 55 healthy control participants (mean ± SD study age, 38.1 ± 1.5 weeks). DT_exp and DT_exp to BSA ratio were significantly lower in the BPD group compared with the healthy control group (mean ± SD, 1.3 ± 0.4 mm vs 1.5 ± 0.4 mm [P = .01] and 7.1 ± 1.4 mm/m² vs 7.8 ± 1.8 mm/m² [P = .03]). DTF and DE were significantly higher in the BPD group vs the healthy control group (mean ± SD, 61.8 ± 26.0 vs 43.3 ± 19.7 [P < .01] and 6.0 ± 1.7 mm vs 4.4 ± 1.6 mm [P < .01], respectively).

INTERPRETATION

In infants with BPD, DT_exp was significantly lower, whereas DTF and DE were significantly higher, compared with healthy, age-matched control participants. Future studies are required and should focus on describing the evolution of diaphragmatic dimensions in preterm infants with and without BPD.

TRIAL REGISTRY

ClinicalTrials.gov; No.: NCT04941963; URL: www.

CLINICALTRIALS

gov.

Ultrasonographic Assessment of Diaphragmatic Function and Its Clinical Application in the Management of Patients with Acute Respiratory Failure

Acute respiratory failure (ARF) is a common life-threatening medical condition, with multiple underlying etiologies. In these cases, many factors related to systemic inflammation, prolonged use of steroids, and lung mechanical abnormalities (such as hyperinflation or increased elastic recoil due to pulmonary oedema or fibrosis) may act as synergic mechanisms leading to diaphragm dysfunction. The assessment of diaphragm function with ultrasound has been increasingly investigated in the emergency department and during hospital stay as a valuable tool for providing additional anatomical and functional information in many acute respiratory diseases. The diaphragmatic ultrasound is a noninvasive and repeatable bedside tool, has no contraindications, and allows the physician to rapidly assess the presence of diaphragmatic dysfunction; this evaluation may help in estimating the need for mechanical ventilation (and the risk of weaning failure), as well as the risk of longer hospital stay and higher mortality rate. This study presents an overview of the recent evidence regarding the evaluation of diaphragmatic function with bedside ultrasound and its clinical applications, including a discussion of real-life clinical cases.

Inspiratory muscle strength and function in mechanically ventilated COVID-19 survivors 3 and 6 months after intensive care unit discharge

Background

Knowledge regarding the long-term impact of invasive mechanical ventilation on the inspiratory muscles and functional outcomes in COVID-19 survivors is limited.

Methods

In this single-centre prospective cohort study, we evaluated invasively ventilated patients with COVID-19 pneumonia 3 and 6 months post-intensive care unit (ICU) discharge. Outcomes included: maximal inspiratory pressure (MIP), ultrasound parameters for diaphragm function, 6-min walk distance (6MWD), dyspnoea and quality of life. We evaluated associations between MIP and duration of mechanical ventilation with follow-up outcomes.

Results

50 COVID-19 survivors discharged from ICU between 15 October 2020 and 1 April 2021 were enrolled. Overall, survivors showed a recovery trajectory over time. However, impaired MIP remained in 24 (48%) and 12 (24%) at 3 and 6 months, respectively. Diaphragm dysfunction was not observed. At 3 months, 23 (46%) had impaired functional capacity versus 10 (20%) at 6 months. Dyspnoea persisted in 44 (88%) patients at 3 months and 38 (76%) at 6 months. Quality of life was slightly decreased at 3 months with further improvements at 6 months. MIP was correlated to 6MWD, 6MWD % predicted, dyspnoea across follow-up, and quality of life at 3 months. The duration of invasive ventilation was correlated with 6MWD and 6MWD % predicted.

Conclusion

In invasively ventilated COVID-19 survivors, inspiratory muscle strength impairments persisted 6 months after ICU discharge, while maintaining normal diaphragm function. Decreased functional capacity, dyspnoea and slightly reduced health status were observed. Early screening of survivors is of utmost importance to identify those with impairments and at risk of delayed or incomplete recovery.

Ultrasonographic assessment of diaphragmatic function in preterm infants on non-invasive neurally adjusted ventilatory assist (NIV-NAVA) compared to nasal intermittent positive-pressure ventilation (NIPPV): a prospective observational study

NIV-NAVA mode for respiratory support in preterm infants is not well-studied. This study aimed to describe the diaphragmatic function, diaphragmatic excursion (DE), and thickness fraction (DTF), in preterm infants < 30 weeks' gestation supported by NIV-NAVA compared to NIPPV using bedside ultrasonography. In this consecutive prospective study, DE, diaphragmatic thickness at end of expiration (DT_exp), end of inspiration (DT_ins), and DTF were assessed using bedside ultrasound. Lung aeration evaluation using lung ultrasound score (LUS) was performed for the two groups. Diaphragmatic measurements and LUS were compared for the 2 groups (NIV-NAVA group versus NIPPV group). Statistical analyses were conducted using the SPSS software version 22. Out of 70 infants evaluated, 40 were enrolled. Twenty infants were on NIV-NAVA and 20 infants on NIPPV with a mean [SD] study age of 25.7 [0.9] weeks and 25.1 [1.4] weeks respectively (p = 0.15). Baseline characteristics and respiratory parameters at the time of the scan showed no significant difference between groups. DE was significantly higher in NIV-NAVA with a mean SD of 4.7 (1.5) mm versus 3.5 (0.9) mm in NIPPV, p = 0.007. Additionally, the mean (SD) of DTF for the NIV-NAVA group was 81.6 (30) % vs 78.2 (27) % for the NIPPV group [p = 0.71]. Both groups showed relatively high LUS but no significant difference between groups [12.8 (2.6) vs 12.6 (2.6), p = 0.8].  Conclusion: Preterm infants managed with NIV-NAVA showed significantly higher DE compared to those managed on NIPPV. This study raises the hypothesis that NIV-NAVA could potentially improve diaphragmatic function due to its synchronization with patients' own breathing. Longitudinal studies to assess diaphragmatic function over time are needed.  Trial registry: Clinicaltrials.gov (NCT05079412). Date of registration September 30, 2021. What is Known: • NIV-NAVA utilizes diaphragmatic electrical activity to provide synchronized breathing support. • Evidence for the effect of NIV-NAVA on diaphragmatic thickness fraction (DTF) and excursion (DE) is limited. What is New: • Ultrasonographic assessment of diaphragmatic function (DTF and DE) is feasible. • In preterm infants, DE was significantly higher in infants supported with NIV-NAVA compared to those supported with NIPPV.