Failure to wean from invasive mechanical ventilation is multifactorial, with diaphragmatic dysfunction a significant contributing factor. Diaphragmatic function can be easily and non-invasively assessed by ultrasound. However, it remains unknown how ultrasound measurements of diaphragm function are affected by changes in apparent work of breathing.

In patients undergoing weaning from mechanical ventilation, we evaluated diaphragmatic ultrasound measurements [diaphragmatic excursion (Dex), diaphragmatic thickening fraction (Tfdi)] simultaneously with manometric indices of breathing effort and load [esophageal pressure swings (ΔPes), transdiaphragmatic pressure swings (ΔPdi), and the pressure-time product of esophageal pressure (PTPes)]. These assessments were performed during two distinct phases; during an unassisted spontaneous breathing trial (phase SBT) and during an inspiratory resistive loading with 30 cmH2O/L/s (phase IRL), applied during the same SBT. Our primary aim was to evaluate the relationship between diaphragmatic ultrasound and breathing effort using the method of repeated measures correlation.

Forty-nine patients were enrolled. Dex correlated with ΔPes (r = 0.5, p < 0.001), ΔPdi (r = 0.55, p =  < 0.001) and PTPes (r = 0.32, p = 0.031). Tfdi did not correlate with ΔPes (r = 0.27, p = 0.052), ΔPdi (r = 0.2, p = 0.235) and PTPes (r = 0.24, p = 0.110). Dex and Tfdi increased during IRL compared to SBT [1.44(0.89-1.96) vs. 1.05(0.7-1.59), p = 0.002], [0.55(± 0.32) vs 0.46(± 0.2), p = 0.019] as did Pes, Pdi and PTPes [(11.87 (7.86, 18.32) vs. 6.8 (4.6-10.23), p < 0.001), (10.89 (± 6.42) vs. 7.94 (± 3.81), p < 0.001), and (181.10 (108.34, 311.7) vs. 97.52 (55.96-179.87), p < 0.001), respectively].

In critical care patients spontaneously breathing under resistive load, diaphragmatic excursion had a weak to moderate correlation with indices of breathing effort and differed between weaning success and failure.

Ventilator-induced diaphragmatic dysfunction is associated with poor patient outcomes. However, the detailed pathophysiology and risk factors underlying the exacerbation of diaphragmatic dysfunction remain unclear. We aimed to evaluate the effect of sedation on diaphragmatic function in extremely preterm infants (EPIs) using ultrasound.

A prospective observational study was conducted on 30 EPIs requiring mechanical ventilation within 6 h of birth between July 2020 and September 2023. Diaphragm ultrasound was performed to measure the end-expiratory and end-inspiratory thicknesses of the diaphragm (Tde and Tdi, respectively) and to calculate diaphragm thickening fraction (DTF) after birth and on day 1 of life. Patients receiving continuous fentanyl administration on day 1 were categorized into the sedated group, whereas those not receiving were categorized into the non-sedated group. Changes in Tde, Tdi, and DTF from day 0 to day 1 were compared between groups.

Baseline Tde, Tdi, and DTF did not differ between groups, and both groups showed significant reductions in Tde, Tdi, and DTF from day 0 to day 1. Analysis of covariance after controlling for gestational age and birth weight revealed that sedation significantly affected the change ratios (Tde, -0.343 vs. -0.157, p = 0.038; Tdi, -0.4 vs. -0.169, p = 0.008; DTF, -0.385 vs. -0.194, p = 0.038).

In this pilot study, we found that sedation may affect Tde, Tdi, and DTF in ventilated EPIs, and that larger, adequately powered studies are required to validate these preliminary findings.

Dynamic hyperinflation in severe acute exacerbation of chronic obstructive pulmonary disease (AECOPD) leads to diaphragmatic fatigue and causes acute respiratory failure. Ultrasound is reliable for evaluating diaphragmatic function. In this study, we aimed to assess the ability of diaphragmatic ultrasound to predict noninvasive ventilation (NIV) failure.

This prospective single-center observational cohort study was performed on patients with AECOPD who required NIV in the emergency department between October 1, 2020, and September 30, 2022, at a tertiary healthcare center. The diaphragmatic ultrasound was measured using diaphragmatic excursion (DE) before applying NIV and diaphragmatic thickening fraction (DTF) during NIV use for 2 h. The area under the receiver-operating characteristic (AUROC) curves analysis and multivariable logistic regression was performed to assess the ability of diaphragmatic ultrasound to predict NIV failure in 48 h.

111 patients were included in this study. DTF was an independent variable associated with NIV failure, with an adjusted odds ratio of 0.91 (95 % confidence interval [CI] 0.85-0.98), with a p-value of 0.009. DE and DTF had AUROC of 0.905 (95 % CI 0.835-0.975) and 0.940 (95 % CI 0.894-0.986), respectively, to predict NIV failure within 48 h. The lower DE and DTF increased the probability of NIV failure. The cutoff value of the DTF was 20 %, with a sensitivity of 92.0 % (95 % CI 74.0 % - 99.0 %) and a specificity of 93.0 % (95 % CI 85.4 % - 97.4 %) and the cutoff of the DE was 1.2 cm, with a sensitivity of 88.0 % (95 % CI 68.8 % - 97.5 %) and a specificity of 84.9 % (95 % CI 75.5 % - 91.7 %).

Diaphragmatic ultrasound, especially DTF at 2 h during NIV use, is a validated tool for predicting NIV failure in patients with AECOPD. Early detection of diaphragmatic dysfunction with diaphragmatic ultrasound in AECOPD with NIV could help identify high-risk patients and guide clinical decisions. However, further benefits from its implementation in management are required.

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

Despite the understanding of the role of diaphragm role as a crucial element in trunk stabilizer performance, limited research has been carried out on the diaphragmatic features particularly in smoking population.

It was aimed to compare the diaphragm structure beside trunk stabilizer performance & body balance of young regular smokers and non-smokers and investigate the relationship between diaphragmatic features and physical performance in regular smokers.

Asymptomatic regular smoker (n = 22) and nonsmoker (n = 22) young male subjects (21.63 ± 2.37 years) were participated to the study. The diaphragmatic ultrasonic scanning and physical performance tests of core muscle strength and endurance & Y balance test were performed.

The duration of prone and lateral side bridge (t = -3.347, t = 3.477, p < 0.001), and modify push-up test repetition (Z = -2.213, p = 0.027) were detected lower in regular smokers. A positive moderate correlation was observed between the duration of the prone bridge test and the maximum inspiration thickness & the thickness difference at inspiration and expiration (r = 0.545, p = 0.009 & r = 0.468, p = 0.028) and between the number of repetitions of the modify push-up and the maximum expiration thickness (r = 0.530, p = 0.011).

While no difference was detected in terms of the diaphragm structure between groups, trunk stabilizer performance was lower and greater diaphragm thickness was associated with better trunk stability in some performance tasks in smokers. While the diaphragm muscle structure, which is the main respiratory muscle, does not differ in young smokers, the effects of the diaphragm muscle on general body biomechanics have been preliminary demonstrated.

Assessing diaphragm function status is vital for diagnosing and treating acute exacerbation of chronic obstructive pulmonary disease (AECOPD). Diaphrag-matic ultrasound has become increasingly important due to its non-invasive nature, absence of radiation exposure, widespread availability, prompt results, high accuracy, and repeatability at the bedside. The diaphragm is a crucial respiratory muscle. Decline or dysfunction of the diaphragm can lead to dyspnea and even respiratory failure in AECOPD patients. In this editorial, we comment on an article, retrospectively analyzed ninety-four acute exacerbations of chronic obstructive pulmonary disease patients who received mechanical ventilation from January 2022 to December 2023. The study found that the diaphragm thickening fraction, an index from diaphragm ultrasound, can better predict the outcome of non-invasive ventilation in patients with AECOPD. The value of non-invasive ventilation in treating respiratory failure caused by AECOPD has been widely acknowledged. Diaphragmatic dysfunction diagnosed with ultrasound is associated with prolonged mechanical ventilation and weaning times and higher mortality.

Pre-operative pulmonary function testing (PFT) plays a key role in predicting postoperative complications or functional impairment. However, PFT requires the subject and examiner to cooperate and the results are influenced by both technical and personal factors. In contrast, the use of ultrasound (US) for structural and functional assessments of the lungs and diaphragm is on the rise, as it requires minimal patient cooperation. Dyspnea is mainly caused by lung or pleural lesions but may also be caused by weak respiratory muscles. As the diaphragm is a primary respiratory muscle, combining lung ultrasonography (LUS) with diaphragm ultrasound (DUS) may enable a more comprehensive assessement of pulmonary function. This study aims to introduce a novel approach for assessing pulmonary function using a mathematical model based on LUS and DUS.

This prospective study was performed at the First Affiliated Hospital of Nanchang University between June 2021 and December 2021, 208 patients were recruited and underwent PFT, LUS, and DUS examinations. An experienced physician, blinded to the clinical history and PFT results, performed LUS and DUS and explored the correlations between a mathematical model (ultrasonographic modeling score (U-score)) using LUS combined with DUS and pulmonary function parameters. Univariate, multivariate, and logistic regression analyses were also performed.

According to the univariate and multivariable analysis, diaphragm thickness fraction in deep breathing (D-DTF) (odds ratio (OR), 0.88; 95% confidence interval (CI) [0.83-0.94]; P < 0.001), and LUS score (OR, 1.44; 95% CI [1.16-1.80]; P < 0.001) were each independently associated with pulmonary function. According to the logistics equation, a U-score of -0.126 × D-DTF + 0.368 × LUS score was produced. The U-score showed a more significant negative correlation with forced expiratory volume in the first second/forced vital capacity (FEV1/FVC) (r = -0.605, P < 0.001) than the LUS or DUS indices alone. The U-score (area under the curve (AUC) = 0.971) was greater than the other indices for assessing pulmonary function.

With validation, the U-score through both lung and diaphragm ultrasound measurements may assist in estimating pulmonary function. This approach facilitates the assessment of pulmonary function in patients who may be unable to reliably participate in PFT.

The primary objective of this study was to evaluate the impact of high-flow nasal cannula oxygen therapy [HFNC] on the diaphragm thickening fraction.

Prospective, descriptive, cohort study SETTING: The study was conducted in the Physiology and Respiratory Care Laboratory, Intensive Care Unit, Hospital Británico de Buenos Aires.

Thirteen healthy subjects >18 years old INTERVENTIONS: High-flow nasal cannula oxygen therapy MAIN VARIABLES OF INTEREST: Demographic data (age and gender), anthropometric data (weight, height, and body mass index), and clinical and respiratory variables (Diaphragm thickening fraction [DTf], esophageal pressure swing, respiratory rate [RR], esophageal pressure-time product per minute [PTPes/min]).

Median DTf decreased significantly as flow increased (p < 0.05). The baseline DTf measurement was 21.4 %, 18.3 % with 20 L/m, and 16.4 % with 40 L/m. We also observed a significant decrease in RR as flow increased in HFNC (p < 0.05). In the 8 subjects with recordings, the PTPes/min was 81.3 (±30.8) cmH2O/sec/min and 64.4 (±25.3) cmH2O/sec/min at baseline and 40 L/m respectively (p = 0.044).

The use of high-flow oxygen therapy through nasal cannula of HFNC in healthy subjects decreases the DTf and RR in association with increased flow. In addition, the use of 40 L/m flow may reduce the muscular work associated with respiration.

Non-invasive respiratory support, namely, non-invasive ventilation, continuous positive airway pressure, and high-flow nasal cannula, has been increasingly used worldwide to treat acute hypoxemic respiratory failure, giving the benefits of keeping spontaneous breathing preserved. In this scenario, monitoring and controlling respiratory drive could be helpful to avoid patient self-inflicted lung injury and promptly identify those patients that require an upgrade to invasive mechanical ventilation. In this review, we first describe the physiological components affecting respiratory drive to outline the risks associated with its hyperactivation. Further, we analyze and compare the leading strategies implemented for respiratory drive monitoring and discuss the sedative drugs and the non-pharmacological approaches used to modulate respiratory drive during non-invasive respiratory support. Refining the available techniques and rethinking our therapeutic and monitoring targets can help critical care physicians develop a personalized and minimally invasive approach.

Diaphragm dysfunction is associated with weaning outcomes in mechanical ventilation patients, in the case of diaphragm dysfunction, the accessory respiratory muscles would be recruited. The main purpose of this study is to explore the performance of parasternal intercostal muscle thickening fraction in relation to diaphragmatic thickening fraction ratio (TFic1/TFdi2) for predicting weaning outcomes, and compare its accuracy with D-RSBI in predicting weaning failure.

We prospectively enrolled consecutive patients from 7/2022-5/2023. We measured TFic, TFdi, and diaphragmatic excursion (DE3) by ultrasound and calculated the TFic/TFdi ratio and diaphragmatic rapid shallow breathing index (D-RSBI4). Receiver-operator characteristic (ROC5) curves evaluated the accuracy of the TFic/TFdi ratio and D-RSBI in predicting weaning failure.

161 were included in the final analysis, 114 patients (70.8%) were successfully weaned from mechanical ventilation. The TFic/TFdi ratio (AUROC = 0.887 (95% CI: 0.821-0.953)) was superior to the D-RSBI (AUROC = 0.875 (95% CI: 0.807-0.944)) for predicting weaning failure.

The TFic/TFdi ratio predicted weaning failure with high accuracy and outperformed the D-RSBI.

To determine the diaphragm thickness, thickening fraction, and excursion and thickness of the quadriceps femoris muscle in full-term newborns and to evaluate the intra- and interrater reliability of these measurements. This was a prospective, observational clinical study including full-term newborns born within the first 48 h after birth. Serial measurements of the thickness, thickening fraction, and mobility of the diaphragm muscles and the thickness of the quadriceps muscle were obtained using ultrasound images. A total of 69 newborns with a mean gestational age of 39 weeks were included. The following measurements were obtained and are expressed as the mean (standard deviation): inspiratory diaphragm thickness, 0.19 cm (0.04); expiratory diaphragm thickness, 0.16 cm (0.04); diaphragm thickness fraction, 16.70 cm (10.27); diaphragmatic excursion, 0.68 cm (0.22); and quadriceps thickness, 0.99 cm (0.14). Intrarater reliability was assessed using intraclass correlation coefficients (ICCs). Excellent intrarater agreement was observed for the two groups of operators (ICC > 0.86, p < 0.001) for all measurements except for the diaphragm thickening fraction, which showed good agreement for both operator groups (ICC = 0.70, p < 0.001). Regarding interrater reliability, moderate agreement between the raters was observed in the means of all measures (ICC > 0.49, p < 0.001), except for the diaphragm thickening fraction, which showed poor agreement.    Conclusion: Good intrarater and moderate interrater reliability were achieved in ultrasound evaluations of the thickness and mobility of the diaphragm and quadriceps femoris muscles in full-term newborns, demonstrating the feasibility of this technique for clinical use. This pioneering study offers reference values for these muscles in a single study, allowing comparisons between different clinical conditions. What is Known: • Ultrasound is a highly reliable tool for muscle assessment that can be used to assess muscular atrophy in critically ill patients. • Muscle atrophy worsens the patient's condition and has been associated with worse outcomes. What is New: • To our knowledge, this is the first study to jointly evaluate the diaphragm and quadriceps muscle thickness and evaluate the reliability of all measurements. • Our study presents reference values for both muscles, enabling comparisons between different clinical conditions.

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

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

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

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

The optimal timing of intubation in acute hypoxaemic respiratory failure is uncertain and became a point of controversy during the COVID-19 pandemic. Invasive mechanical ventilation is a potentially life-saving intervention but carries substantial risks, including injury to the lungs and diaphragm, pneumonia, intensive care unit-acquired muscle weakness, and haemodynamic impairment. In deciding when to intubate, clinicians must balance premature exposure to the risks of ventilation with the potential harms of unassisted breathing, including disease progression and worsening multiorgan failure. Currently, the optimal timing of intubation is unclear. In this Personal View, we examine a range of parameters that could serve as triggers to initiate invasive mechanical ventilation. The utility of a parameter (eg, the ratio of arterial oxygen tension to fraction of inspired oxygen) to predict the likelihood of a patient undergoing intubation does not necessarily mean that basing the timing of intubation on that parameter will improve therapeutic outcomes. We examine options for clinical investigation to make progress on establishing the optimal timing of intubation.

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.

Patient self-inflicted lung injury (P-SILI) is a major challenge for the ICU physician: although spontaneous breathing is associated with physiological benefits, in patients with acute respiratory distress syndrome (ARDS), the risk of uncontrolled inspiratory effort leading to additional injury needs to be assessed to avoid delayed intubation and increased mortality. In the present review, we analyze the available clinical and experimental evidence supporting the existence of lung injury caused by uncontrolled high inspiratory effort, we discuss the pathophysiological mechanisms by which increased effort causes P-SILI, and, finally, we consider the measurements and interpretation of bedside physiological measures of increased drive that should alert the clinician. The data presented in this review could help to recognize injurious respiratory patterns that may trigger P-SILI and to prevent it.

Noninvasive ventilation (NIV) is widely employed as the initial treatment for patients with chronic acute exacerbation of obstructive pulmonary disease (AECOPD). Nevertheless, high-flow nasal cannula (HFNC) has been increasingly utilized and investigated to mitigate the issues associated with NIV. Flow rate may play a significant role in diaphragmatic function among subjects recovering from AECOPD. Based on these observations, we conducted a physiological study to assess the impact of HFNC therapy on diaphragmatic function, as measured by US, respiratory rate (RR), gas exchange, and patient comfort at various flow rates.

A prospective physiological pilot study enrolled subjects with a diagnosis of AECOPD who required NIV for more than 24 h. After stabilization, these subjects underwent a 30-min trial using NIV and HFNC at different sequential flow rates (30-60 L/min). At the end of each trial, diaphragmatic displacement (DD, cm) and diaphragmatic thickness fraction (DTF, %) were measured using ultrasound. Additionally, other physiological variables, such as RR, gas exchange, and patient comfort, were recorded.

A total of 20 patients were included in the study. DD was no different among trials (p = 0.753). DTF (%) was significantly lower with HFNC-30 L/min compared to HFNC-50 and 60 L/min (p < 0.001 for all comparisons). No significant differences were found in arterial pH and PaCO2 at discontinuation of NIV and at the end of HFNC trials (p > 0.050). During HFNC trials, RR remained unchanged without statistically significant differences (p = 0.611). However, we observed that HFNC improved comfort compared to NIV (p < 0.001 for all comparisons). Interestingly, HFNC at 30 and 40 L/min showed greater comfort during trials.

In subjects recovering from AECOPD and receiving HFNC, flows above 40 L/min may not offer additional benefits in terms of comfort and decreased respiratory effort. HFNC could be a suitable alternative to COT during breaks off NIV.

The diaphragm thickening fraction (DTF) may be a valuable tool for estimating respiratory effort in non-invasive ventilation. The primary aim of this physiological study is the investigation of the correlation of DTF with oesophageal pressure swings (ΔPoes). A secondary aim is to assess the discriminatory capacity of the index tests for different exercise loads.

Healthy volunteers underwent spontaneous breathing and non-invasive ventilation with a sequence of different respirator settings. The first sequence was carried out at rest. The same sequence was repeated twice, with additional ergometry of 25 and 50 Watts, respectively. DTF and ΔPoes were measured during each ventilation configuration.

23 individuals agreed to participate. DTF was moderately correlated with ΔPoes (repeated measures correlation ρ = 0.410, p < 0.001). Both ΔPoes and DTF increased consistently with exercise loading in every ventilation configuration, however ΔPoes showed greater discriminatory capacity.

DTF was moderately correlated with ΔPoes and could discriminate reasonably between exercise loads in a small cohort of non-invasively ventilated healthy subjects. While it may not accurately reflect the absolute respiratory effort, DTF might help titrating individual non-invasive respiratory support. Further investigations are needed to test this hypothesis.

This study was not prospectively registered.

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.

To analyze diaphragmatic thickness, at end-inspiration and end-expiration, diaphragmatic thickening index and mobility via US under two different modalities of inspiratory muscle loading, in two different modalities of inspiratory muscle loading and different load intensities at full-vital capacity maneuvers and the relationship between diaphragmatic thickness with pulmonary function tests in participants with HF.

This randomized crossover trial, enrolled with 17 HF subjects, evaluated diaphragm thickness (Tdi, mm), fractional thickness (TFdi, %), and mobility (mm) US during low and high intensities (30% and 60% of maximal inspiratory pressure-MIP) with two modalities of inspiratory muscle loading mechanical threshold loading (MTL) and tapered flow-resistive loading (TFRL).

Both MTL and TFRL produced a increase in Tdi, but only with high intensity loading compared to baseline-2.21 (0.26) vs. 2.68 (0.33) and 2.73 (0.44) mm; p = .01. TFdi was greater than baseline under all conditions, except during low intensity of TFRL. Diaphragm mobility was greater than baseline under all conditions, and high intensity of TFRL elicited greater mobility compared to all other conditions. Additionally, baseline Tdi was moderately correlated with pulmonary function tests.

MTL and TFRL modalities elicit similar increases in diaphragm thickness at loads, but only during high intensity loading it was greater than baseline. Diaphragm mobility was significantly greater than baseline under both loads and devices, and at high intensity compared to low intensity, although TFRL produced greater mobility compared to modalities of inspiratory muscle loading. There is an association between diaphragm thickness and pulmonary function tests.

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.

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.

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.

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.

The aim of this study is to examine the diagnostic significance of using handgrip dynamometry and diaphragmatic ultrasound in intensive care unit-acquired weakness (ICU-AW).

This study included patients who received mechanical ventilation in the ICU at the Fourth Hospital of Hebei Medical University from July to December 2020. We collected comprehensive demographic data and selected conscious patients for muscle strength and ICU-AW assessments. The evaluation comprised grip strength measurement and bedside ultrasound for diaphragmatic excursion (DE) and thickening fraction (DTF). Results were documented for comparative analysis between patient groups, focusing on the diagnostic efficacy of grip strength, DE, DTF, and their combined application in diagnosing ICU-AW.

A total of 95 patients were initially considered for inclusion in this study. Following the exclusion of 20 patients, a final cohort of 75 patients were enrolled, comprising of 32 patients (42.6%) diagnosed with ICU-AW and 43 patients (57.4%) classified as non-ICU-AW. Comparative analysis revealed that grip strength, DE, and DTF were significantly lower in the ICU-AW group (P < 0.05). Subgroup analysis specific to male patients demonstrated a noteworthy decrease in grip strength, DE, and DTF within the ICU-AW group (P < 0.05). Receiver operating characteristic curve analysis indicated statistically significant diagnostic value for ICU-AW with grip strength, DE, DTF, and grip strength and diaphragmatic ultrasound (P < 0.01). Furthermore, it was observed that the amalgamation of grip strength and diaphragmatic ultrasound significantly enhanced the diagnostic accuracy of ICU-AW in patients who are critically ill.

Grip strength, DE, DTF, and the combined use of grip strength with diaphragm ultrasound demonstrated diagnostic efficacy in ICU-AW. Notably, the integration of grip strength with diaphragm ultrasound exhibited a heightened capacity to enhance the diagnostic value specifically in patients diagnosed who are critically ill with ICU-AW.

Although diaphragm ultrasound can be used for detecting residual neuromuscular blockade post-surgery, there exists notable dearth in contemporary research exploring the correlation between preoperative Child-Pugh classification and the effectiveness of sugammadex in reversing rocuronium-induced blockade as evaluated by diaphragmatic ultrasonography.

This was a prospective, double-blind, non-randomized controlled clinical trial conducted on patients scheduled for laparoscopic liver resection surgery. The participants were categorized into two groups, A and B, based on their preoperative Child-Pugh classification. Prior to anesthesia induction, baseline diaphragm thickness was evaluated using ultrasonography. Throughout the surgical procedure, a deep neuromuscular blockade was maintained with rocuronium. Post-surgery, sugammadex (2 mg/kg) was intravenously administered to patients in both groups upon reaching a train-of-four ratio of 0.2. Diaphragm thickness was assessed at 0, 10, and 30 min, as well as 2 h after extubation, to analyze thickening fractioning (TF) and thickness recovery fractioning (TRF).

No significant differences in TF or TRF were observed between the two groups at 0, 10, and 30 min, as well as 2 h after extubation. Furthermore, there were no significant variances in hemodynamic stability following sugammadex administration. However, patients in the Child-Pugh B group experienced a significantly prolonged time from sugammadex administration to tracheal extubation (19 ± 8.0 min vs. 11 ± 6.1 min) and an extended post-anesthesia care unit stay (123 ± 28.3 min vs. 103 ± 26.0 min) compared to those in the Child-Pugh A group.

The preoperative Child-Pugh grades may not exhibit a significant association with the reversal effect of sugammadex on rocuronium, as evaluated through diaphragmatic ultrasonography.

Registered in the ClinicalTrials.gov (NCT05028088) on July 18, 2021.

The incidence, causes and impact of diaphragm thickness evolution in veno-arterial extracorporeal membrane oxygenation (VA-ECMO) for cardiogenic shock are unknown. Our study investigates its evolution during the first week of VA-ECMO and its relationship with sweep gas flow settings.

We conducted a prospective monocentric observational study in a 12-bed ICU in France, enrolling patients on the day of the VA-ECMO implantation. The diaphragm thickness and the diaphragm thickening fraction (as index of contractile activity, dTF; dTF < 20% defined a low contractile activity) were daily measured for one week using ultrasound. Factors associated with diaphragm thickness evolution (categorized as increased, stable, or atrophic based on > 10% modification from baseline to the last measurement), early extubation role (< day4), and patients outcome at 60 days were investigated. Changes in diaphragm thickness, the primary endpoint, was analysed using a mixed-effect linear model (MLM).

Of the 29 included patients, seven (23%) presented diaphragm atrophy, 18 remained stable (60%) and 4 exhibited an increase (17%). None of the 13 early-extubated patients experienced diaphragm atrophy, while 7 (46%) presented a decrease when extubated later (p-value = 0.008). Diaphragm thickness changes were not associated with the dTF (p-value = 0.13) but with sweep gas flow (Beta = - 3; Confidence Interval at 95% (CI) [- 4.8; - 1.2]. p-value = 0.001) and pH (Beta = - 2; CI [- 2.9; - 1]. p-value < 0.001) in MLM. The dTF remained low (< 20%) in 20 patients (69%) at the study's end and was associated with sweep gas flow evolution in MLM (Beta = - 2.8; 95% CI [- 5.2; - 0.5], p-value = 0.017). Odds ratio of death at 60 days in case of diaphragm atrophy by day 7 was 8.50 ([1.4-74], p = 0.029).

In our study, diaphragm thickness evolution was frequent and not associated with the diaphragm thickening fraction. Diaphragm was preserved from atrophy in case of early extubation with ongoing VA-ECMO assistance. Metabolic disorders resulting from organ failures and sweep gas flow were linked with diaphragm thickness evolution. Preserved diaphragm thickness in VA-ECMO survivors emphasizes the importance of diaphragm-protective strategies, including meticulous sweep gas flow titration.

Ventilator-induced diaphragm dysfunction is gaining increased recognition. Evidence of diaphragm weakness can manifest within 12 h to a few days after the initiation of mechanical ventilation. Various noninvasive and invasive methods have been developed to assess diaphragm function. The implementation of diaphragm-protective ventilation strategies is crucial for preventing diaphragm injuries. Furthermore, diaphragm neurostimulation emerges as a promising and novel treatment option. In this rapid review, our objective is to discuss the current understanding of ventilator-induced diaphragm dysfunction, diagnostic approaches, and updates on strategies for prevention and management.

critical illness often leads to malnutrition and diaphragmatic dysfunction (DD), common in intensive care units (ICU). Ultrasonography (US) is a potent tool for detecting DD. This study examines the connection between malnutrition risk and DD in ICU patients using ultrasonographic diaphragm measurements in medical ICU patients.

we assessed nutritional risk using risk screening tools and mid-upper arm circumference measurements (MUAC). Diaphragm atrophy (DA) and DD were evaluated by measuring diaphragmatic excursion (DE), thickness, and thickening fraction (TF) by US. We then compared these diaphragmatic measurements in patients based on their nutritional risk scores.

of the fifty patients studied, 54 % to 78 % were at risk of malnutrition, 28 % exhibited diaphragm atrophy (DA), and 24 % showed DD upon ICU admission. Malnutrition risk diagnosed by all nutritional risk screening tools was significantly more frequent in patients with DD, while diagnosed by MUAC was considerably higher in patients with DA. A total of 16 patients (32 %) died during their ICU stay, with DD, DA, and malnutrition risks (as identified by the mNUTRIC Score) being more prevalent among non-survivors (p < 0.05). Malnutrition risk (as determined by the mNUTRIC Score) was an independent risk factor for DD [OR (95 % CI): 6.6 (1.3-34), p = 0.03].

malnutrition risk may be significantly associated with DD and DA in medical ICU patients upon ICU admission.

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

Various forms of commonly used noninvasive respiratory support strategies have considerable effect on diaphragmatic contractile function which can be evaluated using sonographic diaphragm activity parameters.

To compare the magnitude of respiratory workload decreased as assessed by thickening fraction of the diaphragm and longitudinal diaphragmatic strain while using high-flow nasal cannula (HFNC) and noninvasive ventilation (NIV) modes [nasal intermittent positive pressure ventilation (NIPPV) and bilevel positive airway pressure (BiPAP)] in pediatric patients after cardiothoracic surgery.

This prospective randomized controlled trial was performed at a tertiary care surgical intensive care unit in postcardiac surgery patients aged between 1 and 48 months, who were randomly allocated into three groups: 1) HFNC (with flows at 2 L/kg/min), 2) NIPPV via RAMS cannula in PSV mode (pressure support 8 cmH2O, PEEP 5 cmH2O), and 3) BiPAP in nCPAP mode (CPAP of 5 cmH2O). Measurements were recorded at baseline after extubation (R0) and subsequently every 12 hourly (R1, R2, R3, R4, R5) at 12, 24, 36, 48, and 60 hours respectively until therapy was discontinued.

Sixty patients were included, with 20 patients each in the NIPPV group, HFNC group, and BiPAP group. Longitudinal strain at crura of diaphragm was lower in the BiPAP group as compared to HFNC group at R2-R4 [R2 (-4.27± -2.73 vs - 8.40± -6.40, P = 0.031), R3 (-5.32± -2.28 vs -8.44± -5.6, P = 0.015), and R4 (-3.8± -3.42 vs -12.4± -7.12, P = 0.040)]. PFR was higher in HFNC than NIPPV group at baseline and R1-R3[R0 (323 ± 114 vs 264 ± 80, P = 0.008), R1 (311 ± 114 vs 233 ± 66, P = 0.022), R2 (328 ± 116 vs 237 ± 4, P = 0.002), R3 (346 ± 112 vs 238 ± 54, P = 0.001)]. DTF and clinical parameters of increased work of breathing remain comparable between three groups. The rate of reintubation (within 48 hours of extubation or at ICU discharge) was 0.06% (1 in NIPPV, 1 in BiPAP, 2 in HFNC) and remain comparable between groups (P = 1.0).

BiPAP may provide better decrease in work of breathing compared to HFNC as reflected by lower crural diaphragmatic strain pattern. HFNC may provide better oxygenation compared to NIPPV group, as reflected by higher PFR ratio. Failure rate and safety profile are similar among different methods used.

A variety of parameters and diaphragmatic ultrasound in ventilator weaning has been studied extensively, and the findings yield inconsistent conclusions. The parasternal intercostal muscle holds important substantial respiratory reserve capacity when the central drive is enhanced, the predictive value of combining parasternal intercostal muscle ultrasound parameters with P0.1(airway occlusion pressure at 100 msec) in assessing ventilator weaning outcomes is still unknown.

Our study aimed to evaluate the predictive efficacy of parasternal intercostal muscle ultrasound in conjunction with P0.1 in determining weaning failure.

We recruited patients who had been admitted to ICU and had been receiving mechanical ventilation for over two days. All patients underwent a half-hour spontaneous breathing trial (SBT) with low-level pressure support ventilation (PSV). They were positioned semi-upright for parasternal intercostal muscle ultrasound evaluations, including parasternal intercostal muscle thickness (PIMT), and parasternal intercostal muscle thickening fraction (PIMTF); P0.1 was obtained from the ventilator. Weaning failure was defined as the need for non-invasive positive pressure ventilation or re-intubation within 48 h post-weaning.

Of the 56 enrolled patients with a mean age of 63.04 ± 15.80 years, 13 (23.2%) experienced weaning failure. There were differences in P0.1 (P = .001) and PIMTF (P = .017) between the two groups, but also in patients with a diaphragm thickness ≥ 2 mm. The predictive threshold values were PIMTF ≥ 13.15% and P0.1 ≥ 3.9 cmH2O for weaning failure. The AUROC for predicting weaning failure was 0.721 for PIMTF, 0.792 for P0.1, and 0.869 for the combination of PIMTF and P0.1.

The parasternal intercostal muscle thickening fraction and P0.1 are independently linked to weaning failure, especially in patients with normal diaphragm thickness. The combination of parasternal intercostal muscle thickening fraction and P0.1 can serve as a valuable tool for the precise clinical prediction of weaning outcomes.

Chinese Clinical Trial Registry website (ChiCTR2200065422).

The results of clinical and weaning readiness tests and the spontaneous breathing trial (SBT) are used to predict the success of the weaning process and extubation.

We evaluated the capacity of the cuff leak test, rate of rapid and shallow breathing, cough intensity, and diaphragmatic contraction velocity (DCV) to predict the success of the SBT and extubation in a prospective, multicenter observational study with consecutive adult patients admitted to four intensive care units. We used receiver operating characteristic (ROC) curves to assess the tests' predictive capacity and built predictive models using logistic regression.

We recruited 367 subjects who were receiving invasive mechanical ventilation and on whom 456 SBTs were performed, with a success rate of 76.5%. To predict the success of the SBT, we derived the following equation: (0.56 × Cough) - (0.13 × DCV) + 0.25. When the cutoff point was ≥ 0.83, the sensitivity was 91.5%, the specificity was 22.1%, and the overall accuracy was 76.2%. The area under the ROC curve (AUC-ROC) was 0.63. To predict extubation success, we derived the following equation: (5.7 × SBT) + (0.75 × Cough) - (0.25 × DCV) - 4.5. When the cutoff point was ≥ 1.25, the sensitivity was 96.8%, the specificity was 78.4%, and the overall accuracy was 91.5%. The AUC-ROC of this model was 0.91.

Objective measurement of cough and diaphragmatic contraction velocity could be used to predict SBT success. The equation for predicting successful extubation, which includes SBT, cough, and diaphragmatic contraction velocity values, showed excellent discriminative capacity.

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.

This study aims to determine the relationship between spinal cord perfusion pressure (SCPP) and breathing function in patients with acute cervical traumatic spinal cord injuries.

We included 8 participants without cervical TSCI plus 13 patients with cervical traumatic spinal cord injuries, American Spinal Injury Association Impairment Scale grades A-C. In the TSCI patients, we monitored intraspinal pressure from the injury site for up to a week and computed the SCPP as mean arterial pressure minus intraspinal pressure. Breathing function was quantified by diaphragmatic electromyography using an EDI (electrical activity of the diaphragm) nasogastric tube as well as by ultrasound of the diaphragm and the intercostal muscles performed when sitting at 20°-30°.

We analysed 106 ultrasound examinations (total 1370 images/videos) and 198 EDI recordings in the patients with cervical traumatic spinal cord injuries. During quiet breathing, low SCPP (< 60 mmHg) was associated with reduced EDI-peak (measure of inspiratory effort) and EDI-min (measure of the tonic activity of the diaphragm), which increased and then plateaued at SCPP 60-100 mmHg. During quiet and deep breathing, the diaphragmatic thickening fraction (force of diaphragmatic contraction) plotted versus SCPP had an inverted-U relationship, with a peak at SCPP 80-90 mmHg. Diaphragmatic excursion (up and down movement of the diaphragm) during quiet breathing did not correlate with SCPP, but diaphragmatic excursion during deep breathing plotted versus SCPP had an inverse-U relationship with a peak at SCPP 80-90 mmHg. The thickening fraction of the intercostal muscles plotted versus SCPP also had inverted-U relationship, with normal intercostal function at SCPP 80-100 mmHg, but failure of the upper and middle intercostals to contract during inspiration (i.e. abdominal breathing) at SCPP < 80 or > 100 mmHg.

After acute, cervical traumatic spinal cord injuries, breathing function depends on the SCPP. SCPP 80-90 mmHg correlates with optimum diaphragmatic and intercostal muscle function. Our findings raise the possibility that intervention to maintain SCPP in this range may accelerate ventilator liberation which may reduce stay in the neuro-intensive care unit.

Diaphragm ultrasound is a novel alternative to esophageal pressure measurements in the evaluation of diaphragm function and activity, but data about its reliability in a pediatric setting are lacking. We aimed to compare the esophageal pressure swing (∆P es , gold standard) with the diaphragmatic thickening fraction (DTF) as a measure of inspiratory effort in sedated children. Additionally, we studied the effect of positive end-expiratory pressure (PEEP) on the end-expiratory thickness of the diaphragm (DT ee ).

Prospective open-label non-randomized interventional physiological cohort study.

Operating room in tertiary academic hospital.

Children 28 days to 13 years old scheduled for elective surgery with general anesthesia, spontaneously breathing through a laryngeal mask airway, were eligible for inclusion. Exclusion criteria were disorders or previous surgery of the diaphragm, anticipated difficult airway or acute cardiopulmonary disease. All measurements were performed prior to surgery.

Patients were subjected to different levels of respiratory load, PEEP and anesthetic depth in a total of seven respiratory conditions.

The esophageal pressure and diaphragm thickening fraction were simultaneously recorded for five breaths at each respiratory condition. The relation between ∆P es and DTF was studied in a mixed model. We analyzed 407 breaths in 13 patients. Both DTF ( p = 0.03) and ∆Pes ( p = 0.002) could detect respiratory activity, and ∆P es and DTF were associated across respiratory conditions ( p < 0.001; R2 = 31%). With increasing inspiratory load, ∆P es increased significantly, while DTF did not ( p = 0.08). Additionally, DT ee did not differ significantly between 10, 5, and 0 cm H 2 O PEEP ( p = 0.08).

In spontaneously breathing sedated children and across different respiratory conditions, DTF could differentiate minimal or no inspiratory effort from substantial inspiratory effort and was associated with ∆P es . Increased efforts resulted in higher ∆P es but not larger DTF.

Hemi-diaphragm palsy after brachial plexus block above the clavicle (BPBAC) occurs frequently, but few patients develop post-operative pulmonary complications (PPC). We hypothesized that contralateral hemidiaphragm function increases after BPBAC. This contralateral function preserves global diaphragmatic function, avoiding PPC in the case of ipsilateral hemi-diaphragm palsy.

This prospective observational cohort study included 64 adult patients undergoing shoulder surgery with planned BPBAC (interscalene brachial plexus block and supraclavicular block). The Thickening Fraction (TF) was measured by ultrasound in both hemi-diaphragms, ipsilateral (TF _ipsilateral) and contralateral (TF_{contralateral}) to the BPBAC, before and after the surgery. TF_global is the sum of TF_ipsilateral and TF_{contralateral}. PPC were defined as occurrences of dyspnea, tachypnea, SpO₂ <90% or SpO₂/FiO₂ <315.

TF_{contralateral} increased significantly (an average of 40%) after BPBAC (p = 0.001), and TF_ipsilateral decreased (an average of 72%). After BPBAC, 86% of patients had a decreased TF_ipsilateral and 59% of patients an increased TF_{contralateral} at post-operatively. Only 17% of patients have PPC.

After BPBAC, global diaphragm function decreases because of ipsilateral hemi-diaphragm reduction, but less than expected because of increased contralateral hemi-diaphragm function. As a part of diaphragm function, contralateral hemi-diaphragm function must be checked.

Weaning is a critical stage of an intensive care unit (ICU) stay, in which the respiratory muscles play a major role. Weakness of the respiratory muscles, which is associated with significant morbidity in the ICU, is not limited to atrophy and subsequent dysfunction of the diaphragm; the extradiaphragmatic inspiratory and expiratory muscles also play important parts. In addition to the well-established deleterious effect of mechanical ventilation on the respiratory muscles, other risk factors such as sepsis may be involved. Weakness of the respiratory muscles can be suspected visually in a patient with paradoxical movement of the abdominal compartment. Measurement of maximal inspiratory pressure is the simplest way to assess respiratory muscle function, but it does not specifically take the diaphragm into account. A cut-off value of -30 cmH2O could identify patients at risk for prolonged ventilatory weaning; however, ultrasound may be better for assessing respiratory muscle function in the ICU. Although diaphragm dysfunction has been associated with weaning failure, this diagnosis should not discourage clinicians from performing spontaneous breathing trials and considering extubation. Recent therapeutic developments aimed at preserving or restoring respiratory muscle function are promising.

The WHO recently declared that COVID-19 no longer constitutes a public health emergency of international concern; however, lessons learned through the pandemic should not be left behind. Lung ultrasound was largely utilized as a diagnostic tool thanks to its feasibility, easy application, and the possibility to reduce the source of infection for health personnel. Lung ultrasound scores consist of grading systems used to guide diagnosis and medical decisions, owning a good prognostic value. In the emergency context of the pandemic, several lung ultrasound scores emerged either as new scores or as modifications of pre-existing ones. Our aim is to clarify the key aspects of lung ultrasound and lung ultrasound scores to standardize their clinical use in a non-pandemic context. The authors searched on PubMed for articles related to "COVID-19", "ultrasound", and "Score" until 5 May 2023; other keywords were "thoracic", "lung", "echography", and "diaphragm". A narrative summary of the results was made. Lung ultrasound scores are demonstrated to be an important tool for triage, prediction of severity, and aid in medical decisions. Ultimately, the existence of numerous scores leads to a lack of clarity, confusion, and an absence of standardization.

 Mechanical ventilation is a life-saving intervention for critically ill patients, but it can also lead to diaphragm atrophy, which may prolong the duration of mechanical ventilation and the length of stay in the intensive care unit. IntelliVent-ASV® (Hamilton Medical, Rhäzüns, Switzerland) is a new mode of ventilation that has been developed to reduce diaphragm atrophy by promoting spontaneous breathing efforts. In this study, we aimed to evaluate the effectiveness of IntelliVent-ASV® and pressure support-synchronized intermittent mandatory ventilation (PS-SIMV) mode in reducing diaphragm atrophy by measuring diaphragm thickness using ultrasound (US) imaging.

 We enrolled 60 patients who required mechanical ventilation due to respiratory failure and were randomized into two groups: IntelliVent-ASV^® and PS-SIMV. We measured the diaphragm thickness using US imaging at admission and on the seventh day of mechanical ventilation.

Our results showed that diaphragm thickness decreased significantly in the PS-SIMV group but remained unchanged in the IntelliVent-ASV^® group. The difference in diaphragm thickness between the two groups was statistically significant on the seventh day of mechanical ventilation.

IntelliVent-ASV^® may reduce diaphragm atrophy by promoting spontaneous breathing efforts. Our study suggests that this new mode of ventilation may be a promising approach to preventing diaphragm atrophy in mechanically ventilated patients. Further studies using invasive measures of diaphragm function are warranted to confirm these findings.

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

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

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

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

Introduction: Diaphragm dysfunction is common in patients undergoing mechanical ventilation. The application of positive end-expiratory pressure (PEEP) and the varying end-expiratory lung volume cause changes in diaphragm geometry. We aimed to assess the impact of the level of PEEP and lung inflation on diaphragm thickness, thickening fraction and displacement. Methods: An observational study in a mixed medical and surgical ICU was conducted. The patients underwent a PEEP-titration trial with the application of three random levels of PEEP: 0 cmH₂O (PEEP0), 8 cmH₂O (PEEP8) and 15 cmH₂O (PEEP15). At each step, the indices of respiratory effort were assessed, together with arterial blood and diaphragm ultrasound; end-expiratory lung volume was measured. Results: 14 patients were enrolled. The tidal volume, diaphragm displacement and thickening fraction were significantly lower with higher levels of PEEP, while both the expiratory and inspiratory thickness increased with higher PEEP levels. The inspiratory effort, as evaluated by the esophageal pressure swing, was unchanged. Both the diaphragm thickening fraction and displacement were significantly correlated with inspiratory effort in the whole dataset. For both measurements, the correlation was stronger at lower levels of PEEP. The difference in the diaphragm thickening fraction during tidal breathing between PEEP 15 and PEEP 0 was negatively related to the change in the functional residual capacity and the change in alveolar dead space. Conclusions: Different levels of PEEP significantly modified the diaphragmatic thickness and thickening fraction, showing a PEEP-induced decrease in the diaphragm contractile efficiency. When using ultrasound to assess diaphragm size and function, the potential effect of lung inflation should be taken into account.

Previous literature on the determinants of diaphragm dysfunction in septic patients is limited. The goal of this study is to assess diaphragm dysfunction in terms of its prevalence and its potential associated factors in septic intensive care unit (ICU) patients.

This prospective and observational study was conducted between June 2015 and July 2019. Ultrasound measures of diaphragm thickness were performed daily on septic patients. The primary outcome was the prevalence of diaphragm dysfunction at baseline and during the ICU stay. The secondary outcome was the diaphragm thickness. Possible associated factors were prospectively recorded.

Fifty patients were enrolled in the study. The prevalence of diaphragm dysfunction was 58%. No diaphragm atrophy was found during the ICU stay. Diaphragm dysfunction was associated with the alteration of consciousness, intra-abdominal sepsis, hypnotics and opioids, and mechanical ventilation. Administration of hypnotics, opioids, and steroids was associated with a decreased diaphragm thickening fraction. Diaphragm dysfunction had no impact on patient outcomes.

Our data reveal a high prevalence of diaphragm dysfunction in septic patients at the onset of sepsis. Administration of hypnotics, opioids, and steroids was associated with the alteration of diaphragm function as well as intra-abdominal sepsis.

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.