Ability of parasternal intercostal muscle thickening fraction to predict reintubation in surgical patients with sepsis.

OBJECTIVES: We aimed to evaluate the ability of the parasternal intercostal (PIC) thickening fraction during spontaneous breathing trial (SBT) to predict the need for reintubation within 48 h after extubation in surgical patients with sepsis. METHODS: This prospective observational study included adult patients with sepsis who were mechanically ventilated and indicated for SBT. Ultrasound measurements of the PIC thickening fraction and diaphragmatic excursion (DE) were recorded 15 min after the start of the SBT. After extubation, the patients were followed up for 48 h for the need for reintubation. The study outcomes were the ability of the PIC thickening fraction (primary outcome) and DE to predict reintubation within 48 h of extubation using area under receiver characteristic curve (AUC) analysis. The accuracy of the model including the findings of right PIC thickening fraction and right DE was also assessed using the current study cut-off values. Multivariate analysis was performed to identify independent risk factors for reintubation. RESULTS: We analyzed data from 49 patients who underwent successful SBT, and 10/49 (20%) required reintubation. The AUCs (95% confidence interval [CI]) for the ability of right and left side PIC thickening fraction to predict reintubation were 0.97 (0.88-1.00) and 0.96 (0.86-1.00), respectively; at a cutoff value of 6.5-8.3%, the PIC thickening fraction had a negative predictive value of 100%. The AUCs for the PIC thickening fraction and DE were comparable; and both measures were independent risk factors for reintubation. The AUC (95% CI) of the model including the right PIC thickening fraction > 6.5% and right DE ≤ 18 mm to predict reintubation was 0.99 (0.92-1.00), with a positive predictive value of 100% when both sonographic findings are positive and negative predictive value of 100% when both sonographic findings are negative. CONCLUSIONS: Among surgical patients with sepsis, PIC thickening fraction evaluated during the SBT is an independent risk factor for reintubation. The PIC thickening fraction has an excellent predictive value for reintubation. A PIC thickening fraction of ≤ 6.5-8.3% can exclude reintubation, with a negative predictive value of 100%. Furthermore, a combination of high PIC and low DE can also indicate a high risk of reintubation. However, larger studies that include different populations are required to replicate our findings and validate the cutoff values.

Evaluation of the relationship between intercostal muscle oxygenation measured by near-infrared spectroscopy and exercise capacity in group E COPD patients.

Near-infrared spectroscopy (NIRS) can be used to demonstrate muscle metabolism and oxygenation. NIRS-based oximeters enable the noninvasive measurement of static and dynamic muscle oxygenation. This study aimed to evaluate the relationship between NIRS readings and exercise capacity in group E COPD patients. The prospective study included 40 patients with group E COPD who presented to our outpatient clinic between May 2021 and June 2022. The patients were evaluated with pulmonary function testing, 6-Minute Walk Test (6MWT), echocardiography, and dyspnea and quality of life assessments. NIRS muscle oxygen saturation (SmO2) levels at the start and end of the 6MWT were obtained. 6MWT distance was positively correlated with intercostal SmO2 and fingertip SO2 at the start (R = 0.679, p ≤ 0.001 and R = 0.321, p = 0.04, respectively) and end of the 6MWT (R = 0.693, p ≤ 0.001 and R = 0.635, p ≤ 0.001, respectively) and negatively correlated with the number of hospitalizations due to exacerbations in the last year and mean pulmonary arterial pressure (R = - 0.648, p ≤ 0.001 and R = - 0.676, p ≤ 0.001, respectively). SF-36 score was positively correlated with intercostal SmO2 at the beginning of the 6MWT (R = 0.336, p = 0.03). Intercostal SmO2 levels at the start of the 6MWT positively correlated with diffusing capacity of the lung for carbon dioxide (DLCO) (R = 0.388, p = 0.01) and ratio of DLCO to alveolar volume (DLCO/VA) levels (R = 0.379, p = 0.02), and these correlations persisted more strongly after the 6MWT (R = 0.524, p = 0.01; R = 0.500, p = 0.01, respectively). NIRS is a practical and noninvasive method for measuring muscle oxygenation and can be used as an alternative to 6MWT in the evaluation of exercise capacity in patients with group E COPD.

The ratio of parasternal intercostal muscle-thickening fraction-to-diaphragm thickening fraction for predicting weaning failure.

BACKGROUND: 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. MATERIALS AND METHODS: 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. RESULTS: 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. CONCLUSIONS: The TFic/TFdi ratio predicted weaning failure with high accuracy and outperformed the D-RSBI.

Intercostal Muscle Function During Noninvasive Ventilation and Acute Hypercapnic Respiratory Failure.

BACKGROUND: Noninvasive ventilation (NIV) is a widely used and well-established treatment modality for respiratory failure. In patients with increased respiratory work of breathing, accessory muscles are commonly activated along with the diaphragm. Whereas diaphragm ultrasound has been utilized to assess outcomes of mechanical ventilation, the data on intercostal muscle ultrasound remain limited. We aimed to investigate the association between intercostal muscle thickening fraction (TF) and NIV failure in critical care patients with hypercapnic respiratory failure. METHODS: Critical care subjects receiving NIV for hypercapnic respiratory failure were enrolled in the study. The intercostal muscle TF was measured on admission day (day 0) and the following day (day 1). NIV failure was defined as the need for invasive mechanical ventilation or death during NIV therapy. RESULTS: A total of 158 subjects were enrolled, and 30 experienced NIV failure. Age, sex, and body mass index (BMI) were similar in the NIV success and failure groups. Acute Physiology And Chronic Health Evaluation II (APACHE II) and the Sequential Organ Failure Assessment (SOFA) scores were higher in the NIV failure group. In terms of causes of respiratory failure, the COPD exacerbation rate was higher in the NIV success group. TF was higher in the NIV failure group on both day 0 and day 1. The increased TF on the ICU admission day, with a cutoff value of 12%, was associated with NIV failure after adjusting for age, sex, BMI, APACHE II, and SOFA. Persistence of a higher TF value on both day 0 and day 1 was also associated with NIV failure risk. CONCLUSIONS: There was a positive relation between intercostal muscle TF measured by ultrasound and NIV failure, even after adjusting for APACHE II and SOFA scores.

Association between computed tomography-quantified respiratory muscles and chronic obstructive pulmonary disease: a retrospective study.

BACKGROUND: This study examined the association between chest muscles and chronic obstructive pulmonary disease (COPD) and the relationship between chest muscle areas and acute exacerbations of COPD (AECOPD). METHODS: There were 168 subjects in the non-COPD group and 101 patients in the COPD group. The respiratory and accessory respiratory muscle areas were obtained using 3D Slicer software to analysis the imaging of  computed tomography (CT). Univariate and multivariate Poisson regressions were used to analyze the number of AECOPD cases during the preceding year. The cutoff value was obtained using a receiver operating characteristic (ROC) curve. RESULTS: We scanned 6342 subjects records, 269 of which were included in this study. We then measured the following muscle areas (non-COPD group vs. COPD group): pectoralis major (19.06 ± 5.36 cm2 vs. 13.25 ± 3.71 cm2, P < 0.001), pectoralis minor (6.81 ± 2.03 cm2 vs. 5.95 ± 1.81 cm2, P = 0.001), diaphragmatic dome (1.39 ± 0.97 cm2 vs. 0.85 ± 0.72 cm2, P = 0.011), musculus serratus anterior (28.03 ± 14.95 cm2 vs.16.76 ± 12.69 cm2, P < 0.001), intercostal muscle (12.36 ± 6.64 cm2 vs. 7.15 ± 5.6 cm2, P < 0.001), pectoralis subcutaneous fat (25.91 ± 13.23 cm2 vs. 18.79 ± 10.81 cm2, P < 0.001), paravertebral muscle (14.8 ± 4.35 cm2 vs. 13.33 ± 4.27 cm2, P = 0.007), and paravertebral subcutaneous fat (12.57 ± 5.09 cm2 vs. 10.14 ± 6.94 cm2, P = 0.001). The areas under the ROC curve for the pectoralis major, intercostal, and the musculus serratus anterior muscle areas were 81.56%, 73.28%, and 71.56%, respectively. Pectoralis major area was negatively associated with the number of AECOPD during the preceding year after adjustment (relative risk, 0.936; 95% confidence interval, 0.879-0.996; P = 0.037). CONCLUSION: The pectoralis major muscle area was negative associated with COPD. Moreover, there was a negative correlation between the number of AECOPD during the preceding year and the pectoralis major area.

Graded onset of parasternal intercostal inspiratory activity detected with surface electromyography in healthy young females and males.

Intramuscular recordings of single motor unit activity from parasternal intercostal muscles show a rostrocaudal gradient in timing and amplitude of inspiratory activity. This study determined the feasibility of surface electromyographic activity (EMG) to measure graded parasternal intercostal activity in young females and males during quiet breathing and breathing with inspiratory resistive loads. Surface EMGs were recorded from the 1st-to-5th parasternal intercostal muscles during 10 min of breathing. EMGs were processed to remove 50 Hz and electrocardiogram artifacts and integrated. Amplitude and onset time of inspiratory activity were measured from waveform averages triggered at the onset of inspiratory flow. Onset times were measured independently by two assessors, blinded to interspace and EMG scale, with excellent agreement (ICC3,k = 0.86). The onset of inspiratory activity in the 1st-to-3rd interspaces was at or within ∼400 ms of the start of inspiratory airflow, but activity in the caudal (4th and 5th) spaces was delayed by up to ∼1,000 ms (P < 0.001). There was no main effect of sex on onset time (P = 0.07), but an interaction with interspace (P < 0.001) revealed that inspiratory activity in the caudal interspaces was delayed by 15% of inspiratory time in female participants compared with 30% of inspiratory time in male participants. Inspiratory loads did not affect EMG onset time (P = 0.31). Thus, surface EMG is feasible to assess the onset time of inspiratory activity as a marker of inspiratory neural drive and pattern of activation across spaces, in both females and males.NEW & NOTEWORTHY We demonstrated that surface EMG is a valid method to measure graded inspiratory EMG in the parasternal intercostal muscles in healthy young male and female participants during quiet breathing and loaded breathing. Across the 1st-to-5th interspaces, there was more homogenous activation in women and more graded activity in men across parasternal intercostal muscles during breathing. By recording surface EMG from both male and female participants, we have revealed sex differences in inspiratory activity across intercostal muscles.

Neural respiratory drive assessment and its correlation with inspiratory muscle strength in patients undergoing open-heart surgery: A cross-sectional study.

BACKGROUND AND PURPOSE: Pulmonary dysfunction and inspiratory muscle weakness are frequently observed after cardiac surgery. Understanding the load on and capacity of respiratory muscles can provide valuable insights into the overall respiratory mechanics and neural regulation of breathing. This study aimed to assess the extent of neural respiratory drive (NRD) and determine whether admission-to-discharge differences in NRD were associated with inspiratory muscle strength changes among patients undergoing open-heart surgery. METHODS: This cross-sectional study was conducted on 45 patients scheduled for coronary artery bypass graft or heart valve surgery. NRD was measured using a surface parasternal intercostal electromyogram during resting breathing (sEMGpara tidal) and maximal inspiratory effort (sEMGpara max). Maximal inspiratory pressure (MIP) was used to determine inspiratory muscle strength. Evaluations were performed on the day of admission and discharge. RESULTS: There was a significant increase in sEMGpara tidal (6.9 ± 3.6 µV, p < 0.001), sEMGpara %max (13.7 ± 11.2%, p = 0.008), and neural respiratory drive index (NRDI, the product of EMGpara %max and respiratory rate) (337.7 ± 286.8%.breaths/min, p < 0.001), while sEMGpara max (-43.6 ± 20.4 µV, p < 0.01) and MIP (-24.4 ± 10.7, p < 0.001) significantly decreased during the discharge period. Differences in sEMGpara tidal (r = -0.369, p = 0.045), sEMGpara %max (r = -0.646, p = 0.001), and NRDI (r = -0.639, p = 0.001) were significantly associated with a reduction in MIP. DISCUSSION: The findings indicate that NRD increases after open-heart surgery, which corresponds to a decrease in inspiratory muscle strength.

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.

Emergency ultrasound of respiratory muscles: a promising tool for determining the outcomes of COPD exacerbations.

BACKGROUND: The respiratory muscles of patients with chronic obstructive pulmonary disease (COPD) exhibit structural and functional changes that can be evaluated and monitored by ultrasonography. METHODS: This single-center, prospective study was conducted in the emergency department (ED) of a tertiary care hospital over an eight-month period (September 2020-May 2021). Diaphragmatic excursions, end-expiratory thickness, and thickening fractions, as well as right and left intercostal muscle thicknesses, of all adult subjects manifesting COPD exacerbation, were assessed. The data were analyzed regarding ward/intensive care unit (ICU) hospitalization or discharge from the ED, mortality, and readmission within 15 days. RESULTS: Sixty-three subjects were recruited for the study. Diaphragmatic excursion, end-expiratory diaphragmatic thickness, and intercostal muscle thickness measurements were significantly different between the ward, ICU, and discharge groups (p < 0.001) but lower in the deceased subjects (all p < 0.05). The diaphragmatic excursion value of 3.25 cm was the threshold value measured for distinguishing discharge from ED, and 1.82 cm was measured for admission to the ICU, both with 100% sensitivity and selectivity (AUC = 1). DISCUSSION: Diaphragmatic excursion, diaphragmatic end-expiratory thickness, and right and left intercostal muscle thicknesses vary in the prognosis of subjects presenting with COPD exacerbation.

Effects of high-intensity inspiratory muscle warm-up on inspiratory muscle strength and accessory inspiratory muscle activity.

This study aimed to determine the effects of work-matched moderate-intensity and high-intensity inspiratory muscle warm-up (IMW) on inspiratory muscle strength and accessory inspiratory muscle activity. Eleven healthy men performed three IMWs at different intensities, namely, placebo, moderate-intensity, and high-intensity, set, respectively, at 15 %, 40 %, and 80 % of maximal inspiratory mouth pressure (MIP). MIP was measured before and after IMW. Electromyography (EMG) was recorded for the sternocleidomastoid muscle (SCM) and intercostal muscles (IC) during IMW. MIP increased significantly in the moderate-intensity condition (104.2 ± 5.1 %, p < 0.05) and high-intensity condition (106.5 ± 6.2 %, p < 0.01) after IMW. The EMG amplitudes of the SCM and IC during IMW were significantly higher in the order of high-intensity, moderate-intensity, and placebo conditions. There was a significant correlation between changes in MIP and EMG amplitude of the SCM (r = 0.60, p < 0.01) and IC (r = 0.47, p < 0.01) during IMW. These findings suggest that high-intensity IMW increases neuromuscular activity in the accessory inspiratory muscles, which may improve inspiratory muscle strength.

Relationship between respiratory muscles ultrasound parameters and running tests performance in adolescent football players. A pilot study.

Purpose: Assessing the relationship between ultrasound imaging of respiratory muscles during tidal breathing and running tests (endurance and speed) in adolescent football players. Methods: Ultrasound parameters of the diaphragm and intercostal muscles (shear modulus, thickness, excursion, and velocity), speed (30-m distance), and endurance parameters (multi-stage 20-m shuttle run test) were measured in 22 male adolescent football players. The relation between ultrasound and running tests were analysed by Spearman's correlation. Results: Diaphragm shear modulus at the end of tidal inspiration was moderately negatively (R =  - 0.49; p = 0.2) correlated with the speed score at 10 m. The diaphragm and intercostal muscle shear modulus ratio was moderately to strongly negatively correlated with the speed score at 10 m and 30 m (about R =  - 0.48; p = 0.03). Diaphragm excursion was positively correlated with the speed score at 5 m (R = 0.46; p = 0.04) and 10 m (R = 0.52; p = 0.02). Diaphragm velocity was moderately positively correlated with the speed score at 5 m (R = 0.42; p = 0.06) and 30 m (R = 0.42; p = 0.07). Ultrasound parameters were not significantly related to all endurance parameters (R ≤ 0.36; p ≥ 0.11). Conclusions: Ultrasound parameters of the respiratory muscles are related to speed score in adolescent football players. The current state of knowledge does not allow us to clearly define how important the respiratory muscles' ultrasound parameters can be in predicting some performance parameters in adolescent athletes.

Muscle Ultrasound Changes Correlate With Functional Impairment in Spinal Muscular Atrophy.

OBJECTIVE: We investigated ultrasound patterns of muscle involvement in different types of spinal muscular atrophy (SMA) and their correlation with functional status to determine the pattern of muscle compromise in patients with SMA and the potential role of ultrasound to evaluate disease progression. METHODS: We examined muscles (biceps brachii, rectus femoris, diaphragm, intercostals and thoracic multifidus) of 41 patients with SMA (types 1 to 4) and 46 healthy age- and sex-matched control individuals using B-mode ultrasound for gray-scale analysis (GSA), area (biceps brachii and rectus femoris) and diaphragm thickening ratio. Functional scales were applied to patients only. We analyzed ultrasound abnormalities in specific clinical subtypes and correlated findings with functional status. RESULTS: Compared with controls, patients had reduced muscle area and increased mean GSA for all muscles (p < 0.001), with an established correlation between the increase in GSA and the severity of SMA for biceps brachii, rectus femoris and intercostals (p = 0.03, 0.01 and 0.004 respectively) when using the Hammersmith Functional Motor Scale Expanded. Diaphragm thickening ratio was normal in the majority of patients, and intercostal muscles had higher GSA than diaphragm in relation to the controls. CONCLUSION: Ultrasound is useful for quantifying muscular changes in SMA and correlates with functional status. Diaphragm thickening ratio can be normal even with severe compromise of respiratory muscles in quantitative analysis, and intercostal muscles were more affected than diaphragm.

The effect of inspiratory muscle training and detraining on the respiratory metaboreflex.

NEW FINDINGS: What is the central question of this study? Is the attenuation of the respiratory muscle metaboreflex preserved after detraining? What is the main finding and its importance? Inspiratory muscle training increased respiratory muscle strength and attenuated the respiratory muscle metaboreflex as evident by lower heart rate and blood pressure. After 5 weeks of no inspiratory muscle training (detraining), respiratory muscle strength was still elevated and the metaboreflex was still attenuated. The benefits of inspiratory muscle training persist after cessation of training, and attenuation of the respiratory metaboreflex follows changes in respiratory muscle strength. ABSTRACT: Respiratory muscle training (RMT) improves respiratory muscle (RM) strength and attenuates the RM metaboreflex. However, the time course of muscle function loss after the absence of training or 'detraining' is less known and some evidence suggest the respiratory muscles atrophy faster than other muscles. We sought to determine the RM metaboreflex in response to 5 weeks of RMT and 5 weeks of detraining. An experimental group (2F, 6M; 26 ± 4years) completed 5 weeks of RMT and tibialis anterior (TA) training (each 5 days/week at 50% of maximal inspiratory pressure (MIP) and 50% maximal isometric force, respectively) followed by 5 weeks of no training (detraining) while a control group (1F, 7M; 24 ± 1years) underwent no intervention. Prior to training (PRE), post-training (POST) and post-detraining (DETR), all participants underwent a loaded breathing task (LBT) to failure (60% MIP) while heart rate and mean arterial blood pressure (MAP) were measured. Five weeks of training increased RM (18 ± 9%, P < 0.001) and TA (+34 ± 19%, P < 0.001) strength and both remained elevated after 5 weeks of detraining (MIP-POST vs. MIP-DETR: 154 ± 31 vs. 153 ± 28 cmH2O, respectively, P = 0.853; TA-POST vs. TA-DETR: 86 ± 19 vs. 85 ± 16 N, respectively, P = 0.982). However, the rise in MAP during LBT was attenuated POST (-11 ± 17%, P = 0.003) and DETR (-9 ± 9%, P = 0.007) during the iso-time LBT. The control group had no change in MIP (P = 0.33), TA strength (P = 0.385), or iso-time MAP (P = 0.867) during LBT across all time points. In conclusion, RM and TA have similar temporal strength gains and the attenuation of the respiratory muscle metaboreflex remains after 5 weeks of detraining.

SPECKLE TRACKING QUANTIFICATION PARASTERNAL INTERCOSTAL MUSCLE LONGITUDINAL STRAIN TO PREDICT WEANING OUTCOMES: A MULTICENTRIC OBSERVATIONAL STUDY.

ABSTRACT: Background: The purpose of this study was to determine the feasibility, reliability, and reproducibility of parasternal intercostal muscle longitudinal strain (LSim) quantification by speckle tracking and the value of maximal LSim to predict weaning outcomes. Methods: This study was divided into three phases. Phases 1 and 2 comprehended prospective observational programs to evaluate the feasibility, reliability, and repeatability of speckle tracking to assess LSim in healthy subjects and mechanically ventilated patients. Phase 3 was a multicenter retrospective study to evaluate the value of maximal LSim, intercostal muscle thickening fraction (TFim), diaphragmatic thickening fraction, diaphragmatic excursion, and rapid shallow breathing index to predict weaning outcomes. Results: A total of 25 healthy subjects and 20 mechanically ventilated patients were enrolled in phases 1 and 2, respectively. Maximal LSim was easily accessible, and the intraoperator reliability and interoperator reliability were excellent in eupnea, deep breathing, and mechanical ventilation. The intraclass correlation coefficient ranged from 0.85 to 0.96. Moreover, 83 patients were included in phase 3. The areas under the receiver operating characteristic curve of maximal LSim, TFim, diaphragmatic thickening fraction, diaphragmatic excursion, and rapid shallow breathing index were 0.91, 0.79, 0.71, 0.70, and 0.78 for the prediction of successful weaning, respectively. The best cutoff values of LSim and TFim were >-6% (sensitivity, 100%; specificity, 64.71%) and <7.6% (sensitivity, 100%; specificity, 50.98%), respectively. Conclusions: The quantification of LSim by speckle tracking was easily achievable in healthy subjects and mechanically ventilated patients and presented a higher predictive value for weaning success compared with conventional weaning parameters. Trial registration no. ChiCTR2100049817.

Intra-Rater Reliability of Shear Wave Elastography for the Quantification of Respiratory Muscles in Adolescent Athletes.

The aim of this study was to assess the intra-rater reliability and agreement of diaphragm and intercostal muscle elasticity and thickness during tidal breathing. The diaphragm and intercostal muscle parameters were measured using shear wave elastography in adolescent athletes. To calculate intra-rater reliability, intraclass correlation coefficient (ICC) and Bland-Altman statistics were used. The reliability/agreement for one-day both muscle measurements (regardless of probe orientation) were at least moderate. During the seven-day interval between measurements, the reliability of a single measurement depended on the measured parameter, transducer orientation, respiratory phase, and muscle. Excellent reliability was found for diaphragm shear modulus at the peak of tidal expiration in transverse probe position (ICC3.1 = 0.91-0.96; ICC3.2 = 0.95), and from poor to excellent reliability for the intercostal muscle thickness at the peak of tidal inspiration with the longitudinal probe position (ICC3.1 = 0.26-0.95; ICC3.2 = 0.15). The overall reliability/agreement of the analysed data was higher for the diaphragm measurements (than the intercostal muscles) regardless of the respiratory phase and probe position. It is difficult to identify a more appropriate probe position to examine these muscles. The shear modulus/thickness of the diaphragm and intercostal muscles demonstrated good reliability/agreement so this appears to be a promising technique for their examination in athletes.