Interobserver Reliability of Quantitative Muscle Sonographic Analysis in the Critically Ill Population

Inter-rater reliability of muscle ultrasonography performed by multidisciplinary novice sonographers in the evaluation of critically ill patients with acute kidney injury requiring continuous kidney replacement therapy

Early diagnosis of muscle wasting in critically ill patients with acute kidney injury requiring continuous kidney replacement therapy (AKI-CKRT) may improve outcomes via timely rehabilitation and nutrition. Muscle ultrasound (MUS) has recently gained traction for assessing muscle atrophy in the intensive care unit (ICU) but requires training to achieve reproducibility. We evaluated the inter-rater reliability of MUS in patients with AKI-CKRT performed by multidisciplinary raters including nephrologists. Two blinded independent raters used portable ultrasound to acquire images of the rectus femoris (RF). All raters were clinicians routinely caring for patients with CKRT in the ICU and were initially novices in MUS. They underwent three two-hour teleconference training sessions in MUS led by an experienced physiotherapist. Inter-rater reliability was evaluated with intraclass correlation coefficients (ICCs) [95% confidence interval] using a two-way random-effects model. We analyzed 54 MUS images (27 pairs) from nine patients at baseline (n = 16), day 3 (n = 6), day 7 (n = 8), ICU discharge (n = 10), hospital discharge (n = 10), and 1-3 months after discharge (n = 4). The mean (±standard deviation) values of RF thickness, cross-sectional area, and echointensity were 1.7 ± 1.4 cm, 4.6 ± 2.7 cm2, and 84.0 ± 17.7 AU, respectively. Reliability was excellent for RF thickness (ICC = 0.96 [0.91-0.98], p < 0.001) and cross-sectional area (ICC = 0.92 [0.83-0.96], p < 0.001) but poor for echointensity (ICC = 0.41 [0.04-0.68], p < 0.05). These results demonstrate reliable assessment of muscle size in patients with AKI-CKRT using ultrasound performed by multidisciplinary novice sonographers trained via teleconference, suggesting that this methodology may be useful in future studies of muscle wasting in patients with AKI-CKRT.

Respiratory muscle ultrasound echo characteristics and weaning outcomes in mechanically ventilated patients with sepsis: a prospective observational study

AIM

This study aimed to determine the relationship between changes in the ultrasound echo intensity of respiratory muscles and weaning outcomes in mechanically ventilated patients with sepsis.

METHODS

We prospectively observed patients with sepsis receiving mechanical ventilation admitted to the Department of Critical Care Medicine at our hospital, and categorized them into weaning success (n = 75) and weaning failure (n = 35) groups according to their weaning outcomes. The baseline respiratory muscle echo intensity of the patients was observed, and the relationship between the respiratory muscle ultrasonographic echo characteristics and weaning outcomes was evaluated.

RESULTS

Baseline respiratory muscle echo intensity was significantly higher in the weaning failure group than in the weaning success group. The incidence of respiratory muscle echoes during mechanical ventilation was significantly higher in the weaning failure group than in the weaning success group. The respiratory muscle echo characteristics changed after ICU admission. Increased respiratory muscle echo intensity was detected earlier and more readily in patients with weaning failure than in those with respiratory muscle atrophy, and enhanced respiratory muscle echo was associated with a decrease in the incidence of cumulative weaning success.

CONCLUSION

Mechanically ventilated patients with sepsis with failed weaning had higher respiratory muscle echo intensities than those in the weaning success group. Futhermore, there was an association between the respiratory muscle echo intensity and weaning outcomes.

Development of an artificial intelligence powered software for automated analysis of skeletal muscle ultrasonography

Muscle ultrasound has high utility in clinical practice and research; however, the main challenges are the training and time required for manual analysis to achieve objective quantification of muscle size and quality. We aimed to develop and validate a software tool powered by artificial intelligence (AI) by measuring its consistency and comparability of expert manual analysis quantifying lower limb muscle ultrasound images. Quadriceps complex (QC) and tibialis anterior (TA) muscle images of healthy, intensive care unit, and/or lung cancer participants were captured with portable devices. Manual analyses of muscle size and quality were performed by experienced physiotherapists taking approximately 24 h to analyze all 180 images, while automated analyses were performed using a custom-built deep-learning model (MyoVision-US), taking 247 s (saving time = 99.8%). Consistency between the manual and automated analyses was good to excellent for all QC (ICC = 0.85-0.99) and TA (ICC = 0.93-0.99) measurements, even for critically ill (ICC = 0.91-0.98) and lung cancer (ICC = 0.85-0.99) images. The comparability of MyoVision-US was moderate to strong for QC (adj. R2 = 0.56-0.94) and TA parameters (adj. R2 = 0.81-0.97). The application of AI automating lower limb muscle ultrasound analyses showed excellent consistency and strong comparability compared with human analysis across healthy, acute, and chronic population.

Improving the Reliability of Muscle Tissue Characterization Post-Stroke: A Secondary Statistical Analysis of Echotexture Features

Background/Objectives: Ultrasound (US) imaging and echotexture analysis are emerging techniques for assessing muscle tissue quality in the post-stroke population. Clinical studies suggest that echovariation (EV) and echointensity (EI) serve as objective indicators of muscle impairment, although methodological limitations hinder their clinical translation. This secondary analysis aimed to refine the assessment of echotexture by using robust statistical techniques. Methods: A total of 130 regions of interest (ROIs) extracted from the gastrocnemius medialis of 22 post-stroke individuals were analyzed. First, inter-examiner reliability between two physiotherapists was assessed by using Cohen's kappa for muscle impairment classification (low/high) for each echotexture feature. For each examiner, the correlation between the classification of the degree of impairment and the modified Heckmatt scale for each feature was analyzed. The dataset was then reduced to 44 ROIs (one image per leg per patient) and assessed by three physiotherapists to analyze inter-examiner reliability by using Light´s kappa and correlation between both assessment methods globally. Statistical differences in 21 echotexture features were evaluated according to the degree of muscle impairment. A binary logistic regression model was developed by using features with a Cohen's kappa value greater than 0.9 as predictors. Results: A strong and significant degree of agreement was observed among the three examiners regarding the degree of muscle impairment (Kappalight = 0.85, p < 0.001), with nine of the 21 features showing excellent inter-examiner reliability. The correlation between muscle impairment classification with the modified Heckmatt scale was very high and significant both globally and for each echotexture feature. Significant differences (<0.05) were found for EV, EI, dissimilarity, energy, contrast, maximum likelihood, skewness, and the modified Heckmatt scale. Logistic regression highlighted dissimilarity, entropy, EV, Gray-Level Uniformity (GLU), and EI as the main predictors of muscle tissue impairment. The EV and EI models showed high explanatory power (Nagelkerke's pseudo-R2 = 0.74 and 0.76) and robust classification performance (AUC = 94.20% and 95.45%). Conclusions: This secondary analysis confirms echotexture analysis as a reliable tool for post-stroke muscle assessment, validating EV and EI as key indicators while identifying dissimilarity, entropy, and GLU as additional relevant features.

Which Outcomes Should We be Using in Critical Care Nutrition Trials?

Selecting appropriate outcome measures is a critical component of clinical trial design. Core outcome sets, which utilize stakeholder input to define the most important outcomes for a particular research question, are valuable in improving the consistency of research, such that conclusive recommendations can be made. Alongside these core outcomes, exploratory outcomes are keys to providing novel insights into disease pathophysiology and treatment response. Surrogate outcomes developed through exploratory methods may enable intervention at an earlier stage, with the potential for prevention rather than management of the sequalae of critical illness.

Early detection of muscle wasting assessed by ultrasound and analysis of growth factor and systemic inflammation mediators in critically ill trauma patients: an observational study

PURPOSE

The present study aims to describe initial changes in muscle thickness and composition, muscle growth signaling mediators, and systemic inflammation in critically ill patients after major trauma.

METHODS

This observational study was carried out in a Level-I nonprofit trauma center. Thirty adults requiring mechanical ventilation were assessed within 24 h post-admission. Skeletal muscle wasting was evaluated using ultrasound for muscle thickness and echogenicity along with circulating insulin-like growth factor 1 (IGF-1) and inflammatory cytokines over five consecutive days. Changes over time were assessed using ANOVA repeated-measures analysis with a Bonferroni post-hoc test. Bivariate correlations were evaluated using Pearson or Spearman coefficients.

RESULTS

Over five days, a significant decrease (11%) in rectus femoris thickness (3.91 ± 0.86 to 3.47 ± 0.64, cm, p = 0.01) and an increase (29%) in echogenicity (62.1 ± 13.1 to 80.4 ± 17.3, AU, p < 0.01) were observed among the 30 patients included in this study. Circulating levels of IGF-1 exhibited a 38% reduction (68.8 ± 43.6 to 42.4 ± 29.4, ng/mL, p = 0.01). Furthermore, pro-inflammatory cytokine (IFN-y) increased by 17% (4.83 ± 1.39 to 5.66 ± 1.61, pg./mL, p = 0.02) from day 1 to day 5.

CONCLUSIONS

These findings reveal substantial thickness and muscle composition alterations within 48 h post-admission, worsening over five days. Despite standard rehabilitation care, changes in IGF-1 and IFN-y levels suggest early declines in muscle growth stimulus and increased inflammation.

Methodologies and clinical applications of lower limb muscle ultrasound in critically ill patients: a systematic review and meta-analysis

BACKGROUND

Reduced muscle mass upon admission and development of muscle wasting are frequent in critically ill patients, and linked to unfavorable outcomes. Muscle ultrasound is a promising instrument for evaluating muscle mass. We summarized the findings of lower limb muscle ultrasound values and investigated how the muscle ultrasound parameters of the examination or the patient characteristics influence the results.

METHODS

Systematic review and meta-analysis of studies of lower limb ultrasound critically ill adults. PubMed, CINAHL, Embase, PEDro and Web of Science were searched. PRISMA guidelines were followed, and studies evaluated with the appropriate NIH quality assessment tool. A meta-analysis was conducted to compare the values at admission, short and long follow-up during ICU stay, and the association between baseline values and patient characteristics or ultrasound parameters was investigated with a meta-regression.

RESULTS

Sixty-six studies (3839 patients) were included. The main muscles investigated were rectus femoris cross-sectional area (RF-CSA, n = 33/66), quadriceps muscle layer thickness (n = 32/66), and rectus femoris thickness (n = 19/66). Significant differences were found in the anatomical landmark and ultrasound settings. At ICU admission, RF-CSA ranged from 1.1 [0.73-1.47] to 6.36 [5.45-7.27] cm2 (pooled average 2.83 [2.29-3.37] cm2) with high heterogeneity among studies (I2 = 98.43%). Higher age, higher BMI, more distal landmark and the use of probe compression were associated with lower baseline muscle mass.

CONCLUSIONS

Measurements of muscle mass using ultrasound varied with reference to patient characteristics, patient position, anatomical landmarks used for measurement, and the level of compression applied by the probe; this constrains the external validity of the results and highlights the need for standardization.

STUDY REGISTRATION

PROSPERO CRD42023420376.

Association between quadriceps muscle thickness or echo intensity, malnutrition, and activities of daily living in an integrated medical and long-term care facility: A cross-sectional study

BACKGROUND &AIMS

Malnutrition and physical function impairment are prevalent concerns in long-term care facilities. This study investigated the relationship between quadriceps muscle thickness (QMT) or echo intensity (QEI), nutritional status, and activities of daily living (ADL) in residents of an Integrated Facility for Medical and Long-term Care (IFMLC) in Japan.

METHODS

Using a cross-sectional design, 126 residents (86 women, median age 89 years) at an IFMLC were assessed. Malnutrition was diagnosed using the Global Leadership Initiative on Malnutrition (GLIM) criteria including disease burden/inflammation, while ADL status was evaluated using the Barthel Index (BI). QMT and QEI, indicative of muscle mass and intramuscular adipose tissue, were measured by ultrasound. Multivariate logistic and linear regression analyses were conducted to explore the association of QMT or QEI with malnutrition and ADL.

RESULTS

62 residents (49%) were in the lower QMT group and 63 residents (50%) were in the upper QEI group. The prevalence of severe malnutrition in the lower QMT group was significantly higher than that in the upper QMT group. Moreover, the lower QMT group had significantly lower BI points than the upper QMT group. The upper QEI group had significantly lower BI points than the lower QEI group. lower QMT was associated with severe malnutrition (odds ratio 3.170; 95% CI 1.238 to 8.725; P = 0.016). Furthermore, both lower QMT (B = -12.520; 95% CI -17.069 to -7.973; P < 0.001) and upper QEI (B = -7.598; 95% CI -12.565 to -2.631; P = 0.003) showed an independent correlation with lower BI scores.

CONCLUSION

This study found a relationship between lower QMT correlated with severe malnutrition and poor ADL, while higher QEI is associated with poor ADL.

Nutrition delivery and the relationship with changes in muscle mass in adult patients receiving extracorporeal membrane oxygenation: A retrospective observational study

BACKGROUND

Adverse changes in muscle health (size and quality) are common in patients receiving extracorporeal membrane oxygenation (ECMO). Nutrition delivery may attenuate such changes, yet the relationship with muscle health remains poorly understood. This study explored the association between energy and protein delivery and changes in muscle health measured using ultrasound from baseline to day 10 and 20 in patients receiving ECMO.

METHODS

A secondary analysis of data from a prospective study quantifying changes in muscle health using ultrasound in adults receiving ECMO was completed. Patients were eligible for inclusion if they were prescribed artificial nutrition within 3 days of enrolment and had >1 ultrasound measurement. The primary outcome was the association between protein delivery (grams delivered and percentage of targets received) and change in rectus femoris cross-sectional area (RF-CSA) till day 20. Secondary outcomes were the association between energy and protein delivery and change in RF-CSA till day 10, RF-echogenicity, and quadriceps muscle layer thickness to day 10 and 20. Associations were assessed using Spearman's rank correlation.

RESULTS

Twenty-three patients (age: 48 [standard deviation {SD}: 14], 44% male) were included. Mean energy and protein delivery were 1633 kcal (SD: 374 kcal) and 70 g (SD: 17 g) equating to 79% (SD: 19%) of energy and 73% (SD: 17%) of protein targets. No association was observed between protein delivery (r = 0.167; p = 0.495) or the percentage of targets received (r = 0.096; p = 0.694) and change in RF-CSA till day 20. No other significant associations were found between energy or protein delivery and change in RF-CSA, echogenicity, or quadriceps muscle layer thickness at any time point.

CONCLUSIONS

This exploratory study observed no association between nutrition delivery and changes in muscle health measured using ultrasound in patients receiving ECMO. Larger prospective studies are required to investigate the association between nutrition delivery and changes in muscle health in patients receiving ECMO.

Impact of Muscle Changes Assessed by Ultrasonography on Muscle Strength and Functioning after ICU Discharge: A Systematic Review with Meta-Analysis

BACKGROUND

Ultrasonography has been used to identify structural, quantitative, and qualitative muscle changes. These changes have been assessed in different muscles during ICU stays; however, it is unclear if it can predict functioning after ICU discharge.

OBJECTIVE

To analyze the relationship between muscle changes assessed by ultrasonography and the strength and functioning of ICU survivors.

METHODS

A systematic review with a meta-analysis was performed according to the MOOSE guidelines and registered in PROSPERO. Searches of the following databases were performed by two of the authors: PubMed, Cinahl, Embase, Scopus, LILACS, Web of Science, and Science Direct. Qualitative analysis was performed using NOS and AHRQ scales. Meta-analysis was performed using the "R", "metafor" package. Heterogeneity was assessed by I2 and Cochran's Q test. Meta-regression analyses were performed to verify the moderators, and funnel plots and Egger's regression intercept test were used to analyze the publication bias.

RESULTS

Sixteen articles were included in the qualitative assessment, and nine were used in the quantitative assessment. There is evidence of correlations between MT and muscle strength (r = 0.20 [0.11; 0.27]; p < 0.0001), and MT (r = 0.35 [0.19; 0.49]; p < 0.0001), CSA (r = 0.30 [0.10; 0.47]; p = 0.0038), EI (r = -0.29 [-0.53; -0.01]; p = 0.043) and mobility. In the subgroup analyses, some evidence of a correlation between specific muscles and strength and mobility were found.

CONCLUSIONS

There is evidence for the correlation between muscle characteristics assessed by US and functioning outcomes.

Quantitative muscle ultrasound as a disease biomarker in hereditary transthyretin amyloidosis with polyneuropathy

INTRODUCTION

There is an increasing need for a reproducible and sensitive outcome measure in patients with hereditary transthyretin amyloidosis (ATTRv) with polyneuropathy (PN) due to the emergence of disease modifying therapies. In the current study, we aimed to investigate the role of quantitative muscle ultrasound (QMUS) as a disease biomarker in ATTRv-PN.

METHODS

Twenty genetically confirmed ATTRv amyloidosis patients (nine symptomatic, 11 pre-symptomatic) were enrolled prospectively between January to March 2023. Muscle ultrasound was performed on six muscles at standardized locations. QMUS parameters included muscle thickness (MT) and muscle echo intensity (EI). Twenty-five age- and sex-matched healthy controls were recruited for comparison. Significant QMUS parameters were correlated with clinical outcome measures.

RESULTS

Muscle volume of first dorsal interosseus (FDI) muscle [measured as cross-sectional area (CSA)] was significantly lower in symptomatic patients compared to healthy controls and pre-symptomatic carriers (98.3 ± 58.0 vs. 184.4 ± 42.5 vs. 198.3 ± 56.8, p < 0.001). EI of biceps and FDI for symptomatic ATTRv-PN patients were significantly higher compared to the other two groups (biceps: 76.4 ± 10.8 vs. 63.2 ± 11.5 vs. 59.2 ± 9.0, p = 0.002; FDI: 48.2 ± 7.5 vs. 38.8 ± 7.5 vs. 33.0 ± 5.3, p < 0.001). CSA of FDI and EI of biceps and FDI correlated with previous validated outcome measures [polyneuropathy disability score, neuropathy impairment score, Karnofsky performance scale, Rasch-built overall disability scale, European quality of life (QoL)-5 dimensions and Norfolk QoL questionnaire-diabetic neuropathy].

CONCLUSION

QMUS revealed significant difference between ATTRv amyloidosis patients and healthy controls and showed strong correlation with clinical outcome measures. QMUS serves as a sensitive and reliable biomarker of disease severity in ATTRv-PN.

Evaluating disease status in idiopathic inflammatory myopathies with quantitative muscle ultrasound

INTRODUCTION/AIMS

Muscle strength, functional status, and muscle enzymes are conventionally used to evaluate disease status in idiopathic inflammatory myopathies (IIM). This study aims to investigate the role of quantitative muscle ultrasound in evaluating disease status in IIM patients.

METHODS

Patients with IIM, excluding inclusion body myositis, were recruited along with age- and sex-matched healthy controls (HC). All participants underwent muscle ultrasound and clinical assessments. Six limb muscles were unilaterally scanned using a standardized protocol, measuring muscle thickness (MT) and echo intensity (EI). Results were compared with HC, and correlations were made with outcome measures.

RESULTS

Twenty IIM patients and 24 HC were recruited. The subtypes of IIM were dermatomyositis (6), necrotizing myositis (6), polymyositis (3), antisynthetase syndrome (3), and nonspecific myositis (2). Mean disease duration was 8.7 ± 6.9 years. There were no significant differences in demographics and anthropometrics between patients and controls. MT of rectus femoris in IIM patients was significantly lower than HC. Muscle EI of biceps brachii and vastus medialis in IIM patients were higher than HC. There were moderate correlations between MT of rectus femoris and modified Rankin Scale, Physician Global Activity Assessment, and Health Assessment Questionnaire, as well as between EI of biceps brachii and Manual Muscle Testing-8.

DISCUSSION

Muscle ultrasound can detect proximal muscle atrophy and hyperechogenicity in patients with IIM. The findings correlate with clinical outcome measures, making it a potential tool for evaluating disease activity of patients with IIM in the late phase of the disease.

MyoVision-US: an Artificial Intelligence-Powered Software for Automated Analysis of Skeletal Muscle Ultrasonography

Introduction/Aims

Muscle ultrasound has high utility in clinical practice and research; however, the main challenges are the training and time required for manual analysis to achieve objective quantification of morphometry. This study aimed to develop and validate a software tool powered by artificial intelligence (AI) by measuring its consistency and predictability of expert manual analysis quantifying lower limb muscle ultrasound images across healthy, acute, and chronic illness subjects.

Methods

Quadriceps complex (QC [rectus femoris and vastus intermedius]) and tibialis anterior (TA) muscle ultrasound images of healthy, intensive care unit, and/or lung cancer subjects were captured with portable devices. Automated analyses of muscle morphometry were performed using a custom-built deep-learning model (MyoVision-US), while manual analyses were performed by experts. Consistency between manual and automated analyses was determined using intraclass correlation coefficients (ICC), while predictability of MyoVision -US was calculated using adjusted linear regression (adj.R 2 ).

Results

Manual analysis took approximately 24 hours to analyze all 180 images, while MyoVision - US took 247 seconds, saving roughly 99.8%. Consistency between the manual and automated analyses by ICC was good to excellent for all QC (ICC:0.85-0.99) and TA (ICC:0.93-0.99) measurements, even for critically ill (ICC:0.91-0.98) and lung cancer (ICC:0.85-0.99) images. The predictability of MyoVision-US was moderate to strong for QC (adj.R 2 :0.56-0.94) and TA parameters (adj.R 2 :0.81-0.97).

Discussion

The application of AI automating lower limb muscle ultrasound analyses showed excellent consistency and strong predictability compared with human analysis. Future work needs to explore AI-powered models for the evaluation of other skeletal muscle groups.

Factors influencing the reduction in quadriceps muscle thickness in the paretic limbs of patients with acute stroke

BACKGROUND & AIMS

Muscle atrophy is an early event that occurs after stroke, but there are few reports on the changes in skeletal muscle thickness in acute stroke. This study investigated the factors contributing to reduced muscle thickness in patients with acute stroke.

METHODS

In total, 51 patients with stroke and the National Institute of the Health Stroke Scale (NIHSS) > 3 were included in our study. They were admitted to our hospital between July 2017 and May 2020. The quadriceps muscle thickness was measured with an ultrasound device within 2 days after admission and 14 days later. The collected data included age, sex, body mass index, stroke type, neuromuscular electrical stimulation, NIHSS, serum albumin at admission, start of enteral nutrition, Functional Oral Intake Scale (FOIS), start of mobilization and ambulation, number of physical and occupational therapy units, C-reactive protein at admission and whether surgery had been performed. These data were retrospectively retrieved from medical documents. A dietician calculated energy intake, protein intake, and energy adequacy. Multiple regression analysis was used to identify the factors associated with reduced quadriceps muscle thickness. The independent variables were NIHSS, date of start of enteral feeding, protein intake, FOIS, date of mobilization, and date of start of ambulation training.

RESULTS

The rate of change in quadriceps muscle thickness of the paretic limb was -15.3 % (interquartile range, -46.1-14.8 %). Multiple regression analysis showed that the factors responsible for the decrease in muscle thickness on the paretic side were FOIS (β: 0.376; 95 % Cl, 0.999 to 4.541) and the start date of ambulation (β: -0.378; 95 % Cl, -2.575 to -0.543), with a multiple correlation coefficient of 0.456.

CONCLUSION

The FOIS and the start date of ambulation after acute stroke were related to the rate of reduction in muscle thickness on the paretic side.

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

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

Comparison between ultrasonography and computed tomography for measuring skeletal muscle mass in critically ill patients with different body mass index

BACKGROUND & AIM

Among critical patients, there is an early onset of changes in both the quantity and quality of muscle mass. It is essential to find tools that promptly identify this muscle mass loss. The aim of this study was to compare the ultrasonography of the quadriceps femoris to the gold standard, thigh computed tomography (CT) for assessing the musculature of critically ill patients with different body mass index who have suffered traumatic brain injury.

METHODS

This is a prospective validation study in an Intensive Care Unit (ICU) specialized in trauma care, located at a tertiary teaching hospital. Our study involved a convenience sample of patients. Sequential ultrasound and CT scans were performed at three distinct time intervals: upon admission, between 24 and 96 h' post-admission, and finally, between 96 and 168 h' post-admission. For all ultrasound measurements, we conducted simultaneous quadriceps CT measurements. The correlation between measurements obtained by ultrasound and computed tomography at three different times and in three BMI ranges was analyzed, in individuals with normal weight, overweight and obese.

RESULTS

Results: We analyzed 252 images in 49 patients in time 1, 40 patients in time 2, and 37 in time 3 to compare the thickness quadriceps muscle using US and CT. Of these, 18 patients had a BMI ≤ 24.9 kg/m2 (normal weight), 18 patients from 25 to 29.9 kg/m2 (overweight), and 8 patients had a BMI ≥ 30 kg/m2 (obese). The mean age was 37 years, the majority (94%) were male and the main comorbidities were: hypertension 12%, diabetes 4% and 14% smoking. The results revealed minor discrepancies between measurements obtained through the two methods, these changes were not influenced by the body mass index, with these variations being practically insignificant in the context of clinical application. Thus, the correlation and concordance between the values obtained found a strong positive correlation with good limits of agreement. The Spearman's correlation coefficients obtained were r = 0.89, 0.91 and 0.88, p < 0.01 at T1, T2 and T3 respectively for normal weight, r = 0.91, 0.80 and 0.81, p < 0.01 at T1, T2 and T3 respectively for overweight and r = 0.89, 0.94 and 0.84, p < 0.01 at T1, T2 and T3 respectively for obesity. In addition to a positive correlation, we observed a high agreement between the methods. The Bland & Altman analysis at time 1 showed, respectively, the bias of 1.46, 2.03 and 0.76. At time 2, the bias was 0.42, 3.11 and 2.12. At time 3, the bias was 2.26, 3.38 and 2.11 mm.

CONCLUSION

Our findings suggest that measure femoral quadriceps muscle thickness ultrasound-based exhibits a comparable performance to thigh CT. This conclusion stems from the excellent correlation and good agreement observed between ultrasound and CT, which is considered the gold standard for muscle assessment in critically ill patients.

TRIAL REGISTRATION

This clinical trial is registered at REBEC https://ensaiosclinicos.gov.br/ identifier: RBR-2bzspnz. The protocol was approved, on July 30, 2019, by the Research Ethics Committee of the Hospital das Clínicas, Faculdade de Medicina de Ribeirão Preto - Trial Registration Number: 3,475,851.

Ultrasound for measurement of skeletal muscle mass quantity and muscle composition/architecture in critically ill patients: A scoping review on studies' aims, methods, and findings

AIMS

This scoping review aimed to identify, explore, and map the objectives, methodological aspects, and results of studies that used ultrasound (US) to assess skeletal muscle (SM) in critically ill patients.

METHODS

A scoping review was conducted according to the Joanna Briggs Institute's methodology. All studies that evaluated SM parameters from the US in patients admitted to the intensive care unit (ICU) were considered eligible. We categorized muscle thickness and cross-sectional area as parameters for assessing SM quantity, while echogenicity, fascicle length, and pennation angle analysis were used to evaluate muscle "quality" (composition/architecture). A literature search was conducted using four databases for articles published until December 2022. Independent reviewers selected the studies and extracted data. Descriptive statistics were calculated to present the results.

RESULTS

A total of 107 studies were included, the majority of which were prospective cohort studies (59.8 %) conducted in general ICUs (49.5 %). The most frequent objective of the studies was to evaluate SM quantity depletion during the ICU stay (25.2 %), followed by determining whether a specific intervention would modify SM (21.5 %). Most studies performed serial SM evaluations (76.1 %). The rectus femoris muscle thickness was evaluated in most studies (67.9 %), followed by the rectus femoris cross-sectional area (54.3 %) and the vastus intermedius muscle thickness (40.2 %). The studies demonstrated the feasibility and reproducibility of US for SM evaluation, especially related to quantitative parameters. Most studies (70.3 %) reported significant SM quantity depletion during hospitalization. However, the accuracy of the US in measuring SM varied across the studies.

CONCLUSIONS

The lack of detailed description and standardization in the protocols adopted by the studies included in this scoping review precludes the translation of the evidence related to US for SM assessment into clinical practice.

Reliability of a special device for measuring the cross-sectional area of the patellar tendon by ultrasonography

The objective of this study was to evaluate the intra- and inter-rater reliability and agreement between conditions with and without a special device (SD) in the evaluation of the patellar tendon (PT) cross-sectional area (CSA). Forty trained adult volunteers participated in the study. With the knee positioned at 90°, the ultrasound probe was placed in the transverse plane at 25, 50, and 75% of the PT length. Two raters and one analyzer obtained the images. We use a two-way ANOVA with a significance level of α = 0.05. No significant differences were found between raters or conditions. Intra-rater reliability ranged from moderate to good. Inter-rater reliability without the SD ranged from low to good, improving from moderate to good when the SD was used. Evaluation of the PT ends showed a lower coefficient of variation with the SD. We observed a moderate correlation at the ends and a strong correlation in the middle between conditions. The mean difference in the three positions is small (~ 0.013 cm2/ ~ 1.7%) with an upper limit of 43.2% and a lower limit of 32.5%. Therefore, we conclude that the use of the SD can be employed for evaluating the PT ends, while for the central region, it becomes optional.

Construct and criterion validity of muscle ultrasonography for assessment of skeletal muscle in patients recovering from COVID-19

Background: The purpose was to investigate the content, construct, and criterion validity of muscle ultrasound in a mixed cohort of participants recovering from mild and critical COVID-19. Methods: A secondary analysis of a prospective cross-sectional study was conducted on data obtained from a battery of muscle and physical function assessments including a muscle biopsy and muscle ultrasonography (US). Rectus femoris (RF) muscle thickness (mT), quadricep complex (QC) mT, RF muscle cross-sectional area (CSA) using 2D freeform trace and estimated from Feret's diameter, and RF echo intensity (EI) were assessed with US. Muscle fiber CSA, fiber type, protein content in muscle fibers, extracellular matrix content (ECM; wheat-germ agglutin), and percent area of collagen in ECM (picrosirius red) were examined from vastus lateralis muscle biopsies. Spearman rho correlations (r) were performed to assess validity of ultrasound parameters. Results: Thirty-three individuals participated including 11 patients surviving critical COVID-19, 15 individuals recovering from mild-COVID, and 7 controls. There were several significant correlations between RF mT, QC mT, RF CSA, and RF EI with age, comorbid burden, body-mass index, and measures of muscle strength, muscle power, and physical function (range r = 0.35-0.83). RF Feret's CSA correlated to CSA of type II muscle fibers (r = 0.41, p = 0.022) and the average size of all muscle fibers (r = 0.39, p = 0.031). RF EI was correlated with collagen in muscle ECM (r = 0.53, p = 0.003) and protein content in muscle tissue (r = -0.52, p = 0.012). Conclusion: Muscle size and quality measured using US has moderate content and construct validity, and to lesser extent, fair to moderate criterion validity in a mixed cohort of individuals recovering from COVID. Muscle ultrasound quality (EI) appears to be sensitive at detecting muscle dysfunction as it is associated with strength, power, physical function, and collagen distribution in a mixed group of individuals recovering from COVID-19.

Ultrasound utilized by registered dietitians for body composition measurement, nutritional assessment, and nutritional management

BACKGROUND AND AIMS

Ultrasound has been used primarily as a tool for body composition measurement in the field of clinical nutrition. Although many recent reports have demonstrated that ultrasound could be a useful tool for nutritional assessment, it is not well incorporated into registered dietitians' (RDs) practice. The aim of this review was to summarize the usefulness of ultrasound in assessing body composition and nutritional status and in nutritional management by RDs.

METHODS

Studies on ultrasonography, nutritionists, body composition, nutritional assessment, and diet therapy was searched using the MEDLINE databases.

RESULTS

After reviewing the articles, we categorized them into the following topics; 1) principles of muscle measurement using the ultrasound, types of muscle that can be measured, 2) indices of muscle and muscle mass and quality as assessed using ultrasound and its relationship to nutritional indicator, 3) diagnosis of the Global Leadership Initiative on Malnutrition (GLIM) criteria malnutrition using ultrasound, 4) practical nutritional management using ultrasound and 5) education and issues for ultrasound implementation. Ultrasound can evaluate low body mass index, unintentional loss of body weight, low skeletal muscle mass index, decreased food intake/assimilation, and disease burden/inflammation, all which are essential items of the phenotypic and etiologic criteria of the GLIM.

CONCLUSION

Ultrasound may be useful for RDs to perform body composition measurement, nutritional assessment, and nutritional management. It will be important to identify the cutoff values for ultrasound-based measurements of muscle mass. In order for RDs to perform a body composition measurement, nutritional assessment, and nutritional management using ultrasound, educational issues need to be addressed.

Serum metabolomics analysis for quantification of muscle loss in critically ill patients: An explorative study

BACKGROUND

During Intensive Care Unit (ICU) admission, patients demonstrate up to 15% muscle loss per week, contributing to neuromuscular weakness, complicating recovery and delaying return to daily life. Biomarkers for muscle loss could aid in early detection of patients at risk and help guide resources to mitigate muscle loss, e.g. physical therapy and protein supplementation.

AIMS

To explore serum biomarkers for muscle mass and muscle loss in ICU patients using a metabolomics approach.

METHODS

Mechanically ventilated patients with an unplanned ICU admission between June and December 2021 were prospectively studied. The cross-sectional area of the rectus femoris muscle was assessed using ultrasound (RFcsa) and 188 serum metabolites were assessed using the Biocrates™ AbsoluteIDQ p180 kit for targeted metabolomics. Patients were eligible for analysis when a serum sample drawn within 5 days of ICU admission and at least 1 RFcsa were available. In patients with sequential RFcsa measurements, muscle loss was defined as the negative slope of the regression line fitted to the RFcsa measurements per patient in the first 10 days of ICU admission. Correlations between baseline metabolite concentrations and baseline muscle mass, as well as between baseline metabolite concentrations and muscle loss were assessed using Pearson's test for correlations. To correct for multiple testing, the Benjamini-Hochberg procedure was used.

RESULTS

Seventeen patients were eligible for analysis. Mean age was 62 (SD ± 9) years and the cohort was predominantly male (76%). Four metabolites correlated with baseline muscle mass: creatinine (R = 0.5, p = 0.041), glycerophospholipid PC_ae_C30_0 (R = 0.5, p = 0.034) and two acylcarnitines: C14_2 (R = 0.5, p = 0.042) and C10_2 (R = 0.5, p = 0.049). For muscle loss, significant associations were found for histidine (R = -0.8, p = 0.002) and three glycerophospholipids; PC_aa_C40_2 (R = 0.7, p = 0.015), PC_ae_C40_1 (R = 0.6, p = 0.032) and PC_aa_C42_1 (R = 0.6, p = 0.037). After correction for multiple testing, no significant associations remained.

CONCLUSIONS

This exploratory analysis found certain metabolites to be associated with muscle mass and muscle loss. Future research, specifically addressing these metabolites is necessary to confirm or refute an association with muscle loss and determine their role as potential muscle loss marker.

Early Neuromuscular Electrical Stimulation Preserves Muscle Size and Quality and Maintains Systemic Levels of Signaling Mediators of Muscle Growth and Inflammation in Patients with Traumatic Brain Injury: A Randomized Clinical Trial

Objective

To investigate the effects of an early neuromuscular electrical stimulation (NMES) protocol on muscle quality and size as well as signaling mediators of muscle growth and systemic inflammation in patients with traumatic brain injury (TBI).

Design

Two-arm, single-blinded, parallel-group, randomized, controlled trial with a blinded assessment. Setting. Trauma intensive care unit at a university hospital. Participants. Forty consecutive patients on mechanical ventilation (MV) secondary to TBI were prospectively recruited within the first 24 hours following admission. Interventions. The intervention group (NMES; n = 20) received a daily session of NMES on the rectus femoris muscle for five consecutive days (55 min/each session). The control group (n = 20) received usual care. Main Outcome Measures. Muscle echogenicity and thickness were evaluated by ultrasonography. A daily blood sample was collected to assess circulating levels of insulin-like growth factor I (IGF-I), inflammatory cytokines, and matrix metalloproteinases (MMP).

Results

Both groups were similar at baseline. A smaller change in muscle echogenicity and thickness (difference between Day 1 and Day 7) was found in the control group compared to the NMES group (29.9 ± 2.1 vs. 3.0 ± 1.2, p < 0.001; -0.79 ± 0.12 vs. -0.01 ± 0.06, p < 0.001, respectively). Circulating levels of IGF-I, pro-inflammatory cytokines (IFN-y), and MMP were similar between groups.

Conclusion

An early NMES protocol can preserve muscle size and quality and maintain systemic levels of signaling mediators of muscle growth and inflammation in patients with TBI. This trial is registered with https://www.ensaiosclinicos.gov.br under number RBR-2db.

Critical illness myopathy and trajectory of recovery in acute kidney injury requiring continuous renal replacement therapy: a prospective observational trial protocol

INTRODUCTION

Acute kidney injury requiring renal replacement therapy (AKI-RRT) is common in the intensive care unit (ICU) and is associated with significant morbidity and mortality. Continuous RRT (CRRT) non-selectively removes large amounts of amino acids from plasma, lowering serum amino acid concentrations and potentially depleting total-body amino acid stores. Therefore, the morbidity and mortality associated with AKI-RRT may be partly mediated through accelerated skeletal muscle atrophy and resulting muscle weakness. However, the impact of AKI-RRT on skeletal muscle mass and function during and following critical illness remains unknown. We hypothesise that patients with AKI-RRT have higher degrees of acute muscle loss than patients without AKI-RRT and that AKI-RRT survivors are less likely to recover muscle mass and function when compared with other ICU survivors.

METHODS AND ANALYSIS

This protocol describes a prospective, multicentre, observational trial assessing skeletal muscle size, quality and function in ICU patients with AKI-RRT. We will perform musculoskeletal ultrasound to longitudinally evaluate rectus femoris size and quality at baseline (within 48 hours of CRRT initiation), day 3, day 7 or at ICU discharge, at hospital discharge, and 1-3 months postdischarge. Additional skeletal muscle and physical function tests will be performed at hospital discharge and postdischarge follow-up. We will analyse the effect of AKI-RRT by comparing the findings in enrolled subjects to historical controls of critically ill patients without AKI-RRT using multivariable modelling.

ETHICS AND DISSEMINATION

We anticipate our study will reveal that AKI-RRT is associated with greater degrees of muscle loss and dysfunction along with impaired postdischarge recovery of physical function. These findings could impact the in-hospital and postdischarge treatment plan for these patients to include focused attention on muscle strength and function. We intend to disseminate findings to participants, healthcare professionals, the public and other relevant groups via conference presentation and publication without any publication restrictions.

TRIAL REGISTRATION NUMBER

NCT05287204.

Reliability of ultrasound in the assessment of muscle thickness in critically ill children

INTRODUCTION

Ultrasound has been used to quantify and qualify muscle morphology in critically ill children and can detect changes in muscle thickness. The aim of this study was to assess the reliability of ultrasound measurement of muscle thickness in critically ill children and to compare the assessments made by an expert with those made by inexperienced sonographers.

MATERIAL AND METHODS

Cross-sectional observational study conducted in the paediatric intensive care unit of a tertiary care university hospital in Brazil. The sample included patients aged 1 month to 12 years who received invasive mechanical ventilation for at least 24 h. Ultrasound images of the biceps brachii/brachialis and quadriceps femoris were obtained by one experienced sonographer and several inexperienced sonographers. We assessed intrarater and inter-rater reliability by means of the intraclass correlation coefficient (ICC) and Bland-Altman plot analysis.

RESULTS

Muscle thickness was measured in 10 children with a mean age of 15.5 months. The mean thickness of the assessed muscles as 1.14 cm for the biceps brachii/brachialis (standard deviation [SD], 0.27) and 1.85 cm for the quadriceps femoris (SD, 0.61). The intrarater and inter-rater reliability were good for all sonographers (ICC > 0.81). The differences were small, there was no significant bias in the Bland-Altman plots and all measurements were within the limits of agreement, except for 1 measurement of biceps and quadriceps.

CONCLUSION

Sonography can be used in critically ill children to accurately assess changes in muscle thickness, even by different evaluators. More studies are needed to establish a standardised approach to the use of ultrasound for monitoring muscle loss in order to incorporate it in clinical practice.

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

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

Reliability and feasibility of skeletal muscle ultrasound in the acute burn setting

OBJECTIVES

Despite the impact of muscle wasting after burn, tools to quantify muscle wasting are lacking. This multi-centre study examined the utility of ultrasound to measure muscle mass in acute burn patients comparing different methodologies.

METHODS

B-mode ultrasound was used by two raters to determine feasibility and inter-rater reliability in twenty burned adults following admission. Quadriceps muscle layer thickness (QMLT) and rectus femoris cross-sectional area (RF-CSA) were measured, comparing the use of i) a single versus average measurements, ii) a proximal versus distal location for QMLT, and iii) a maximum- versus no-compression technique for QMLT.

RESULTS

Analysis of twenty burned adults (50 years [95%CI 42-57], 32%TBSA [95%CI 23-40]) yielded ICCs of> 0.97 for QMLT (for either location and compression technique) and> 0.95 for RF-CSA, using average measurements. Relative minimal detectable changes were smaller using no-compression than maximum-compression (6.5% vs. 15%). Using no-compression to measure QMLT was deemed feasible for both proximal and distal locations (94% and 96% of attempted measurements). In 9.5% of cases maximum-compression was not feasible. 95% of RF-CSA measurements were successfully completed.

CONCLUSION

Ultrasound provides feasible and reliable values of quadriceps muscle architecture that can be adapted to clinical scenarios commonly encountered in acute burn settings.

Incidence of muscle wasting in the critically ill: a prospective observational cohort study

Loss of muscle mass occurs rapidly during critical illness and negatively affects quality of life. The incidence of clinically significant muscle wasting in critically ill patients is unclear. This study aimed to assess the incidence of and identify predictors for clinically significant loss of muscle mass in this patient population. This was a single-center observational study. We used ultrasound to determine the rectus femoris cross-sectional area (RFcsa) on the first and seventh day of ICU stay. The primary outcome was the incidence of significant muscle wasting. We used a logistic regression model to determine significant predictors for muscle wasting. Ultrasound measurements were completed in 104 patients. Sixty-two of these patients (59.6%) showed ≥ 10% decreases in RFcsa. We did not identify any predictor for significant muscle wasting, however, age was of borderline significance (p = 0.0528). The 28-day mortality rate was higher in patients with significant wasting, but this difference was not statistically significant (30.6% versus 16.7%; p = 0.165). Clinically significant muscle wasting was frequent in our cohort of patients. Patient age was identified as a predictor of borderline significance for muscle wasting. The results could be used to plan future studies on this topic.Trial registration: ClinicalTrials.gov NCT03865095, date of registration: 06/03/2019.

Ultrasonographic findings in long COVID: A cross-sectional study of 312 patients

Background

Fatigue and muscle weakness are common complaints in COVID-19 survivors. However, little is still known about the skeletal muscle qualitative and quantitative characteristics after hospitalization due to moderate and severe COVID-19.

Objectives

To assess rectus femoris and vastus intermedius muscle thickness (MT) and rectus femoris echo intensity (EI) and to establish its association with demographic, clinical, functional, and inflammatory parameters in long COVID patients after hospital discharge.

Methods

Cross-sectional study with 312 COVID-19 patients (53.53% male; age: 54.59 ± 13.50 years), with a laboratory-confirmed diagnosis of COVID-19. Patients were assessed 3-11 months after hospital discharge. We evaluated MT of the right rectus femoris and vastus intermedius and EI of the right rectus femoris using a portable ultrasound system, 6-13 MHz, broadband linear transducer. We corrected EI using the subcutaneous fat thickness. Ultrasonographic parameters were tested in association with demographic (sex and age); functional (Handgrip strength measurement, Timed Up and Go, 1 min Sit-to-Stand test, EuroQoL-5 Dimensions-5 Levels, World Health Organization Disability Assessment Schedule (WHODAS 2.0), Post-COVID-19 Functional Status, Functional Assessment of Chronic Illness Therapy-Fatigue (FACIT), Medical Research Council (MRC) sum score, Borg Dyspnea Scale, MRC Dyspnea score, Visual Analogue Scale (VAS), Epworth Sleepiness Scale, Insomnia Severity Index, Functional Independence Measurement (FIM), and Functional Oral Intake Scale); clinical (length of hospital stay, intubation, and presence of comorbidities such as systemic hypertension, diabetes, obesity, chronic obstructive pulmonary disease, asthma), and inflammatory data assessed by the C-reactive protein and D-dimer serum concentrations.

Results

Rectus femoris MT was associated with age, handgrip strength, Epworth Sleepiness Scale, and subcutaneous fat thickness (r² = 27.51%; p < 0.0001). Vastus intermedius MT was associated with age, pain intensity, handgrip strength, Epworth Sleepiness scale, FIM, and time since hospital discharge (r² = 21.12%; p < 0.0001). Rectus femoris EI was significantly associated with the male sex, TUG, Epworth Sleepiness Scale, and C-Reactive Protein levels (r² = 44.39%; p < 0.0001). Mean MT of rectus femoris and vastus intermedius are significantly different (p < 0.001).

Conclusion

After hospital discharge, long COVID patients present qualitative and quantitative skeletal muscle characteristics associated with a combination of demographic, clinical, and functional parameters.

Relationship Between Skeletal Muscle Quality and Hospital-Acquired Disability in Patients With Sepsis Admitted to the ICU: A Pilot Study

Early risk assessment of functional decline in patients with sepsis is clinically challenging. Recently, there is increasing interest in the nonvolitional evaluation of skeletal muscle quality.

OBJECTIVES

The aim of this study was to assess the relationship between skeletal muscle quality and functional decline after intensive care.

DESIGN SETTING AND PARTICIPANTS

This pilot study was a single-center prospective observational study conducted from March 2021 to February 2022. We included consecutive patients with sepsis who were admitted to our ICU.

MAIN OUTCOMES AND MEASURES

The primary outcome was hospital-acquired disability (HAD), which is defined as a decrease in the Barthel index score of at least 5 points from pre-hospital to hospital discharge. Muscle quality was assessed by: 1) muscle echogenicity with ultrasound and 2) phase angle (PhA) with bioelectrical impedance analysis, both of which were measured on ICU days less than 3, 3-5, 5-7, 7-10, and 10-14. We compared longitudinal changes in muscle echogenicity and PhA between the HAD and non-HAD groups using two-way repeated measures analysis of variance with mixed models.

RESULTS

Among the 22 patients, 7 (31.8%) had HAD. Muscle echogenicity was higher in the HAD group than in the non-HAD group (p < 0.001); however, no interaction effects were found between the two groups (p = 0.189). PhA showed a main effect on each evaluation day in patients (p = 0.040) and a significant interaction effect between the groups, including an early decreased pattern in the HAD group (p = 0.036).

CONCLUSIONS AND RELEVANCE

Higher muscle echogenicity and a decreased PhA pattern are related to HAD. Noninvasive assessment of muscle quality using ultrasound and bioelectrical impedance analysis may be useful in predicting the functional prognosis of patients with sepsis.

The rate and assessment of muscle wasting during critical illness: a systematic review and meta-analysis

BACKGROUND

Patients with critical illness can lose more than 15% of muscle mass in one week, and this can have long-term detrimental effects. However, there is currently no synthesis of the data of intensive care unit (ICU) muscle wasting studies, so the true mean rate of muscle loss across all studies is unknown. The aim of this project was therefore to systematically synthetise data on the rate of muscle loss and to identify the methods used to measure muscle size and to synthetise data on the prevalence of ICU-acquired weakness in critically ill patients.

METHODS

We conducted a systematic literature search of MEDLINE, PubMed, AMED, BNI, CINAHL, and EMCARE until January 2022 (International Prospective Register of Systematic Reviews [PROSPERO] registration: CRD420222989540. We included studies with at least 20 adult critically ill patients where the investigators measured a muscle mass-related variable at two time points during the ICU stay. We followed Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines and assessed the study quality using the Newcastle-Ottawa Scale.

RESULTS

Fifty-two studies that included 3251 patients fulfilled the selection criteria. These studies investigated the rate of muscle wasting in 1773 (55%) patients and assessed ICU-acquired muscle weakness in 1478 (45%) patients. The methods used to assess muscle mass were ultrasound in 85% (n = 28/33) of the studies and computed tomography in the rest 15% (n = 5/33). During the first week of critical illness, patients lost every day -1.75% (95% CI -2.05, -1.45) of their rectus femoris thickness or -2.10% (95% CI -3.17, -1.02) of rectus femoris cross-sectional area. The overall prevalence of ICU-acquired weakness was 48% (95% CI 39%, 56%).

CONCLUSION

On average, critically ill patients lose nearly 2% of skeletal muscle per day during the first week of ICU admission.

Comparison of ultrasound with computed tomography to measure skeletal muscle mass in critically ill patients: A prospective study protocol

INTRODUCTION

Therapy and nutritional status directly interfere in the clinical evolution of critically ill patients, in reducing morbidity and mortality, by maintaining the functional integrity of the gastrointestinal tract, decreasing the catabolic response, besides contributing to the reduction of hospitalization time resulting in less treatment cost. Critical patients and trauma victims suffer early changes in the quantity and quality of muscle mass. Tools to identify the groups most susceptible to these complications are necessary so that interventions can minimize the deleterious effects of malnutrition in critically ill patients.

METHODS AND ANALYSIS

The aim of the present study is to measure muscle mass loss by measuring the thickness of the rectus femoris muscle by bedside ultrasound in critically ill patients admitted to the Intensive Care Unit (ICU) of a university hospital. Information will be collected regarding the length of hospital and ICU stay, the reason for admission, anthropometric data at admission and during hospitalization, energy needs, nutritional therapy used, and fasting time. This is a prospective, observational study that will be carried out in a single center in an ICU of a tertiary university hospital. The study population will undergo 3 tomographic images and 3 ultrasounds of the rectus femoris of each patient at different times. We propose, unprecedentedly, performing a validation study of ultrasound with the gold standard Computed tomography to evaluate the musculature of critically ill patients victims of traumatic brain injury. The results got will texto be fundamental for the development of new fields of investigation and certainly contribute to the discovery of a new approach to treat sarcopenia in critically ill patients. The Research Ethics Committee approved the study and all patients included will sign an informed consent form. (Clinical Record: RBR-2bzspnz).

Increased diaphragm echodensity correlates with postoperative pulmonary complications in patients after major abdominal surgery: a prospective observational study

Background

Associated with increased morbidity and mortality, postoperative pulmonary complications (PPCs) often occur after major abdominal surgery. Diaphragmatic dysfunction is suggested to play an important role in the development of PPCs and diaphragm echodensity can be used as an indicator of diaphragm function. This study aimed to determine whether diaphragm echodensity could predict the occurrence of PPCs in patients after major abdominal surgery.

Methods

Diaphragm ultrasound images of patients after major abdominal surgery were collected during spontaneous breathing trials. Echodensity was quantified based on the right-skewed distribution of grayscale values (50th percentile, ED50; 85th percentile, ED85; mean, EDmean). Intra- and inter-analyzer measurement reproducibility was determined. Outcomes including occurrence of PPCs, reintubation rate, duration of ventilation, and length of ICU stay were recorded.

Results

Diaphragm echodensity was measured serially in 117 patients. Patients who developed PPCs exhibited a higher ED50 (35.00 vs. 26.00, p < 0.001), higher ED85 (64.00 vs. 55.00, p < 0.001) and higher EDmean (39.32 vs. 33.98, p < 0.001). In ROC curve analysis, the area under the curve of ED50 for predicting PPCs was 0.611. The optimal ED50 cutoff value for predicting the occurrence of PPCs was 36. According to this optimal ED50 cutoff value, patients were further divided into a high-risk group (ED50 > 36, n = 35) and low-risk group (ED50 ≤ 36, n = 82). Compared with the low-risk group, the high-risk group had a higher incidence of PPCs (unadjusted p = 0.003; multivariate-adjusted p < 0.001).

Conclusion

Diaphragm echodensity can be feasibly and reproducibly measured in mechanically ventilated patients. The increase in diaphragm echodensity during spontaneous breathing trials was related to an increased risk of PPCs in patients after major abdominal surgery.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12890-022-02194-6.

Utility of ultrasound as a promising diagnostic tool for stroke-related sarcopenia: A retrospective pilot study

Stroke patients undergo extensive changes in muscle mass which lead to stroke-related sarcopenia. Stroke-related sarcopenia has a significant impact on the functional outcome of stroke survivors. So, it is important to measure muscle mass in stroke patients. This study aimed to examine the correlation between ultrasonographic quadriceps muscle thickness (QMT) and dual-energy X-ray absorptiometry (DXA) derived appendicular lean mass (ALM) in patients with acute hemiplegic stroke. Twenty five participants were included (13 men and 12 women) in this study, who were diagnosed with stroke within 1 month. For both paretic and non-paretic legs, QMT was measured by an ultrasound and ALM was obtained by performing DXA scan. We analyzed the difference and the correlation between ultrasonographic QMT and DXA-derived lean body mass of both paretic and non-paretic legs. Stroke patients were divided into 2 groups according to the paretic knee extensor power. Ultrasonographic QMT, DXA scan findings, and functional parameters were compared. There was a significant correlation between QMT and ALM index, and between QMT and site-specific lean mass (SSLM) of both the legs for both the sexes (P < .05). In multivariate linear regression model, we made adjustments for the confounding factors of age, sex, body mass index (BMI) and paretic knee extensor power. We observed a positive relationship between QMT and ALM index (P < .05), and between QMT and SSLM of both the legs (P < .05). The % QMT showed higher difference than % SSLM between paretic and non-paretic legs (10.25% vs 4.58%). The QMT measurements of ultrasound show a great relationship with DXA scan findings. Ultrasound better reflects the change of muscle mass between paretic and non-paretic legs than DXA scan at an acute phase of stroke. Ultrasound could be a useful tool to evaluate stroke-related sarcopenia.

[Assessment and technical monitoring of nutritional status of patients in intensive and intermediate care units : Position paper of the Section Metabolism and Nutrition of the German Interdisciplinary Association for Intensive and Emergency Medicine (DIVI)]

At the time of admission to an intensive or intermediate care unit, assessment of the patients' nutritional status may have both prognostic and therapeutic relevance with regard to the planning of individualized medical nutrition therapy (MNT). MNT has definitely no priority in the initial treatment of a critically ill patient, but is often also neglected during the course of the disease. Especially with prolonged length of stay, there is an increasing risk of malnutrition with considerable prognostic macro- and/or micronutrient deficit. So far, there are no structured, evidence-based recommendations for assessing nutritional status in intensive or intermediate care patients. This position paper of the Section Metabolism and Nutrition of the German Interdisciplinary Association for Intensive and Emergency Medicine (DIVI) presents consensus-based recommendations for the assessment and technical monitoring of nutritional status of patients in intensive and intermediate care units. These recommendations supplement the current S2k guideline "Clinical Nutrition in Intensive Care Medicine" of the German Society for Nutritional Medicine (DGEM) and the DIVI.

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 (ICC_3.1 = 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 (ICC_3.1 = 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.

Sonographic Evaluation of Muscle Echogenicity for the Detection of Intensive Care Unit-Acquired Weakness: A Pilot Single-Center Prospective Cohort Study

Qualitative assessment by the Heckmatt scale (HS) and quantitative greyscale analysis of muscle echogenicity were compared for their value in detecting intensive care unit-acquired weakness (ICU-AW). We performed muscle ultrasound (MUS) of eight skeletal muscles on day 3 and day 10 after ICU admission. We calculated the global mean greyscale score (MGS), the global mean z-score (MZS) and the global mean Heckmatt score (MHS). Longitudinal outcome was defined by the modified Rankin scale (mRS) and Barthel index (BI) after 100 days. In total, 652 ultrasound pictures from 38 critically ill patients (18 with and 20 without ICU-AW) and 10 controls were analyzed. Patients with ICU-AW had a higher MHS on day 10 compared to patients without ICU-AW (2.6 (0.4) vs. 2.2 (0.4), p = 0.006). The MHS was superior to ROC analysis (cut-off: 2.2, AUC: 0.79, p = 0.003, sensitivity 86%, specificity 60%) in detecting ICU-AW compared to MGS and MZS on day 10. The MHS correlated with the Medical Research Council sum score (MRC-SS) (r = −0.45, p = 0.004), the mRS (r = 0.45; p = 0.007) and BI (r = −0.38, p = 0.04) on day 100. Qualitative MUS analysis seems superior to quantitative greyscale analysis of muscle echogenicity for the detection of ICU-AW.

Association of diaphragm thickness and echogenicity with age, sex, and body mass index in healthy subjects

Introduction/Aims

Diaphragm ultrasound is increasingly used in the diagnosis of diaphragm dysfunction and to guide respiratory management in patients with neuromuscular disorders and those who are critically ill. However, the association between diaphragm ultrasound variables and demographic factors like age, sex, and body mass index (BMI) are understudied. Such relationships are important for correct interpretation of normative values and comparison with selected patients groups. The aim of this study was to determine the associations between diaphragm ultrasound variables and subject characteristics.

Methods

B‐mode ultrasound was used to image the diaphragm at the zone of apposition in 83 healthy subjects. Diaphragm thickness at resting end‐expiration (T_end‐exp), diaphragm thickness at maximal end‐inspiration (T_max‐insp), diaphragm thickening ratio (T_max‐insp/T_end‐exp), and diaphragm echogenicity were measured. Multivariate linear regression was used to explore the associations between diaphragm ultrasound variables and subject characteristics.

Results

T_end‐exp, T_max‐insp, and thickening ratio do not change with age whereas diaphragm echogenicity increases with age. The thickening ratio had a weak negative association with BMI, while T_end‐exp was positively associated with BMI. Men had a larger T_end‐exp and T_max‐insp than women (T_end‐exp 1.6 ± 0.5 and 1.4 ± 0.3 mm; p = .011, T_max‐insp 3.8 ± 1.0 and 3.2 ± 0.9 mm; p = .004), but similar thickening ratios.

Discussion

Diaphragm thickness, thickening, and echogenicity measured with ultrasound are associated with factors such as age, BMI, and sex. Therefore, subject characteristics should be considered when interpreting diaphragm ultrasound measurements. In the absence of normative values, matched control groups are a prerequisite for research and in clinical practice.

Deep learning based sarcopenia prediction from shear-wave ultrasonographic elastography and gray scale ultrasonography of rectus femoris muscle

We aim to evaluate the performance of a deep convolutional neural network (DCNN) in predicting the presence or absence of sarcopenia using shear-wave elastography (SWE) and gray-scale ultrasonography (GSU) of rectus femoris muscle as an imaging biomarker. This retrospective study included 160 pair sets of GSU and SWE images (n = 160) from December 2018 and July 2019. Two radiologists scored the echogenicity of muscle on GSU (4-point score). Among them, 141 patients underwent CT and their L3 skeletal muscle index (SMI) were measured to categorize the presence or absence of sarcopenia. For DCNN, we used three CNN architectures (VGG19, ResNet-50, DenseNet 121). The accuracies of DCNNs for sarcopenia classification were 70.0–80.0% (based on SWE) and 65.0–75.0% (based on GSU). The DCNN application to SWE images highlights the utility of deep-learning base SWE for sarcopenia prediction. DCNN application to SWE images might be a potentially useful biomarker to predict sarcopenic status.

β-Hydroxy-β-methylbutyrate (HMB) supplementation and functional outcomes in multi-trauma patients: a study protocol for a pilot randomised clinical trial (BOOST trial)

Background

There are no therapies proven to diminish the muscle wasting that occurs in patients after major trauma who are admitted to the intensive care unit (ICU). β-Hydroxy-β-methylbutyrate (HMB) is a nutrition intervention that may attenuate muscle loss and, thereby, improve recovery. The primary aim of this study is to determine the feasibility of a blinded randomised clinical trial of HMB supplementation to patients after major trauma who are admitted to the ICU. Secondary aims are to establish estimates for the impact of HMB when compared to placebo on muscle mass and nutrition-related patient outcomes.

Methods

This prospective, single-centre, blinded, randomised, placebo-controlled, parallel-group, feasibility trial with allocation concealment will recruit 50 participants over 18 months. After informed consent, participants will be randomised [1:1] to receive either the intervention (three grams of HMB dissolved in either 150 ml of orange juice for those allowed oral intake or 150 ml of water for those being enterally fed) or placebo (150 ml of orange juice for those allowed oral intake or 150 ml of water for those being enterally fed). The intervention will be commenced in ICU, continued after ICU discharge and ceased at hospital discharge or day 28 post randomisation, whichever occurs first. The primary outcome is the feasibility of administering the intervention. Secondary outcomes include change in muscle thickness using ultrasound and other nutritional and patient-centred outcomes.

Discussion

This study aims to determine the feasibility of administering HMB to critically ill multi-trauma patients throughout ICU admission until hospital discharge. Results will inform design of a larger randomised clinical trial.

Trial registration

The protocol is registered with Australian New Zealand Clinical Trials Registry (ANZCTR) ANZCTR: 12620001305910. UTN: U1111-1259-5534.

Intermittent fasting and continuous energy restriction result in similar changes in body composition and muscle strength when combined with a 12 week resistance training program

Purpose

The objective of this study was to compare the effects of 12 weeks of resistance training combined with either 5:2 intermittent fasting or continuous energy restriction on body composition, muscle size and quality, and upper and lower body strength.

Methods

Untrained individuals undertook 12 weeks of resistance training plus either continuous energy restriction [20% daily energy restriction (CERT)] or 5:2 intermittent fasting [~ 70% energy restriction 2 days/week, euenergetic consumption 5 days/week (IFT)], with both groups prescribed a mean of ≥ 1.4 g of protein per kilogram of body weight per day. Participants completed 2 supervised resistance and 1 unsupervised aerobic/resistance training combination session per week. Changes in lean body mass (LBM), thigh muscle size and quality, strength and dietary intake were assessed.

Results

Thirty-four participants completed the study (CERT = 17, IFT = 17). LBM was significantly increased (+ 3.7%, p < 0.001) and body weight (− 4.6%, p < 0.001) and fat (− 24.1%, p < 0.001) were significantly reduced with no significant difference between groups, though results differed by sex. Both groups showed improvements in thigh muscle size and quality, and reduced intramuscular and subcutaneous fat assessed by ultrasonography and peripheral quantitative computed tomography (pQCT), respectively. The CERT group demonstrated a significant increase in muscle surface area assessed by pQCT compared to the IFT group. Similar gains in upper and lower body strength and muscular endurance were observed between groups.

Conclusion

When combined with resistance training and moderate protein intake, continuous energy restriction and 5:2 intermittent fasting resulted in similar improvements in body composition, muscle quality, and strength. ACTRN: ACTRN12620000920998, September 2020, retrospectively registered.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00394-022-02804-3.

Inter-Rater Reliability of Quantitative Ultrasound Measures of Muscle in Critically ill Patients

INTRODUCTION

Quantitative neuromuscular ultrasound is increasingly used to study muscle pathology and changes in muscle mass during critical illness. Ultrasound's advantages are high axial resolution, low procedural risks, no ionizing radiation, and ease of use early in the course of disease. However, ultrasound is known to be an operator dependent imaging modality and the ICU setting poses additional challenges to obtaining reliable measurements. There is limited evidence validating the feasibility and reliability of its application in this setting.

OBJECTIVE

A standardized protocol for measuring muscle linear depth and cross-sectional area in critical ill populations can be conducted with a high degree of inter-rater agreement and feasibility.

DESIGN

Prospective observational cohort study of inter-rater reliability.

SETTING

Medical intensive care unit at an academic medical center and a level one trauma and burn center PATIENTS: Fifteen critically ill patients were evaluated using a standardized ultrasound protocol measuring total elbow flexor, knee extensor and tibialis anterior depth, as well as rectus femoris cross sectional area. Each site was independently scanned by two investigators. Reliability of measurements between observers was determined by calculating intra-class correlation coefficients (ICCs) using a two- way random effects model and absolute agreement. An ICC > 0.75 was considered good and >0.90 was considered excellent.

RESULTS

In critically ill patients, Inter-rater reliability of linear depth measured at elbow flexor, knee extensor, tibialis anterior and cross-sectional area of rectus femoris sites was good to excellent with ICC between 0.87 (0.54-0.97) and 0.99 (0.97-1.00). Inter-rater reliability was improved by creating a summary index of measures resulting in an ICC of 0.99 (0.98-1.00). Feasibility, as definite by the percentage of each measure that was obtainable, ranged from 75-100%.

CONCLUSIONS

Using a standardized protocol, ultrasound measures obtained in critically ill patients demonstrated high levels of inter-rater agreement and with good to excellent feasibility. This article is protected by copyright. All rights reserved.

Comparison of quadriceps muscle size and quality in adults with cystic fibrosis with different severities of cystic fibrosis transmembrane conductance regulator protein dysfunction

Background

Cystic fibrosis (CF) is characterized by CF transmembrane conductance regulator (CFTR) dysfunction. CFTR protein is expressed in human skeletal muscle; however, its impact on skeletal muscle is unknown. The objectives of this study were to compare quadriceps muscle size and quality between adults with various severities of CFTR protein dysfunction.

Methods

We conducted a prospective, cross-sectional study comparing 34 adults with severe versus 18 with mild CFTR protein dysfunction, recruited from a specialized CF centre. Ultrasound images of rectus femoris cross-sectional area (RF-CSA) and quadriceps layer thickness for muscle size, and rectus femoris echogenicity (RF-ECHO) (muscle quality) were obtained. Multivariable linear regression models were developed using purposeful selection technique.

Results

People with severe CFTR protein dysfunction had larger RF-CSA by 3.22 cm², 95% CI (1.03, 5.41) cm², p=.0049], after adjusting for oral corticosteroid use and Pseudomonas aeruginosa colonization. However, a sensitivity analysis indicated that the result was influenced by the specific confounders being adjusted for in the model. We did not find any significant differences in quadriceps layer thickness or RF-ECHO between the two groups.

Conclusion

We found no differential impact of the extent of diminished CFTR protein activity on quadriceps muscle size or quality in our study cohort. Based on these findings, CFTR mutation status cannot be used differentiate leg muscle size or quality in people with CF.

Ultrasound imaging of quadriceps muscle in patients with knee osteoarthritis: The test-retest and inter-rater reliability and concurrent validity of echo intensity measurement

BACKGROUND

Echo intensity(EI) on ultrasonography images of skeletal muscle reflects muscle composition.

OBJECTIVES

The primary aim of the study was to investigate the inter-rater and test-retest reliability of EI using grayscale histogram analysis of the cross-sectional area of quadriceps femoris(QF) muscle in patients with knee osteoarthritis(KOA). The secondary aim of the study was to determine the concurrent validity of the Free Hand Tool(FHT) when compared to Rectangular Marquee Tool(RMT) for calculating the region of interest(ROI) in ImageJ.

METHODS

This study included thirty patients with KOA. Echogenicity of the QF muscle were performed by two different raters. The reliability analysis was applied using intraclass correlation coefficient(ICC), standard error of measurement(SEM) and coefficient of variation(CV). Spearman rank correlation coefficients were calculated for assessing concurrent validity of the FHT to RMT. The Bland-Altman plots was used to show disagreement between tools. Wilcoxon signed-rank test was used for differences in assessments between test/retest sessions, raters, tools.

RESULTS

The inter-rater and test-retest reliability of the EI using FHT and RMT was found to be excellent (ICC_FHT = 0.91-0.95, 0.98-0.99, ICC_RMT = 0.91-0.98, 0.91-0.99,respectively). Bland-Altman analysis demonstrated a slight bias when region ROI calculations were collected from RMT or FHT (bias ranging from 2.75 to-2.40 a. u). There were no significant differences between test/retest sessions, raters and tools(p > 0.05). Spearman correlation coefficient showed excellent correlation between tools used for echogenicity assessment of QF muscle(p < 0.001).

CONCLUSION

EI assessment using ultrasonography in the QF muscle showed excellent reliability. Evaluating muscle echogenicity using both FHT and RMT appears to be reliable and validity for monitoring muscle changes due to KOA.

Nutritional state assessed by ultrasonography, but not by bioelectric impedance, predicts 28-day mortality in critically ill patients. Prospective cohort study

BACKGROUND & AIMS

Malnutrition is a disease associated with unfavorable outcomes and high prevalence among critically ill patients. The primary aim of the study was to correlate the nutritional status of patients recently admitted to the intensive care unit (ICU) with the 28-day mortality rate. The secondary aim was to establish cut-off values for the bioelectrical impedance analysis (BIA) and ultrasonography (USG) methods for the classification of the nutritional status of critically ill patients.

METHODS

Cohort-type prospective observational study design, with the inclusion of critically ill clinical-surgical patients, ≥18 years old, mechanically ventilated. Their nutritional status was assessed by phase angle and skeletal muscle mass (using BIA), and the sectional area of the rectus femoris muscle (RFM) (using USG) within the first 48 h of ICU admission.

RESULTS

Among the patients included (n = 160), the non-survivors had lower values related to the survivors for averages of the phase angle (4.4 ± 1.5° vs 4.9 ± 1.2°; p = 0.041) and sectional area of the RFM (6.1 ± 1.6 cm²/m²vs 7.4 ± 1.8 cm²/m²; p = 0.030). Cut-off values were identified using the ROC curves for phase angle (≤4.4°), skeletal muscle mass (≤19.2 kg/m²), and sectional area of the RFM (≤5.9 cm²/m²). In multivariate logistic regression analysis, the sectional area of the RFM (≤5.9 cm²/m²) was the only independent predictor of 28-day mortality (OR = 6.08; p = 0.028). In the survival analysis, greater survival at 28 days was demonstrated for patients with phase angle >4.4° (p = 0.020) and sectional area of the RFM >5.9 cm²/m² (p = 0.001). Malnourished patients had higher mortality than nourished patients according to the phase angle (31.5% vs 15.1%, respectively; p = 0.015) and the sectional area of the RFM (38.9% vs 6.3%, respectively; p = 0.001).

CONCLUSIONS

The USG of the RFM is an efficient method for both classifying the nutritional status at ICU admission and assessing the prognosis of critically ill patients.

Ultrasound Protocols to Assess Skeletal and Diaphragmatic Muscle in People Who Are Critically Ill: A Systematic Review

This study aims to review published studies that use protocols and ultrasound measurements to evaluate skeletal and diaphragmatic muscles in patients who are critically ill. We searched for references on databases through September 2020 and included in our systematic review studies that used muscular ultrasound to assess skeletal or diaphragm muscles in patients who are critically ill. Seventy-six studies were included, 32 (1720 patients) using skeletal-muscle ultrasound and 44 (2946 patients) using diaphragmatic-muscle ultrasound, with a total of 4666 patients. The population is predominantly adult men. As for designs, most studies (n = 62) were cohort studies. B-mode B was dominant in the evaluations. Medium-to-high frequency bands were used in the analysis of peripheral muscles and medium-to-low frequency bands for diaphragmatic muscles. Evaluation of the echogenicity, muscle thickness and pennation angle of the muscle was also reported. These variables are important in the composition of the diagnosis of muscle loss. Studies demonstrate great variability in their protocols, and sparse description of the important variables that can directly interfere with the quality and validity of these measures. Therefore, a document is needed that standardizes these parameters for ultrasound assessment in patients who are critically ill.

Ultrasound Assessment of Quadriceps Femoris Muscle Thickness in Critically Ill Children

OBJECTIVES

Evaluate the reliability of ultrasound to measure quadriceps femoris muscle thickness in critically ill children and to describe serial changes in quadriceps femoris muscle thickness in relation to fluid balance and nutritional intake.

DESIGN

Prospective observational study.

SETTING

Tertiary care children's hospital.

PATIENTS

Inpatients age 3 months to 18 years recently admitted to the ICU who were sedated and mechanically ventilated at the time of the first ultrasound scan.

METHODS

Prospective observational study to examine the reliability of averaged ultrasound measurements of quadriceps femoris muscle thickness. Change in average quadriceps femoris muscle thickness over time was correlated with fluid balance and nutritional intake.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Averaged quadriceps femoris muscle thickness demonstrated good to excellent reliability when comparing pediatric critical care providers to pediatric radiologists and when comparing between different pediatric critical care providers. We found no significant association between fluid balance over 1 or 3 days and change in quadriceps femoris muscle thickness over the same time frame. However, there was a significant association between percent of goal calories (p < 0.001) or percent of goal protein (p < 0.001) over 6 days and change in quadriceps femoris muscle thickness over the same time frame.

CONCLUSIONS

Averaged ultrasound measurements of quadriceps femoris muscle thickness demonstrate good to excellent reliability, are not confounded by fluid balance, and are useful for tracking changes in muscle thickness that are associated with nutritional intake. Ultrasound-based assessment of quadriceps femoris is a clinically useful tool for evaluating muscle mass and may be a proxy for nutritional status.