Methodological and Clinimetric Evaluation of Inspiratory Respiratory Muscle Ultrasound in the Critical Care Setting: A Systematic Review and Meta-Analysis.

OBJECTIVE: Significant variations exist in the use of respiratory muscle ultrasound in intensive care with no society-level consensus on the optimal methodology. This systematic review aims to evaluate, synthesize, and compare the clinimetric properties of different image acquisition and analysis methodologies. DATA SOURCES: Systematic search of five databases up to November 24, 2021. STUDY SELECTION: Studies were included if they enrolled at least 50 adult ICU patients, reported respiratory muscle (diaphragm or intercostal) ultrasound measuring either echotexture, muscle thickness, thickening fraction, or excursion, and evaluated at least one clinimetric property. Two independent reviewers assessed titles, abstracts, and full text against eligibility. DATA EXTRACTION: Study demographics, ultrasound methodologies, and clinimetric data. DATA SYNTHESIS: Sixty studies, including 5,025 patients, were included with 39 studies contributing to meta-analyses. Most commonly measured was diaphragm thickness (DT) or diaphragm thickening fraction (DTF) using a linear transducer in B-mode, or diaphragm excursion (DE) using a curvilinear transducer in M-mode. There are significant variations in imaging methodology and acquisition across all studies. Inter- and intrarater measurement reliabilities were generally excellent, with the highest reliability reported for DT (ICC, 0.98; 95% CI, 0.94-0.99). Pooled data demonstrated acceptable to excellent accuracy for DT, DTF, and DE to predicting weaning outcome after 48 to 72 hours postextubation (DTF AUC, 0.79; 95% CI, 0.73-0.85). DT imaging was responsive to change over time. Only three eligible studies were available for intercostal muscles. Intercostal thickening fraction was shown to have excellent accuracy of predicting weaning outcome after 48-hour postextubation (AUC, 0.84; 95% CI, 0.78-0.91). CONCLUSIONS: Diaphragm muscle ultrasound is reliable, valid, and responsive in ICU patients, but significant variation exists in the imaging acquisition and analysis methodologies. Future work should focus on developing standardized protocols for ultrasound imaging and consider further research into the role of intercostal muscle imaging.

Malnutrition defined by GLIM criteria identifies a higher incidence of malnutrition and is associated with pulmonary complications after oesophagogastric cancer surgery, compared to ICD-10-defined malnutrition.

BACKGROUND & OBJECTIVES: Low muscle mass, measured using computed tomography (CT), is associated with poor surgical outcomes. We aimed to include CT-muscle mass in malnutrition diagnosis using the Global Leadership Initiative on Malnutrition (GLIM) criteria, compare it to the International Classification of Diseases 10th Revision (ICD-10) criteria, and assess the impact on postoperative outcomes after oesophagogastric (OG) cancer surgery. METHODS: One hundred and eight patients who underwent radical OG cancer surgery and had preoperative abdominal CT imaging were included. GLIM and ICD-10 malnutrition data were assessed against complication and survival outcomes. Low CT-muscle mass was determined using predefined cut-points. RESULTS: GLIM-defined malnutrition prevalence was significantly higher than ICD-10-malnutrition (72.2% vs. 40.7%, p < 0.001). Of the 78 patients with GLIM-defined malnutrition, low muscle mass (84.6%) was the predominant phenotypic criterion. GLIM-defined malnutrition was associated with pneumonia (26.9% vs. 6.7%, p = 0.010) and pleural effusions (12.8% vs. 0%, p = 0.029). Postoperative complications did not correlate with ICD-10 malnutrition. Severe GLIM (HR: 2.51, p = 0.014) and ICD-10 (HR: 2.15, p = 0.039) malnutrition were independently associated with poorer 5-year survival. CONCLUSIONS: GLIM criteria appear to identify more malnourished patients and more closely relate to surgical risk than ICD-10 malnutrition, likely due to incorporating objective muscle mass assessment.

Examining the Effect of Time-From-Treatment on Activities of Daily Living Kinematics in Breast Cancer Survivors.

Breast cancer affects one in 8 females with a 5-year survival rate of 89%. Up to 72% of breast cancer survivors have trouble with activities of daily living (ADL) following treatment. Increased time-from-treatment improves some measures of function, yet ADL limitations persist. Therefore, this study assessed the effect of time-from-treatment on upper extremity kinematics during ADLs in breast cancer survivors. Twenty-nine female breast cancer survivors were divided into 2 groups: <1 year (n = 12) and 1-2 years (n = 17) from treatment. Kinematics were collected during 6 ADL tasks, and humerothoracic joint angles were quantified. A 2-way mixed analysis of variance assessed the effects of time-from-treatment and arm on maximum angles for each ADL. Decreased maximum angle existed for breast cancer survivors with increased time-from-treatment during all ADLs. Breast cancer survivors in the 1-2 years group used ∼28° to 32° lower elevation, ∼14° to 28° lower axial rotation, and ∼10° to 14° lower plane of elevation range across tasks. Decreased ranges of arm movement during ADLs with increased time-from-treatment may reflect compensatory movement strategies. Recognizing this shift in strategies and accompanying underlying disease progression can help inform responses to functional performance limitations in breast cancer survivors as delayed effects are present posttreatment.

Influence of Subcutaneous Adipose Tissue and Skeletal Muscle Thickness on Rectus Femoris Echo Intensity in Younger and Older Males and Females.

OBJECTIVES: Ultrasound measurements of muscle echo intensity are commonly used surrogates of muscle composition (eg, intramuscular adipose tissue). However, given that soundwaves are increasingly attenuated with tissue depth, the interpretation of echo intensity may be confounded by adipose and skeletal muscle thickness. Our objectives are to compare the associations between adipose or muscle tissue thickness and rectus femoris echo intensity in younger and older males and females. METHODS: Participants included in this analysis were derived from 3 previously published cohorts of younger (<45 years) and older (≥60 years) males and females. Ultrasound images of the rectus femoris were evaluated for muscle thickness, echo intensity, and subcutaneous adipose tissue thickness. RESULTS: Older adults (n: 49 males, 19 females) had a higher body mass index (P = .001) compared with younger adults (n: 37 males, 49 females). Muscle thickness was negatively associated with echo intensity in older males (r = -0.59) and females (r = -0.53), whereas no associations were observed in younger males (r = 0.00) or females (r = -0.11). Subcutaneous adipose tissue thickness displayed no associations with echo intensity in any group. CONCLUSIONS: Despite the known influence of subcutaneous adipose tissue thickness on beam attenuation, we observed no association with muscle echo intensity, indicating that adipose tissue correction may be required to better understand muscle echo intensity across differences in adiposity. The negative associations between muscle thickness and echo intensity in older, but not younger adults, suggests these associations may be related to the co-occurrence of skeletal muscle atrophy and intramuscular adipose tissue infiltration with advancing age.

Telephone Administration of the Automated Self-Administered 24-hour Dietary Assessment in Older Adults: Lessons Learned.

Automated Self-Administered 24-hour Dietary Assessment (ASA24) is an economical method of estimating dietary intake as nutrient analysis is automated, but its use in older adults is limited. The purpose of this work was to guide dietitians and future researchers on how to use the ASA24 with older adults, considering potential barriers encountered and strategies used to support completion based on our experience using this tool in a pilot clinical trial. ASA24 was completed by phone interview with 39 older adults. Challenges included: recalling food intake in detail, recording frequent eating occasions and complicated recipes, and general problems with communication. Strategies to support collection included making morning phone calls and suggesting that seniors write down the food consumed. Phone interviews were acceptable to older adults, but sufficient time was required. Dietitians and future researchers can use these findings to obtain dietary intake data from this hard-to-reach group.

The Effects of Body Position on Trochanteric Soft Tissue Thickness-Implications for Predictions of Impact Force and Hip Fracture Risk During Lateral Falls.

Trochanteric soft tissue thickness (TSTT) is a protective factor against fall-related hip fractures. This study's objectives were to determine: (1) the influence of body posture on TSTT and (2) the downstream effects of TSTT on biomechanical model predictions of fall-related impact force (Ffemur) and hip fracture factor of risk. Ultrasound was used to measure TSTT in 45 community-dwelling older adults in standing, supine, and side-lying positions with hip rotation angles of -25°, 0°, and 25°. Supine TSTT (mean [SD] = 5.57 [2.8] cm) was 29% and 69% greater than in standing and side-lying positions, respectively. The Ffemur based on supine TSTT (3380 [2017] N) was 19% lower than the standing position (4173 [1764] N) and 31% lower than the side-lying position (4908 [1524] N). As factor of risk was directly influenced by Ffemur, the relative effects on fracture risk were similar. While less pronounced (<10%), the effects of hip rotation angle were consistent across TSTT, Ffemur, and factor of risk. Based on the sensitivity of impact models to TSTT, these results highlight the need for a standardized TSTT measurement approach. In addition, the consistent influence of hip rotation on TSTT (and downstream model predictions) support its importance as a factor that may influence fall-related hip fracture risk.

Assessment of muscle mass using ultrasound with minimal versus maximal pressure compared with computed tomography in critically ill adult patients.

BACKGROUND: Preserved skeletal muscle mass identified using computed tomography (CT) predicts improved outcomes from critical illness; however, CT imaging have few limitations such that it involves a radiation dose and transferring patients out of the intensive care unit. This study aimed to assess in critically ill patients the relationship between muscle mass estimates obtained using minimally invasive ultrasound techniques with both minimal and maximal pressure compared with CT images at the third lumber vertebra level. METHODS: All patients were treated in a single Australian intensive care unit. Eligible patients had paired assessments, within a 72-h window, of muscle mass by ultrasound (quadriceps muscle layer thickness in centimetres, with maximal and minimal pressure) and CT axial cross-sectional area (cm2). Data are presented as mean (standard deviation), median (interquartile range), and frequencies [n (%)]. RESULTS: Thirty-five patients [mean (standard deviation) age = 55 (16) years, median (interquartile range) body mass index = 27 (25-32) kg/m2, and 26 (74%) men] contributed 41 paired measurements. Quadriceps muscle thickness measured using the maximal pressure technique was a strong independent predictor of lumbar muscle cross-sectional area. Within a multivariate mixed linear regression model and adjusting for sex, age, and body mass index, for every 1 cm increase in quadriceps muscle layer thickness, the lumbar muscle cross-sectional area increased by 35 cm2 (95% confidence interval = 11-59 cm2). Similar univariate associations were observed using minimal pressure; however, as per multivariate analysis, there was no strength in this relationship [8 cm2 (95% confidence interval = -5 to 22 cm2)]. CONCLUSION: Ultrasound assessment of the quadriceps muscle using maximal pressure reasonably predicts the skeletal muscle at the third lumbar vertebra level of critically ill patients. However, there is substantial uncertainty within these regression estimates, and this may reduce the current utility of this technique as a minimally invasive surrogate for CT assessment of skeletal muscle mass.

Profiling Determinants of Resting Energy Expenditure in Colorectal Cancer.

Background: Understanding resting energy expenditure (REE) is important for determining energy requirements; REE might be altered in individuals with cancer. The objective of this study was to characterize determinants of REE in patients with stages II-IV colorectal cancer (CRC).Methods: REE was measured via indirect calorimetry in patients with newly diagnosed CRC. Computerized tomography images from medical records ascertained skeletal muscle and total adipose tissue cross-sectional areas, which were then transformed to lean soft tissue (LST) and fat mass (FM) values (in kg). Linear regression assessed determinants of REE.Results: 86 patients were included (n = 55, 64.0% male; 60 ± 12 years old; median body mass index: 27.6, interquartile range: 24.3-31.2 kg/m2), with most (n = 40) having stage III disease. Age, sex, and weight were significant predictors of REE [R2 = 0.829, standard error of the estimate (SEE): 128 kcal/day, P < 0.001]. Replacing weight with LST and FM yielded a similar model, with age, sex, LST, and FM predictive of REE (R2 = 0.820, SEE: 129 kcal/day, p < 0.001).Conclusion: Age, sex, weight, LST, and FM were the main contributors to REE. Further investigation of REE changes over time and its relationship to total energy expenditure, dietary intake, and clinical outcomes should be explored.

Acute high intensity interval exercise reduces colon cancer cell growth.

KEY POINTS: Physical activity is associated with reduced mortality rates for survivors of colorectal cancer. Acute high intensity interval exercise (HIIE) reduced colon cancer cell number in vitro and promoted increases in inflammatory cytokines immediately following exercise. This acute suppression of colon cancer cell number was transient and not observed at 120 minutes post-acute HIIE. The acute effects of exercise may constitute an important mechanism by which exercise can influence colorectal cancer outcomes. ABSTRACT: Physical activity is associated with significant reductions in colorectal cancer mortality. However, the mechanisms by which exercise mediates this anti-oncogenic effect are not clear. In the present study, colorectal cancer survivors completed acute (n = 10) or chronic (n = 10) exercise regimes. An acute high intensity interval exercise session (HIIE; 4 × 4 min at 85-95% peak heart rate) was completed with serum samples collected at baseline, as well as 0 and 120 min post-exercise. For the 'chronic' intervention, resting serum was sampled before and after 4 weeks (12 sessions) of HIIE. The effect of serum on colon cancer cell growth was evaluated by incubating cells (CaCo-2 and LoVo) for up to 72 h and assessing cell number. Serum obtained immediately following HIIE, but not 120 min post-HIIE, significantly reduced colon cancer cell number. Significant increases in serum interleukin-6 (P = 0.023), interleukin-8 (P = 0.036) and tumour necrosis factor-α (P = 0.003) were found immediately following acute HIIE. At rest, short-term HIIE training did not promote any changes in cellular growth or cytokine concentrations. The acute effects of HIIE and the cytokine flux may be important mediators of reducing colon cancer cell progression. Repetitive exposure to these acute effects may contribute to the relationship between exercise and improved colorectal cancer survival.

Evaluating Muscle Mass in Survivors of Acute Respiratory Distress Syndrome: A 1-Year Multicenter Longitudinal Study.

OBJECTIVES: Rapid muscle wasting occurs during acute respiratory failure, resulting in muscle weakness and functional impairments. This study examines survivors' body composition in the year after acute respiratory distress syndrome and tests associations of patient characteristics, hospital exposures, and survivors' strength and physical functioning with whole body percent lean mass. DESIGN: Prospective cohort study with 6- and 12-month follow-up. SETTING: National study enrolling patients from five study centers. PATIENTS: Acute respiratory distress syndrome survivors (n = 120). INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Lean and fat mass from dual energy x-ray absorptiometry. On average, survivors gained whole body total mass (+1.4 kg; 0.1-2.7) and fat mass (+1.2 kg; 0.2-2.2) and maintained lean mass (+0.2 kg; -0.4 to 0.8) between 6 and 12 months. Proportionally, percent fat mass increased and percent lean mass decreased for the whole body, trunk, and legs (p < 0.05). Greater whole body percent lean mass was associated with younger age, male sex, and lower baseline body mass index, but not other patient characteristics or ICU/hospital exposures. Greater percent lean mass was also significantly associated with gait speed and 6-minute walk distance, but not volitional strength or self-reported functional status. CONCLUSIONS: In the first year after acute respiratory distress syndrome, patients gained fat mass and maintained lean mass. We found no association of whole body percent lean mass with commonly hypothesized hospital risk factors. Direct measurement of body composition and performance-based functional measures may be helpful for understanding functional recovery in ICU survivors.

A practical approach to nutritional screening and assessment in cirrhosis.

Malnutrition is one of the most common complications of cirrhosis, associated with an increased risk of morbidity and mortality. As a potentially modifiable condition, it is of particular importance to identify malnourished patients so that nutritional therapy can be instituted. Nutrition screening and assessment are infrequently performed in patients with cirrhosis. The reasons for this are multifactorial, including the absence of a validated "rapid" screening tool, multiple definitions of what constitutes malnutrition, and challenges with interpreting body composition and laboratory results in the setting of volume overload and liver dysfunction. This article summarizes the clinically relevant evidence and presents key issues, tools, and clinical options that are applicable to patients with cirrhosis. The definition, etiology, and clinically relevant outcomes associated with malnutrition are reviewed. Rapid nutritional screening is differentiated from more detailed nutritional assessment. Nutritional assessment in special populations, including women and the obese, and the role of inflammation are discussed. Multicenter studies using a common nutritional screening/assessment strategy are the next steps to fast-track adoption and implementation of nutrition-related evaluations into routine clinical practice. (Hepatology 2017;65:1044-1057).

Association between Low Testosterone Levels and Sarcopenia in Cirrhosis: A Cross-sectional Study.

INTRODUCTION AND AIM: Sarcopenia is an independent predictor of mortality in cirrhosis. Hypogonadism is common in cirrhosis and has been associated with sarcopenia in non-cirrhotic chronic liver disease populations. The aim of this study is to investigate if sarcopenia is associated with low testosterone levels in patients with cirrhosis. MATERIAL AND METHODS: This is a retrospective analysis of prospectively collected data of 211 cirrhotic patients undergoing evaluation for liver transplantation. Sarcopenia was defined by computed tomography (CT) scan using specific cutoffs of the 3rd lumbar vertebra skeletal muscle index (L3 SMI). Morning testosterone levels were obtained in all patients. RESULTS: Of the 211 patients, sarcopenia was noted in 94 (45%). Testosterone levels were lower in sarcopenic patients (10.7 ± 1.1 vs. 13.7 ± 1.4 nmol/L, p = 0.03) and hypotestosteronemia was more frequent in them too (34 vs. 16%, p = 0.004). In males, those with sarcopenia had lower testosterone levels (14.6 ± 1.4 vs. 21.9 ± 1.8, p = 0.002), and the corresponding frequency of hypotestosteronemia (42 vs. 19%, p = 0.006) was also higher. There were no significant differences in female patients. There was a weak correlation between L3 SMI and testosterone levels (r 0.37, p < 0.001). On multivariable regression analysis including sex, body mass index (BMI), hypotestosteronemia, MELD and etiology of cirrhosis, only hypotestosteronemia (RR 2.76, p = 0.005) and BMI (RR 0.88, p < 0.001) were independently associated with sarcopenia. CONCLUSION: Low testosterone levels are associated with sarcopenia in male cirrhotic patients. The potential therapeutic effect of testosterone to reverse sarcopenia in these patients warrants evaluation in future trials.

Elevated C-Peptides, Abdominal Obesity, and Abnormal Adipokine Profile are Associated With Higher Gleason Scores in Prostate Cancer.

BACKGROUND: Prostate cancer development is associated with numerous lifestyle factors (i.e., physical activity, nutrition intake) and metabolic perturbations. These factors have been studied independently; here, we used an integrative approach to characterize these lifestyle and metabolic parameters in men undergoing diagnostic prostate biopsies. METHODS: We prospectively evaluated 51 consecutive men for body composition, metabolic factors including glucose- and lipid-related measures, as well as lifestyle factors prior to prostate biopsy. Evaluations were performed in a blinded manner and were subsequently related to biopsy outcomes for: (i) presence or absence of cancer; and (ii) where cancer was present, Gleason score. RESULTS: Serum C-peptide concentrations were significantly greater in participants with Gleason scores ≥4 + 3 (2.8 ± 1.1 ng/ml) compared to those with Gleason 3 + 3 (1.4 ± 0.6 ng/ml) or Gleason 3 + 4 (1.3 ± 0.8 ng/ml, P = 0.002), suggesting greater insulin secretion despite lack of differences in fasting glucose concentrations. Central adiposity, measured by waist circumference, was significantly greater in participants with Gleason ≥4 + 3 (110.1 ± 7.4 cm) compared to those with Gleason 3 + 4 (102.0 ± 9.5 cm, P = 0.028). Men with Gleason ≥4 + 3 also had significantly greater leptin concentrations than those with lower Gleason scores (Gleason ≥4 + 3: 15.6 ± 3.3 ng/ml vs. Gleason 3 + 4: 8.1 ± 8.1 ng/ml, P < 0.05) and leptin:adiponectin ratio (Gleason ≥4 + 3: 9.7 ± 6.1 AU, Gleason 3 + 4: 2.9 ± 3.2, Gleason 3 + 3: 2.4 ± 2.1 AU, P = 0.013). CONCLUSIONS: We profiled a cluster of obesity-related metabolic perturbations (C-peptide, central adiposity, leptin, and leptin:adiponectin ratios) which may associate with more aggressive prostate cancer histology. Prostate 77:211-221, 2017. © 2016 Wiley Periodicals, Inc.

The Voice of Experience: Diet and Weight Change in Women with Breast Cancer Associate with Psychosocial and Treatment-Related Challenges.

PURPOSE: This study investigated relationships between psychosocial and treatment-related factors, diet, and weight change in women treated with chemotherapy for early-stage breast cancer. METHODS: Comprehensive qualitative interviews were conducted with 28 women who were within 12 months of completing chemotherapy treatment. RESULTS: Changes in food intake and eating patterns were universal over the course of chemotherapy, with broad variability in treatment effects and associated dietary responses linked to weight change. Increased appetite, food cravings, and intake of energy-dense comfort foods were more common among women who gained weight during treatment (n = 11). Changes in taste, nausea, and emotional distress were central in promoting these dietary responses. Women who lost weight during treatment (n = 6) tended to report more severe and persistent side effects of treatment leading to poor appetite and lower food intake, and they were more likely to live alone. CONCLUSIONS: While the etiology of weight change in this population is complex, this study suggests that changes in food intake related to treatment and psychosocial challenges may play an important role for some women. These findings may help to identify women who are most at risk of weight change during treatment and may inform the development of tailored dietary interventions.

A Model to Identify Sarcopenia in Patients With Cirrhosis.

BACKGROUND & AIMS: The severe depletion of muscle mass at the third lumbar vertebral level (sarcopenia) is a marker of malnutrition and is independently associated with mortality in patients with cirrhosis. Instead of monitoring sarcopenia by cross-sectional imaging, we investigated whether ultrasound-based measurements of peripheral muscle mass, measures of muscle function, along with nutritional factors, are associated with severe loss of muscle mass. METHODS: We performed a prospective study of 159 outpatients with cirrhosis (56% male; mean age, 58 ± 10 years; mean model for end-stage liver disease score, 10 ± 3; 60% Child-Pugh class A) evaluated at the Cirrhosis Care Clinic at the University of Alberta Hospital from March 2011 through September 2012. Lumbar skeletal muscle indices were determined by computed tomography or magnetic resonance imaging. We collected clinical data and data on patients' body composition, nutrition, and thigh muscle thickness (using ultrasound analysis). We also measured mid-arm muscle circumference, mid-arm circumference, hand grip, body mass index, and serum level of albumin; patients were evaluated using the subjective global assessment scale. Findings from these analyses were compared with those from cross-sectional imaging, for each sex, using logistic regression analysis. RESULTS: Based on cross-sectional imaging analysis, 43% of patients had sarcopenia (57% of men and 25% of women). Results from the subjective global assessment, serum level of albumin, and most nutritional factors were significantly associated with sarcopenia. We used multivariate analysis to develop a model to identify patients with sarcopenia, and developed a nomogram based on body mass index and thigh muscle thickness for patients of each sex. Our model identified men with sarcopenia with an area under the receiver operating characteristic curve value of 0.78 and women with sarcopenia with an area under the receiver operating characteristic curve value of 0.89. CONCLUSIONS: In a prospective study of patients with cirrhosis, we found that the combination of body mass index and thigh muscle thickness (measured by ultrasound) can identify male and female patients with sarcopenia almost as well as cross-sectional imaging (area under the receiver operating characteristic curve values of 0.78 and 0.89, respectively). These factors might be used in screening and routine nutritional monitoring of patients with cirrhosis.

Assessment of skeletal muscle mass in critically ill patients: considerations for the utility of computed tomography imaging and ultrasonography.

PURPOSE OF REVIEW: Low muscularity and skeletal muscle atrophy are commonly exhibited in critically ill patients and have major implications on patient outcomes. Typically, in the ICU, body composition is assessed through anthropometrics or bioelectrical impedance analysis, but these modalities cannot specifically quantify skeletal muscle; thus, we evaluate the merits and challenges of using computed tomography (CT) and ultrasonography to specifically measure skeletal muscle in the ICU. RECENT FINDINGS: CT-based cut points have been used to identify critically ill patients with low muscle mass, and low muscularity associates with poor clinical outcomes and function. Ultrasonography is emerging as a useful tool to quantify skeletal muscle loss and degradation in architecture, as well as prospectively track changes in these parameters over time. Rates of muscle atrophy and changes in muscle architecture has been quantified by ultrasonography and associated with poor clinical outcomes, but identification of critically ill patients with low muscularity is still in its infancy. SUMMARY: CT imaging and ultrasonography require additional comprehensive validations against accurate measures of whole body muscle mass. As these validations begin to emerge, there will be a need to translate this knowledge into a simple tool that clinicians can apply as part of routine care.

Bedside ultrasound measurement of skeletal muscle.

PURPOSE OF REVIEW: Skeletal muscle and lean body mass may be vital to prognosis and functional recovery in chronic and acute illness, particularly in conditions in which muscle atrophy is prevalent. Ultrasound provides a precise and expedient method to measure muscle mass and changes in skeletal muscle at the bedside. RECENT FINDINGS: Here, we describe the various methodological approaches along with the validation and reliability tests that have been performed in various populations. Current applications of ultrasound in chronic and acute illness as well as its limitations and strengths in quantifying the muscle mass and changes in muscle over time are discussed. To capitalize on the beneficial features of ultrasound for measuring muscle, we describe the work that is needed to optimize the usefulness of ultrasound in chronic disease and acute care. SUMMARY: Given the precision, practicality, and ease of use, ultrasound is emerging as a highly useful tool in expediently measuring the muscle mass and changes in muscle tissue at the bedside. Ultrasound may be valuable in identifying patients who are at risk of malnutrition, in tracking muscle atrophy for the purpose of calculating nutrient delivery, and in assessing the success or failure of nutrition, pharmacological and rehabilitative interventions that aim to counter muscle atrophy.

Force magnitude and distribution during impacts to the hip are affected differentially by body size and body composition.

Hip fractures are a severe health concern among older adults. While anthropometric factors have been shown to influence hip fracture risk, the low fidelity of common body composition metrics (e.g. body mass index) reduces our ability to infer underlying mechanisms. While simulation approaches can be used to explore how body composition influences impact dynamics, there is value in experimental data with human volunteers to support the advancement of computational modeling efforts. Accordingly, the goal of this study was to use a novel combination of subject-specific clinical imaging and laboratory-based impact paradigms to assess potential relationships between high-fidelity body composition and impact dynamics metrics (including load magnitude and distribution and pelvis deflection) during sideways falls on the hip in human volunteers. Nineteen females (<35 years) participated. Body composition was assessed via DXA and ultrasound. Participants underwent low-energy (but clinically relevant) sideways falls on the hip during which impact kinetics (total peak force, contract area, peak pressure) and pelvis deformation were measured. Pearson correlations assessed potential relationships between body composition and impact characteristics. Peak force was more strongly correlated with total mass (r = 0.712) and lean mass indices (r = 0.510-0.713) than fat mass indices (r = 0.401-0.592). Peak deflection was positively correlated with indices of adiposity (all r > 0.7), but not of lean mass. Contact area and peak pressure were positively and negatively associated, respectively, with indices of adiposity (all r > 0.49). Trochanteric soft tissue thickness predicted 59 % of the variance in both variables, and was the single strongest correlate with peak pressure. In five-of-eight comparisons, hip-local (vs. whole body) anthropometrics were more highly associated with impact dynamics. In summary, fall-related impact dynamics were strongly associated with body composition, providing support for subject-specific lateral pelvis load prediction models that incorporate soft tissue characteristics. Integrating soft and skeletal tissue properties may have important implications for improving the biomechanical effectiveness of engineering-based protective products.

Influence of test paradigm on loading dynamics during proximal femur fracture tests simulating sideways falls.

Fall-related hip fractures are a serious public health issue in older adults. As most mechanistic hip fracture risk prediction models incorporate tissue tolerance, test methods that can accurately characterize the fracture force of the femur (and factors that influence it) are imperative. While bone possesses viscoelastic properties, experimental characterization of rate-dependencies has been inconsistent in the whole-femur literature. The goal of this study was to investigate the influence of experimental paradigm on loading rate and fracture force (both means and variability) during mechanical tests simulating lateral fall loadings on the proximal femur. Six pairs of matched femurs were split randomly between two test paradigms: a 'lower rate' materials testing system (MTS) with a constant displacement rate of 60 mm/s, and a hip impact test system (HIT) comprised of a custom-built vertical drop tower utilizing an impact velocity of 4 m/s. The loading rate was 88-fold higher for the HIT (mean (SD) = 2465.49 (807.38) kN/s) compared to the MTS (27.78 (10.03) kN/s) paradigm. However, no difference in fracture force was observed between test paradigms (mean (SD) = 4096.4 (1272.6) N for HIT, and 3641.3 (1285.8) N for MTS). Within-paradigm variability was not significantly different across paradigms for either loading rate or fracture force (coefficients of variation ranging from 0.311 to 0.361). Within each test paradigm, significant positive relationships were observed between loading rate and fracture force (HIT adjusted R2 = 0.833, p = 0.007; MTS adjusted R2 = 0.983, p < 0.0001). Overall, this study provides evidence that energy-based impact simulators can be a valid method to measure femoral bone strength in the context of fall-related hip fractures. This study motivates future research to characterize potential non-linear relationships between loading rate and fracture threshold at both macro and microscales.

Radiodensities of Skeletal Muscle and Visceral Adipose Tissues Are Prognostic Factors in Clear-Cell Renal Cell Carcinoma.

BACKGROUND: Body composition may be related to survival in patients with clear-cell renal cell carcinoma (ccRCC), but studies have not simultaneously considered adipose and muscle tissue quantity and radiodensity. METHODS: We analyzed data from 1,022 patients with ccRCC who underwent nephrectomy between 2000 and 2020 at Memorial Sloan Kettering Cancer Center. Skeletal muscle, visceral adipose tissue, and subcutaneous adipose tissue indexes (cm2/m2) and radiodensities [Hounsfield units (HU)] were assessed from noncontrast presurgical CT scans; clinical and demographic characteristics were available from the time of surgery. HRs and confidence intervals were estimated for overall (OS) and disease-free survival (DFS) through March 2023 in multivariable models that simultaneously accounted for all body composition measures. RESULTS: The median age of the patients was 58 years, 69% were male, and 90% were White. There were 169 OS events over 8,392 person-years and 253 DFS events over 7,753 person-years of follow-up. In adjusted analyses, poor OS was associated with lower skeletal muscle radiodensity [-10 HU, HR (95% confidence interval), 1.37 (1.05-1.77)] and greater visceral adipose tissue radiodensity [+10 HU, 1.66 (1.06-2.59)], with similar findings for DFS. Poor survival was also associated with greater visceral adipose tissue index [+40 cm2/m2, OS: 1.32 (0.97, 1.79); DFS: 1.33 (1.04, 1.71)]. Associations with skeletal muscle radiodensity were limited to patients with stage 1/2 disease. CONCLUSIONS: Radiodensities of skeletal muscle and visceral adipose tissues may be novel presurgical prognostic factors for patients with ccRCC. IMPACT: The findings underscore the importance of evaluating the full range of body composition features simultaneously in multivariable models.