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

In vitro and in vivo muscle mass and strength during the first week of critical illness

BACKGROUND

Loss of muscle mass and strength is provoked by critical illness. Our primary aim was to study the development of muscle atrophy and weakness in vitro in isolated myofibers and in vivo muscle mass and in vitro muscle strength during the first week of critical illness. Furthermore, we explored how in vitro muscle strength compares to healthy controls. Finally, we studied correlations between in vitro muscle mass and strength and in vivo muscle mass in critically ill patients.

METHODS

We performed a secondary analysis using data from a randomized controlled trial. We studied contractile force of single myofibers isolated from muscle biopsies around admission (day 1-3) and around 1 week after inclusion (day 8-10). Furthermore, we studied myofiber cross-sectional area (CSA), proportion of fast-twitch myofibers, bio-electrical impedance analysis-derived fat-free mass index (FFMI), ultrasound-derived quadriceps muscle layer thickness (QMLT) and diaphragm thickness. In the control group, only contractile force outcomes were available.

RESULTS

In total, ten ICU patients had two muscle biopsies taken. Maximum force of both fast and slow-twitch myofibers was reduced at day 8-10 compared to day 1-3, even though there were no differences in normalized force and calcium sensitivity. FFM and QMLT did not change over time, nor were there differences between groups. Compared to healthy controls, maximum force of myofibers was lower in the ICU group at day 8-10 in both slow and fast-twitch myofibers, while the calcium sensitivity of force was lower in slow-twitch myofibers. We found a significant correlation between myofiber CSA vs. FFMI (r = 0.68) and maximum force of the fast-twitch fibers vs. QMLT (r = 0.72).

CONCLUSIONS

During the first week of critical illness, maximum force declined over time, while no other in vitro parameters changed. We found a moderate correlation between myofiber CSA vs. FFMI and maximum force of the fast-twitch fibers vs. QMLT.

Ultrasound for skeletal muscle assessment in surgical oncology: A scoping review

BACKGROUND

Skeletal muscle wasting in cancer patients is associated with adverse outcomes. Ultrasound offers a non-invasive muscle assessment, but no previous review has focused on its application during perioperative period. This scoping review aims to map the current literature on the ultrasound use for skeletal muscle assessment in cancer patients during the perioperative period and identify knowledge gaps for future research.

METHODS

A systematic literature search was conducted in the Cochrane Central Register of Controlled Trials, the Cochrane Database of Systematic Reviews, Embase, Medline, and Web of Science. Two independent reviewers screened studies for eligibility and extracted relevant data, including study characteristics, population, ultrasound protocols, and outcomes. Inclusion criteria were primary studies involving adults undergoing cancer surgery with ultrasound used for skeletal muscle assessment during the perioperative period.

RESULTS

Thirteen studies were included. The majority assessed quantitative parameters, with the rectus femoris muscle being the most evaluated. Muscle thickness and cross-sectional area were the most frequently reported parameters. Studies validated ultrasound parameters against established tools and clinical indicators, including sarcopenia, frailty, muscle strength, and biomarker. Ultrasound was also used to predict postoperative outcomes and assess perioperative interventions. However, variability in ultrasound protocols highlights the need for standardized practices, and the lack of consensus on cutoffs warrants future research.

CONCLUSIONS

This review demonstrated the validity and the applications of ultrasound for skeletal muscle assessment in cancer patients during the perioperative period. Significant variability in ultrasound protocols and the absence of standardized cutoffs highlight the need for further research.

A new anthropometry-based muscle quality index predicts adverse outcomes in hospitalized patients

BACKGROUND

Muscle quality index (MQI) is computed as the ratio of strength to muscle mass (MM), estimating functional muscle quality. Imaging methods are used to assess MM and compute the MQI, being challenging for use in clinical practice. Anthropometry has become an alternative marker of MM that can be used within MQI, although few studies have explored this approach.

OBJECTIVE

To evaluate the prognostic value of mid-arm muscle circumference (MAMC cm), corrected arm muscle area (AMA cm2), and calf circumference adjusted for body mass index (CC-BMI adjusted cm) as markers of MM within MQI in predicting adverse outcomes in hospitalized patients.

METHODS

A secondary analysis was conducted on a cohort with prospective data collection. Adult and older hospitalized patients were evaluated up to 48 h after hospitalization. MQI was calculated as the ratio of handgrip strength (HGS) to MM evaluated by MAMC (MQIMAMC), MAM (MQIMAM), and CC-BMI adjusted (MQICC-BMI). The outcomes of interest were prolonged hospital stay, in-hospital and 6-month mortality. Logistic and Cox regression analyses adjusted for Charlson comorbidity index, ethnicity, surgery, and sex were performed.

RESULTS

554 patients were included (55.2 ± 14.9 years, 52.9 % of males, 518 had MACM and MAM available). Each one-unit MQI increase reduced the risk by 32 %, 44 %, and 33 % in prolonged hospitalization for MQIMAMC (RR = 0.68, 95 % CI 0.52-0.90), MQIAMA (RR = 0.56, 95 % CI 0.35-0.89), and MQICC-BMI (RR = 0.67, 95 % CI 0.46-0.96). A higher MQICC-BMI was an independent predictor of a lower risk of 6-month mortality after discharge (RR = 0.26, 95 % CI 0.08-0.84).

CONCLUSIONS

Higher MQI values using anthropometric markers (MAMC, AMA, and CC-BMI) were inversely associated with adverse in-hospital and 6-month after-discharge outcomes, reinforcing its use as a muscle-related prognostic index.

Body Composition Assessment in Critically Ill Adults - Where are We now?

This narrative review provides an overview of body composition methods available for use in critically ill patients. It focuses on the relevance and discussion of the most commonly used techniques. Further, we discuss the validity of these methods with a focus on muscle mass assessment, measuring changes over time and the identification of patients with lower-than-normal muscularity. Current available evidence, as well as future directions is highlighted.

Poor muscle quality: A hidden and detrimental health condition in obesity

Poor muscle quality (MQ) is a hidden health condition in obesity, commonly disregarded and underdiagnosed, associated with poor health-related outcomes. This narrative review provides an in-depth exploration of MQ in obesity, including definitions, available assessment methods and challenges, pathophysiology, association with health outcomes, and potential interventions. MQ is a broad term that can include imaging, histological, functional, or metabolic assessments, evaluating beyond muscle quantity. MQ assessment is highly heterogeneous and requires further standardization. Common definitions of MQ include 1) muscle-specific strength (or functional MQ), the ratio between muscle strength and muscle quantity, and 2) muscle composition (or morphological MQ), mainly evaluating muscle fat infiltration. An individual with obesity might still have normal or higher muscle quantity despite having poor MQ, and techniques for direct measurements are needed. However, the use of body composition and physical function assessments is still limited in clinical practice. Thus, more accessible techniques for assessing strength, muscle mass, and composition should be further explored. Obesity leads to adipocyte dysfunction, generating a low-grade chronic inflammatory state, which leads to mitochondrial dysfunction. Adipocyte and mitochondrial dysfunction result in metabolic dysfunction manifesting clinically as insulin resistance, dyslipidemia, and fat infiltration into organs such as muscle, which in excess is termed myosteatosis. Myosteatosis decreases muscle cell function and insulin sensitivity, creating a vicious cycle of inflammation and metabolic derangements. Myosteatosis increases the risk of poor muscle function, systemic metabolic complications, and mortality, presenting prognostic potential. Interventions shown to improve MQ include nutrition, physical activity/exercise, pharmacology, and metabolic and bariatric surgery.

[Thickness of the rectus femorius muscle and vastus intermedium muscle in older Mexican adults with frailty and sarcopenia]

BACKGROUND AND OBJECTIVE

Frailty in older adults is a geriatric syndrome that has gained importance in the last decade. However, there is still no consolidated information regarding diagnostic tools that allow timely identification, and therefore, provide an appropriate therapeutic approach. The objective is to determine the Thickness of the Rectus Femoris Muscle (GMRF) and Thickness of the Vastus Intermedius Muscle (GMVI) in older Mexican adults with frailty and sarcopenia.

MATERIAL AND METHODS

Cross-sectional, descriptive and comparative study in patients ≥65 years of age, admitted to the geriatrics service. The selection was according to the FRAIL (frail vs. non-frail) and SARC-F (high risk vs. low risk) classification; evaluating GMRF and GMVI by ultrasound. The data were analyzed through the statistical software Statistical Package for Social Sciences (SPSS) ver. 25.

RESULTS

The number of patients evaluated in the study and control group were 136 respectively. Significant differences were found regarding frailty status in age (years) (Frail: 75.06±7.92 vs. Non-frail: 71.60±5.56; P<.001), GMRF (mm) (Frail: 8.41±3.08 vs. Non-frail: 11.03±3.50; P<.001) and GMVI (mm) (Frail: 6.53±2.64 vs. Non-frail: 8.66±2.68; P<.001); Considering sarcopenia, there were differences in age (years) (High risk sarcopenia: 75.17±7.84: vs low risk sarcopenia; 71.49±5.60; P<.001), GMRF (mm) (high risk sarcopenia: 8.45±3.11 vs low risk sarcopenia: 10.98±3.50; P<.001) and GMVI (mm) (High risk Sarcopenia: 6.67±2.63 vs Low risk Sarcopenia: 8.52±2.79; P<.001).

CONCLUSIONS

The results found show that there is a significant difference in GMRF and GMVI in Mexican older adults with respect to frailty and sarcopenia. In this way, the present investigation establishes clinical bases for the use of ultrasonography assessments in the geriatric population.

Phase Angle and Ultrasound Assessment of the Rectus Femoris for Predicting Malnutrition and Sarcopenia in Patients with Esophagogastric Cancer: A Cross-Sectional Pilot Study

BACKGROUND

Disease-related malnutrition (DRM) and sarcopenia are prevalent conditions in gastrointestinal cancer patients, whose early diagnosis is essential to establish a nutritional treatment that contributes to optimizing adverse outcomes and improving prognosis. Phase angle (PhA) and rectus femoris ultrasound measurements are considered effort-independent markers of muscle wasting, which remains unrecognized in oncology patients.

OBJECTIVE

This study aimed to evaluate the potential utility of PhA, rectus femoris cross-sectional area (RFCSA), and rectus femoris thickness (RF-Y-axis) in predicting malnutrition and sarcopenia in patients with esophagogastric cancer (EGC).

METHODS

This was a cross-sectional study of patients diagnosed with EGC. PhA was obtained using bioelectrical impedance vector analysis (BIVA) along with ASMMI. The RFCSA and RF-Y-axis were measured using nutritional ultrasound (NU®). Muscle capacity was assessed using handgrip strength (HGS), and functionality by applying the Short Physical Performance Battery (SPPB). Malnutrition and sarcopenia were determined according to the GLIM and EWGSOP2 criteria, respectively.

RESULTS

Out of the 35 patients evaluated, 82.8% had malnutrition and 51.4% had sarcopenia. The RFCSA (r = 0.582) and RF-Y-axis (r = 0.602) showed significant, moderate correlations with ASMMI, unlike PhA (r = 0.439), which displayed a weak correlation with this parameter. However, PhA (OR = 0.167, CI 95%: 0.047-0.591, p = 0.006), RFCSA (OR = 0.212, CI 95%: 0.074-0.605, p = 0.004), and RF-Y-axis (OR = 0.002, CI 95%: 0.000-0.143, p = 0.004) all showed good predicting ability for sarcopenia in the crude models, but only the RF-Y-axis was able to explain malnutrition in the regression model (OR = 0.002, CI 95%: 0.000-0.418, p = 0.023).

CONCLUSIONS

The RF-Y-axis emerged as the only independent predictor of both malnutrition and sarcopenia in this study, likely due to its stronger correlation with ASMMI compared to PhA and RFCSA.

Rectus Femoris Muscle Segmentation on Ultrasound Images of Older Adults Using Automatic Segment Anything Model, nnU-Net and U-Net-A Prospective Study of Hong Kong Community Cohort

Sarcopenia is characterized by a degeneration of muscle mass and strength that incurs impaired mobility, posing grievous impacts on the quality of life and well-being of older adults worldwide. In 2018, a new international consensus was formulated to incorporate ultrasound imaging of the rectus femoris (RF) muscle for early sarcopenia assessment. Nonetheless, current clinical RF muscle identification and delineation procedures are manual, subjective, inaccurate, and challenging. Thus, developing an effective AI-empowered RF segmentation model to streamline downstream sarcopenia assessment is highly desirable. Yet, this area of research readily goes unnoticed compared to other disciplines, and relevant research is desperately wanted, especially in comparison among traditional, classic, and cutting-edge segmentation networks. This study evaluated an emerging Automatic Segment Anything Model (AutoSAM) compared to the U-Net and nnU-Net models for RF segmentation on ultrasound images. We prospectively analyzed ultrasound images of 257 older adults (aged > 65) in a community setting from Hong Kong's District Elderly Community Centers. Three models were developed on a training set (n = 219) and independently evaluated on a testing set (n = 38) in aspects of DICE, Intersection-over-Union, Hausdorff Distance (HD), accuracy, precision, recall, as well as stability. The results indicated that the AutoSAM achieved the best segmentation agreement in all the evaluating metrics, consistently outperforming the U-Net and nnU-Net models. The results offered an effective state-of-the-art RF muscle segmentation tool for sarcopenia assessment in the future.

Acute Skeletal Muscle Wasting is Associated with Prolonged Hospital Stay in Critical Illness with Brain Injury

BACKGROUND

Acute muscle wasting is common in critically ill patients, and this can lead to unfavorable clinical outcomes. The aim of this study was to identify factors associated with muscle wasting and to investigate the association between skeletal muscle wasting and prolonged hospital stay in critically ill patients with acute brain injury.

METHODS

This single-center prospective observational study was conducted in critically ill patients with acute brain injury who stayed in the intensive care unit for at least 1 week. The rectus femoris cross-sectional area was measured via ultrasound at baseline and a week after the first assessment. Univariate and multivariate logistic regression analyses were performed to identify factors that predicted prolonged hospital stay.

RESULTS

A total of 86 patients were included in the study. Their mean age was 49.4 ± 16.9 years, 57% were male, and 46.5% had an admission diagnosis of subarachnoid hemorrhage. The percentage change in the rectus femoris cross-sectional area was 15.8% (95% confidence interval [CI] - 19.8% to - 12.0%; p < 0.001), and 57% of all patients had acute muscle wasting. According to the univariate analysis, there was a significant association between prolonged hospital stay and acute muscle wasting (odds ratio [OR] 3.677; 95% CI 1.487-9.043; p = 0.005), mechanical ventilation status (OR 3.600; 95% CI 1.455-8.904; p = 0.006), and Glasgow Coma Scale score (OR 0.888; 95% CI 0.808-0.976; p = 0.014) at intensive care unit admission. The multivariate analysis demonstrated that acute muscle wasting (OR 3.449; 95% CI 1.344-8.853; p = 0.010) was an independent risk factor for prolonged hospital stay.

CONCLUSIONS

There was considerable muscle wasting in critically ill patients with brain injuries over a 1-week period. Acute muscle wasting was associated with prolonged hospital stay in critically ill patients with acute brain injury.

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.

Functional Magnetic Neuromuscular Stimulation vs. Routine Physiotherapy in the Critically Ill for Prevention of ICU Acquired Muscle Loss: A Randomised Controlled Trial

Background and Objectives: Muscle loss is a known complication of ICU admission. The aim of the study was to investigate the effect of neuromuscular functional magnetic stimulation (FMS) on quadriceps muscle thickness in critically ill patients. Materials and Methods: Among ICU patients one quadriceps was randomized to FMS (Tesla Stym, Iskra Medical, Ljubljana, Slovenia) stimulation and the other to control care. Quadriceps thickness was measured by ultrasound (US) in transversal and longitudinal planes at enrolment, Days 3-5, and Days 9-12. The trial stopped early following an interim analysis comparing muscle thickness differences between groups using repeated measures ANOVA. Results: Of 18 patients randomized, 2 died before completing the trial. The final analysis reported included 16 patients (female 38%, age 68 ± 10 years, SOFA 10.8 ± 2.7). Three mild skin thermal injuries were noted initially, which were later avoided with proper positioning of FMS probe. Primary outcome comparison showed that quadriceps thickness in transversal and longitudinal planes decreased in the non-stimulated legs and, but it did not change in FMS legs (-4.1 mm (95%CI: -9.4 to -0.6) vs. -0.7 mm (95%CI: -4.1 to -0.7) (p = 0.03) and -4.4 mm (95%CI: -8.9 to -1.1) vs. -1.5 mm (95%CI: -2.6 to -2.2) (p = 0.02), respectively) (ANOVA difference between groups p = 0.036 and 0.01, respectively). Conclusions: In the critically ill, neuromuscular FMS is feasible and safe with precautions applied to avoid possible skin thermal injury. FMS decreases the loss of quadriceps muscle thickness.

Nutrition considerations for patients with persistent critical illness: A narrative review

Critically ill patients experience high rates of malnutrition and significant muscle loss during their intensive care unit (ICU) admission, impacting recovery. Nutrition is likely to play an important role in mitigating the development and progression of malnutrition and muscle loss observed in ICU, yet definitive clinical trials of nutrition interventions in ICU have failed to show benefit. As improvements in the quality of medical care mean that sicker patients are able to survive the initial insult, combined with an aging and increasingly comorbid population, it is anticipated that ICU length of stay will continue to increase. This review aims to discuss nutrition considerations unique to critically ill patients who have persistent critical illness, defined as an ICU stay of >10 days. A discussion of nutrition concepts relevant to patients with persistent critical illness will include energy and protein metabolism, prescription, and delivery; monitoring of nutrition at the bedside; and the role of the healthcare team in optimizing nutrition support.

Advances in nutritional metabolic therapy to impede the progression of critical illness

With the advancement of medical care and the continuous improvement of organ support technologies, some critically ill patients survive the acute phase of their illness but still experience persistent organ dysfunction, necessitating long-term reliance on intensive care and organ support, known as chronic critical illness. Chronic critical illness is characterized by prolonged hospital stays, high mortality rates, and significant resource consumption. Patients with chronic critical illness often suffer from malnutrition, compromised immune function, and poor baseline health, which, combined with factors like shock or trauma, can lead to intestinal mucosal damage. Therefore, effective nutritional intervention for patients with chronic critical illness remains a key research focus. Nutritional therapy has emerged as one of the essential components of the overall treatment strategy for chronic critical illness. This paper aims to provide a comprehensive review of the latest research progress in nutritional support therapy for patients with chronic critical illness.