Use of Bedside Ultrasound to Assess Muscle Changes in the Critically Ill Surgical Patient

Point of care ultrasonography of quadriceps femoris muscle thickness for assessing nutritional status in critically ill children

Muscle wasting occurs early during critical illness. It is associated with poor PICU outcomes. Ultrasonography can detect muscle thickness in critically ill children. Study quadriceps muscle thickness to assess the nutritional status on admission and follow the muscle thickness change throughout the first week of admission in PICU using point-of-care ultrasonography. This cohort study was conducted on 55 critically ill mechanically ventilated children aged between 2 months and 14 years. Serial measurements of quadriceps muscle thickness were done by ultrasound, during the first week of admission. Quadriceps muscle thickness decreased by 16.4% over the 1st week of admission. The muscle wasting was significantly correlated with STRONGkids score, the inability to achieve target caloric requirements during the 1st week of admission, duration of ventilation, PRISM score, and mortality. Point of care ultrasonography is an easy tool for assessing PICU muscle wasting. Loss of muscle mass during the first week of PICU admission is correlated to mortality, thus it can be utilized in predicting PICU outcomes.

Accuracy and costs of bedside methods for confirming nasoenteral feeding tube position: a diagnostic accuracy study

AIM

To analyze the accuracy and costs of bedside methods for confirming the position of a nasoenteral feeding tube newly inserted blindly by nurses.

DESIGN

Diagnostic accuracy study of three clinical methods (ultrasound, epigastric auscultation, and pH measurement) compared to radiography. The direct costs of each method used to confirm the positioning of the nasoenteral tube were also measured.

METHODS

Seventy-six adult patients underwent a total of 87 nasoenteral tube insertion procedures in hospital units located within the Northeast region of the State of São Paulo, Brazil. The clinical methods were conducted on all study participants in the specified sequence: ultrasound (as index test), followed by epigastric auscultation and pH measurement (also index tests).

RESULTS

The outcomes regarding the confirmation of the accurate positioning of the nasoenteral tube are as follows: ultrasonography demonstrated sensitivity and specific of 79.0% and 66.7%, respectively. Epigastric auscultation exhibited a sensitivity of 81.3% and specificity of 83.3%. The pH measurement method displayed sensitivity and specificity of 89.3% and 100% respectively. Additionally, in terms of estimated direct costs, the pH measurement method incurred a higher cost (USD $8.31) compared to the other methods, with a difference of USD $6.68.

CONCLUSIONS

Based on these results, X-ray examination remains the primary method for confirming the placement of nasoenteral tubes recently inserted blindly at the bedside. However, when considering the costs of the evaluated methods, it is advisable to consider the variations in expenses between non-radiological methods and X-ray examinations.

Ultrasonographic assessment of the muscle mass of the rectus femoris in mechanically ventilated patients at intensive care unit discharge is associated with deterioration of functional status at hospital discharge: a prospective cohort study

OBJECTIVE

To verify whether the rectus femoris muscle mass in mechanically ventilated patients assessed by ultrasonography at intensive care unit discharge is associated with functional status at hospital discharge.

METHODS

This cohort study was conducted at a tertiary hospital in Brazil between August 2019 and November 2020. We included patients over 18 years who were previously independent (Barthel index > 60) and underwent mechanical ventilation for at least 48 hours within 96 hours of admission. Ultrasonographic measurements of the rectus femoris cross-sectional area and right quadriceps thickness were performed upon enrollment, five days after enrollment, and at intensive care unit discharge. The primary outcome was assessing functional capacity via the Barthel index at hospital discharge.

RESULTS

Of the 78 patients included, 35 had assessable primary outcomes. Twenty (57.1%) patients were considered functionally dependent (Barthel index < 60). The Barthel index at hospital discharge was correlated with the cross-sectional area (r = 0.53; p = 0.001) and quadriceps thickness (r = 0.43; p = 0.01) at intensive care unit discharge. Multiple linear regression analysis revealed that the cross-sectional area at intensive care unit discharge was independently associated with the Barthel index.

CONCLUSION

We found that muscle mass assessed by cross-sectional area ultrasonography at intensive care unit discharge was significantly correlated with functional capacity at hospital discharge.

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.

Nutrition determinants of acute skeletal muscle loss in critically ill patients: A prospective observational cohort study

BACKGROUND

Skeletal muscle loss is associated with adverse outcomes in critically ill patients and risk factors of acute skeletal muscle loss are not well described. This study aims to determine the factors associated with acute skeletal muscle loss in critically ill patients.

METHODS

This prospective observational cohort study was conducted with patients who were expected to stay in the intensive care unit (ICU) for at least a week. Rectus femoris cross-sectional area (RFCSA) measurements were performed within 48 h of ICU admission and on study day 7. The percentage change in RFCSA and variables associated with this change were evaluated by univariate and multivariate regression analysis.

RESULTS

Over a 12-month period, 518 patients were assessed for eligibility and 44 critically ill patients with a mean age of 59.3 ± 10.9 years were enrolled; 52.3% of them were female. There were significant reductions in RFCSA (16.8 ± 16.5%; P < 0.001). The mean amounts of protein and energy consumed compared with those prescribed were 67.0 ± 28.8% and 71.5 ± 38.3%, respectively. Multivariate regression analysis revealed that frailty was independently associated with acute skeletal muscle loss after adjusting for confounding factors in our cohort of patients.

CONCLUSION

Frailty status before ICU admission is associated with acute skeletal muscle loss and may be important for identifying critically ill patients at high risk of muscle wasting.

Uncovering sarcopenia and frailty in older adults by using muscle ultrasound-A narrative review

Muscle ultrasound is a valuable non-invasive and cost-effective method in assessing muscle mass and structure, both of which are significant indicators for the development of sarcopenia and frailty in elderly individuals. Sarcopenia refers to the loss of muscle mass and strength that occurs with age, whereas frailty is a complex geriatric syndrome characterized by reduced physical function and an increased susceptibility to negative health outcomes. Both conditions are prevalent in older adults and are associated with higher risks of falls, disability, and mortality. By measuring muscle size and structure and several other ultrasound parameters, including muscle thickness, cross-sectional area, echogenicity (brightness in the ultrasound image), pennation angle, and fascicle length ultrasound can assist in identifying sarcopenia and frailty in older adults. In addition, ultrasound can be used to evaluate muscle function such as muscle contraction and stiffness, which may also be affected in sarcopenia and frailty. Therefore, muscle ultrasound could lead to better identification and tracking of sarcopenia and frailty. Such advancements could result in the implementation of earlier interventions to prevent or treat these conditions, resulting in an overall improvement in the health and quality of life of the elderly population. This narrative review describes the benefits and challenges when using ultra-sound for the evaluation of frailty and sarcopenia.

Clinical practice guidelines for nutritional assessment and monitoring of adult ICU patients in China

The Chinese Society of Critical Care Medicine (CSCCM) has developed clinical practice guidelines for nutrition assessment and monitoring for patients in adult intensive care units (ICUs) in China. This guideline focuses on nutrition evaluation and metabolic monitoring to achieve optimal and personalized nutrition therapy for critically ill patients. This guideline was developed by experts in critical care medicine and evidence-based medicine methodology and was developed after a thorough review of the system and a summary of relevant trials or studies published from 2000 to July 2023. A total of 18 recommendations were formed and consensus was reached through discussions and reviews by expert groups in critical care medicine, parenteral and enteral nutrition, and surgery. The recommendations are based on currently available evidence and cover several key fields, including screening and assessment, evaluation and assessment of enteral feeding intolerance, metabolic and nutritional measurement and monitoring during nutrition therapy, and organ function evaluation related to nutrition supply. Each question was analyzed according to the Population, Intervention, Comparison, and Outcome (PICO) principle. In addition, interpretations were provided for four questions that did not reach a consensus but may have potential clinical and research value. The plan is to update this nutrition assessment and monitoring guideline using the international guideline update method within 3-5 years.

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.

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.

Nascent to novel methods to evaluate malnutrition and frailty in the surgical patient

Preoperative nutrition status is an important determinant of surgical outcomes, yet malnutrition assessment is not integrated into all surgical pathways. Given its importance and the high prevalence of malnutrition in patients undergoing surgical procedures, preoperative nutrition screening, assessment, and intervention are needed to improve postoperative outcomes. This narrative review discusses novel methods to assess malnutrition and frailty in the surgical patient. The Global Leadership Initiative for Malnutrition (GLIM) criteria are increasingly used in surgical settings although further spread and implementation are strongly encouraged to help standardize the diagnosis of malnutrition. The use of body composition (ie, reduced muscle mass) as a phenotypic criterion in GLIM may lead to a greater number of patients identified as having malnutrition, which may otherwise be undetected if screened by other diagnostic tools. Skeletal muscle loss is a defining criterion of malnutrition and frailty. Novel direct and indirect approaches to assess muscle mass in clinical settings may facilitate the identification of patients with or at risk for malnutrition. Selected imaging techniques have the additional advantage of identifying myosteatosis (an independent predictor of morbidity and mortality for surgical patients). Feasible pathways for screening and assessing frailty exist and may determine the cost/benefit of surgery, long-term independence and productivity, and the value of undertaking targeted interventions. Finally, the evaluation of nutrition risk and status is essential to predict and mitigate surgical outcomes. Nascent to novel approaches are the future of objectively identifying patients at perioperative nutrition risk and guiding therapy toward optimal perioperative standards of care.

Evaluation of muscle loss by ultrasonography in critically ill patients

BACKGROUND

Critically ill patients have intense muscle tissue mobilization, and attenuating protein catabolism may contribute to improved outcomes.

OBJECTIVE

To evaluate short-term muscle loss in critically ill patients.

METHODS

In this prospective observational study, we evaluated the thickness of the rectus femoris muscle by ultrasonography in young and older adults of both sexes admitted to a cardiological intensive care unit within 48 h of admission (baseline) and after 7 days. The results were compared and correlated with anthropometric, clinical, and biochemical parameters. The significance level for all statistical analyses was 0.05.

RESULTS

The final sample comprised 88 patients with a mean age of 66.2 ± 11.8 years. There was an average 13.5% reduction in rectus femoris muscle thickness over the study period (P < 0.001), regardless of the thigh circumference maintenance (P = 0.229). This reduction occurred even with improved clinical parameters (C-reactive protein, Simplified Acute Physiology Score) and was greater in patients receiving mechanical ventilation and sedation and in those who died. Regarding nutrition status, malnourished and eutrophic individuals showed greater muscle loss than overweight individuals. There was also an inverse correlation of muscle loss (percentage) with body mass index, arm circumference, and calf circumference (P < 0.05), demonstrating that the lower these anthropometric measurements, the higher the muscle loss obtained by ultrasound.

CONCLUSION

Ultrasonography assessment detected muscle mass loss in the short-term more sensitively than the anthropometric method. However, it demands caution and further studies demonstrating this analysis.

The current use of ultrasound to measure skeletal muscle and its ability to predict clinical outcomes: a systematic review

Quantification and monitoring of lean body mass is an important component of nutrition assessment to determine nutrition status and muscle loss. The negative impact of reduced muscle mass and muscle function is increasingly evident across acute and chronic disease states but is particularly pronounced in patients with cancer. Ultrasound is emerging as a promising tool to directly measure skeletal muscle mass and quality. Unlike other ionizing imaging techniques, ultrasound can be used repeatedly at the bedside and may compliment nutritional risk assessment. This review aims to describe the current use of skeletal muscle ultrasound (SMUS) to measure muscle mass and quality in patients with acute and chronic clinical conditions and its ability to predict functional capacity, severity of malnutrition, hospital admission, and survival. Databases were searched from their inception to August 2021 for full-text articles in English. Relevant articles were included if SMUS was investigated in acute or chronic clinical contexts and correlated with a defined clinical outcome measure. Data were synthesized for narrative review due to heterogeneity between studies. This review analysed 37 studies (3100 patients), which met the inclusion criteria. Most studies (n = 22) were conducted in critical care. The clinical outcomes investigated included functional status at discharge (intensive care unit-acquired weakness), nutritional status, and length of stay. SMUS was also utilized in chronic conditions such as chronic obstructive pulmonary disease, chronic heart failure, and chronic renal failure to predict hospital readmission and disease severity. Only two studies investigated the use of SMUS in patients with cancer. Of the 37 studies, 28 (76%) found that SMUS (cross-sectional area, muscle thickness, and echointensity) showed significant associations with functional capacity, length of stay, readmission, and survival. There was significant heterogeneity in terms of ultrasound technique and outcome measurement across the included studies. This review highlights that SMUS continues to gain momentum as a potential tool for skeletal muscle assessment and predicting clinically important outcomes. Further work is required to standardize the technique in nutritionally vulnerable patients, such as those with cancer, before SMUS can be widely adopted as a bedside prognostic tool.

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.

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.

Academy of Nutrition and Dietetics and American Society for Parenteral and Enteral Nutrition: Revised 2021 Standards of Practice and Standards of Professional Performance for Registered Dietitian Nutritionists (Competent, Proficient, and Expert) in Nutrition Support

Nutrition support is a therapy that crosses all ages, diseases, and conditions as health care practitioners strive to meet the nutritional requirements of individuals who are unable to meet nutritional and/or hydration needs with oral intake alone. Registered dietitian nutritionists (RDNs), as integral members of the nutrition support team provide needed information, such as identification of malnutrition risk, macro- and micronutrient requirements, and type of nutrition support therapy (eg, enteral or parenteral), including the route (eg, nasogastric vs nasojejunal or tunneled catheter vs port). The Dietitians in Nutrition Support Dietetic Practice Group, American Society for Parenteral and Enteral Nutrition, along with the Academy of Nutrition and Dietetics Quality Management Committee, have updated the Standards of Practice (SOP) and Standards of Professional Performance (SOPP) for RDNs working in nutrition support. The SOP and SOPP for RDNs in Nutrition Support provide indicators that describe the following 3 levels of practice: competent, proficient, and expert. The SOP uses the Nutrition Care Process and clinical workflow elements for delivering patient/client care. The SOPP describes the 6 domains that focus on professional performance. Specific indicators outlined in the SOP and SOPP depict how these standards apply to practice. The SOP and SOPP are complementary resources for RDNs and are intended to be used as a self-evaluation tool for assuring competent practice in nutrition support and for determining potential education and training needs for advancement to a higher practice level in a variety of settings.

Academy of Nutrition and Dietetics and American Society for Parenteral and Enteral Nutrition: Revised 2021 standards of practice and standards of professional performance for registered dietitian nutritionists (competent, proficient, and expert) in nutrition support

Nutrition support is a therapy that crosses all ages, diseases, and conditions as health care practitioners strive to meet the nutrition requirements of individuals who are unable to meet nutrition and/or hydration needs with oral intake alone. Registered dietitian nutritionists (RDNs), as integral members of the nutrition support team provide needed information, such as identification of malnutrition risk, macro- and micronutrient requirements, and type of nutrition support therapy (eg, enteral or parenteral), including the route (eg, nasogastric vs nasojejunal or tunneled catheter vs port). The Dietitians in Nutrition Support Dietetic Practice Group, American Society for Parenteral and Enteral Nutrition, along with the Academy of Nutrition and Dietetics Quality Management Committee, have updated the Standards of Practice (SOP) and Standards of Professional Performance (SOPP) for RDNs working in nutrition support. The SOP and SOPP for RDNs in Nutrition Support provide indicators that describe the following 3 levels of practice: competent, proficient, and expert. The SOP uses the Nutrition Care Process and clinical workflow elements for delivering patient/client care. The SOPP describes the 6 domains that focus on professional performance. Specific indicators outlined in the SOP and SOPP depict how these standards apply to practice. The SOP and SOPP are complementary resources for RDNs and are intended to be used as a self-evaluation tool for assuring competent practice in nutrition support and for determining potential education and training needs for advancement to a higher practice level in a variety of settings.

Monitoring muscle mass using ultrasound: a key role in critical care

PURPOSE OF REVIEW

The loss of muscle mass in critically ill patients contributes to morbidity and mortality, and results in impaired recovery of physical functioning. The number of publications on the topic is increasing. However, there is a lack of consistent methodology and the most optimal methodology remains unclear, hampering its broad use in clinical practice.

RECENT FINDINGS

There is a large variety of studies recently published on the use of ultrasound for assessment of muscle mass. A selection of studies has been made, focusing on monitoring of muscle mass (repeated measurements), practical aspects, feasibility and possible nutrition and physical therapy interventions. In this review, 14 new small (n = 19-121) studies are categorized and reviewed as individual studies.

SUMMARY

The use of ultrasound in clinical practice is feasible for monitoring muscle mass in critically ill patients. Assessment of muscle mass by ultrasound is clinically relevant and adds value for guiding therapeutic interventions, such as nutritional and physical therapy interventions to maintain muscle mass and promote recovery in critically ill patients.

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.

Association of Ultrasound-Derived Metrics of the Quadriceps Muscle with Protein Energy Wasting in Hemodialysis Patients: A Multicenter Cross-Sectional Study

This study aimed to assess muscle wasting and risk of protein energy wasting (PEW) in hemodialysis (HD) patients using an ultrasound (US) imaging method. PEW was identified using the ISRNM criteria in 351 HD patients. Quadriceps muscle thickness of rectus femoris (RF) and vastus intermedius (VI) muscles and cross-sectional area (CSA) of the RF muscle (RF_CSA) were measured using US and compared with other physical measures. Associations of US indices with PEW were determined by logistic regression. Irrespective of gender, PEW vs. non-PEW patients had smaller RF, VI muscles, and RF_CSA (all p < 0.001). US muscle sites (all p < 0.001) discriminated PEW from non-PEW patients, but the RF_CSA compared to bio-impedance spectroscopy had a greater area under the curve (AUC, 0.686 vs. 0.581), sensitivity (72.8% vs. 65.8%), and specificity (55.6% vs. 53.9%). AUC of the RF_CSA was greatest for PEW risk in men (0.74, 95% CI: 0.66–0.82) and women (0.80, 95% CI: 0.70–0.90) (both p < 0.001). Gender-specific RF_CSA values (men < 6.00 cm²; women < 4.47 cm²) indicated HD patients with smaller RF_CSA were 8 times more likely to have PEW (AOR = 8.63, 95% CI: 4.80–15.50, p < 0.001). The US approach enabled discrimination of muscle wasting in HD patients with PEW. The RF_CSA was identified as the best US site with gender-specific RF_CSA values to associate with PEW risk, suggesting potential diagnostic criteria for muscle wasting.