Muscle weakness and nutrition therapy in ICU

Interaction between malnutrition and physical disability in older adults: is there a malnutrition-disability cycle?

Malnutrition and physical disability are urgent issues in super-aging societies and the 2 phenomena are closely linked in older adults. Both conditions have common underlying causes, including physiological changes due to aging and burdens imposed by disease or injury. Accordingly, a concept of the malnutrition-disability cycle was generated and a comprehensive literature search was performed. There was insufficient evidence to prove an interrelationship between malnutrition and physical disabilities, because of the study design and poor quality, among other factors. However, some evidence exists for the interaction between low body mass index and swallowing disorders, and the effects of some malnutrition and disability components. This review provides the rationale for this interaction, the concept of a malnutrition-disability cycle is proposed, and the available evidence is critically appraise.

Changes in muscle ultrasound for the diagnosis of intensive care unit acquired weakness in critically ill patients

To test diagnostic accuracy of changes in thickness (TH) and cross-sectional area (CSA) of muscle ultrasound for diagnosis of intensive care unit acquired weakness (ICU-AW). Fully conscious patients were subjected to muscle ultrasonography including measuring the changes in TH and CSA of biceps brachii (BB) muscle, vastus intermedius (VI) muscle, and rectus femoris (RF) muscles over time. 37 patients underwent muscle ultrasonography on admission day, day 4, day 7, and day 10 after ICU admission, Among them, 24 were found to have ICW-AW. Changes in muscle TH and CSA of RF muscle on the right side showed remarkably higher ROC-AUC and the range was from 0.734 to 0.888. Changes in the TH of VI muscle had fair ROC-AUC values which were 0.785 on the left side and 0.779 on the right side on the 10th day after ICU admission. Additionally, Sequential Organ Failure Assessment (SOFA), Acute Physiology, and Chronic Health Evaluation II (APACHE II) scores also showed good discriminative power on the day of admission (ROC-AUC 0.886 and 0.767, respectively). Ultrasonography of changes in muscles, especially in the TH of VI muscle on both sides and CSA of RF muscle on the right side, presented good diagnostic accuracy. However, SOFA and APACHE II scores are better options for early ICU-AW prediction due to their simplicity and time efficiency.

Novel High-Quality Sonographic Methods to Diagnose Muscle Wasting in Long-Stay Critically Ill Patients: Shear Wave Elastography, Superb Microvascular Imaging and Contrast-Enhanced Ultrasound

Novel ultrasound (US) methods are required to assess qualitative changes in the quadriceps rectus femoris (QRF) muscle when evaluating mechanically ventilated, long-stay ICU patients with suspected neuromuscular acquired weakness (ICUAW). Our aim was to analyze novel US muscle assessment methods in these patients versus healthy controls by carrying out a prospective observational study. Shear wave elastography (SWE) showed, with a receiver operating characteristic (ROC) curve of 0.972 (95% confidence interval (CI) = 0.916–1.000), that patients increased muscle stiffness associated with muscle fibrosis when diagnosed with ICUAW. We also performed, for the first time, superb microvascular imaging (SMI), which is an innovative US technique designed for imaging microvascularization unseen with color Doppler US, and observed that 53.8% of cases had significantly lower QRF muscle microvascular angiogenic activity than controls (p < 0.001). Finally, we used contrast-enhanced ultrasound (CEUS) to analyze maximum and minimum QRF muscle perfusion and obtained a ROC curve of 0.8, but when used as markers for SMI, their diagnostic capacity increased to 0.988 (CI = 0.965–1) and 0.932 (CI = 0.858–1), respectively. These findings show, for the first time, that these novel sonographic muscle methods should be used for their diagnostic capacity when assessing sarcopenic processes associated with this group of critically ill patients.

Hypoalbuminemia on Admission as an Independent Risk Factor for Acute Functional Decline after Infection

The risk of acute functional decline increases with age, and concepts including frailty and post-acute care syndrome have been proposed; however, the effects of the nutritional status currently remain unclear. Patients admitted to the emergency department of Hitachi General Hospital for infectious diseases between April 2018 and May 2019 were included. To identify risk factors for functional decline at discharge, defined as Barthel Index <60, we investigated basic characteristics, such as age, sex, disease severity, the pre-morbid care status, and cognitive impairment, as well as laboratory data on admission, including albumin as a nutritional assessment indicator. In total, 460 surviving patients out of 610 hospitalized for infection were analyzed. In a multivariable logistic regression analysis, factors independently associated with Barthel Index <60 at discharge were age (adjusted OR 1.03, 95%CI 1.01–1.06, p = 0.022), serum albumin (adjusted OR: 0.63, 95%CI: 0.41–0.99, p = 0.043), and the need for care prior to admission (adjusted OR: 5.92, 95%CI: 3.15–11.15, p < 0.001). Hypoalbuminemia on admission in addition to age and the need for care prior to admission were identified as risk factors for functional decline in patients hospitalized for infection. Functional decline did not correlate with the severity of illness.

Impact of Nutrition Therapy and Rehabilitation on Acute and Critical Illness: A Systematic Review

There have been no reviews describing the efficacy of the combination of both rehabilitation and nutritional treatments. This systematic review aimed to assess the effects of nutritional therapy on patients with an acute and critical illness undergoing rehabilitation. Online searches using PubMed (MEDLINE), Cochrane Central Register of Controlled Trials, EMBASE (ELSEVIER), and Ichu-shi Web databases identified 986 articles, and 16 additional articles were found through other sources. Each trial assessed for the risk of bias using the Cochrane Collaboration's tool, and the quality of the body of evidence with The Grading of Recommendations Assessment, Development and Evaluation approach. Two randomized controlled trials were included in this review. Jones et al reported that with an enhanced rehabilitation program, there was no effect of nutritional intervention on quality of life (standardized mean difference [SMD] 0.55, 95% confidence intervals [CI] -0.05 to 1.15; P = 0.12). However, Hegerova et al reported positive effects of physical therapy and oral supplements on muscle mass (0.65; 95% CI, 0.36 to 0.93; P < 0.00001) and activities of daily living (SMD 0.28, 95% CI 0.00 to 0.56; P = 0.05). Strengthened nutritional intervention with enhanced rehabilitation treatment for patients with acute and critical illness may possibly be effective for increasing muscle mass, as well as for improving activities of daily living within a short period after discharge.

Effect of early activity combined with early nutrition on acquired weakness in ICU patients

INTRODUCTION

Intensive care unit-acquired weakness (ICU-AW) occurs in 25% to 100% of critically ill patients, and is associated with prolonged mechanical ventilation, extended ICU stay, and total hospital stay, increased hospital costs, higher risk of death, impaired physical function, and decreased quality of life. However, there are not any current guidelines that mention management of ICU-AW. The present study will evaluate the effects of a combination of early nutrition and early exercise compared to those of either early exercise alone or the standard care for patients in ICUs.

METHODS

This is a 3-arm, parallel, randomized controlled trial including an estimated 147 critically ill patients aged ≥18 years recruited from the ICUs of 2 hospitals in Heilongjiang, China. Patients will be prospectively randomized 1:1:1 to receive early mobilization, early nutrition combined with early mobilization, or standard care (minimal exercises, experience-based initiation and enrollment of nutrition support). Outcomes are assessed at ICU discharge after baseline. The primary outcome is occurrence of ICU-AW according to the Medical Research Council scale at the end of treatment. Muscle strength, organ failure, functional independence, self-care ability, time of ICU stay, duration of mechanical ventilation, and ICU mortality are secondary outcome measures.

DISCUSSION

This trial has the potential to identify a novel strategy for preventing or managing ICU-AW. The findings may increase the clinical knowledge about nutrition and mobilization interventions for people with ICU-AW, and contribute to the formation of practice guidelines for managing this condition.

TRIAL REGISTRATION NUMBER

ChiCTR2000033482.

Nutrition and Exercise in Critical Illness Trial (NEXIS Trial): a protocol of a multicentred, randomised controlled trial of combined cycle ergometry and amino acid supplementation commenced early during critical illness

INTRODUCTION

Survivors of critical illness often experience significant morbidities, including muscle weakness and impairments in physical functioning. This muscle weakness is associated with longer duration mechanical ventilation, greater hospital costs and increased postdischarge impairments in physical function, quality of life and survival. Compared with standard of care, the benefits of greater protein intake combined with structured exercise started early after the onset of critical illness remain uncertain. However, the combination of protein supplementation and exercise in other populations has demonstrated positive effects on strength and function. In the present study, we will evaluate the effects of a combination of early implementation of intravenous amino acid supplementation and in-bed cycle ergometry exercise versus a 'usual care' control group in patients with acute respiratory failure requiring mechanical ventilation in an intensive care unit (ICU).

METHODS AND ANALYSIS

In this multicentre, assessor-blinded, randomised controlled trial, we will randomise 142 patients in a 1:1 ratio to usual care (which commonly consists of minimal exercise and under-achievement of guideline-recommended caloric and protein intake goals) versus a combined intravenous amino acid supplementation and in-bed cycle ergometery exercise intervention. We hypothesise that this novel combined intervention will (1) improve physical functioning at hospital discharge; (2) reduce muscle wasting with improved amino acid metabolism and protein synthesis in-hospital and (3) improve patient-reported outcomes and healthcare resource utilisation at 6 months after enrolment. Key cointerventions will be standardised. In-hospital outcome assessments will be conducted at baseline, ICU discharge and hospital discharge. An intent-to-treat analysis will be used to analyse all data with additional per-protocol analyses.

ETHICS AND DISSEMINATION

The trial received ethics approval at each institution and enrolment has begun. These results will inform both clinical practice and future research in the area. We plan to disseminate trial results in peer-reviewed journals, at national and international conferences, and via nutritional and rehabilitation-focused electronic education and knowledge translation platforms.

TRIAL REGISTRATION NUMBER

NCT03021902; Pre-results.

Autophagy flux in critical illness, a translational approach

Recent clinical trials suggest that early nutritional support might block the induction of autophagy in critically ill patients leading to the development of organ failure. However, the regulation of autophagy, especially by nutrients, in critical illness is largely unclear. The autophagy flux (AF) in relation to critical illness and nutrition was investigated by using an in vitro model of human primary myotubes incubated with serum from critically ill patients (ICU). AF was calculated as the difference of p62 expression in the presence and absence of chloroquine (50 µM, 6 h), in primary myotubes incubated for 24 h with serum from healthy volunteers (n = 10) and ICU patients (n = 93). We observed 3 different phenotypes in AF, non-altered (ICU non-responder group), increased (ICU inducer group) or blocked (ICU blocker group). This block was not associate with a change in amino acids serum levels and was located at the accumulation of autophagosomes. The increase in the AF was associated with lower serum levels of non-essential amino acids. Thus, early nutrition during critical illness might not block autophagy but could attenuate the beneficial effect of starvation on reactivation of the autophagy process. This could be of clinical importance in the individual patients in whom this process is inhibited by the critical illness insult.

Body Composition Technology: Implications for the ICU

Malnutrition continues to be highly prevalent in hospitalized and critically ill patients and is associated with significant morbidity and mortality. Additionally, survivors of critical illness have an increased risk for sarcopenia, which leads to weakness and physical debilitation that can persist for years. Nutrition risk assessment tools have been developed and validated in critically ill patients but have limitations. Variables such as body weight, body mass index, weight change, or percentage of food intake can be difficult to obtain in critically ill patients and may be misleading given changes in body composition, such as an increase in body water. Assessment of body composition through new techniques provides a unique opportunity to counter some of these limitations and develop improved methods of nutrition risk assessment based on objective data. The present manuscript provides a review of the most commonly available clinical technology for assessment of body composition (bioimpedance, computed tomography, and ultrasound), including data from trials in critically ill patients highlighting the benefits and weaknesses of each modality.

Assessment of Muscle Wasting in Long-Stay ICU Patients Using a New Ultrasound Protocol

There is currently no standardized procedure to assess sarcopenia in long-stay catabolic patients. Our aim is to analyze a novel ultrasound muscle assessment protocol in these patients versus healthy controls, by carrying out a prospective observational study. We designed a new ultrasound protocol that assesses quadriceps rectus femoris (QRF) muscle quality in real-time B-mode, color-Doppler, and M-mode ultrasound, and evaluates QRF intramuscular central tendon thickness, cross-sectional area, and muscle thickness in ultrasound B-mode. Logistic regression was performed as a multivariable analysis on 29 cases and 19 controls. The QRF muscle area and thickness were shown to significantly decrease (p ≤ 0.001), and the central tendon thickness significantly increased (p = 0.047) in cases versus controls. The QRF muscle echogenicity and angiogenic activity fasciculations, subcutaneous edema, and intramuscular fluid were also significantly different between the two groups (p < 0.001). The selected variables in the multivariate logit analysis were the muscle area (OR per cm² = 0.07; 95% confidence interval (CI) = 0.012–0.41) and the central tendon thickness (OR per mm 1.887; 95% CI = 2.66–13.38).

GTS-21 attenuates loss of body mass, muscle mass, and function in rats having systemic inflammation with and without disuse atrophy

Muscle changes of critical illness are attributed to systemic inflammatory responses and disuse atrophy. GTS-21 (3-(2,4-dimethoxy-benzylidene)anabaseine), also known as DMBX-A) is a synthetic derivative of the natural product anabaseine that acts as an agonist at α7-acetylcholine receptors (α7nAChRs). Hypothesis tested was that modulation of inflammation by agonist GTS-21 (10 mg/kg b.i.d. intraperitoneally) will attenuate body weight (BW) and muscle changes. Systemic sham inflammation was produced in 125 rats by Cornyebacterium parvum (C.p.) or saline injection on days 0/4/8. Seventy-four rats had one immobilized-limb producing disuse atrophy. GTS-21 effects on BW, tibialis muscle mass (TMM), and function were assessed on day 12. Systemically, methemoglobin levels increased 26-fold with C.p. (p < 0.001) and decreased significantly (p < 0.033) with GTS-21. Control BW increased (+ 30 ± 9 g, mean ± SD) at day 12, but decreased with C.p. and superimposed disuse (p = 0.005). GTS-21 attenuated BW loss in C.p. (p = 0.005). Compared to controls, TMM decreased with C.p. (0.43 ± 0.06 g to 0.26 ± 0.03 g) and with superimposed disuse (0.18 ± 0.04 g); GTS-21 ameliorated TMM loss to 0.32 ± 0.04 (no disuse, p = 0.028) and to 0.22 ± 0.03 (with disuse, p = 0.004). Tetanic tensions decreased with C.p. or disuse and GTS-21 attenuated tension decrease in animals with disuse (p = 0.006) and in animals with C.p. and disuse (p = 0.029). C.p.-induced 11-fold increased muscle α7nAChR expression was decreased by > 60% with GTS-21 treatment. In conclusion, GTS-21 modulates systemic inflammation, evidenced by both decreased methemoglobin levels and decrease of α7nAChR expression, and mitigates inflammation-mediated loss of BW, TMM, fiber size, and function.

An attenuated rate of leg muscle protein depletion and leg free amino acid efflux over time is seen in ICU long-stayers

BACKGROUND

There is extensive documentation on skeletal muscle protein depletion during the initial phase of critical illness. However, for intensive care unit (ICU) long-stayers, objective data are very limited. In this study, we examined skeletal muscle protein and amino acid turnover in patients with a prolonged ICU stay.

METHODS

Patients (n = 20) were studied serially every 8-12 days between days 10 and 40 of their ICU stay as long as patients stayed in the ICU. Leg muscle protein turnover was assessed by measurements of phenylalanine kinetics, for which we employed a stable isotope-labeled phenylalanine together with two-pool and three-pool models for calculations, and results were expressed per 100 ml of leg volume. In addition, leg muscle amino acid flux was studied.

RESULTS

The negative leg muscle protein net balance seen on days 10-20 of the ICU stay disappeared by days 30-40 (p = 0.012). This was attributable mainly to an increase in the de novo protein synthesis rate (p = 0.007). It was accompanied by an attenuated efflux of free amino acids from the leg. Leg muscle protein breakdown rates stayed unaltered (p = 0.48), as did the efflux of 3-methylhistidine. The arterial plasma concentrations of free amino acids did not change over the course of the study.

CONCLUSIONS

In critically ill patients with sustained organ failure and in need of a prolonged ICU stay, the initial high rate of skeletal muscle protein depletion was attenuated over time. The distinction between the acute phase and a more prolonged and more stable phase concerning skeletal muscle protein turnover must be considered in study protocols as well as in clinical practice.

TRIAL REGISTRATION

Australian New Zealand Trial Registry, ACTRN12616001012460 . Retrospectively registered on 1 August 2016.

Point-of-Care Ultrasound to Evaluate Thickness of Rectus Femoris, Vastus Intermedius Muscle, and Fat as an Indicator of Muscle and Fat Wasting in Critically Ill Patients in a Multidisciplinary Intensive Care Unit

Background:

Muscular atrophy is the universal feature in patients with ICUAW. Muscles of the lower limb are more prone to early atrophy. Measurement of fat thickness is used to assess malnutrition. This study was designed to evaluate if, subcutaneous fat also reduces along with muscle thickness and if it can be reliably used as an indicator of nutritional assessment in critically ill patients using point of care ultrasound.

Materials and Methods:

An observational clinical study of 100 patients admitted to multidisciplinary intensive care units (ICUs). Total anterior thigh thickness, thickness of the rectus femoris muscle, fat thickness, and the combined thickness of vastus intermedius and rectus femoris were taken on day 1, 3, and 7 of ICU admission.

Results:

There was progressive loss of muscle mass from day 1 to day 7. Muscle loss was not only limited to rectus femoris, but vastus intermedius also showed a significant decrease as indicated by the bone to muscle measurement. Skin to bone measurement which includes both muscle and fat compartment showed a decline.

Conclusions:

There is potential utility of ultrasound for early detection and probable corrective measures to prevent ICUAW. The rectus femoris thickness, skin to bone, and bone to muscle thickness show statistically significant difference on day 3, day 7 compared to day 1. Fat layer did not show statistically significant decrease.

The response of muscle progenitor cells to cutaneous thermal injury

BACKGROUND

Severe burn results in a systemic response that leads to significant muscle wasting. It is believed that this rapid loss in muscle mass occurs due to increased protein degradation combined with reduced protein synthesis. Alterations in the microenvironment of muscle progenitor cells may partially account for this pathology. The aim of this study was to ascertain the response of muscle progenitor cells following thermal injury in mice and to enlighten the cellular cascades that contribute to the muscle wasting.

METHODS

C57BL/6 mice received a 20% total body surface area (TBSA) thermal injury. Gastrocnemius muscle was harvested at days 2, 7, and 14 following injury for protein and histological analysis.

RESULTS

We observed a decrease in myofiber cross-sectional area at 2 days post-burn. This muscle atrophy was compensated for by an increase in myofiber cross-sectional area at 7 and 14 days post-burn. Myeloperoxidase (MPO)-positive cells (neutrophils) increased significantly at 2 days. Moreover, through Western blot analysis of two key mediators of the proteolytic pathway, we show there is an increase in Murf1 and NF-κB 2 days post-burn. MPO-positive cells were also positive for NF-κB, suggesting that neutrophils attain NF-κB activity in the muscle. Unlike inflammatory and proteolytic pathways, the number of Pax7-positive muscle progenitor cells decreased significantly 2 days post-burn. This was followed by a recovery in the number of Pax7-positive cells at 7 and 14 days, suggesting proliferation of muscle progenitors that accompanied regrowth.

CONCLUSION

Our data show a biphasic response in the muscles of mice exposed to burn injury, with phenotypic characteristics of muscle atrophy at 2 days while compensation was observed later with a change in Pax7-positive muscle progenitor cells. Targeting muscle progenitors may be of therapeutic benefit in muscle wasting observed after burn injury.

Thigh Ultrasound Monitoring Identifies Decreases in Quadriceps Femoris Thickness as a Frequent Observation in Critically Ill Children

OBJECTIVES

Significant muscle wasting develops in critically ill adults, with subsequent worse outcomes. In the pediatric setting, occurrence and effects of muscle wasting are undescribed; this is in part due to a lack of validated, objective methods for assessing muscle wasting. A single measurement of quadriceps femoris thickness has failed to show consistent reproducibility. We hypothesized that averaging repeated measurements could afford good reproducibility to allow for quadriceps femoris thickness decline detection and monitoring.

DESIGN

A prospective bedside observational study.

SETTING

Two PICUs.

PATIENTS

Mechanically ventilated critically ill children were 15 years and younger.

INTERVENTIONS

Transverse and longitudinal axis measurements of quadriceps femoris anterior thickness were undertaken using bedside ultrasound. The average of four measurement values was recorded. The location of measurement was marked for consistency within subsequent measurements by the same or another trained operator, to assess intra- and interoperator repeatability and reproducibility of the technique. Where feasible, serial measurements were undertaken until the time of extubation in a group of children with prolonged PICU stay (> 5 d).

MEASUREMENTS AND MAIN RESULTS

Seventy-three children were enrolled to assess intra- and interoperator ultrasound reliability. Their median (25-75 interquartile range) age and weight were 30 months (4.5-96) and 10 kg (5-23.5). In the intraoperator repeatability study, mean relative difference in quadriceps femoris muscle thickness was 0.36% ± 2.5% (lower and upper limits of agreement: -4.5/+5.2%). In the interoperator reproducibility study, intraclass correlation coefficient was 0.998. In the 17 children monitored over their PICU stay, quadriceps femoris thickness significantly decreased at day 5 by 9.8% (p = 0.006) and by 13.3% (< 0.001) at the last performed measurement.

CONCLUSIONS

Quadriceps femoris thickness decrease, proposed as a surrogate for muscle mass, is an early, frequent, and intense phenomenon in PICU. Quadriceps femoris ultrasonography is a reliable technique to monitor this process and in future could help to guide rehabilitation and nutrition interventions.

Bedside Ultrasound Measurement of Rectus Femoris: A Tutorial for the Nutrition Support Clinician

Intensive care unit acquired weakness is a long-term consequence after critical illness; it has been related to muscle atrophy and can be considered as one of the main nutritional support challenges at the intensive care unit. Measuring muscle mass by image techniques has become a new area of research for the nutritional support field, extending our knowledge about muscle wasting and the impact of nutritional approaches in the critical care setting, although currently there is no universally accepted technique to perform muscle measurements by ultrasound. Because of this, we present this tutorial for nutrition support clinicians, in order to understand and perform muscle measurements by this reliable, accessible, low-cost, and easy-to-use technique. Reviewing issues such as quadriceps muscle anatomy, correct technique (do's and don'ts), identification of structures, and measurement of the rectus femoris and vastus intermedius muscles helps to acquire the basic concepts of this technique and encouraging more research in this field.

Intensive care unit-acquired weakness

When critically ill, a severe weakness of the limbs and respiratory muscles often develops with a prolonged stay in the intensive care unit (ICU), a condition vaguely termed intensive care unit-acquired weakness (ICUAW). Many of these patients have serious nerve and muscle injury. This syndrome is most often seen in surviving critically ill patients with sepsis or extensive inflammatory response which results in increased duration of mechanical ventilation and hospital length of stay. Patients with ICUAW often do not fully recover and the disability will seriously impact on their quality of life. In this chapter we discuss the current knowledge on the pathophysiology and risk factors of ICUAW. Tools to diagnose ICUAW, how to separate ICUAW from other disorders, and which possible treatment strategies can be employed are also described. ICUAW is finally receiving the attention it deserves and the expectation is that it can be better understood and prevented.

Proceedings of the 2016 Clinical Nutrition Week Research Workshop-The Optimal Dose of Protein Provided to Critically Ill Patients

Recent literature has created considerable confusion about the optimal amount of protein/amino acids that should be provided to the critically ill patient. In fact, the evidentiary basis that directly tries to answer this question is relatively small. As a clinical nutrition research community, there is an urgent need to develop the optimal methods to assess the impact of exogenous protein/amino acid administration in the intensive care unit setting. That assessment can be conducted at various levels: (1) impact on stress response pathways, (2) impact on muscle synthesis and protein balance, (3) impact on muscle mass and function, and (4) impact on the patient's recovery. The objective of this research workshop was to review current literature relating to protein/amino acid administration for the critically ill patient and clinical outcomes and to discuss the key measurement and methodological features of future studies that should be done to inform the optimal protein/amino acid dose provided to critically ill patients.

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.