Models of disuse muscle atrophy: therapeutic implications in critically ill patients

Atenolol Ameliorates Skeletal Muscle Atrophy and Oxidative Stress Induced by Cast Immobilization in Rats

(1) Background: Skeletal muscle atrophy is a common and debilitating condition associated with disease, bed rest, and inactivity. We aimed to investigate the effect of atenolol (ATN) on cast immobilization (IM)-induced skeletal muscle loss. (2) Methods: Eighteen male albino Wistar rats were divided into three groups: a control group, an IM group (14 days), and an IM+ATN group (10 mg/kg, orally for 14 days). After the last dose of atenolol, forced swimming test, rotarod test, and footprint analysis were performed, and skeletal muscle loss was determined. Animals were then sacrificed. Serum and gastrocnemius (GN) muscles were then collected, serum creatinine, GN muscle antioxidant, and oxidative stress levels were determined, and histopathology and 1H NMR profiling of serum metabolites were performed. (3) Results: Atenolol significantly prevented immobilization-induced changes in creatinine, antioxidant, and oxidative stress levels. Furthermore, GN muscle histology results showed that atenolol significantly increased cross-sectional muscle area and Feret's diameter. Metabolomics profiling showed that glutamine-to-glucose ratio and pyruvate, succinate, valine, citrate, leucine, isoleucine, phenylalanine, acetone, serine, and 3-hydroxybutyrate levels were significantly higher, that alanine and proline levels were significantly lower in the IM group than in the control group, and that atenolol administration suppressed these metabolite changes. (4) Conclusions: Atenolol reduced immobilization-induced skeletal muscle wasting and might protect against the deleterious effects of prolonged bed rest.

Value of the Preoperative D-Dimer to Albumin Ratio for Survival and Recurrence Patterns in Gastric Cancer

BACKGROUND

D-dimer (DDI) and albumin are prognostic markers for numerous cancers; however, the predictive value of the preoperative DDI-to-albumin ratio (DAR) on the survival and recurrence patterns of gastric cancer (GC) remains unclear.

OBJECTIVE

The aim of this study was to explore the prognostic value of the DAR in GC.

METHODS

Our study included 1766 patients with GC, divided into training and testing cohorts at a ratio of 7:3. Patients were classified into either a high-DAR group (> 0.0145) or low-DAR group (≤ 0.0145) according to the cut-off value of receiver operating characteristic (ROC) curve analysis. The relationship between the DAR and recurrence pattern was analyzed in stage II/III patients.

RESULTS

Eight preoperative hematological factors were included and 17 composite inflammatory markers were constructed. ROC and random forest analyses indicated that among 17 markers, DAR was the best predictor for overall survival (OS) in GC (p < 0.01). High DAR was significantly associated with poor OS (hazard ratio [HR] 1.89, p < 0.001) and recurrence-free survival (RFS; HR 1.85, p < 0.001). Subgroup analysis showed no differences in OS and RFS between the high- and low-DAR groups in stage I or pT1/2 or pN0/1 patients; however, in stage II/III or pT3/4 or pN2/3 patients, the high-DAR group had shorter OS and RFS rates than the low-DAR group (p < 0.001). Similar results were found in the testing cohort. According to the multivariate analysis based on the training cohort, five indices, including DAR, cT stage, cN stage, age and body mass index (BMI), were incorporated to establish a nomogram model to predict the long-term prognosis of GC. The model showed comparable forecast performance in predicting OS (C-index: 0.773 vs. 0.786) and RFS (C-index: 0.788 vs. 0.795) compared with pTNM. Recurrence pattern analysis in stage II/III patients showed that the high-DAR group had a higher incidence of peritoneal implantation and early recurrence (ER) than the low-DAR group, and the post-recurrence survival in the high-DAR group was significantly shorter than that in the low-DAR group (p = 0.016).

CONCLUSION

The preoperative DAR is a new biomarker for the long-term survival prediction of GC. In advanced GC, a preoperative DAR > 0.0145 aids the timely detection of ER and peritoneal recurrence after surgery, thus guiding individual follow-up strategies.

Muscle dysfunction in the long coronavirus disease 2019 syndrome: Pathogenesis and clinical approach

In long coronavirus disease 2019 (long COVID-19), involvement of the musculoskeletal system is characterised by the persistence or appearance of symptoms such as fatigue, muscle weakness, myalgia, and decline in physical and functional performance, even at 4 weeks after the onset of acute symptoms of COVID-19. Muscle injury biomarkers are altered during the acute phase of the disease. The cellular damage and hyperinflammatory state induced by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection may contribute to the persistence of symptoms, hypoxaemia, mitochondrial damage, and dysregulation of the renin-angiotensin system. In addition, the occurrence of cerebrovascular diseases, involvement of the peripheral nervous system, and harmful effects of hospitalisation, such as the use of drugs, immobility, and weakness acquired in the intensive care unit, all aggravate muscle damage. Here, we review the multifactorial mechanisms of muscle tissue injury, aggravating conditions, and associated sequelae in long COVID-19.

Passive motion of the lower extremities in sedated and ventilated patients in the ICU - a systematic review of early effects and replicability of Interventions

Early mobilization, which includes active / passive motion in bed along with mobilization out of bed, is recommended to prevent the development of intensive care unit acquired-weakness (ICU-AW) for patients with critical illness on the intensive care unit. To date, the impact of passive motion of the lower extremities in sedated and ventilated patients remains unclear. The aim of the study is to systematically review and summarize the currently available randomized controlled trials in English or German language on the impact of passive motion of the lower extremities in sedated and ventilated patients ≥ 18 years in the intensive care unit on musculature, inflammation and immune system and the development of intensive care unit-acquired weakness and to evaluate the replicability of interventions and the methodological quality of included studies. A systematic literature search was performed up to 20th February 2022 in the databases Medline, Embase, Cochrane Library, CINAHL and PEDro. The description of the intervention (TIDieR checklist) and the methodological quality (Downs and Black checklist) were assessed. Five studies were included in the qualitative syntheses. On average, the studies were rated with 6.8 out of 12 points according to the TIDieR checklist. For the methodological quality an average of 19.8 out of 27 points on the Downs and Black checklist was reported. The results of included studies indicated that muscle loss may be reduced by passive manual movement, passive cycling and passive motion on a continuous passive motion-unit. In addition, positive effects were reported on the reduction of nitrosative stress and the immune response. The impact on the development of ICU-AW remains unclear. In conclusion, passive movement show a slight tendency for beneficial changes on cellular level in sedated and ventilated patients in the ICU within the first days of admission, which may indicate a reduction of muscle wasting and could prevent the development of ICU-AW. Future randomized controlled trials should use larger samples, use complete intervention description, use a comparable set of outcome measures, use rigorous methodology and examine the effect of passive motion on the development of ICU-AW.

Excessive fat expenditure in cachexia is associated with dysregulated circadian rhythm: a review

Cachexia is a progressive metabolic disorder characterized by the excessive depletion of adipose tissue. This hypermetabolic condition has catastrophic impacts on the survival and quality of life for patients suffering from critical illness. However, efficient therapies to prevent adipose expenditure have not been discovered. It has been established that the circadian clock plays an important role in modulating fat metabolic processes. Recently, an increasing number of studies had provided evidence showing that disrupted circadian rhythm leads to insulin resistance and obesity; however, studies analyzing the relationship between circadian misalignment and adipose tissue expenditure in cachexia are scarce. In the present review, we cover the involvement of the circadian clocks in the regulation of adipogenesis, lipid metabolism and thermogenesis as well as inflammation in white and brown adipose tissue. According to the present review, we conclude that circadian clock disruption is associated with lipid metabolism imbalance and elevated adipose tissue inflammation. Moreover, under cachexia conditions, lipid synthesis and storage processes lost rhythm and decreased, while lipolysis and thermogenesis activities remained high for 24 h. Therefore, disordered circadian clock may be responsible for fat expenditure in cachexia by adversely influencing lipid synthesis/ storage/lipolysis/utilization. Further study needs to be performed to explore the direct interaction between circadian clock and fat expenditure in cachexia, it will likely provide potential efficient drugs for the treatment of fat expenditure in cachexia.

High-dose intravenous immunoglobulins as a therapeutic option in critical illness polyneuropathy accompanying SARS-CoV-2 infection: A case-based review of the literature (Review)

The still ongoing COVID-19 pandemic has exposed the medical community to a number of major challenges. A significant number of patients require admission to intensive care unit (ICU) services due to severe respiratory, thrombotic and septic complications and require long-term hospitalization. Neuromuscular weakness is a common complication in critically ill patients who are treated in ICUs and are mechanically ventilated. This complication is frequently caused by critical illness myopathy (CIM) or critical illness polyneuropathy (CIP) and leads to difficulty in weaning from the ventilator. It is thought to represent an important neurologic manifestation of the systemic inflammatory response syndrome (SIRS). COVID-19 infection is known to trigger strong immune dysregulation, with an intense cytokine storm, as a result, the frequency of CIP is expected to be higher in this setting. The mainstay in the diagnosis of this entity beside the high level of clinical awareness is the electrophysiological examination that provides evidence of axonal motor and sensory polyneuropathy. The present article presents the case of a 54-year-old woman with severe COVID 19 infection who developed neuromuscular weakness, which turned out to be secondary to CIP and was treated successfully with a high dose of human intravenous immunoglobulins. Related to this case, we reviewed the relevant literature data regarding the epidemiology, pathophysiology and clinical features of this important complication and discussed also the treatment options and prognosis.

The risk factors of postoperative delirium in general anesthesia patients with hip fracture: Attention needed

Delirium is a common postoperative complication of patients with hip fracture, yet the risk factors for postoperative delirium in patients with hip fracture remain unclear. We aimed to evaluate the associated risk factors of postoperative delirium in patients with hip fracture, to provide evidence for formulating coping measures of postoperative delirium prevention and treatment in clinical practice.Patients undergoing surgery for hip fracture from March 1, 2018 to September 30, 2020 in our hospital were included. The related characteristics and related lab examination results were reviewed and collected. The univariate and logistic regression analyses were performed to identify the potential risk factors.A total of 462 patients were included, the incidence of postoperative delirium in patients with hip fracture was 16.02%. Logistic regression analyses indicated that history of delirium (OR = 4.38, 1.15-9.53), diabetes mellitus (OR = 5.31, 1.23-10.75), hypoalbuminemia (OR = 4.97, 1.37-9.86), postoperative hypoxemia (OR = 5.67, 2.24-13.42), and body mass index (BMI) (kg/m2) (OR = 3.03, 1.36-6.18) were the independent risk factors for the delirium in patients with hip fracture surgery (all P < 0.05). The cutoff value of postoperative blood sugar, albumin, and BMI for delirium prediction was 8.05 (mmol/L), 32.26 (g/L), and 19.35 (kg/m2), respectively, and the area under curve of postoperative blood sugar, albumin, and BMI was 0.792, 0.714, and 0.703, respectively.Those patients with a history of delirium, postoperative hypoxemia, blood glucose ≥8.05 mmol/L, albumin ≤32.26 g/L, and BMI ≤19.35 kg/m2 particularly need the attention of healthcare providers for the prevention of delirium.

Alternative splicing transitions associate with emerging atrophy phenotype during denervation-induced skeletal muscle atrophy

Alternative splicing (AS) presents a key posttranscriptional regulatory mechanism associated with numerous physiological processes. However, little is known about its role in skeletal muscle atrophy. In this study, we used a rat model of denervated skeletal muscle atrophy and performed RNA-sequencing to analyze transcriptome profiling of tibialis anterior muscle at multiple time points following denervation. We found that AS is a novel mechanism involving muscle atrophy, which is independent changes at the transcript level. Bioinformatics analysis further revealed that AS transitions are associated with the appearance of the atrophic phenotype. Moreover, we found that the inclusion of multiple highly conserved exons of Obscn markedly increased at 3 days after denervation. In addition, we confirmed that this newly transcript inhibited C2C12 cell proliferation and exacerbated myotube atrophy. Finally, our study revealed that a large number of RNA-binding proteins were upregulated when the atrophy phenotype appeared. Our data emphasize the importance of AS in this process.

Peripheral muscular ultrasound as outcome assessment tool in critically ill patients on mechanical ventilation: An observational cohort study

BACKGROUND & AIMS

Survivors of critical illness experience significant skeletal muscle wasting that may predict clinical outcome. Ultrasound (US) is a noninvasive method that can measure muscle quadriceps muscle layer thickness (QMLT) at the bedside. The aim of this study was to determine the muscle loss assessed by ultrasonography (US) of the quadriceps femoris muscle in critically ill patients on mechanical ventilation and its relationship with hospital outcomes.

METHODS

This study involved patients ≥18 years admitted to the intensive care unit who needed mechanical ventilation for at least 48 h. The quadriceps muscle layer thickness (QMLT) in the two-thirds of the thigh was quantified using bedside US. The QMLT of the left and right legs on the first (D1), third (D3), and seventh (D7) days were measured.

RESULTS

US quadriceps thickness measurements were performed in 74 critically ill patients. The mean age was 62.3 ± 19.5 years, 54.1% of the patients were men, with a BMI of 25.5 ± 4.6 kg/m2, SAPS 3 of 55.2 ± 17.2, and NRS of 3.2 ± 1.0. The percentage muscle thickness declined at the right leg in 15% (95%CI, 10.5%-19.4%), and 12.7% (95%CI, 9.1%-16.3%) at the left leg from the first to the seventh day. Receiver operating characteristic showed cutoff value in muscle thickness of ≤1.64 cm on day 7 could predict survival (area under then curve = 0.7; 95% CI, 0.582-0.801). In Cox regression after adjusting, the probability of patients remaining on mechanical ventilation was higher with ≤1.64 cm loss of thigh muscle thickness on day 7; HR = 2.1 (95% CI 1.1-3.8, P = 0.017). The same occurred about ICU survival probability; HR = 3.7 (95% CI 1.2 to 11.5) and hospital survival probability; HR = 4.5 (95% CI 1.5 to 13.7).

CONCLUSIONS

The measurement of QMLT using US showed that critically ill patients on mechanical ventilation presented with muscle wasting and greater loss of muscle thickness was associated with worse outcomes.

Investigating inpatient rehabilitation outcomes of patients with intensive care unit-acquired weakness, and identifying comorbidities associated with unfavorable outcomes

INTRODUCTION

Data are consistent on the benefits of inpatient rehabilitation for intensive care unit-acquired weaknesses (ICUAW), including critical illness myopathy, critical illness polyneuropathy, critical illness polyneuromyopathy, and disuse atrophy. This study focuses on the effects of inpatient rehabilitation on patients with ICUAW, specifically those with a clinical pattern of proximal muscle weakness and sensory sparing.

OBJECTIVES

To evaluate the impact of inpatient rehabilitation on patients with ICUAW versus other medically complex patients, and to identify comorbidities associated with poor rehabilitation outcomes.

DESIGN

Retrospective cohort study.

SETTING

Institutional, inpatient rehabilitation hospital.

PATIENTS

Two hundred seventy adult patients (≥18 years) divided into two groups: diagnosis of ICUAW (N = 55) or otherwise medically complex (N = 215), and admitted under the care of one physiatrist.

INTERVENTIONS

Not applicable.

MAIN OUTCOME MEASURES

For all patients we compared functional independence measure (FIM) gain, FIM efficiency, rehabilitation length of stay (RLOS), discharge disposition, and major medical comorbidities.

RESULTS

Patients with ICUAW had significantly greater FIM gain (P = .015) and RLOS (P = .02). There was no significant difference in FIM efficiency (P = .15). Patients with ICUAW had a significantly lower odds of acute hospital transfer (odds ratio [OR] = 0.52, with 95% confidence interval [CI] 0.47, 0.58) and skilled nursing facility discharge (OR = 0.19, with 95% CI 0.038, 0.95). However, patients with ICUAW did have a higher percent of acute hospital transfers than other medically complex patients (P = .017). In addition, patients with ICUAW were more medically complex, as evidenced by a significantly higher Charlson Comorbidity Index (P < .001), prevalence of anemia (P < .001), atrial fibrillation (P = .009), obstructive sleep apnea (P = .018), and bacteremia (P = .041).

CONCLUSIONS

Patients with ICUAW with a clinical pattern of proximal muscle weakness and sensory sparing benefit from inpatient rehabilitation as evidenced by FIM gain and high home discharge rate. However, they have multiple medical comorbidities, which require judicious medical management and may contribute to a longer RLOS.

[Effect of rehabilitation initiation timing in the intensive care unit on outcomes in patients with pneumonia]

Early rehabilitation in the intensive care unit is a promising component of post-intensive care syndrome (PICS) treatment and prevention. However, the optimal time to start mobilizing critically ill patients is still to be determined.

OBJECTIVE

To evaluate the effect of rehabilitation initiation timing on outcomes in patients with pneumonia.

MATERIAL AND METHODS

The study included 106 patients with pneumonia (27 patients with community-acquired pneumonia and 79 patients with early-onset healthcare associated pneumonia) who received daily rehabilitation treatment for at least 7 days in the intensive care unit. All patients were retrospectively assigned to the early rehabilitation (ER) group if rehabilitation treatment was started within the first 48 hours of admission to the intensive care unit or the delayed rehabilitation (DR) group if mobilization was not initiated within this time frame.

RESULTS

The baseline clinical and demographic characteristics of the patients did not differ between the groups. During rehabilitation, rates of catecholamine use and the psychiatric signs of PICS frequency were also comparable. The duration of mechanical ventilation was 1.5 times shorter in ER group patients than in DR group (8 vs. 6 days and 13 vs. 9 days, respectively; p=0.003). The ICU and hospital stay were also significantly shorter in ER group compared with the DR group (12 (9-16) vs. 19 (13-30), respectively; p<0.001; 23 (12) vs. 31 (13) as inpatients, respectively; p=0.005). Mortality and severe complications rate were comparable between the groups.

CONCLUSIONS

The earliest possible start of rehabilitation provided the patient's condition is stable, can reduce the duration of respiratory support and hospital stay for patients with pneumonia.

Prolonged Immobilization Exacerbates the Loss of Muscle Mass and Function Induced by Cancer-Associated Cachexia through Enhanced Proteolysis in Mice

We hypothesized that in mice with lung cancer (LC)-induced cachexia, periods of immobilization of the hindlimb (7 and 15 days) may further aggravate the process of muscle mass loss and function. Mice were divided into seven groups (n = 10/group): (1) non-immobilized control mice, (2) 7-day unloaded mice (7-day I), (3) 15-day unloaded mice (15-day I), (4) 21-day LC-cachexia group (LC 21-days), (5) 30-day LC-cachexia group (LC 30-days), (6) 21-day LC-cachexia group besides 7 days of unloading (LC 21-days + 7-day I), (7) 30-day LC-cachexia group besides 15 days of unloading (LC 30-days + 15-day I). Physiological parameters, body weight, muscle and tumor weights, phenotype and morphometry, muscle damage (including troponin I), proteolytic and autophagy markers, and muscle regeneration markers were identified in gastrocnemius muscle. In LC-induced cachexia mice exposed to hindlimb unloading, gastrocnemius weight, limb strength, fast-twitch myofiber cross-sectional area, and muscle regeneration markers significantly decreased, while tumor weight and area, muscle damage (troponin), and proteolytic and autophagy markers increased. In gastrocnemius of cancer-cachectic mice exposed to unloading, severe muscle atrophy and impaired function was observed along with increased muscle proteolysis and autophagy, muscle damage, and impaired muscle regeneration.

Intensive Care Unit-Acquired Weakness: Not just Another Muscle Atrophying Condition

Intensive care unit-acquired weakness (ICUAW) occurs in critically ill patients stemming from the critical illness itself, and results in sustained disability long after the ICU stay. Weakness can be attributed to muscle wasting, impaired contractility, neuropathy, and major pathways associated with muscle protein degradation such as the ubiquitin proteasome system and dysregulated autophagy. Furthermore, it is characterized by the preferential loss of myosin, a distinct feature of the condition. While many risk factors for ICUAW have been identified, effective interventions to offset these changes remain elusive. In addition, our understanding of the mechanisms underlying the long-term, sustained weakness observed in a subset of patients after discharge is minimal. Herein, we discuss the various proposed pathways involved in the pathophysiology of ICUAW, with a focus on the mechanisms underpinning skeletal muscle wasting and impaired contractility, and the animal models used to study them. Furthermore, we will explore the contributions of inflammation, steroid use, and paralysis to the development of ICUAW and how it pertains to those with the corona virus disease of 2019 (COVID-19). We then elaborate on interventions tested as a means to offset these decrements in muscle function that occur as a result of critical illness, and we propose new strategies to explore the molecular mechanisms of ICUAW, including serum-related biomarkers and 3D human skeletal muscle culture models.

Inhibition of central activation of the diaphragm: a mechanism of weaning failure

During a T-tube trial following disconnection of mechanical ventilation, patients failing the trial do not develop contractile diaphragmatic fatigue despite increases in inspiratory pressure output. Studies in volunteers, patients, and animals raise the possibility of spinal and supraspinal reflex mechanisms that inhibit central-neural output under loaded conditions. We hypothesized that diaphragmatic recruitment is submaximal at the end of a failed weaning trial despite concurrent respiratory distress. Tidal transdiaphragmatic pressure (ΔP_di) and electrical activity (ΔEA_di) were recorded with esophago-gastric catheters during a T-tube trial in 20 critically ill patients. During the T-tube trial, ∆EA_di was greater in weaning failure patients than in weaning success patients (P = 0.049). Despite increases in ΔP_di, from 18.1 ± 2.5 to 25.9 ± 3.7 cm H₂O (P < 0.001), rate of transdiaphragmatic pressure development (from 22.6 ± 3.1 to 37.8 ± 6.7 cm H₂O/s; P < 0.0004), and concurrent respiratory distress, ∆EA_di at the end of a failed T-tube trial was half of maximum, signifying inhibition of central neural output to the diaphragm. The increase in ΔP_di in the weaning failure group, while ∆EA_di remained constant, indicates unexpected improvement in diaphragmatic neuromuscular coupling (from 46.7 ± 6.5 to 57.8 ± 8.4 cm H₂O/%; P = 0.006). Redistribution of neural output to the respiratory muscles characterized by a progressive increase in rib cage and accessory muscle contribution to tidal breathing and expiratory muscle recruitment contributed to enhanced coupling. In conclusion, diaphragmatic recruitment is submaximal at the end of a failed weaning trial despite concurrent respiratory distress. This finding signifies that reflex inhibition of central neural output to the diaphragm contributes to weaning failure.

NEW & NOTEWORTHY Research into pathophysiology of failure to wean from mechanical ventilation has excluded several factors, including contractile fatigue, but the precise mechanism remains unknown. We recorded transdiaphragmatic pressure and diaphragmatic electrical activity in patients undergoing a T-tube trial. Diaphragmatic recruitment was submaximal at the end of a failed trial despite concurrent respiratory distress, signifying that inhibition of central neural output to the diaphragm is an important mechanism of weaning failure.

Older Adults in the Cardiac Intensive Care Unit: Factoring Geriatric Syndromes in the Management, Prognosis, and Process of Care: A Scientific Statement From the American Heart Association

Longevity is increasing, and more adults are living to the stage of life when age-related biological factors determine a higher likelihood of cardiovascular disease in a distinctive context of concurrent geriatric conditions. Older adults with cardiovascular disease are frequently admitted to cardiac intensive care units (CICUs), where care is commensurate with high age-related cardiovascular disease risks but where the associated geriatric conditions (including multimorbidity, polypharmacy, cognitive decline and delirium, and frailty) may be inadvertently exacerbated and destabilized. The CICU environment of procedures, new medications, sensory overload, sleep deprivation, prolonged bed rest, malnourishment, and sleep is usually inherently disruptive to older patients regardless of the excellence of cardiovascular disease care. Given these fundamental and broad challenges of patient aging, CICU management priorities and associated decision-making are particularly complex and in need of enhancements. In this American Heart Association statement, we examine age-related risks and describe some of the distinctive dynamics pertinent to older adults and emerging opportunities to enhance CICU care. Relevant assessment tools are discussed, as well as the need for additional clinical research to best advance CICU care for the already dominating and still expanding population of older adults.

Muscle atrophy and regeneration associated with behavioural loss and recovery of function after sciatic nerve crush

AIM

To resolve timing and coordination of denervation atrophy and the re-innervation recovery process to discern correlations indicative of common programs governing these processes.

METHODS

Female Sprague-Dawley (SD) rats had a unilateral sciatic nerve crush. Based on longitudinal behavioural observations, the triceps surae muscle was analysed at different time points post-lesion.

RESULTS

Crush results in a loss of muscle function and mass (-30%) followed by a recovery to almost pre-lesion status at 30 days post-crush (dpc). There was no loss of fibres nor any significant change in the number of nuclei per fibre but a shift in fibres expressing myosins I and II that reverted back to control levels at 30 dpc. A residual was the persistence of hybrid fibres. Early on a CHNR -ε to -γ switch and a re-expression of embryonic MyHC showed as signs of denervation. Foxo1, Smad3, Fbxo32 and Trim63 transcripts were upregulated but not Myostatin, InhibinA and ActivinR2B. Combined this suggests that the mechanism instigating atrophy provides a selectivity of pathway(s) activated. The myogenic differentiation factors (MDFs: Myog, Myod1 and Myf6) were upregulated early on suggesting a role also in the initial atrophy. The regulation of these transcripts returned towards baseline at 30 dpc. The examined genes showed a strong baseline covariance in transcript levels which dissolved in the response to crush driven mainly by the MDFs. At 30 dpc the naïve expression pattern was re-established.

CONCLUSION

Peripheral nerve crush offers an excellent model to assess and interfere with muscle adaptions to denervation and re-innervation.

Design and Validation of Multichannel Wireless Wearable SEMG System for Real-Time Training Performance Monitoring

Monitoring of training performance and physical activity has become indispensable these days for athletes. Wireless technologies have started to be widely used in the monitoring of muscle activation, in the sport performance of athletes, and in the examination of training efficiency. The monitorability of performance simultaneously in the process of training is especially a necessity for athletes at the beginner level to carry out healthy training in sports like weightlifting and bodybuilding. For this purpose, a new system consisting of 4 channel wireless wearable SEMG circuit and analysis software has been proposed to detect dynamic muscle contractions and to be used in real-time training performance monitoring and analysis. The analysis software, the Haar wavelet filter with threshold cutting, can provide performance analysis by using the methods of moving RMS and %MVC. The validity of the data obtained from the system was investigated and compared with a biomedical system. In this comparison, 90.95% ± 3.35 for left biceps brachii (BB) and 90.75% ± 3.75 for right BB were obtained. The output of the power and %MVC analysis of the system was tested during the training of the participants at the gym, and the training efficiency was measured as 96.87% ± 2.74.

Nutrient pattern analysis in critically ill patients using Omics technology (NAChO) - Study protocol for a prospective observational study

INTRODUCTION

Intensive care unit-acquired weakness (ICU-AW) is often observed in critically ill patients with prolonged intensive care unit (ICU) stay. We hypothesized that evolving metabolic abnormalities during prolonged ICU stay are reflected by changing nutrient patterns in blood, urine and skeletal muscle, and that these patterns differ in patients with/without ICU-AW and between patients with/without sepsis.

METHODS

In a prospective single-center observational trial, we aim to recruit 100 critically ill patients (ICU length of stay ≥ 5 days) with severe sepsis/septic shock ("sepsis group", n = 50) or severe head trauma/intracerebral hemorrhage ("CNS group", n = 50). Patients will be sub-grouped for presence or absence of ICU-AW as determined by the Medical Research Council sum score. Blood and urine samples will be collected and subjected to comprehensive nutrient analysis at different time points by targeted quantitative mass spectrometric methods. In addition, changes in muscular tissue (biopsy, when available), muscular architecture (ultrasound), electrophysiology, body composition analyses (bioimpedance, cerebral magnetic resonance imaging), along with clinical status will be assessed. Patients will be followed-up for 180 and 360 days including assessment of quality of life.

DISCUSSION

Key objective of this trial is to assess changes in nutrient pattern in blood and urine over time in critically ill patients with/without ICU-AW by using quantitative nutrient analysis techniques. Peer-reviewed published NAChO data will allow for a better understanding of metabolic changes in critically ill patients on standard liquid enteral nutrition and will likely open up new avenues for future therapeutic and nutritional interventions.

Trends of loss of peripheral muscle thickness on ultrasonography and its relationship with outcomes among patients with sepsis

Background and aims

Data regarding trends of muscle loss on ultrasonography (USG) and its relationship with various outcomes among critically ill patients is limited. This study aimed to describe the trends of loss of muscle thickness of the arm and thigh (assessed using USG) and to determine the relationship between loss of muscle thickness and in-hospital and post-discharge outcomes.

Methods

Muscle thickness of 70 patients with sepsis was measured at the level of the mid-arm and mid-thigh using bedside USG on days 1, 3, 5, 7, 10 and 14 and then weekly till discharge or death. Patients were followed up for 90 days after discharge.

Results

The muscle thickness (mean ± SD) at the level of the mid-arm and mid-thigh on day 1 was 23.13 ± 4.83 mm and 31.21 ± 8.56 mm, respectively. The percentage muscle thickness [median (min, max)] decline at the mid-arm and mid-thigh was 7.61 (- 1.51, 32.05)% and 10.62 (- 1.48, 32.06)%, respectively on day 7 as compared to baseline (p < 0.001). The decline in muscle thickness at the mid-arm and mid-thigh were higher among non-survivors compared to survivors at all time points. Also, the decline in muscle thickness was significantly higher among patients with worse outcome at day 90. Patients with ICU-acquired weakness also had significantly higher decline in muscle thickness (p < 0.05). Early decline (from day 1 to day 3) in muscle thickness was associated with in-hospital mortality. The probability of death by day 14 was higher for patients who had early decline (from day 1 to day 3) in muscle thickness of ≥ 6.59% and ≥ 5.20% at the mid-arm [HR 7.3 (95% CI 1.5, 34.2)] and the mid-thigh [HR 8.1 (95% CI 1.7, 37.9)], respectively. Decline in thickness from day 1 to day 3 was a good predictor of in-hospital mortality with area under the curve (AUC) of 0.81 and 0.86 for arm and thigh muscles, respectively.

Conclusions

Critically ill patients with sepsis exhibit a gradual decline in muscle thickness of both the arm and thigh. Decline in muscle thickness was associated with in-hospital mortality. USG has a potential to identify patients at risk of worse in-hospital and post-discharge outcomes.

Respiratory and Peripheral Muscle Assessment in the Intensive Care Unit

Atrophy and weakness of the respiratory and peripheral muscles is a common problem in the intensive care unit (ICU). It is difficult to diagnose, particularly in the early stages of critical disease. Consequently, many cases are detected only in advanced stages, for example, when difficulties in mechanical ventilation weaning are encountered. The aim of this review is to describe the main tools that are currently available for evaluation of peripheral and respiratory muscles in the ICU. Techniques of varying complexity and specificity are discussed, and particular emphasis is placed on those with greater relevance in daily clinical practice, such as ultrasound.

The Pathophysiology of Neuromuscular Dysfunction in Critical Illness

Disability after critical illness is heterogeneous and related to multiple morbidities. Muscle and nerve injury represent prevalent and important determinants of long-term disability. As the population ages and accrues a greater burden of comorbid illness and medical complexity, those patients admitted to an intensive care unit will be challenged in their recovery because of diminished organ reserve and variable tissue resiliency. This represents a significant burgeoning public health concern. This article presents a brief overview of the pathophysiology and the emerging basic science of neuromuscular dysfunction in critical illness.