Bed rest and myopathies

Association of longitudinal changes in skeletal muscle mass with prognosis and nutritional intake in acutely hospitalized patients with abdominal trauma: a retrospective observational study

Background

The objective of this study was to explore whether longitudinal changes in skeletal muscle mass, from hospital admission to 3  weeks post-trauma, are associated with poor prognosis and nutritional intake in acutely hospitalized patients with abdominal trauma.

Methods

A single-center retrospective observational review was conducted on 103 patients with abdominal trauma admitted to the Affiliated Jinling Hospital, Medical School of Nanjing University between January 2010 and April 2020. Skeletal muscle mass was assessed by abdominal computed tomography (CT) performed within 14 days before surgery and on post-trauma days 1-3 (week 0), 7-10 (week 1), 14-17 (week 2), and 21-24 (week 3). The skeletal muscle index (SMI) at L3, change in SMI per day (ΔSMI/day), and percent change in SMI per day (ΔSMI/day [%]) were calculated. The receiver-operating characteristic (ROC) curve was used to evaluate the discriminatory performance of ΔSMI/day (%) for mortality. Linear correlation analysis was used to evaluate the associations between ΔSMI/day (%) and daily caloric or protein intake.

Results

Among the included patients, there were 91 males and 12 females (mean age ± standard deviation 43.74 ± 15.53 years). ΔSMI_4-1/d (%) had a ROC-area under the curve of 0.747 (p = 0.048) and a cut-off value of -0.032 for overall mortality. There were significant positive correlations between ΔSMI_4-1/d (%) and daily caloric intake and protein intake (Y = 0.0007501*X - 1.397, R² = 0.282, R = 0.531, p < 0.001; Y = 0.008183*X - 0.9228, R² = 0.194, R = 0.440, p < 0.001). Δ SMI/day (%) was positively correlated with daily caloric intake ≥80% of resting energy expenditure in weeks 2, 3, and 1-3 post-trauma and with protein intake >1.2 g/kg/d in weeks 3 and 1-3 post-trauma.

Conclusion

Loss of skeletal muscle mass is associated with poor prognosis and nutritional intake in patients admitted to hospital with abdominal trauma.

Impact of structured physical therapy protocol among heart transplant recipients while on intra-aortic balloon pump in the pretransplant period

BACKGROUND

Use of prolonged femoral intra-aortic balloon pump support limits the mobility of patients awaiting heart transplant. We assessed the safety and outcomes of a structured, tilting physical therapy protocol in patients supported by intra-aortic balloon pumps while awaiting transplant.

METHODS

We retrospectively reviewed five years of transplant patients. Eighteen patients received femoral intra-aortic balloon support, a heart transplant, and met all eligibility criteria. We compared complications and outcomes between patients who received the structured, tilting physical therapy (Protocol Group) and those that received standard of care (Control Group).

RESULTS

Complications were not significantly different between groups. The majority of the Protocol Group were discharged to home (10/12), while half (3/6) of the Control Group were discharged to a rehabilitation facility. Post-transplant length of stay was significantly less in the Protocol Group (median 16 vs. 28 days, p = 0.03).

CONCLUSION

Despite the small number analyzed, the data indicates that the structured, tilting physical therapy protocol led to a significantly reduced length of stay post-transplantation. Importantly, use of the protocol did not result in access site complications, thrombosis, or arrhythmias in the majority of the patients.

The Vascular Side of Chronic Bed Rest: When a Therapeutic Approach Becomes Deleterious

The interplay between chronic constraint and advanced aging on blood flow, shear-rate, vascular function, nitric oxide (NO)-bioavailability, microcirculation, and vascular inflammation factors is still a matter of debate. Ninety-eight individuals (Young, n = 28, 23 ± 3 yrs; Old, n = 36, 85 ± 7 yrs; Bedridden, n = 34, 88 ± 6 yrs) were included in the study. The bedridden group included old individuals chronically confined to bed (3.8 ± 2.3 yrs). A blood sample was collected and analyzed for plasma nitrate, and vascular inflammatory markers. Hyperemic response (∆peak) during the single passive leg movement (sPLM) test was used to measure vascular function. Skeletal muscle total hemoglobin was measured at the vastus lateralis during the sPLM test, by means of near infrared spectroscopy (NIRS). Bedridden subjects revealed a depletion of plasma nitrates compared with Old (−23.8%) and Young (−31.1%). Blood flow was lower in the Bedridden in comparison to Old (−20.1%) and Young (−31.7%). Bedridden presented lower sPLM ∆peak compared Old (−72.5%) and the Young (−83.3%). ∆peak of NIRS total hemoglobin was lower in the Bedridden compared to that in the Young (−133%). All vascular inflammatory markers except IL-6 were significantly worse in the Bedridden compared to Old and Young. No differences were found between the Old and Young in inflammatory markers. Results of this study confirm that chronic physical constraint induces an exacerbation of vascular disfunction and differential regulation of vascular-related inflammatory markers. The mechanisms involved in these negative adaptations seems to be associated with endothelial dysfunction and consequent diminished NO-bioavailability likely caused by the reduced shear-rate consequential to long-term reduction of physical activity.

Body weight changes and incidence of cachexia after stroke

BACKGROUND

Body weight loss is a frequent complication after stroke, and its adverse effect on clinical outcome has been shown in several clinical trials. The purpose of this prospective longitudinal single-centre observational study was to investigate dynamical changes of body composition and body weight after ischemic stroke and an association with functional outcome.

METHODS

Sixty-seven consecutive patients (age 69 ± 11 years, body mass index 27.0 ± 4.1 kg/m² , 42% female patient, mean ± SD) with acute ischemic stroke with mild to moderate neurological deficit (National Institute of Health Stroke Scale median 4, ranged 0-12) were analysed in the acute phase (4 ± 2 days) and at 12 months (389 ± 26 days) follow-up. Body composition was examined by dual energy X-ray absorptiometry. Cachexia was defined according to the consensus definition by body weight loss ≥5% within 1 year and additional clinical signs. Lean tissue wasting was considered if a ratio of upper and lower limbs lean mass sum to squared height (kg/m² ) was ≤5.45 kg/m² for female patient and ≤7.25 kg/m² for male patient.

RESULTS

According to the body weight changes after 12 months, 42 (63%) patients had weight gain or stable weight, 11 (16%) patients had moderate weight loss, and 14 (21%) patients became cachectic. A relative decline of 19% of fat tissue and 6.5% of lean tissue was observed in cachectic patients, while no changes of lean tissue were observed in non-cachectic patients after 12 months. The modified Rankin Scale was 48% higher (2.1 ± 1.6, P < 0.05), Barthel Index was 22% lower (71 ± 39, P < 0.01), and handgrip strength was 34% lower (21.9 ± 13.0, P < 0.05) in cachectic compared to non-cachectic patients after 12 months. The low physical performance if defined by Barthel Index <60 points was linked to the lean tissue wasting (OR 44.8, P < 0.01), presence of cachexia (OR 20.8, P < 0.01), and low body mass index <25 kg/m² (OR 11.5, P < 0.05). After adjustment for cofounders, lean tissue wasting remained independently associated with the low physical performance at 12 months follow-up (OR 137.9, P < 0.05).

CONCLUSIONS

In this cohort study, every fifth patient with ischemic stroke fulfilled the criteria of cachexia within 12 months after index event. The incidence of cachexia was 21%. Cachectic patients showed the lowest functional and physical capacity.

Variation in Protein Origin and Utilization: Research and Clinical Application

Muscle health can be rapidly compromised in clinical environments. Modifiable strategies to preserve metabolic homeostasis in adult patient populations include physical activity and pharmacologic support; however, optimizing dietary practices, or more specifically protein intake, is a necessary prerequisite for any other treatment strategy to be fully effective. Simply increasing protein intake is a well-intentioned but often unfocused strategy to protect muscle health in an intensive care setting. Protein quality is a frequently overlooked factor with the potential to differentially influence health outcomes. Quality can be assessed by a variety of techniques, with digestible indispensable amino acid score being the current and most comprehensive technique endorsed by the Food and Agriculture Organization. In practical terms, animal-based proteins are consistently scored higher in quality compared with incomplete proteins, regardless of the assessment method. Consequently, choosing parenteral and/or enteral feeding options that contain high-quality proteins, rich in the branched-chain amino acid leucine, may help establish a dietary framework with the potential to support clinical practice and improve health outcomes in critically ill patients.

Evaluation of the site specificity of acute disuse muscle atrophy developed during a relatively short period in critically ill patients according to the activities of daily living level: A prospective observational study

INTRODUCTION

In critically ill patients, excessive bed rest and immobilisation have been shown to cause disuse muscle atrophy, which contributes to prolonged hospitalisation and decreased activity of daily living (ADL) levels. However, the degree and site specificity of acute disuse muscle atrophy in critically ill patients during a relatively short intensive care unit (ICU) stay have not been fully elucidated.

METHODS

Critically ill patients, who required bed rest on ICU admission, were eligible for this study. The degree of skeletal muscle atrophy was evaluated on the day of, and 72 and 144h after ICU admission by measuring the limb circumference in ADL-dependent or -independent patients separately at five different sites: the midpoint of the upper limb between the acromion and the olecranon, the maximum diameter of the triceps surae in the lower leg, and three different sites in the thigh at 5, 10, and 15cm above the superior pole of the patella. Value of the limb circumference was presented as a percentage relative to the baseline (median).

RESULTS

In ADL-dependent patients, limb circumferences at all five sites were decreased significantly at 144h compared with the baseline (98.9-100% in the upper limbs, 97.1-97.2% in the lower legs, and 96.5-99.1% in the thighs), but not at 72h. In contrast, the limb circumferences at almost all sites decreased significantly at both 72 and 144h (100% in the upper limbs, 94.5-94.7% in the lower legs, and 89.7-94.7% in the thighs), compared with the baseline in ADL-independent patients. Muscle atrophy was greater at the four different lower-limb sites compared to the upper limb during 144h in the ICU in the ADL-independent, but not in the ADL-dependent patients.

CONCLUSIONS

Compared to ADL-dependent patients, ADL-independent patients are prone to develop muscle weakness, especially in the lower limbs.

Muscle wasting and early mobilization in acute respiratory distress syndrome

Survivors of acute respiratory distress syndrome often sustain muscle wasting and functional impairment related to intensive care unit (ICU)-acquired weakness (ICUAW) and this disability may persist for years after ICU discharge. Early diagnosis in cooperative patients by physical examination is recommended to identify patients at risk for weaning failure and to minimize prolongation of risk factors for ICUAW. When possible, early rehabilitation in critically ill patients improves functional outcomes, likely by reducing disuse atrophy. Interventions designed to correct the functional impairment are lacking and further research to delineate the molecular pathways that give rise to ICUAW are needed.

Isotopic decay of urinary or plasma 3-methylhistidine as a potential biomarker of pathologic skeletal muscle loss

BACKGROUND

Skeletal muscle loss accompanying aging or cancer is associated with reduced physical function and predicts morbidity and mortality. 3-Methylhistidine (3MH) has been proposed as a biomarker of myofibrillar proteolysis, which may contribute to skeletal muscle loss.

METHODS

We hypothesized that the terminal portion of the isotope decay curve following an oral dose of isotopically labeled 3MH can be measured non-invasively from timed spot urine samples. We investigated the feasibility of this approach by determining isotope enrichment in spot urine samples and corresponding plasma samples and whether meat intake up to the time of dosing influences the isotope decay.

RESULTS

Isotope decay constants (k) were similar in plasma and urine, regardless of diet. Post hoc comparison of hourly sampling over 10 h with three samples distributed over 10 or fewer hours suggests that three distributed samples over 5-6 h of plasma or urine sampling yield decay constants similar to those obtained over 10 h of hourly sampling.

CONCLUSION

The findings from this study suggest that an index of 3MH production can be obtained from an easily administered test involving oral administration of a stable isotope tracer of 3MH followed by three plasma or urine samples collected over 5-6 h the next day.

IGF-1, the cross road of the nutritional, inflammatory and hormonal pathways to frailty

The decline in functional capacity is a heterogeneous phenomenon in the elderly. An accelerated ageing determines a frail status. It results in an increased vulnerability to stressors for decreased physiological reserves. The early identification of a frail status is essential for preventing loss of functional capacity, and its clinical consequences. Frailty and mobility limitation result from an interplay of different pathways including multiple anabolic deficiency, inflammation, oxidative stress, and a poor nutritional status. However, the age-related decline in insulin-like growth factor 1 (IGF-1) bioactivity deserves special attention as it could represent the ideal crossroad of endocrine, inflammatory, and nutritional pathways to frailty. Several minerals, namely magnesium, selenium, and zinc, appear to be important determinants of IGF-1 bioactivity. This review aims to provide an overview of the potential usefulness of nutrients modulating IGF-1 as potential therapeutic targets in the prevention of mobility limitation occurring in frail older subjects.

Severe burn and disuse in the rat independently adversely impact body composition and adipokines

Introduction

Severe trauma is accompanied by a period of hypermetabolism and disuse. In this study, a rat model was used to determine the effects of burn and disuse independently and in combination on body composition, food intake and adipokines.

Methods

Male rats were assigned to four groups 1) sham ambulatory (SA), 2) sham hindlimb unloaded (SH), 3) 40% total body surface area full thickness scald burn ambulatory (BA) and 4) burn and hindlimb unloaded (BH). Animals designated to the SH and BH groups were placed in a tail traction system and their hindlimbs unloaded. Animals were followed for 14 days. Plasma, urine, fecal and tissue samples were analyzed.

Results

SA had a progressive increase in body mass (BM), SH and BA no change and BH a reduction. Compared to SA, BM was reduced by 10% in both SH and BA and by 17% when combined in BH. Compared to SA, all groups had reductions in lean and fat body mass with BH being greater. The decrease in lean mass was associated with the rate of urinary corticosterone excretion. The loss in fat mass was associated with decreases in plasma leptin and adiponectin and an increase in ghrelin. Following the acute response to injury, BH had a greater food intake per 100 g BM. Food intake was associated with the levels of leptin, adiponectin and ghrelin.

Conclusions

The effects of the combination of burn and disuse in this animal model were additive, therefore in assessing metabolic changes with severe trauma both injury and disuse should be considered. Furthermore, the observed changes in adipokines, corticosterone and ghrelin provide insights for interventions to attenuate the hypermetabolic state following injury, possibly reducing catabolism and muscle loss and subsequent adverse effects on recovery and function.

Nonsurgically induced disuse muscle atrophy and neuromuscular dysfunction upregulates alpha7 acetylcholine receptors

Previous models of muscle disuse have invariably used surgical methods that require the repetitive application of plaster casts. A method of disuse atrophy that does not require such repetitive applications is described herein. Modified plastic pipette tubing was applied to a single hindlimb (mouse), from thigh to foot, resulting in immobilization of the knee in the extension position, and the ankle in the plantar flexion position. This method resulted in the loss of soleus muscle to 11%, 22%, 39%, and 45% of its original mass at 3, 7, 14, and 21 days, respectively, in association with a significant decrease of tibialis twitch (25%) and tetanic tensions (26%) at 21 days, compared with the contralateral side and (or) sham-immobilized controls. Immunohistochemical analysis of the soleus using fluorescent α-bungarotoxin revealed a significant increase in the number of synapses per unit area (818 + 31 compared with 433 + 16/mm(2)) and an increase in muscle fibers per unit area (117 compared with 83/mm(2)), most likely related to the atrophy of muscle fibers bringing synapses closer. A 3-fold increase in alpha7 acetylcholine receptor (α7AChR) protein expression, along with increased expression of α1AChR subunit in the immobilized side compared with the contralateral side was observed. The physiology and pharmacology of the novel finding of upregulation of α7AChRs with disuse requires further study.

Neuromuscular electrical stimulation for intensive care unit-acquired weakness: protocol and methodological implications for a randomized, sham-controlled, phase II trial

BACKGROUND

As the population ages and critical care advances, a growing number of survivors of critical illness will be at risk for intensive care unit (ICU)-acquired weakness. Bed rest, which is common in the ICU, causes adverse effects, including muscle weakness. Consequently, patients need ICU-based interventions focused on the muscular system. Although emerging evidence supports the benefits of early rehabilitation during mechanical ventilation, additional therapies may be beneficial. Neuromuscular electrical stimulation (NMES), which can provide some muscular activity even very early during critical illness, is a promising modality for patients in the ICU.

OBJECTIVE

The objectives of this article are to discuss the implications of bed rest for patients with critical illness, summarize recent studies of early rehabilitation and NMES in the ICU, and describe a protocol for a randomized, phase II pilot study of NMES in patients receiving mechanical ventilation.

DESIGN

The study was a randomized, sham-controlled, concealed, phase II pilot study with caregivers and outcome assessors blinded to the treatment allocation.

SETTING

The study setting will be a medical ICU.

PARTICIPANTS

The study participants will be patients who are receiving mechanical ventilation for 1 day or more, who are expected to stay in the ICU for an additional 2 days or more, and who meet no exclusion criteria.

INTERVENTION

The intervention will be NMES (versus a sham [control] intervention) applied to the quadriceps, tibialis anterior, and gastrocnemius muscles for 60 minutes per day.

MEASUREMENTS

Lower-extremity muscle strength at hospital discharge will be the primary outcome measure.

LIMITATIONS

Muscle strength is a surrogate measure, not a patient-centered outcome. The assessments will not include laboratory, genetic, or histological measures aimed at a mechanistic understanding of NMES. The optimal duration or dose of NMES is unclear.

CONCLUSIONS

If NMES is beneficial, the results of the study will help advance research aimed at reducing the burden of muscular weakness and physical disability in survivors of critical illness.

[Intensive care unit-acquired weakness in the critically ill : critical illness polyneuropathy and critical illness myopathy]

Intensive care unit-acquired weakness (ICUAW) is a severe complication in critically ill patients which has been increasingly recognized over the last two decades. By definition ICUAW is caused by distinct neuromuscular disorders, namely critical illness polyneuropathy (CIP) and critical illness myopathy (CIM). Both CIP and CIM can affect limb and respiratory muscles and thus complicate weaning from a ventilator, increase the length of stay in the intensive care unit and delay mobilization and physical rehabilitation. It is controversially discussed whether CIP and CIM are distinct entities or whether they just represent different organ manifestations with common pathomechanisms. These basic pathomechanisms, however, are complex and still not completely understood but metabolic, inflammatory and bioenergetic alterations seem to play a crucial role. In this respect several risk factors have recently been revealed: in addition to the administration of glucocorticoids and non-depolarizing muscle relaxants, sepsis and multi-organ failure per se as well as elevated levels of blood glucose and muscular immobilization have been shown to have a profound impact on the occurrence of CIP and CIM. For the diagnosis, careful physical and neurological examinations, electrophysiological testing and in rare cases nerve and muscle biopsies are recommended. Nevertheless, it appears to be difficult to clearly distinguish between CIM and CIP in a clinical setting. At present no specific therapy for these neuromuscular disorders has been established but recent data suggest that in addition to avoidance of risk factors early active mobilization of critically ill patients may be beneficial.

Proteomic analysis of skeletal muscle tissue using SELDI-TOF MS: application to disuse atrophy

Skeletal muscle atrophy in response to disuse/unloading is a complex adaptation that involves many components of the muscle tissue. The underlying mechanisms that initiate and control the loss of muscle tissue during this response, especially contractile proteins located within the myofibers, are as yet unclear. One approach capable of distinguishing protein changes specifically associated with disuse/unloading-induced skeletal muscle atrophy is to compare the proteomic profiles of similar muscles between control, unloaded/atrophied, and unloaded/"atrophy-protected" experimental conditions. By utilizing a subtractive proteomic analysis approach, those proteins specifically modulated during the atrophic response can be identified and discriminated from those associated with disuse in general. We here describe the use of SELDI-TOF MS coupled with micro-scale preparative ion-exchange chromatography to detect proteins potentially specifically associated with the atrophic response in rat skeletal muscle.

Critical illness neuromyopathy and muscle weakness in patients in the intensive care unit

Neuromuscular complications of critical illness are common and can be severe and persistent in some patients. Neuromyopathy from critical illness and disuse atrophy from prolonged immobility contribute to muscle weakness acquired while in the intensive care unit. Although various risk factors (eg, severity of illness, corticosteroids, neuromuscular blocking agents) have been implicated in critical illness neuromyopathy (CINM), the evidence supporting these associations is inconsistent. Hyperglycemia may be an important risk factor for CINM, with tight glycemic control through intensive insulin therapy reducing the incidence of CINM. Early mobility in the intensive care unit may minimize disuse atrophy and possibly CINM, through exercise training and its anti-inflammatory effects. Although emerging data have demonstrated the safety, feasibility, and benefit of early mobility in critically ill patients, randomized controlled trials are needed to thoroughly evaluate its potential benefits on patients' muscle strength, physical function, and quality of life. Future studies are needed to elucidate the multiple mechanisms by which immobility, CINM, and other aspects of critical illness lead to muscle loss and neuromuscular dysfunction.

Bed rest in health and critical illness: a body systems approach

Bed rest is a common intervention for critically ill adults. Associated with both benefits and adverse effects, bed rest is undergoing increasing scrutiny as a therapeutic option in the intensive care unit. Bed rest has molecular and systemic effects, ultimately affecting functional outcomes in healthy individuals as well as in those with acute and critical illnesses. Using empirical sources, the purpose of this article was to describe the consequences of bed rest and immobility, especially consequences with implications for critically ill adults in the intensive care unit. This review uses body systems to cluster classic and current results of bed rest studies, beginning with cardiovascular and including pulmonary, renal, skin, nervous, immune, gastrointestinal/ metabolic, and skeletal systems. It concludes with effects on muscles, a system profoundly affected by immobility and bed rest.

Parenteral nutrition in the critically ill patient

A 67-year-old woman with type 2 diabetes mellitus undergoes extensive resection of the small bowel and right colon with a jejunostomy and colostomy because of mesenteric ischemia. In the surgical intensive care unit, severe systemic inflammatory response syndrome with possible sepsis develops. The patient is treated with volume resuscitation, vasopressor support, mechanical ventilation, broad-spectrum antibiotics, and intravenous insulin infusion. Low-dose tube feedings are initiated postoperatively through a nasogastric tube. However, these feedings are discontinued after the development of escalating vasopressor requirements, worsening abdominal distention, and increased gastric residual volume, along with an episode of emesis. The hospital nutritional-support service is consulted for feeding recommendations. A discussion with the patient's family reveals that during the previous 6 months, she lost approximately 15% of her usual body weight and decreased her food intake because of abdominal pain associated with eating. Her preoperative body weight was 51 kg (112 lb), or 90% of her ideal body weight. The physical examination reveals mild wasting of skeletal muscle and fat. Blood tests show hypomagnesemia, hypophosphatemia, and normal hepatic and renal function. Central venous parenteral nutrition is recommended.

Bench-to-bedside review: mobilizing patients in the intensive care unit--from pathophysiology to clinical trials

As the mortality from critical illness has improved in recent years, there has been increasing focus on patient outcomes after hospital discharge. Neuromuscular weakness acquired in the intensive care unit (ICU) is common, persistent, and often severe. Immobility due to prolonged bed rest in the ICU may play an important role in the development of ICU-acquired weakness. Studies in other patient populations have demonstrated that moderate exercise is beneficial in altering the inflammatory milieu associated with immobility, and in improving muscle strength and physical function. Recent studies have demonstrated that early mobility in the ICU is safe and feasible, with a potential reduction in short-term physical impairment. However, early mobility requires a significant change in ICU practice, with reductions in heavy sedation and bed rest. Further research is required to determine whether early mobility in the ICU can improve patients' short-term and long-term outcomes.

Fundamental questions about genes, inactivity, and chronic diseases

Currently our society is faced with the challenge of understanding the biological basis for the epidemics of obesity and many chronic diseases, including Type 2 diabetes. Physical inactivity increases the relative risk of coronary artery disease by 45%, stroke by 60%, hypertension by 30%, and osteoporosis by 59%. Moreover, physical inactivity is cited as an actual cause of chronic disease by the US Centers of Disease Control. Physical activity was obligatory for survival for the Homo genus for hundreds of thousands of years. This review will present evidence that suggests that metabolic pathways selected during the evolution of the human genome are inevitably linked to physical activity. Furthermore, as with many other environmental interactions, cycles of physical activity and inactivity interact with genes resulting in a functional outcome appropriate for the environment. However, as humans are less physically active, there is a maladaptive response that leads to metabolic dysfunction and many chronic diseases. How and why these interactions occur are fundamental questions in biology. Finally, a perspective to future research in physical inactivity-gene interaction is presented. This information is necessary to provide the molecular evidence required to further promote the primary prevention of chronic diseases through physical activity, identify those molecules that will allow early disease detection, and provide society with the molecular information needed to counter the current strategy of adding physical inactivity into our lives.