Usefulness of a clinical diagnosis of ICU-acquired paresis to predict outcome in patients with SIRS and acute respiratory failure

Optimal timing for early mobilization initiatives in intensive care unit patients: A systematic review and network meta-analysis

OBJECTIVES

Analyse the effect of varying start times for early exercise interventions on the prevention of intensive care unit-acquired weakness.

RESEARCH METHODOLOGY

We conducted a comprehensive search on PubMed, Cochrane Library, Web of Science, Embase, China Biology Medicine Disc, China National Knowledge Infrastructure, Wan Fang Database, and reference lists up to May 2023.

SETTING

We systematically searched the literature for all randomized controlled trials on the effect of early mobilization in patients with critical illness.

MAIN OUTCOME MEASURES

The primary outcome assessed was the incidence of intensive care unit-acquired weakness. The secondary outcomes included: the Medical Research Council Score, the Barthel Index, duration of mechanical ventilation, length of intensive care unit stay, total length of hospital stay, mortality and incidence of intensive care unit-related complications.

RESULTS

The results of meta-analysis showed that compared with routine care, less than 24 hours after admission (RR = 0.44, 95 %CI: 0.28-0.68), more than 24 hours (RR = 0.33, 95 %CI: 0.16-0.67), less than 72 hours after admission (RR = 0.33, 95 %CI: 0.20-0.52) may lead to a lower incidence of intensive care unit-acquired weakness. The results of under surface cumulative ranking showed that early mobilization within 72 hours may have the lowest incidence of intensive care unit-acquired weakness (SUCRA = 81.9 %).

CONCLUSIONS

The current empirical evidence from intensive care unit patients suggests that initiating mobilization protocols within 24-72 hours timeframe following admission to the intensive care unit could potentially be the most beneficial strategy to reduce the incidence of intensive care unit-acquired weakness and the related medical complications. Moreover, this strategy seems to significantly improve rehabilitation and treatment outcomes for these patients.

IMPLICATIONS FOR CLINICAL PRACTICE

According to this study, medical and nursing staff in the intensive care unit have the chance to identify the most suitable timing for the implementation of early rehabilitative measures for patients. This can potentially prevent intensive care unit-acquired weakness and enhance various clinical outcomes for patients.

Efficacy of the "Start to move" protocol on functionality, ICU-acquired weakness and delirium: A randomized clinical trial

OBJECTIVE

To evaluate the efficacy of the Start to move protocol compared to conventional treatment in subjects over 15 years of age hospitalized in the ICU on an improvement in functionality, decrease in ICU-acquired weakness (DAUCI), incidence of delirium, days of mechanical ventilation (MV), length of stay in ICU and mortality at 28 days.

DESIGN

randomized controlled clinical trial.

SETTING

Intensive Care Unit.

PARTICIPANTS

Includes adults older than 15 years with invasive mechanical ventilation more than 48h, randomized allocation.

INTERVENTIONS

Start to move protocol and conventional treatment.

MAIN VARIABLES OF INTEREST

Functionality, incidence of ICU-acquired weakness, incidence of delirium, days on mechanical ventilation, ICU stay and mortality-28 days, ClinicalTrials.gov number, NCT05053724.

RESULTS

69 subjects were admitted to the study, 33 to the Start to move group and 36 to conventional treatment, clinically and sociodemographic comparable. In the "Start to move" group, the incidence of IUCD at ICU discharge was 35.7% vs. 80.7% in the "conventional treatment" group (p=0.001). Functionality (FSS-ICU) at ICU discharge corresponds to 26 vs. 17 points in favor of the "Start to move" group (p=0.001). The difference in Barthel at ICU discharge was 20% in favor of the "Start to move" group (p=0.006). There were no significant differences in the incidence of delirium, days of mechanical ventilation, ICU stay and 28-day mortality. The study did not report adverse events or protocol suspension.

CONCLUSIONS

The application of the "Start to move" protocol in ICU showed a reduction in the incidence of IUAD, an increase in functionality and a smaller decrease in Barthel score at discharge.

Early detection and assessment of intensive care unit-acquired weakness: a comprehensive review

Intensive care unit-acquired weakness (ICU-AW) is a serious complication in critically ill patients. Therefore, timely and accurate diagnosis and monitoring of ICU-AW are crucial for effectively preventing its associated morbidity and mortality. This article provides a comprehensive review of ICU-AW, focusing on the different methods used for its diagnosis and monitoring. Additionally, it highlights the role of bedside ultrasound in muscle assessment and early detection of ICU-AW. Furthermore, the article explores potential strategies for preventing ICU-AW. Healthcare providers who manage critically ill patients utilize diagnostic approaches such as physical exams, imaging, and assessment tools to identify ICU-AW. However, each method has its own limitations. The diagnosis of ICU-AW needs improvement due to the lack of a consensus on the appropriate approach for its detection. Nevertheless, bedside ultrasound has proven to be the most reliable and cost-effective tool for muscle assessment in the ICU. Combining the Sequential Organ Failure Assessment (SOFA) score, Acute Physiology and Chronic Health Evaluation (APACHE) II score assessment, and ultrasound can be a convenient approach for the early detection of ICU-AW. This approach can facilitate timely intervention and prevent catastrophic consequences. However, further studies are needed to strengthen the evidence.

The association between reduced calf and mid-arm circumferences and ICU mortality in critically ill COVID-19 patients

BACKGROUND & AIMS

Patients with COVID-19 are at a high risk of malnutrition caused by inflammatory syndrome and persistent hypermetabolism, which may affect clinical outcomes. This study aimed to evaluate the changes in nutritional status indicators between two time points of nutritional assessments of COVID-19 patients during their stay in the intensive care unit (ICU). Moreover, the study also assessed the association of nutritional status with ICU mortality.

METHODS

This cohort study included retrospective data of adult patients admitted to a public hospital ICU in southern Brazil, between March and September 2020. These participants with confirmed COVID-19 diagnosis received nutritional assessment within the first 72 h after ICU admission. The anthropometric measurements collected included mid-arm circumference (MAC) and calf circumference (CC). The percentage (%) of MAC adequacy was calculated, and values < 50th percentile for sex and age were considered low. CC values of ≤33 cm for women and ≤34 cm for men were indicative of reduced muscle mass. Data on the date of discharge from the ICU and mortality outcome were collected.

RESULTS

A total of 249 patients were included (53.4% men, 62.2 ± 13.9 years of age, SOFA severity score 9.6 ± 3.5). Of these, 22.7 and 39.1% had reduced MAC and CC at ICU admission, respectively. In these participants, weight, MAC, CC, and % MAC decreased significantly from the first to second nutritional assessment (p < 0.05), but there was no significant difference between survivors and non-survivors. Patients with reduced CC (HR = 2.63; 95% CI 1.65-4.18) or reduced MAC (HR = 2.11; 95% CI 1.37-3.23) at the first nutritional assessment had approximately twice the risk of death in the ICU than those with normal CC and normal MAC, regardless of the severity assessed by the SOFA score and age.

CONCLUSION

Reduced MAC and CC values were identified in approximately 20 and 40% of COVID-19 patients admitted to the ICU, respectively. Additionally, these indicators of nutritional depletion were associated with an approximately 2-fold increase in the risk of ICU mortality. A significant reduction in anthropometric indicators during the first weeks of ICU stay confirmed the deterioration of nutritional status in these patients, although this was not associated with mortality.

Association between neuromuscular blocking agents and the development of intensive care unit-acquired weakness (ICU-AW): A systematic review with meta-analysis and trial sequential analysis

BACKGROUND

The present study aims to review the literature and synthesize evidence concerning the effects of the use of neuromuscular blocking agents (NMBA) regarding the development of intensive care unit-acquired weakness (ICU-AW).

METHODS

This study was registered in the PROSPERO database CRD42020142916. Systematic review in PubMed, Embase, and the Cochrane Central, Randomized clinical trials (RCTs), and cohort studies with adults that reported the use of NMBA and the development of ICU-AW were included. Pre-specified subgroup analyses were performed for presence of sepsis and type of NMBA used. The quality of evidence for intervention effects was summarized. The certainty of evidence was assessed using the GRADE approach.

RESULTS

We included 30 studies, four RCTs, 21 prospective and 5 retrospective cohorts, enrolling a total of 3839 patients. Most of the included studies were observational with high heterogeneity, whereas the RCTs had a high risk of bias. The use of NMBA increased the odds of developing ICU-AW (OR = 2.77 [95% CI 1.98-3.88], I² = 62%), with low-quality of evidence. A trial sequential analysis showed the need to include 22,330 patients in order to provide evidence for either beneficial or harmful intervention effects.

CONCLUSIONS

This meta-analysis suggests that the use of NMBA might be implicated in the development of ICU-AW. However, there is not enough evidence to definitively conclude about the association between the use of NMBA and the development of ICU-AW, as these results are based mostly on observational studies with high heterogeneity.

The rate and assessment of muscle wasting during critical illness: a systematic review and meta-analysis

BACKGROUND

Patients with critical illness can lose more than 15% of muscle mass in one week, and this can have long-term detrimental effects. However, there is currently no synthesis of the data of intensive care unit (ICU) muscle wasting studies, so the true mean rate of muscle loss across all studies is unknown. The aim of this project was therefore to systematically synthetise data on the rate of muscle loss and to identify the methods used to measure muscle size and to synthetise data on the prevalence of ICU-acquired weakness in critically ill patients.

METHODS

We conducted a systematic literature search of MEDLINE, PubMed, AMED, BNI, CINAHL, and EMCARE until January 2022 (International Prospective Register of Systematic Reviews [PROSPERO] registration: CRD420222989540. We included studies with at least 20 adult critically ill patients where the investigators measured a muscle mass-related variable at two time points during the ICU stay. We followed Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines and assessed the study quality using the Newcastle-Ottawa Scale.

RESULTS

Fifty-two studies that included 3251 patients fulfilled the selection criteria. These studies investigated the rate of muscle wasting in 1773 (55%) patients and assessed ICU-acquired muscle weakness in 1478 (45%) patients. The methods used to assess muscle mass were ultrasound in 85% (n = 28/33) of the studies and computed tomography in the rest 15% (n = 5/33). During the first week of critical illness, patients lost every day -1.75% (95% CI -2.05, -1.45) of their rectus femoris thickness or -2.10% (95% CI -3.17, -1.02) of rectus femoris cross-sectional area. The overall prevalence of ICU-acquired weakness was 48% (95% CI 39%, 56%).

CONCLUSION

On average, critically ill patients lose nearly 2% of skeletal muscle per day during the first week of ICU admission.

Prevalence and evaluation of oropharyngeal dysphagia in patients with severe acute respiratory syndrome coronavirus 2 infection in the intensive care unit

Objective

The main objective was to assess the prevalence of dysphagia in the intensive care unit in patients with coronavirus disease 2019.

Methods. A cohort, observational, retrospective study was conducted of patients admitted to the intensive care unit for severe acute respiratory syndrome coronavirus 2 pneumonia at the University Hospital of Rouen in France.

Results

Over 4 months, 58 patients were intubated and ventilated, 43 of whom were evaluated. Screening revealed post-extubation dysphagia in 62.7 per cent of patients. In univariate analysis, a significant association was found between the presence of dysphagia and: the severity of the initial pathology, the duration of intubation, the duration of curare use, the degree of muscle weakness and the severity indicated on the initial scan. At the end of intensive care unit treatment, 22 per cent of the dysphagic patients had a normal diet, 56 per cent had an adapted diet and 22 per cent still received exclusive tube feeding.

Conclusion

Post-extubation dysphagia is frequent and needs to be investigated.

Myostatin deficiency not only prevents muscle wasting but also improves survival in septic mice

Sepsis remains a leading cause of mortality in critically ill patients. Muscle wasting is a major complication of sepsis and negatively affects clinical outcomes. Despite intense investigation for many years, the molecular mechanisms underlying sepsis-related muscle wasting are not fully understood. In addition, a potential role of muscle wasting in disease development of sepsis has not been studied. Myostatin is a myokine that downregulates skeletal muscle mass. We studied the effects of myostatin deficiency on muscle wasting and other clinically relevant outcomes, including mortality and bacterial clearance, in mice. Myostatin deficiency prevented muscle atrophy along with inhibition of increases in muscle-specific RING finger protein 1 (MuRF-1) and atrogin-1 expression and phosphorylation of signal transducer and activator of transcription protein 3 (STAT3; major players of muscle wasting) in septic mice. Moreover, myostatin deficiency improved survival and bacterial clearance of septic mice. Sepsis-induced liver dysfunction, acute kidney injury, and neutrophil infiltration into the liver and kidney were consistently mitigated by myostatin deficiency, as indicated by plasma concentrations of aspartate aminotransferase (AST), alanine aminotransferase (ALT), and neutrophil gelatinase-associated lipocalin (NGAL) and myeloperoxidase activity in the organs. Myostatin deficiency also inhibited sepsis-induced increases in plasma high-mobility group protein B1 (HMGB1) and macrophage inhibitory cytokine (MIC)-1/growth differentiation factor (GDF)-15 concentrations. These results indicate that myostatin plays an important role not only in muscle wasting but also in other clinically relevant outcomes in septic mice. Furthermore, our data raise the possibility that muscle wasting may not be simply a complication, but myostatin-mediated muscle cachexia and related changes in muscle may actually drive the development of sepsis as well.NEW & NOTEWORTHY Muscle wasting is a major complication of sepsis, but its role in the disease development is not known. Myostatin deficiency improved bacterial clearance and survival and mitigated damage in the liver and kidney in septic mice, which paralleled prevention of muscle wasting. These results raise the possibility that muscle wasting may not simply be a complication of sepsis, but myostatin-mediated cachexic changes may have a role in impaired bacterial clearance and mortality in septic mice.

Intensive Care Unit-Acquired Weakness: A Review of Recent Progress With a Look Toward the Future

Intensive care unit-acquired weakness (ICU-AW), a common neuromuscular complication associated with patients in the ICU, is a type of skeletal muscle dysfunction that commonly occurs following sepsis, mobility restriction, hyperglycemia, and the use of glucocorticoids or neuromuscular blocking agents. ICU-AW can lead to delayed withdrawal of mechanical ventilation and extended hospitalization. Patients often have poor prognosis, limited mobility, and severely affected quality of life. Currently, its pathogenesis is uncertain, with unavailability of specific drugs or targeted therapies. ICU-AW has gained attention in recent years. This manuscript reviews the current research status of the epidemiology, pathogenesis, diagnosis, and treatment methods for ICU-AW and speculates the novel perspectives for future research.

ICU outcomes can be predicted by noninvasive muscle evaluation: a meta-analysis

BACKGROUND

The relationship between muscle function in critically ill patients assessed using bedside techniques and clinical outcomes has not been systematically described. We aimed to evaluate the association between muscle weakness assessed by bedside evaluation and mortality or weaning from mechanical ventilation, and the capacity of each evaluation tool to predict outcomes.

METHODS

Five databases (PubMed, Embase, CINAHL, Cochrane Library, Science Direct) were searched from January 2000 to December 2018. Data were extracted and random effects meta-analyses were performed.

RESULTS

60 studies were analysed, including 4382 patients. Intensive care unit (ICU)-related muscle weakness was associated with an increase in overall mortality with odds ratios ranging from 1.2 (95% CI 0.60-2.40) to 4.48 (95% CI 1.49-13.42). Transdiaphragmatic twitch pressure had the highest predictive capacity for overall mortality, with a sensitivity of 0.87 (95% CI 0.76-0.93) and a specificity of 0.36 (95% CI 0.27-0.43). The area under the curve (AUC) was 0.74 (95% CI 0.70-0.78). Muscle weakness was associated with an increase in mechanical ventilation weaning failure rate with an odds ratio ranging from 2.64 (95% CI 0.72-9.64) to 19.07 (95% CI 9.35-38.9). Diaphragm thickening fraction had the highest predictive capacity for weaning failure with a sensitivity of 0.76 (95% CI 0.67-0.83) and a specificity of 0.86 (95% CI 0.78-0.92). The AUC was 0.86 (95% CI 0.83-0.89).

CONCLUSION

ICU-related muscle weakness detected by bedside techniques is a serious issue associated with a high risk of death or prolonged mechanical ventilation. Evaluating diaphragm function should be a clinical priority in the ICU.

Interrater Reliability of Muscle Ultrasonography Image Acquisition by Physical Therapists in Patients Who Have or Who Survived Critical Illness

OBJECTIVE

Previous studies have demonstrated that muscle ultrasound (US) can be reliably performed at the patient bedside by novice assessors with minimal training. The primary objective of this study was to determine the interrater reliability of muscle US image acquisition by physical therapists and physical therapist students. Secondarily, this study was designed to elucidate the process for training physical therapists to perform peripheral skeletal muscle US.

METHODS

This was a cross-sectional observational study. Four novices and 1 expert participated in the study. Novice sonographers engaged in a structured training program prior to implementation. US images were obtained on the biceps brachii, quadriceps femoris, and tibialis anterior muscles in 3 groups: patients in the intensive care unit, patients on the hospital ward, and participants in the outpatient gym who were healthy. Reliability of image acquisition was analyzed compared with the expert sonographer.

RESULTS

Intraclass correlation coefficient values ranged from 0.76 to 0.97 with an average for all raters and all muscles of 0.903, indicating excellent reliability of image acquisition. In general, the experienced physical therapist had higher or similar intraclass correlation coefficient values compared with the physical therapist students in relation to the expert sonographer.

CONCLUSIONS

Excellent interrater reliability for US was observed regardless of the level of experience, severity of patient illness, or patient setting. These findings indicate that the use of muscle US by physical therapists can accurately capture reliable images in patients with a range of illness severity and different clinical practice settings across the continuum of care.

IMPACT

Physical therapists can utilize US to obtain images to assess muscle morphology.

LAY SUMMARY

Physical therapists can use noninvasive US as an imaging tool to assess the size and quality of peripheral skeletal muscle. This study demonstrates that physical therapists can receive training to reliably obtain muscle images in patients admitted to the intensive care unit who may be at risk for muscle wasting and may benefit from early rehabilitation.

Skeletal Muscle Aging Atrophy: Assessment and Exercise-Based Treatment

In the ordinary course of aging, individuals change their body composition, mainly reducing their skeletal muscle mass and increasing their fat mass. In association, muscle strength and functionality also decrease. The geriatric assessment allows knowing the baseline situation of the patients, determines the impact of diseases, and defines specific treatments. There are various tools to evaluate the health condition of older people. These tools include the assessment scales of necessary Activities of Daily Living (ADL) and Instrumental Activities of Daily Living (IADL), physical and functional assessment scales, and instruments that assess the cognitive state of the person. There are several strategies that have been proposed to combat skeletal muscle atrophy due to aging, such as physical exercise, nutritional supplements, or drugs. Some researchers have highlighted the efficacy of the combination of the mentioned strategies. In this chapter, we will focus only on physical exercise as a strategy to reduce skeletal muscle loss during aging.

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.

Impact of Vasoactive Medications on ICU-Acquired Weakness in Mechanically Ventilated Patients

BACKGROUND

Vasoactive medications are commonly used in the treatment of critically ill patients, but their impact on the development of ICU-acquired weakness is not well described. The objective of this study is to evaluate the relationship between vasoactive medication use and the outcome of ICU-acquired weakness.

METHODS

This is a secondary analysis of mechanically ventilated patients (N = 172) enrolled in a randomized clinical trial of early occupational and physical therapy vs conventional therapy, which evaluated the end point of ICU-acquired weakness on hospital discharge. Patients underwent bedside muscle strength testing by a therapist blinded to study allocation to evaluate for ICU-acquired weakness. The effects of vasoactive medication use on the incidence of ICU-acquired weakness in this population were assessed.

RESULTS

On logistic regression analysis, the use of vasoactive medications increased the odds of developing ICU-acquired weakness (odds ratio [OR], 3.2; P = .01) independent of all other established risk factors for weakness. Duration of vasoactive medication use (in days) (OR, 1.35; P = .004) and cumulative norepinephrine dose (μg/kg/d) (OR, 1.01; P = .02) (but not vasopressin or phenylephrine) were also independently associated with the outcome of ICU-acquired weakness.

CONCLUSIONS

In mechanically ventilated patients enrolled in a randomized clinical trial of early mobilization, the use of vasoactive medications was independently associated with the development of ICU-acquired weakness. Prospective trials to further evaluate this relationship are merited.

TRIAL REGISTRY

ClinicalTrials.gov; No.: NCT01777035; URL: www.clinicaltrials.gov.

Corticosteroid use and intensive care unit-acquired weakness: a systematic review and meta-analysis

Background

The association between corticosteroid use and intensive care unit (ICU)-acquired weakness remains unclear. We evaluated the relationship between corticosteroid use and ICU-acquired weakness in critically ill adult patients.

Methods

The PubMed, Embase, Web of Science, Cochrane Central Register of Controlled Trials, and Cumulative Index of Nursing and Allied Health Literature databases were searched from database inception until October 10, 2017. Two authors independently screened the titles/abstracts and reviewed full-text articles. Randomized controlled trials and prospective cohort studies evaluating the association between corticosteroids and ICU-acquired weakness in adult ICU patients were selected. Data extraction from the included studies was accomplished by two independent reviewers. Meta-analysis was performed using Stata version 12.0. The results were analyzed using odds ratios (ORs) and 95% confidence intervals (CIs). Data were pooled using a random effects model, and heterogeneity was evaluated using the χ² and I² statistics. Publication bias was qualitatively analyzed with funnel plots, and quantitatively analyzed with Begg’s test and Egger’s test.

Results

One randomized controlled trial and 17 prospective cohort studies were included in this review. After a meta-analysis, the effect sizes of the included studies indicated a statistically significant association between corticosteroid use and ICU-acquired weakness (OR 1.84; 95% CI 1.26–2.67; I² = 67.2%). Subgroup analyses suggested a significant association between corticosteroid use and studies limited to patients with clinical weakness (OR 2.06; 95% CI 1.27–3.33; I² = 60.6%), patients with mechanical ventilation (OR 2.00; 95% CI 1.23–3.27; I² = 66.0%), and a large sample size (OR 1.61; 95% CI 1.02–2.53; I² = 74.9%), and not studies limited to patients with abnormal electrophysiology (OR 1.65; 95% CI 0.92–2.95; I² = 70.6%) or patients with sepsis (OR 1.96; 95% CI 0.61–6.30; I² = 80.8%); however, statistical heterogeneity was obvious. No significant publication biases were found in the review. The overall quality of the evidence was high for the randomized controlled trial and very low for the included prospective cohort studies.

Conclusions

The review suggested a significant association between corticosteroid use and ICU-acquired weakness. Thus, exposure to corticosteroids should be limited, or the administration time should be shortened in clinical practice to reduce the risk of ICU-acquired weakness.

Electronic supplementary material

The online version of this article (10.1186/s13054-018-2111-0) contains supplementary material, which is available to authorized users.

Risk factors for intensive care unit-acquired weakness: A systematic review and meta-analysis

Intensive care unit-acquired weakness (ICUAW) occurs frequently in the context of critical illness without alternative plausible cause and specific treatment options, and it is important to identify and summarize the independent risk factors for ICUAW. PubMed, Embase, Central, China Biological Medicine, China National Knowledge Infrastructure, VIP and Wanfang databases were searched from database inception until 10 July 2017. Prospective cohort studies on adult ICU patients who were diagnosed with ICUAW using either clinical or electrophysiological criteria were selected. Meta-analysis was performed using Stata version 12.0. The results were analysed using odds ratios (OR) and 95% confidence intervals (CI). Data were pooled using a random-effects model, and heterogeneity was assessed using the I² statistic. Qualitative analysis and systematic review were used for risk factors that were deemed inappropriate to combine. Fourteen prospective cohort studies were included in this review. The meta-analysis showed that Acute Physiology and Chronic Health Evaluation II score (OR, 1.05; 95%CI, 1.01-1.10), neuromuscular blocking agents (OR, 2.03; 95%CI, 1.22-3.40) and aminoglycosides (OR, 2.27; 95%CI, 1.07-4.81) were found to be significantly associated with ICUAW. Other risk factors, including female, multiple organ failure, systemic inflammatory response syndrome, sepsis, electrolyte disturbances, hyperglycaemia, hyperosmolarity, high lactate level, duration of mechanical ventilation, parenteral nutrition and use of norepinephrine, were statistically significant on multivariable analysis in each single studies. This review provides a number of independent risk factors for ICUAW, which should be guided for early prediction and prevention of the disorder.

Effects of early, combined endurance and resistance training in mechanically ventilated, critically ill patients: a study protocol for a randomised controlled trial

Background

Prolonged need for intensive care is associated with neuromuscular weakness, termed Intensive Care Unit Acquired Weakness. Those affected suffer from severe functional impairment that can persist for years. First studies suggest a positive effect of physiotherapy and early mobilisation. However, the ideal intervention for a preferential functional outcome is not known. So far no randomised controlled trial has been conducted to specifically evaluate an early endurance and resistance training in the mechanically ventilated, critically ill patient.

Methods/design

A randomised controlled trial with blinded assessors and 6-month follow-up will be conducted in a tertiary, interdisciplinary intensive care unit in Switzerland. Participants (n = 115; expected dropouts: n = 15) will be randomised to a control group receiving standard physiotherapy and to an experimental group that undergoes early mobilisation combined with endurance and resistance training. The inclusion criteria are being aged 18 years or older, expected mechanical ventilation for more than 72 h and qualitative independence before the illness.

Primary endpoints are functional capacity (6-Minute Walk Test) and the ability to perform activities of daily living (Functional Independence Measure) measured at hospital discharge. Secondary endpoints include muscle strength (Medical Research Council sum score, handgrip strength and handheld dynamometry for quadriceps muscle), joint contractures (range of motion), exercise capacity (Timed ‘Up & Go’ Test) and health-related quality of life (Short Form 36). Safety will be monitored during interventions by indirect calorimetry and continuous intensive care standard monitoring. All previously defined adverse events will be noted. The statistical analysis will be by intention-to-treat with the level of significance set at p < 0.05.

Discussion

This prospective, single-centre, allocation-concealed and assessor-blinded randomised controlled trial will evaluate participant’s function after an early endurance and resistance training compared to standard care. Limitations of this study are the heterogeneity of the critically ill and the discontinuity of the protocol after relocation to the ward. The strengths lie in the pragmatic design and the clinical significance of the chosen outcome measures.

Trial registration

German Clinical Trials Register (DRKS): DRKS00004347, registered on 10 September 2012.

The outcomes and prognostic factors of patients requiring prolonged mechanical ventilation

The aims of this study were to investigate the outcomes of patients requiring prolonged mechanical ventilation (PMV) and to identify risk factors associated with its mortality rate. All patients admitted to the respiratory care centre (RCC) who required PMV (the use of MV ≥21 days) between January 2006 and December 2014 were enrolled. A total of 1,821 patients were identified; their mean age was 69.8 ± 14.2 years, and 521 patients (28.6%) were aged >80 years. Upon RCC admission, the APACHE II scores were 16.5 ± 6.3, and 1,311 (72.0%) patients had at least one comorbidity. Pulmonary infection was the most common diagnosis (n = 770, 42.3%). A total of 320 patients died during hospitalization, and the in-hospital mortality rate was 17.6%. A multivariate stepwise logistic regression analysis indicated that patients were more likely to die if they who were >80 years of age, had lower albumin levels (<2 g/dl) and higher APACHE II scores (≥15), required haemodialysis, or had a comorbidity. In conclusion, the in-hospital mortality for patients requiring PMV in our study was 17%, and mortality was associated with disease severity, hypoalbuminaemia, haemodialysis, and an older age.

Acquired Muscle Weakness in the Surgical Intensive Care Unit

Muscle weakness is common in the surgical intensive care unit (ICU). Low muscle mass at ICU admission is a significant predictor of adverse outcomes. The consequences of ICU-acquired muscle weakness depend on the underlying mechanism. Temporary drug-induced weakness when properly managed may not affect outcome. Severe perioperative acquired weakness that is associated with adverse outcomes (prolonged mechanical ventilation, increases in ICU length of stay, and mortality) occurs with persistent (time frame: days) activation of protein degradation pathways, decreases in the drive to the skeletal muscle, and impaired muscular homeostasis. ICU-acquired muscle weakness can be prevented by early treatment of the underlying disease, goal-directed therapy, restrictive use of immobilizing medications, optimal nutrition, activating ventilatory modes, early rehabilitation, and preventive drug therapy. In this article, the authors review the nosology, epidemiology, diagnosis, and prevention of ICU-acquired weakness in surgical ICU patients.

The Sick and the Weak: Neuropathies/Myopathies in the Critically Ill

Critical illness polyneuropathies (CIP) and myopathies (CIM) are common complications of critical illness. Several weakness syndromes are summarized under the term intensive care unit-acquired weakness (ICUAW). We propose a classification of different ICUAW forms (CIM, CIP, sepsis-induced, steroid-denervation myopathy) and pathophysiological mechanisms from clinical and animal model data. Triggers include sepsis, mechanical ventilation, muscle unloading, steroid treatment, or denervation. Some ICUAW forms require stringent diagnostic features; CIM is marked by membrane hypoexcitability, severe atrophy, preferential myosin loss, ultrastructural alterations, and inadequate autophagy activation while myopathies in pure sepsis do not reproduce marked myosin loss. Reduced membrane excitability results from depolarization and ion channel dysfunction. Mitochondrial dysfunction contributes to energy-dependent processes. Ubiquitin proteasome and calpain activation trigger muscle proteolysis and atrophy while protein synthesis is impaired. Myosin loss is more pronounced than actin loss in CIM. Protein quality control is altered by inadequate autophagy. Ca(2+) dysregulation is present through altered Ca(2+) homeostasis. We highlight clinical hallmarks, trigger factors, and potential mechanisms from human studies and animal models that allow separation of risk factors that may trigger distinct mechanisms contributing to weakness. During critical illness, altered inflammatory (cytokines) and metabolic pathways deteriorate muscle function. ICUAW prevention/treatment is limited, e.g., tight glycemic control, delaying nutrition, and early mobilization. Future challenges include identification of primary/secondary events during the time course of critical illness, the interplay between membrane excitability, bioenergetic failure and differential proteolysis, and finding new therapeutic targets by help of tailored animal models.

Clinical Outcomes Related to Protein Delivery in a Critically Ill Population: A Multicenter, Multinational Observation Study

OBJECTIVE

Optimal intake of energy and protein is associated with improved outcomes, although outcomes relative to protein intake are very limited. Our purpose was to evaluate the impact of prescribed protein delivery on mortality and time to discharge alive (TDA) using data from the International Nutrition Survey 2013. We hypothesized that greater protein delivery would be associated with lower mortality and shorter TDA.

METHODS

The sample included patients in the intensive care unit (ICU) ≥ 4 days (n = 2828) and a subsample in the ICU ≥ 12 days (n = 1584). Models were adjusted for evaluable nutrition days, age, body mass index, sex, admission type, acuity scores, and geographic region. Percentages of prescribed protein and energy intake were compared with mortality outcomes using logistic regression and with Cox proportional hazards for TDA.

RESULTS

Mean intake for the 4-day sample was protein 51 g (60.5% of prescribed) and 1100 kcal (64.1% of prescribed); for the 12-day sample, mean intake was protein 57 g (66.7% of prescribed) and 1200 kcal (70.7% of prescribed). Achieving ≥ 80% of prescribed protein intake was associated with reduced mortality (4-day sample: odds ratio [OR], 0.68; 95% confidence interval [CI], 0.50-0.91; 12-day sample: OR, 0.60; 95% CI, 0.39-0.93), but ≥ 80% of prescribed energy intake was not. TDA was shorter with ≥ 80% prescribed protein (hazard ratio [HR], 1.25; 95% CI, 1.04-1.49) in the 12-day sample but longer with ≥ 80% prescribed energy in the 4-day sample (HR, 0.82; 95% CI, 0.69-0.96).

CONCLUSION

Achieving at least 80% of prescribed protein intake may be important to survival and shorter TDA in ICU patients. Efforts to achieve prescribed protein intake should be maximized.

Assessment of impairment and activity limitations in the critically ill: a systematic review of measurement instruments and their clinimetric properties

PURPOSE

To identify measures used to evaluate the broad constructs of functional impairment and limitations in the critically ill across the continuum of recovery, and to evaluate, synthesise and compare the clinimetric properties of the measures identified.

METHODS

A systematic review of articles was carried out using the databases Medline (1950-2014), CINAHL (1982-2014), EMBASE (1980-2014), Cochrane Library (2014) and Scopus (1960-2014). Additional studies were identified by searching personal files. Eligibility criteria for selection: Search 1: studies which assessed muscle mass, strength or function using objective non-laboratory measures; Search 2: studies which evaluated a clinimetric property (reliability, measurement error, validity or responsiveness) for one of the measures identified in search one. Two independent reviewers assessed articles for inclusion and assessed risk of bias using the consensus-based standards for selection of health status measurement instruments checklist.

RESULTS

Thirty-three measures were identified; however, only 20 had established clinimetric properties. Ultrasonography, dynamometry, physical function in intensive care test scored and the Chelsea critical care physical assessment tool performed the strongest for the measurement of impairment of body systems (muscle mass and strength) and activity limitations (physical function), respectively.

CONCLUSIONS

There is considerable variability in the type of measures utilized to measure physical impairments and limitations in survivors of critical illness. Future work should identify a core set of standardized measures, which can be utilized across the continuum of critical illness recovery embedded within the International Classification of Functioning framework. This will enable improved comparisons between future studies, which in turn will assist in identifying the most effective treatment strategies to ameliorate the devastating longer-term outcomes of a critical illness.

The incidence of intensive care unit-acquired weakness syndromes: A systematic review

We conducted a literature review of the intensive care unit-acquired weakness syndromes (critical illness polyneuropathy, critical illness myopathy and critical illness neuromyopathy) with the primary objective of determining their incidence as a combined group. Studies were identified through MEDLINE, Embase, Cochrane Database and article reference list searches and were included if they evaluated the incidence of one or more of these conditions in an adult intensive care unit population. The incidence of an intensive care unit-acquired weakness syndrome in the included studies was 40% (1080/2686 patients, 95% confidence interval 38-42%). The intensive care unit populations included were heterogeneous though largely included patients receiving mechanical ventilation for seven or more days. Additional prespecified outcomes identified that the incidence of intensive care unit-acquired weakness varied with the diagnostic technique used, being lower with clinical (413/1276, 32%, 95% CI 30-35%) compared to electrophysiological techniques (749/1591, 47%, 95% CI 45-50%). Approximately a quarter of patients were not able to comply with clinical evaluation and this may be responsible for potential underreporting of this condition.

Interventions for preventing critical illness polyneuropathy and critical illness myopathy

BACKGROUND

Critical illness polyneuropathy or myopathy (CIP/CIM) is a frequent complication in the intensive care unit (ICU) and is associated with prolonged mechanical ventilation, longer ICU stay and increased mortality. This is an interim update of a review first published in 2009 (Hermans 2009). It has been updated to October 2011, with further potentially eligible studies from a December 2013 search characterised as awaiting assessment.

OBJECTIVES

To systematically review the evidence from RCTs concerning the ability of any intervention to reduce the incidence of CIP or CIM in critically ill individuals.

SEARCH METHODS

On 4 October 2011, we searched the Cochrane Neuromuscular Disease Group Specialized Register, CENTRAL, MEDLINE, and EMBASE. We checked the bibliographies of identified trials and contacted trial authors and experts in the field. We carried out an additional search of these databases on 6 December 2013 to identify recent studies.

SELECTION CRITERIA

All randomised controlled trials (RCTs), examining the effect of any intervention on the incidence of CIP/CIM in people admitted to adult medical or surgical ICUs. The primary outcome was the incidence of CIP/CIM in ICU, based on electrophysiological or clinical examination. Secondary outcomes included duration of mechanical ventilation, duration of ICU stay, death at 30 and 180 days after ICU admission and serious adverse events from the treatment regimens.

DATA COLLECTION AND ANALYSIS

Two authors independently extracted the data and assessed the risk of bias in included studies.

MAIN RESULTS

We identified five trials that met our inclusion criteria. Two trials compared intensive insulin therapy (IIT) to conventional insulin therapy (CIT). IIT significantly reduced CIP/CIM in the screened (n = 825; risk ratio (RR) 0.65, 95% confidence interval (CI) 0.55 to 0.77) and total (n = 2748; RR 0.70, 95% CI 0.60 to 0.82) population randomised. IIT reduced duration of mechanical ventilation, ICU stay and 180-day mortality, but not 30-day mortality compared with CIT. Hypoglycaemia increased with IIT but did not cause early deaths.One trial compared corticosteroids with placebo (n = 180). The trial found no effect of treatment on CIP/CIM (RR 1.27, 95% CI 0.77 to 2.08), 180-day mortality, new infections, glycaemia at day seven, or episodes of pneumonia, but did show a reduction of new shock events.In the fourth trial, early physical therapy reduced CIP/CIM in 82/104 evaluable participants in ICU (RR 0.62. 95% CI 0.39 to 0.96). Statistical significance was lost when we performed a full intention-to-treat analysis (RR 0.81, 95% CI 0.60 to 1.08). Duration of mechanical ventilation but not ICU stay was significantly shorter in the intervention group. Hospital mortality was not affected but 30- and 180-day mortality results were not available. No adverse effects were noticed.The last trial found a reduced incidence of CIP/CIM in 52 evaluable participants out of a total of 140 who were randomised to electrical muscle stimulation (EMS) versus no stimulation (RR 0.32, 95% CI 0.10 to 1.01). These data were prone to bias due to imbalances between treatment groups in this subgroup of participants. After we imputed missing data and performed an intention-to-treat analysis, there was still no significant effect (RR 0.94, 95% CI 0.78 to 1.15). The investigators found no effect on duration of mechanical ventilation and noted no difference in ICU mortality, but did not report 30- and 180-day mortality.We updated the searches in December 2013 and identified nine potentially eligible studies that will be assessed for inclusion in the next update of the review.

AUTHORS' CONCLUSIONS

There is moderate quality evidence from two large trials that intensive insulin therapy reduces CIP/CIM, and high quality evidence that it reduces duration of mechanical ventilation, ICU stay and 180-day mortality, at the expense of hypoglycaemia. Consequences and prevention of hypoglycaemia need further study. There is moderate quality evidence which suggests no effect of corticosteroids on CIP/CIM and high quality evidence that steroids do not affect secondary outcomes, except for fewer new shock episodes. Moderate quality evidence suggests a potential benefit of early rehabilitation on CIP/CIM which is accompanied by a shorter duration of mechanical ventilation but without an effect on ICU stay. Very low quality evidence suggests no effect of EMS, although data are prone to bias. Strict diagnostic criteria for CIP/CIM are urgently needed for research purposes. Large RCTs need to be conducted to further explore the role of early rehabilitation and EMS and to develop new preventive strategies.

Interventions for preventing critical illness polyneuropathy and critical illness myopathy

BACKGROUND

Critical illness polyneuropathy or myopathy (CIP/CIM) is a frequent complication in the intensive care unit (ICU) and is associated with prolonged mechanical ventilation, longer ICU stay and increased mortality. This is an interim update of a review first published in 2009 (Hermans 2009). It has been updated to October 2011, with further potentially eligible studies from a December 2013 search characterised as awaiting assessment.

OBJECTIVES

To systematically review the evidence from RCTs concerning the ability of any intervention to reduce the incidence of CIP or CIM in critically ill individuals.

SEARCH METHODS

On 4 October 2011, we searched the Cochrane Neuromuscular Disease Group Specialized Register, CENTRAL, MEDLINE, and EMBASE. We checked the bibliographies of identified trials and contacted trial authors and experts in the field. We carried out an additional search of these databases on 6 December 2013 to identify recent studies.

SELECTION CRITERIA

All randomised controlled trials (RCTs), examining the effect of any intervention on the incidence of CIP/CIM in people admitted to adult medical or surgical ICUs. The primary outcome was the incidence of CIP/CIM in ICU, based on electrophysiological or clinical examination. Secondary outcomes included duration of mechanical ventilation, duration of ICU stay, death at 30 and 180 days after ICU admission and serious adverse events from the treatment regimens.

DATA COLLECTION AND ANALYSIS

Two authors independently extracted the data and assessed the risk of bias in included studies.

MAIN RESULTS

We identified five trials that met our inclusion criteria. Two trials compared intensive insulin therapy (IIT) to conventional insulin therapy (CIT). IIT significantly reduced CIP/CIM in the screened (n = 825; risk ratio (RR) 0.65, 95% confidence interval (CI) 0.55 to 0.77) and total (n = 2748; RR 0.70, 95% CI 0.60 to 0.82) population randomised. IIT reduced duration of mechanical ventilation, ICU stay and 180-day mortality, but not 30-day mortality compared with CIT. Hypoglycaemia increased with IIT but did not cause early deaths.One trial compared corticosteroids with placebo (n = 180). The trial found no effect of treatment on CIP/CIM (RR 1.27, 95% CI 0.77 to 2.08), 180-day mortality, new infections, glycaemia at day seven, or episodes of pneumonia, but did show a reduction of new shock events.In the fourth trial, early physical therapy reduced CIP/CIM in 82/104 evaluable participants in ICU (RR 0.62. 95% CI 0.39 to 0.96). Statistical significance was lost when we performed a full intention-to-treat analysis (RR 0.81, 95% CI 0.60 to 1.08). Duration of mechanical ventilation but not ICU stay was significantly shorter in the intervention group. Hospital mortality was not affected but 30- and 180-day mortality results were not available. No adverse effects were noticed.The last trial found a reduced incidence of CIP/CIM in 52 evaluable participants out of a total of 140 who were randomised to electrical muscle stimulation (EMS) versus no stimulation (RR 0.32, 95% CI 0.10 to 1.01). These data were prone to bias due to imbalances between treatment groups in this subgroup of participants. After we imputed missing data and performed an intention-to-treat analysis, there was still no significant effect (RR 0.94, 95% CI 0.78 to 1.15). The investigators found no effect on duration of mechanical ventilation and noted no difference in ICU mortality, but did not report 30- and 180-day mortality.We updated the searches in December 2013 and identified nine potentially eligible studies that will be assessed for inclusion in the next update of the review.

AUTHORS' CONCLUSIONS

There is moderate quality evidence from two large trials that intensive insulin therapy reduces CIP/CIM, and high quality evidence that it reduces duration of mechanical ventilation, ICU stay and 180-day mortality, at the expense of hypoglycaemia. Consequences and prevention of hypoglycaemia need further study. There is moderate quality evidence which suggests no effect of corticosteroids on CIP/CIM and high quality evidence that steroids do not affect secondary outcomes, except for fewer new shock episodes. Moderate quality evidence suggests a potential benefit of early rehabilitation on CIP/CIM which is accompanied by a shorter duration of mechanical ventilation but without an effect on ICU stay. Very low quality evidence suggests no effect of EMS, although data are prone to bias. Strict diagnostic criteria for CIP/CIM are urgently needed for research purposes. Large RCTs need to be conducted to further explore the role of early rehabilitation and EMS and to develop new preventive strategies.

Global muscle strength but not grip strength predicts mortality and length of stay in a general population in a surgical intensive care unit

BACKGROUND

Paresis acquired in the intensive care unit (ICU) is common in patients who are critically ill and independently predicts mortality and morbidity. Manual muscle testing (MMT) and handgrip dynamometry assessments have been used to evaluate muscle weakness in patients in a medical ICU, but similar data for patients in a surgical ICU (SICU) are limited.

OBJECTIVE

The purpose of this study was to evaluate the predictive value of strength measured by MMT and handgrip dynamometry at ICU admission for in-hospital mortality, SICU length of stay (LOS), hospital LOS, and duration of mechanical ventilation.

DESIGN

This investigation was a prospective, observational study.

METHODS

One hundred ten patients were screened for eligibility for testing in the SICU of a large, academic medical center. The Acute Physiology and Chronic Health Evaluation (APACHE) II score, diagnoses, and laboratory data were collected. Measurements were obtained by MMT quantified with the sum (total) score on the Medical Research Council Scale and by handgrip dynamometry. Outcome data, including in-hospital mortality, SICU LOS, hospital LOS, and duration of mechanical ventilation, were collected for all participants.

RESULTS

One hundred seven participants were eligible for testing; 89% were tested successfully at a median of 3 days (25th-75th percentiles=3-6 days) after admission. Sedation was the most frequent barrier to testing (70.6%). Manual muscle testing was identified as an independent predictor of mortality, SICU LOS, hospital LOS, and duration of mechanical ventilation. Grip strength was not independently associated with these outcomes.

LIMITATIONS

This study did not address whether muscle weakness translates to functional outcome impairment.

CONCLUSIONS

In contrast to handgrip strength, MMT reliably predicted in-hospital mortality, duration of mechanical ventilation, SICU LOS, and hospital LOS.

Is critical illness neuromyopathy and duration of mechanical ventilation decreased by strict glucose control?

Strict glycemic control (SGC) is reported to have a beneficial effect on critical illness polyneuropathy/myopathy (CINM) and the duration of mechanical ventilation. The methodology used to diagnose CINM differs substantially in studies on this topic. This may influence the reported treatment effect. We reviewed literature on the effect of SGC on CINM and duration of ventilation by conducting a OVID Medline systematic electronic search of literature describing effects of SGC on occurrence of CINM and the effect of SGC on the duration of mechanical ventilation. A beneficial effect of SGC on CINM, diagnosed by needle myography, was reported in three studies. One of these studies showed that the incidence of weakness or failure to wean did not decrease by SGC, as the number of electrophysiological studies (EMG) ordered for these problems remained the same. Another study reported no improvement of muscle strength due to SGC. SGC reduced the duration of mechanical ventilation in three studies while six other studies did not report this beneficial effect. SGC seems to have a beneficial effect on CINM, but the reported risk reduction is likely to be an overestimation of the treatment effect due to the diagnostic methods used. Duration of mechanical ventilation may not be a reliable surrogate marker for CINM and a beneficial effect of SGC on this parameter has not been proven. We propose to use the recently developed diagnostic criteria for ICU-acquired weakness and critical illness neuromyopathy in future studies.

Increased Vitamin B12 levels are associated with mortality in critically ill medical patients

BACKGROUND & AIMS

We describe an observational study in critically ill medical patients showing the association between serum Vitamin B12 levels measured on or near admission and the outcome in these patients.

METHODS

We used the database of patients admitted to the Medical Intensive Care Unit (MICU) at the Hadassah-Hebrew University Medical Center in Jerusalem, Israel, to analyze associations between patient demographics, background, diagnoses and serum Vitamin B12 levels with hospital and 90 day outcomes.

RESULTS

Higher mean Vitamin B12 levels were found in patients who did not survive their hospital stay (1719 pg/ml vs 1003 pg/ml, p < 0.01). Those who had died by 90 days after admission to the MICU also had higher Vitamin B12 levels than survivors (1593 pg/ml vs 990 pg/ml). Regression analysis showed that elevated Vitamin B12 levels were associated with increased 90 day mortality, even after controlling for other variables. Survival analysis also showed an increased mortality rate in patients with Vitamin B12 levels over 900 pg/ml (p < 0.0002).

CONCLUSIONS

Our data show that high serum Vitamin B12 levels are associated with increased mortality in critically ill medical patients. We suggest that Vitamin B12 levels should be included in the work-up of all medical intensive care patients, particularly those with a chronic health history and increased severity of illness.

Muscle membrane dysfunction in critical illness myopathy assessed by velocity recovery cycles

OBJECTIVE

To test the hypothesis that muscle fibers are depolarized in patients with critical illness myopathy by measuring velocity recovery cycles (VRCs) of muscle action potentials.

METHODS

VRCs were recorded from brachioradialis muscle by direct muscle stimulation in 10 patients in intensive care with evidence of critical illness myopathy (CIM). Two sets of recordings were made, mean 3.9 d apart, and compared with those from 10 age-matched controls.

RESULTS

Muscle supernormality was reduced in the patients by 50% compared with controls (P<0.002) and relative refractory period was increased by 59% (P<0.01). Supernormality was correlated with plasma potassium levels (R=-0.753, P<0.001), and the slope of this relationship was much steeper than previously reported for non-critically ill patients with renal failure (P<0.01).

CONCLUSIONS

The abnormal excitability properties indicate that the muscle fibers in CIM were depolarized, and/or that sodium channel inactivation was increased. The heightened sensitivity to potassium is consistent with the hypothesis that an endotoxin reduces sodium channel availability in depolarized muscle fibers.

SIGNIFICANCE

VRCs provide a practicable means to monitor muscle membrane changes in intensive care and to investigate the pathogenesis of CIM.