Skeletal Muscle Myokine Expression in Critical Illness, Association With Outcome and Impact of Therapeutic Interventions

Context

Muscle expresses and secretes several myokines that bring about benefits in distant organs.

Objective

We investigated the impact of critical illness on muscular expression of irisin, kynurenine aminotransferases, and amylase; association with clinical outcome; and impact of interventions that attenuate muscle wasting/weakness.

Methods

We studied critically ill patients who participated in 2 randomized controlled trials (EPaNIC/NESCI) and documented time profiles in critically ill mice. Included in the study were 174 intensive care unit (ICU) patients (day 8 ± 1) vs 19 matched controls, and 60 mice subjected to surgery/sepsis vs 60 pair-fed healthy mice. Interventions studied included 7-day neuromuscular electrical stimulation (NMES), and withholding parenteral nutrition (PN) in the first ICU week (late PN) vs early PN. The main outcome measures were FNDC5 (irisin- precursor), KYAT1, KYAT3, and amylase mRNA expression in skeletal muscle.

Results

Critically ill patients showed 34% to 80% lower mRNA expression of FNDC5, KYAT1, and amylases than controls (P < .0001). Critically ill mice showed time-dependent reductions in all mRNAs compared with healthy mice (P ≤ .04). The lower FNDC5 expression in patients was independently associated with a higher ICU mortality (P = .015) and ICU-acquired weakness (P = .012), whereas the lower amylase expression in ICU survivors was independently associated with a longer ICU stay (P = .0060). Lower amylase expression was independently associated with a lower risk of death (P = .048), and lower KYAT1 expression with a lower risk of weakness (P = .022). NMES increased FNDC5 expression compared with unstimulated muscle (P = .016), and late PN patients had a higher KYAT1 expression than early PN patients (P = .022).

Conclusion

Expression of the studied myokines was affected by critical illness and associated with clinical outcomes, with limited effects of interventions that attenuate muscle wasting or weakness.

Recognition and diagnosis of acute type A aortic dissection in a large Belgian referral center – can we do better?

Background: Acute type A aortic dissection (ATAAD) has a poor prognosis unless promptly diagnosed and surgically treated. As ATAAD is relatively rare and clinical presentation may mimic other pathologies, diagnosis can be challenging. Objectives: The aim of this study is to evaluate the difficulties in diagnosing ATAAD. Methods: A monocentric, retrospective analysis was conducted of all patients undergoing surgical repair for acute type A aortic dissection in our hospital (a large Belgian referral center) between the 1st of January 2016 and the 31st of December 2020. Data were collected regarding patient’s demographics i.e. age and gender, time of first medical contact, referral from other hospitals, presenting symptoms, initial diagnosis, inappropriate antiplatelet or antithrombotic therapy, time to the correct diagnosis, time to initiate surgical repair, and one- year mortality. Results: Thirty-three patients were included. We found that a correct initial diagnosis was only made in twelve percent of patients with ATAAD. In twenty-one percent of patients, misdiagnoses led to inappropriate administration of antiplatelet or antithrombotic drugs pre-operatively. There was a difference in time from first medical contact to initiation of surgical repair between referred and non-referred patients. This time interval tended to be shorter in the latter group. Conclusions: The main finding of this analysis is the delayed diagnosis of ATAAD in the majority of patients. This trend is slightly higher in patients referred from other hospitals. To improve outcome in ATAAD, efforts should be made to increase awareness for the presenting symptoms, and appropriate diagnostic imaging should be performed in a timely manner.

Early neuromuscular electrical stimulation reduces the loss of muscle mass in critically ill patients - A within subject randomized controlled trial

PURPOSE

To investigate the effect of Neuromuscular Electrical Stimulation (NMES) on muscle thickness, strength and morphological and molecular markers of the quadriceps.

MATERIALS AND METHODS

Adult critically ill patients with an expected prolonged stay received unilateral quadriceps NMES sessions for 7 consecutive days. Before and after the intervention period, quadriceps thickness was measured with ultrasound. After the intervention period, strength was assessed in cooperative patients and muscle biopsies were taken. Multivariable regression was performed to identify factors affecting muscle thickness loss.

RESULTS

Muscle thickness decreased less in the stimulated leg (-6 ± 16% versus -12 ± 15%, p = 0.014, n = 47). Strength was comparable. Opioid administration, minimal muscle contraction and more muscle thickness loss in the non-stimulated muscle were independently associated with better muscle thickness preservation. Stimulated muscles showed a shift towards larger myofibers and higher MyHC-I gene expression. NMES did not affect gene expression of other myofibrillary proteins, MuRF-1 or atrogin-1. Signs of myofiber necrosis and inflammation were comparable for both muscles.

CONCLUSIONS

NMES attenuated the loss of muscle mass, but not of strength, in critically ill patients. Preservation of muscle mass was more likely in patients receiving opioids, patients with a minimal muscle contraction during NMES and patients more prone to lose muscle mass.

TRIAL REGISTRATION

clinicaltrials.govNCT02133300.

Early mobilization in clinical practice: the reliability and feasibility of the 'Start To Move' Protocol

PURPOSE

The properties of a local Intensive Care Unit early mobilization protocol ('Start To Move As Soon As Possible') in critically ill patients, consisting of an objective diagnostic assessment linked to six treatment levels were evaluated. This study aimed to investigate whether the protocol can be reliably applied by different health-care providers (reliability), to examine the associations between prescribed and delivered treatments (feasibility) and to explore safety and patient satisfaction with the protocol.

METHODS

Cross-sectional observational study evaluating the reliability of the protocol between physiotherapist was evaluated with Cohen's kappa, percentage of agreement, and intraclass correlation coefficients in 61 patients. Feasibility was analyzed as agreement between prescribed and delivered treatments with Spearman's rank correlation coefficients in 60 patients. A satisfaction survey was used to evaluate patient satisfaction with the protocol.

RESULTS

Excellent agreement was observed between physiotherapists for diagnostic level assignment (Kappa = 0.92), while the majority of the treatment proposals per level showed moderate to substantial agreement between the physiotherapists (Kappa range: 0.40-0.89). Three hundred and thirteen treatments were prescribed. Perfect agreement was observed between prescribed and delivered treatments in level 0 (Spearman's rho 1.00) and excellent associations for levels 1-5 (0.941, 0.995, 0.951, 0.998, and 0.999), respectively. Unwanted safety events rate was 3%. Most patients (92%) were very satisfied with physiotherapy.

CONCLUSION

Excellent inter-rater agreement for diagnostic level assignment and moderate to substantial agreement for proposed treatments support the reliability of the protocol. Perfect to excellent associations between prescribed and delivered treatments supports its feasibility. Complications were rare, and most patients were very positive regarding the care provided by physiotherapists during their stay in the ICU.

Markov Tail Chains

The extremes of a univariate Markov chain with regularly varying stationary marginal distribution and asymptotically linear behavior are known to exhibit a multiplicative random walk structure called the tail chain. In this paper we extend this fact to Markov chains with multivariate regularly varying marginal distributions inRd. We analyze both the forward and the backward tail process and show that they mutually determine each other through a kind of adjoint relation. In a broader setting, we will show that even for non-Markovian underlying processes a Markovian forward tail chain always implies that the backward tail chain is also Markovian. We analyze the resulting class of limiting processes in detail. Applications of the theory yield the asymptotic distribution of both the past and the future of univariate and multivariate stochastic difference equations conditioned on an extreme event.

Heat and emergency room admissions in the Netherlands

Background

Due to a global warming-related increase in heatwaves, it is important to obtain detailed understanding of the relationship between heat and health. We assessed the relationship between heat and urgent emergency room admissions in the Netherlands.

Methods

We collected daily maximum temperature and relative humidity data over the period 2002–2007. Daily urgent emergency room admissions were divided by sex, age group and disease category. We used distributed lag non-linear Poisson models, estimating temperature-admission associations. We estimated the relative risk (RR) for urgent hospital admissions for a range of temperatures compared to a baseline temperature of 21 °C. In addition, we compared the impact of three different temperature scenarios on admissions using the RR.

Results

There is a positive relationship between increasing temperatures above 21 °C and the RR for urgent emergency room admissions for the disease categories ‘Potential heat-related diseases’ and ‘Respiratory diseases’. This relationship is strongest in the 85+ group. The RRs are strongest for lag 0. For admissions for ‘circulatory diseases’, there is only a small significant increase of RRs within the 85+ age group for moderate heat, but not for extreme heat. The RRs for a one-day event with extreme heat are comparable to the RRs for multiple-day events with moderate heat.

Conclusions

Hospitals should adjust the capacity of their emergency departments on warm days, and the days immediately thereafter. The elderly in particular should be targeted through prevention programmes to reduce harmful effects of heat. The fact that this increase in admissions already occurs in temperatures above 21 °C is different from previous findings in warmer countries. Given the similar impact of three consecutive days of moderate heat and one day of extreme heat on admissions, criteria for activation of national heatwave plans need adjustments based on different temperature scenarios.

Electronic supplementary material

The online version of this article (10.1186/s12889-017-5021-1) contains supplementary material, which is available to authorized users.

Rare events, temporal dependence, and the extremal index

Classical extreme value theory for stationary sequences of random variables can to a large extent be paraphrased as the study of exceedances over a high threshold. A special role within the description of the temporal dependence between such exceedances is played by the extremal index. Parts of this theory can be generalized not only to random variables on an arbitrary state space hitting certain failure sets, but even to a triangular array of rare events on an abstract probability space. In the case of M4 (maxima of multivariate moving maxima) processes, the arguments take a simple and direct form.

Functionals of clusters of extremes

For arbitrary stationary sequences of random variables satisfying a mild mixing condition, distributional approximations are established for functionals of clusters of exceedances over a high threshold. The approximations are in terms of the distribution of the process conditionally on the event that the first variable exceeds the threshold. This conditional distribution is shown to converge to a nontrivial limit if the finite-dimensional distributions of the process are in the domain of attraction of a multivariate extreme-value distribution. In this case, therefore, limit distributions are obtained for functionals of clusters of extremes, thereby generalizing results for higher-order stationary Markov chains by Yun (2000).

Feasibility of neuromuscular electrical stimulation in critically ill patients

OBJECTIVE

Critically ill patients often develop intensive care unit-acquired weakness. Reduction in muscle mass and muscle strength occurs early after admission to the intensive care unit (ICU). Although early active muscle training could attenuate this intensive care unit-acquired weakness, in the early phase of critical illness, a large proportion of patients are unable to participate in any active mobilization. Neuromuscular electrical stimulation (NMES) could be an alternative strategy for muscle training. The aim of this study was to investigate the safety and feasibility of NMES in critically ill patients.

DESIGN

This is an observational study.

SETTING

The setting is in the medical and surgical ICUs of a tertiary referral university hospital.

PATIENTS

Fifty patients with a prognosticated prolonged stay of at least 6 days were included on day 3 to 5 of their ICU stay. Patients with preexisting neuromuscular disorders and patients with musculoskeletal conditions limiting quadriceps contraction were excluded.

INTERVENTION

Twenty-five minutes of simultaneous bilateral NMES of the quadriceps femoris muscle. This intervention was performed 5 days per week (Monday-Friday). Effective muscle stimulation was defined as a palpable and visible contraction (partial or full muscle bulk).

MEASUREMENTS

The following parameters, potentially affecting contraction upon NMES, were assessed: functional status before admission to the ICU (Barthel index), type and severity of illness (Acute Physiology And Chronic Health Evaluation II score and sepsis), treatments possibly influencing the muscle contraction (corticosteroids, vasopressors, inotropes, aminoglycosides, and neuromuscular blocking agents), level of consciousness (Glasgow Coma Scale, score on 5 standardized questions evaluating awakening, and sedation agitation scale), characteristics of stimulation (intensity of the NMES, number of sessions per patient, and edema), and neuromuscular electrophysiologic characteristics. Changes in heart rate, blood pressure, oxygen saturation, respiratory rate, and skin reactions were registered to assess the safety of the technique.

RESULTS

In 50% of the patients, an adequate quadriceps contraction was obtained in at least 75% of the NMES sessions. Univariate analysis showed that lower limb edema (P<.001), sepsis (P=.008), admission to the medical ICU (P=.041), and treatment with vasopressors (P=.011) were associated with impaired quadriceps contraction. A backward multivariate analysis identified presence of sepsis, lower limb edema, and use of vasopressors as independent predictors of impaired quadriceps contraction (R2=59.5%). Patients responded better to NMES in the beginning of their ICU stay in comparison with after 1 week of ICU stay. There was no change in any of the safety end points with NMES.

CONCLUSIONS

Critically ill patients having sepsis, edema, or receiving vasopressors were less likely to respond to NMES with an adequate quadriceps contraction. Neuromuscular electrical stimulation is a safe intervention to be administered in the ICU.

Interobserver agreement of Medical Research Council sum-score and handgrip strength in the intensive care unit

INTRODUCTION

Muscle weakness often complicates critical illness and is associated with devastating short- and long-term consequences. For interventional studies, reliable measurements of muscle force in the intensive care unit (ICU) are needed.

METHODS

To examine interobserver agreement, two observers independently measured Medical Research Council (MRC) sum-score (n = 75) and handgrip strength (n = 46) in a cross-sectional ICU sample.

RESULTS

The intraclass correlation coefficient (ICC) for MRC sum-score was 0.95 (0.92-0.97). The kappa coefficient for identifying "significant weakness" (MRC sum-score <48, MRC subtotal upper limbs <24) and "severe weakness" (MRC sum-score <36) was 0.68 ± 0.09, 0.88 ± 0.07, and 0.93 ± 0.07, respectively. The ICC for left and right handgrip strength was 0.97 (0.94-0.98) and 0.93 (0.86-0.97), respectively.

CONCLUSIONS

Interobserver agreement on MRC sum-score and handgrip strength in the ICU was very good. Agreement on "severe weakness" (MRC sum-score <36) was excellent and supports its use in interventional studies. Agreement on "significant weakness" (MRC sum-score <48) was good, but even better using the equivalent cut-off in the upper limbs. It remains to be determined whether this may serve as a substitute.

Impact of inspiratory muscle training in patients with COPD: what is the evidence?

A meta-analysis including 32 randomised controlled trials on the effects of inspiratory muscle training (IMT) in chronic obstructive pulmonary disease (COPD) patients was performed. Overall and subgroup analyses with respect to training modality (strength or endurance training, added to general exercise training) and patient characteristics were performed. Significant improvements were found in maximal inspiratory muscle strength (P(I,max); +13 cmH₂O), endurance time (+261 s), 6- or 12-min walking distance (+32 and +85 m respectively) and quality of life (+3.8 units). Dyspnoea was significantly reduced (Borg score -0.9 point; Transitional Dyspnoea Index +2.8 units). Endurance exercise capacity tended to improve, while no effects on maximal exercise capacity were found. Respiratory muscle endurance training revealed no significant effect on P(I,max), functional exercise capacity and dyspnoea. IMT added to a general exercise programme improved P(I,max) significantly, while functional exercise capacity tended to increase in patients with inspiratory muscle weakness (P(I,max) <60 cmH₂O). IMT improves inspiratory muscle strength and endurance, functional exercise capacity, dyspnoea and quality of life. Inspiratory muscle endurance training was shown to be less effective than respiratory muscle strength training. In patients with inspiratory muscle weakness, the addition of IMT to a general exercise training program improved P(I,max) and tended to improve exercise performance.