Dysfunction of respiratory muscles in critically ill patients on the intensive care unit

Effects of different masks on diaphragm motion in OSAS patients undergoing CPAP: results from an ultrasound-based proof of concept study

PURPOSE

Obstructive sleep apnea (OSA) is characterized by recurrent upper airway narrowing or collapse during sleep. Continuous positive airway pressure (CPAP) remains the preferred treatment in selected patients and masks' choice plays an important role for subsequent respiratory events' reduction. It is known that oronasal masks are not as effective at opening the upper airway compared to nasal ones. Thus, the objective of this study was to investigate differences in US-assessed diaphragmatic excursion (DE) using oronasal vs. nasal CPAP masks.

METHODS

This observational study included 50 OSA patients presenting a moderate to severe apnea-hypopnea index and requiring CPAP treatment. All participants received US evaluations on diaphragm motion during their oronasal and nasal CPAP trial at equal positive end-expiratory pressure level.

RESULTS

The difference of DE switching mask during CPAP was assessed by using the non-parametric Wilcoxon signed-rank test. A statistically significant increase in US- assessed DE was found when shifting from oronasal to nasal mask (p-value < 0.01). Linear regression models revealed that increased neck circumference and more severe AHI were associated with decreased DE when shifting to an oronasal mask.

CONCLUSION

This study evaluated the acute impact on US-assessed DE after changing CPAP route from oronasal to nasal mask. Our results suggest that the nasal type should be the more suitable option for most patients with OSA, especially those with higher nasal circumference. Diaphragmatic motion throughout US may become a practical tool to help in the choice of the fittest mask in patients undergoing CPAP.

β-hydroxybutyrate exposure restores mitochondrial function in skeletal muscle satellite cells of critically ill patients

BACKGROUND & AIM

Dysfunction of skeletal muscle satellite cells might impair muscle regeneration and prolong ICU-acquired weakness, a condition associated with disability and delayed death. This study aimed to elucidate the distinct metabolic effects of critical illness and β-OH-butyrate on satellite cells isolated from these patients.

METHODS

Satellite cells were extracted from vastus lateralis muscle biopsies of patients with ICU-acquired weakness (n = 10) and control group of healthy volunteers or patients undergoing elective hip replacement surgery (n = 10). The cells were exposed to standard culture media supplemented with β-OH-butyrate to assess its influence on cell proliferation by ELISA, mitochondrial functions by extracellular flux analysis, electron transport chain complexes by high resolution respirometry, and ROS production by confocal microscopy.

RESULTS

Critical illness led to a decline in maximal respiratory capacity, ATP production and glycolytic capacity and increased ROS production in ICU patients' cells. Notably, the function of complex II was impaired due to critical illness but restored to normal levels upon exposure to β-OH-butyrate. While β-OH-butyrate significantly reduced ROS production in both control and ICU groups, it had no significant impact on global mitochondrial functions.

CONCLUSION

Critical illness induces measurable bioenergetic dysfunction of skeletal muscle satellite cells. β-OH-butyrate displayed a potential in rectifying complex II dysfunction caused by critical illness and this warrants further exploration.

Physical and Cognitive Impairment in Acute Respiratory Failure

Recent research has brought renewed attention to the multifaceted physical and cognitive dysfunction that accompanies acute respiratory failure (ARF). This state-of-the-art review provides an overview of the evidence landscape encompassing ARF-associated neuromuscular and neurocognitive impairments. Risk factors, mechanisms, assessment tools, rehabilitation strategies, approaches to ventilator liberation, and interventions to minimize post-intensive care syndrome are emphasized. The complex interrelationship between physical disability, cognitive dysfunction, and long-term patient-centered outcomes is explored. This review highlights the need for comprehensive, multidisciplinary approaches to mitigate morbidity and accelerate recovery.

A Predictive Nomogram for Intensive Care-Acquired Weakness after Cardiopulmonary Bypass

PURPOSE

Intensive care unit-acquired weakness (ICUAW) affects patient prognosis after cardiopulmonary bypass (CPB) surgery, but its risk factors remain unclear. We investigated these risk factors and developed a nomogram for predicting ICUAW after CPB.

METHODS

Baseline characteristics, preoperative laboratory data, and intra- and postoperative variables of 473 patients after CPB were determined in this prospective cohort study. Lower limb muscles on bedside ultrasound images were compared 1 day before and 7 days after CPB. Risk factors were assessed using logistic regression models.

RESULTS

Approximately 50.95% of the patients developed ICUAW after CPB. The body mass index (BMI), New York Heart Association (NYHA) class, lactate, albumin, aortic clamping time, operation time, and acute physiological and chronic health evaluation II were determined as independent risk factors. The average absolute error of coincidence was 0.019; the area under the curve, sensitivity, and specificity were 0.811, 0.727, and 0.733, respectively, for the predictive nomogram.

CONCLUSION

A high BMI, poor NYHA class, preoperative high serum lactate, low serum albumin, long surgical duration, aortic clamping, and high acute physiological and chronic health evaluation II score are risk factors for ICUAW after CPB. This robust and easy-to-use nomogram was developed for clinical decision-making.

Ultrasonographic Features of Muscular Weakness and Muscle Wasting in Critically Ill Patients

Muscle wasting begins as soon as in the first week of one's ICU stay and patients with multi-organ failure lose more muscle mass and suffer worse functional impairment as a consequence. Muscle wasting and weakness are mainly characterized by a generalized, bilateral lower limb weakness. However, the impairment of the respiratory and/or oropharyngeal muscles can also be observed with important consequences for one's ability to swallow and cough. Muscle wasting represents the result of the disequilibrium between breakdown and synthesis, with increased protein degradation relative to protein synthesis. It is worth noting that the resulting functional disability can last up to 5 years after discharge, and it has been estimated that up to 50% of patients are not able to return to work during the first year after ICU discharge. In recent years, ultrasound has played an increasing role in the evaluation of muscle. Indeed, ultrasound allows an objective evaluation of the cross-sectional area, the thickness of the muscle, and the echogenicity of the muscle. Furthermore, ultrasound can also estimate the thickening fraction of muscle. The objective of this review is to analyze the current understanding of the pathophysiology of acute skeletal muscle wasting and to describe the ultrasonographic features of normal muscle and muscle weakness.

Advancing healthcare through thoracic ultrasound research in older patients

This paper reports the proceedings of a meeting convened by the Research Group on Thoracic Ultrasound in Older People of the Italian Society of Gerontology and Geriatrics, to discuss the current state-of-the-art of clinical research in the field of geriatric thoracic ultrasound and identify unmet research needs and potential areas of development. In the last decade, point-of-care thoracic ultrasound has entered clinical practice for diagnosis and management of several respiratory illnesses, such as bacterial and viral pneumonia, pleural effusion, acute heart failure, and pneumothorax, especially in the emergency-urgency setting. Very few studies, however, have been specifically focused on older patients with frailty and multi-morbidity, who frequently exhibit complex clinical pictures needing multidimensional evaluation. At the present state of knowledge, there is still uncertainty on the best requirements of ultrasound equipment, methodology of examination, and reporting needed to optimize the advantages of thoracic ultrasound implementation in the care of geriatric patients. Other issues regard differential diagnosis between bacterial and aspiration pneumonia, objective grading of interstitial syndrome severity, quantification and monitoring of pleural effusions and solid pleural lesions, significance of ultrasonographic assessment of post-COVID-19 sequelae, and prognostic value of assessment of diaphragmatic thickness and motility. Finally, application of remote ultrasound diagnostics in the community and nursing home setting is still poorly investigated by the current literature. Overall, the presence of several open questions on geriatric applications of thoracic ultrasound represents a strong call to implement clinical research in this field.

Electrical stimulation mitigates muscle degradation shift in gene expressions during 12-h mechanical ventilation

Ventilator-induced diaphragm dysfunction (VIDD), a dysfunction of the diaphragm muscle caused by prolonged mechanical ventilation (MV), is an important factor that hinders successful weaning from ventilation. We evaluated the effects of electrical stimulation of the diaphragm muscle (pulsed current with off-time intervals) on genetic changes during 12 h of MV (E-V12). Rats were divided into four groups: control, 12-h MV, sham operation, and E-V12 groups. Transcriptome analysis using an RNA microarray revealed that 12-h MV caused upregulation of genes promoting muscle atrophy and downregulation of genes facilitating muscle synthesis, suggesting that 12-h MV is a reasonable method for establishing a VIDD rat model. Of the genes upregulated by 12-h MV, 18 genes were not affected by the sham operation but were downregulated by E-V12. These included genes related to catabolic processes, inflammatory cytokines, and skeletal muscle homeostasis. Of the genes downregulated by 12-h MV, 6 genes were not affected by the sham operation but were upregulated by E-V12. These included genes related to oxygen transport and mitochondrial respiration. These results suggested that 12-h MV shifted gene expression in the diaphragm muscle toward muscle degradation and that electrical stimulation counteracted this shift by suppressing catabolic processes and increasing mitochondrial respiration.

Prediction of Weaning Outcome from Mechanical Ventilation Using Ultrasound Assessment of Parasternal Intercostal Muscle Thickness

Background

Monitoring the function of parasternal intercostal muscles provides information on respiratory load and capacity and thus can be a weaning monitoring tool.

Objective

The goal was to study the diagnostic accuracy of parasternal intercostal muscle thickness fraction (PICTF%) as a predictor of weaning.

Materials and methods

A prospective observational study on consecutively admitted patients who were intubated and mechanically ventilated for a duration of at least 48 hours was carried out. When an SBT was planned by the treating physician, the study examiner performed the ultrasound measurements of parasternal intercostal muscle thickness (inspiration and expiration) and thickening fraction using M-mode ultrasonography (USG). The PICTF% was calculated as "(peak inspiratory thickness - end-expiratory thickness)/end-expiratory thickness) × 100." Weaning failure was defined if the patient had a failed spontaneous breathing trial (SBT) or the need for a reintubation within 48 hours following extubation. The SBT failure was defined as the need to connect the patient back to the ventilator prior to its completion due to any reason as decided by the clinician.

Results

Of 81 screened patients, 60 patients met the inclusion criteria, of whom 49 patients had successful SBT, and 48 patients could be successfully extubated. The PMTF% cut-off value more than or equal to 15.38% was associated with the best sensitivity (75%) and specificity (87.8%) in predicting extubation failure.

Conclusion

The PICTF% has a good diagnostic accuracy in predicting weaning failure.

How to cite this article

Ramaswamy A, Kumar R, Arul M, Ish P, Madan M, Gupta NK, et al. Prediction of Weaning Outcome from Mechanical Ventilation Using Ultrasound Assessment of Parasternal Intercostal Muscle Thickness. Indian J Crit Care Med 2023;27(10):704-708.

Respiratory Musculature Evaluated by Computed Tomography in the Setting of Prolonged Mechanical Ventilation

BACKGROUND

Diaphragm atrophy has been observed in subjects who undergo invasive mechanical ventilation. We propose a new method to assess for respiratory muscle (RM) changes in subjects who undergo invasive mechanical ventilation by assessing for changes in respiratory muscles through computed tomography (CT).

METHODS

A retrospective case series study was conducted on subjects who underwent invasive mechanical ventilation and received at least 2 chest CT scans during admission. Exclusion criteria included history of chronic mechanical ventilation dependence and neuromuscular disease. Respiratory muscle cross-sectional area (CSA) was measured at the T6 vertebrae.

RESULTS

Fourteen subjects were included: mean (± SD) age, BMI, and admission APACHE II scores were 54.0 y (± 14.9), 32.6 kg/m2 (± 10.9), and 23.5 (± 6.0), respectively. Ten (71%) subjects were male. Mean length of time between CT chest scans was 7.5 d (± 3.3). Mean duration of invasive mechanical ventilation was 4.5 d (± 3.4). The percentage change in TM CSA among those who underwent invasive mechanical ventilation was 10.5% (± 6.1).

CONCLUSIONS

We demonstrated that serial analysis of respiratory muscle CSA through CT chest scans can be a method to assess for respiratory muscle atrophy in subjects undergoing mechanical ventilation. Future prospective studies involving larger populations are needed to better understand how this method can be used to predict outcomes in mechanically ventilated patients.

Undernutrition and 60-day mortality in critically ill children with respiratory failure: a prospective cohort study

BACKGROUND

To determine whether undernutrition affects 60-day mortality in pediatric acute respiratory failure.

METHODS

Subjects with acute respiratory failure aged between two months and 13 years were included in the study. The Z-scores were calculated on admission and children were categorized into two groups of undernutrition and normal nutrition. The nutritional intake of the children was measured daily. The outcome was 60-day mortality.

RESULTS

A total of 126 patients met the inclusion criteria; 41% were undernourished based on the Z-score of BMI and weight for height, 50% based on the Z-score of height and length for age and 45% based on the Z-score of weight for age. Overall, the 60-day mortality rate was 27.8%. The Cox regression analysis adjusted with PIM2, age and gender, showed that undernutrition has a significant relationship with 60-day mortality based on the weight for age Z-score (HR = 2.33; CI: 1.175-4.638). In addition, undernutrition has a significant relationship with 60-day mortality based on the BMI for age (HR = 3.04; CI:1.070-8.639) and weight for height (HR = 2.62; CI: 1.605-6.658) Z-scores. The mean calorie and protein intake of 72% of the children was less than 80% of their calorie needs. The time to start feeding in 63% of the children was more than 48 h. There was no relationship between the time of starting nutrition and nutritional intake during PICU admission and mortality.

CONCLUSION

Undernutrition is prevalent in mechanically ventilated children in the PICU and may be associated with 60-day mortality.

First non-invasive magnetic phrenic nerve and diaphragm stimulation in anaesthetized patients: a proof-of-concept study

BACKGROUND

Mechanical ventilation has side effects such as ventilator-induced diaphragm dysfunction, resulting in prolonged intensive care unit length of stays. Artificially evoked diaphragmatic muscle contraction may potentially maintain diaphragmatic muscle function and thereby ameliorate or counteract ventilator-induced diaphragm dysfunction. We hypothesized that bilateral non-invasive electromagnetic phrenic nerve stimulation (NEPNS) results in adequate diaphragm contractions and consecutively in effective tidal volumes.

RESULTS

This single-centre proof-of-concept study was performed in five patients who were 30 [IQR 21-33] years old, 60% (n = 3) females and undergoing elective surgery with general anaesthesia. Following anaesthesia and reversal of muscle relaxation, patients received bilateral NEPNS with different magnetic field intensities (10%, 20%, 30%, 40%); the stimulation was performed bilaterally with dual coils (connected to one standard clinical magnetic stimulator), specifically designed for bilateral non-invasive electromagnetic nerve stimulation. The stimulator with a maximal output of 2400 Volt, 160 Joule, pulse length 160 µs at 100% intensity was limited to 50% intensity, i.e. each single coil had a maximal output of 0.55 Tesla and 1200 Volt. There was a linear relationship between dosage (magnetic field intensity) and effect (tidal volume, primary endpoint, p < 0.001). Mean tidal volume was 0.00, 1.81 ± 0.99, 4.55 ± 2.23 and 7.43 ± 3.06 ml/kg ideal body weight applying 10%, 20%, 30% and 40% stimulation intensity, respectively. Mean time to find an initial adequate stimulation point was 89 (range 15-441) seconds.

CONCLUSIONS

Bilateral non-invasive electromagnetic phrenic nerve stimulation generated a tidal volume of 3-6 ml/kg ideal body weight due to diaphragmatic contraction in lung-healthy anaesthetized patients. Further perspectives in critically ill patients should include assessment of clinical outcomes to confirm whether diaphragm contraction through non-invasive electromagnetic phrenic nerve stimulation potentially ameliorates or prevents diaphragm atrophy.

Reliability and feasibility of skeletal muscle ultrasound in the acute burn setting

OBJECTIVES

Despite the impact of muscle wasting after burn, tools to quantify muscle wasting are lacking. This multi-centre study examined the utility of ultrasound to measure muscle mass in acute burn patients comparing different methodologies.

METHODS

B-mode ultrasound was used by two raters to determine feasibility and inter-rater reliability in twenty burned adults following admission. Quadriceps muscle layer thickness (QMLT) and rectus femoris cross-sectional area (RF-CSA) were measured, comparing the use of i) a single versus average measurements, ii) a proximal versus distal location for QMLT, and iii) a maximum- versus no-compression technique for QMLT.

RESULTS

Analysis of twenty burned adults (50 years [95%CI 42-57], 32%TBSA [95%CI 23-40]) yielded ICCs of> 0.97 for QMLT (for either location and compression technique) and> 0.95 for RF-CSA, using average measurements. Relative minimal detectable changes were smaller using no-compression than maximum-compression (6.5% vs. 15%). Using no-compression to measure QMLT was deemed feasible for both proximal and distal locations (94% and 96% of attempted measurements). In 9.5% of cases maximum-compression was not feasible. 95% of RF-CSA measurements were successfully completed.

CONCLUSION

Ultrasound provides feasible and reliable values of quadriceps muscle architecture that can be adapted to clinical scenarios commonly encountered in acute burn settings.

Feasibility of transesophageal phrenic nerve stimulation

BACKGROUND

Every year, more than 2.5 million critically ill patients in the ICU are dependent on mechanical ventilation. The positive pressure in the lungs generated by the ventilator keeps the diaphragm passive, which can lead to a loss of myofibers within a short time. To prevent ventilator-induced diaphragmatic dysfunction (VIDD), phrenic nerve stimulation may be used.

OBJECTIVE

The goal of this study is to show the feasibility of transesophageal phrenic nerve stimulation (TEPNS). We hypothesize that selective phrenic nerve stimulation can efficiently activate the diaphragm with reduced co-stimulations.

METHODS

An in vitro study in saline solution combined with anatomical findings was performed to investigate relevant stimulation parameters such as inter-electrode spacing, range to target site, or omnidirectional vs. sectioned electrodes. Subsequently, dedicated esophageal electrodes were inserted into a pig and single stimulation pulses were delivered simultaneously with mechanical ventilation. Various stimulation sites and response parameters such as transdiaphragmatic pressure or airway flow were analyzed to establish an appropriate stimulation setting.

RESULTS

Phrenic nerve stimulation with esophageal electrodes has been demonstrated. With a current amplitude of 40 mA, similar response figures of the diaphragm activation as compared to conventional stimulation with needle electrodes at 10mA were observed. Directed electrodes best aligned with the phrenic nerve resulted in up to 16.9 % higher amplitude at the target site in vitro and up to 6 cmH20 higher transdiaphragmatic pressure in vivo as compared to omnidirectional electrodes. The activation efficiency was more sensitive to the stimulation level inside the esophagus than to the inter-electrode spacing. Most effective and selective stimulation was achieved at the level of rib 1 using sectioned electrodes 40 mm apart.

CONCLUSION

Directed transesophageal phrenic nerve stimulation with single stimuli enabled diaphragm activation. In the future, this method might keep the diaphragm active during, and even support, artificial ventilation. Meanwhile, dedicated sectioned electrodes could be integrated into gastric feeding tubes.

Diaphragmatic Dynamics and Thickness Parameters Assessed by Ultrasonography Predict Extubation Success in Critically Ill Patients

INTRODUCTION

A frequent cause of weaning and extubation failure in critically ill mechanically ventilated patients is diaphragm muscle dysfunction. Ultrasound (US) evaluation of the diaphragm yields important data regarding its thickness (diaphragm thickening fraction [TFdi]) and its movement or excursion (diaphragmatic dynamics) that reveal the presence of diaphragmatic dysfunction.

METHODS

Cross-sectional study, which included patients older than 18 years with invasive mechanical ventilation with an expected duration of more than 48 h, in a tertiary referral center in Colombia. The excursion of the diaphragm, inspiratory and expiratory thickness, and TFdi were evaluated by US. Prevalence and use of medications were evaluated, and the association with failure in ventilatory weaning and extubation was analyzed.

RESULTS

Sixty-one patients were included. The median age and APACHE IV score were 62.42 years and 78.23, respectively. The prevalence of diaphragmatic dysfunction (assessed by excursion and TFdi) was 40.98%. The sensibility, specificity, positive predictive value, and negative predictive value for TFdi < 20% was 86%, 24%, 75%, and 40%, respectively, with an area under the receiver operating characteristic (ROC) curve of 0.6. The ultrasonographic analysis of excursion of the diaphragm, inspiratory and expiratory thickness, and TFdi (>20%) allow in its set and with normal values, predict success or failure for the extubation with an area under the ROC curve of 0.87.

CONCLUSION

Diaphragmatic dynamics and thickness parameters together assessed by ultrasonography could predict the success of extubation in critically ill patients in Colombia, based on the finding of diaphragmatic dysfunction.

Impact of cancer cachexia on respiratory muscle function and the therapeutic potential of exercise

Cancer cachexia is defined as a multi-factorial syndrome characterised by an ongoing loss of skeletal muscle mass and progressive functional impairment, estimated to affect 50-80% of patients and responsible for 20% of cancer deaths. Elevations in the morbidity and mortality rates of cachectic cancer patients has been linked to respiratory failure due to atrophy and dysfunction of the ventilatory muscles. Despite this, there is a distinct scarcity of research investigating the structural and functional condition of the respiratory musculature in cancer, with the majority of studies exclusively focusing on limb muscle. Treatment strategies are largely ineffective in mitigating the cachectic state. It is now widely accepted that an efficacious intervention will likely combine elements of pharmacology, nutrition and exercise. However, of these approaches, exercise has received comparatively little attention. Therefore, it is unlikely to be implemented optimally, whether in isolation or combination. In consideration of these limitations, the current review describes the mechanistic basis of cancer cachexia and subsequently explores the available respiratory- and exercise-focused literature within this context. The molecular basis of cachexia is thoroughly reviewed. The pivotal role of inflammatory mediators is described. Unravelling the mechanisms of exercise-induced support of muscle via antioxidant and anti-inflammatory effects in addition to promoting efficient energy metabolism via increased mitochondrial biogenesis, mitochondrial function and muscle glucose uptake provide avenues for interventional studies. Currently available pre-clinical mouse models including novel transgenic animals provide a platform for the development of multi-modal therapeutic strategies to protect respiratory muscles in people with cancer.

The effects of COVID-19 on respiratory muscle performance: making the case for respiratory muscle testing and training

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection results in multiorgan damage primarily mediated by viral infiltration via angiotensin-converting enzyme-2 receptors on the surface of cells. A primary symptom for many patients is exertional dyspnoea which may persist even beyond recovery from the viral infection. Respiratory muscle (RM) performance was hypothesised as a contributing factor to the severity of coronavirus disease 2019 (COVID-19) symptoms, such as dyspnoea, and outcomes. This was attributed to similarities between patient populations at elevated risk for severe COVID-19 symptoms and those with a greater likelihood of baseline RM weakness and the effects of prolonged mechanical ventilation. More recent evidence suggests that SARS-CoV-2 infection itself may cause damage to the RM, and many patients who have recovered report persistent dyspnoea despite having mild cases, normal lung function or undamaged lung parenchyma. These more recent findings suggest that the role of RM in the persistent dyspnoea due to COVID-19 may be more substantial than originally hypothesised. Therefore, screening for RM weakness and providing interventions to improve RM performance appears to be important for patients with COVID-19. This article will review the impact of SARS-CoV-2 infection on RM performance and provide clinical recommendations for screening RM performance and treatment interventions.

Variability in Skeletal Muscle Protein Synthesis Rates in Critically Ill Patients

(1) Background: Muscle protein synthesis in critically ill patients is, on average, normal despite dramatic muscle loss, but the variation is much larger than in controls. Here, we evaluate if this variation is due to 1) heterogeneity in synthesis rates, 2) morphological variation or infiltrating cells, or 3) heterogeneity in the synthesis of different protein fractions. (2) Methods: Muscle biopsies were taken from both legs of critically ill patients (n = 17). Mixed and mitochondrial protein synthesis rates and morphologies were evaluated in both legs. Synthesis rates of myosin and actin were determined in combined biopsies and compared with controls. (3) Results: Muscle protein synthesis rates had a large variability in the patients (1.4-10.8%/day). No differences in mixed and mitochondrial protein synthesis rates between both legs were observed. A microscopic examination revealed no morphological differences between the two legs or any infiltrating inflammatory cells. The synthesis rates for myosin were lower and for actin they were higher in the muscles of critically ill patients, compared with the controls. (4) Conclusions: The large variation in muscle protein synthesis rates in critically ill patients is not the result of heterogeneity in synthesis rates, nor due to infiltrating cells. There are differences in the synthesis rates of different proteins, but these do not explain the larger variations.

Development and early diagnosis of critical illness myopathy in COVID-19 associated acute respiratory distress syndrome

BACKGROUND

The COVID-19 pandemic has greatly increased the incidence and clinical importance of critical illness myopathy (CIM), because it is one of the most common complications of modern intensive care medicine. Current diagnostic criteria only allow diagnosis of CIM at an advanced stage, so that patients are at risk of being overlooked, especially in early stages. To determine the frequency of CIM and to assess a recently proposed tool for early diagnosis, we have followed a cohort of COVID-19 patients with acute respiratory distress syndrome and compared the time course of muscle excitability measurements with the definite diagnosis of CIM.

METHODS

Adult COVID-19 patients admitted to the Intensive Care Unit of the University Hospital Bern, Switzerland requiring mechanical ventilation were recruited and examined on Days 1, 2, 5, and 10 post-intubation. Clinical examination, muscle excitability measurements, medication record, and laboratory analyses were performed on all study visits, and additionally nerve conduction studies, electromyography and muscle biopsy on Day 10. Muscle excitability data were compared with a cohort of 31 age-matched healthy subjects. Diagnosis of definite CIM was made according to the current guidelines and was based on patient history, results of clinical and electrophysiological examinations as well as muscle biopsy.

RESULTS

Complete data were available in 31 out of 44 recruited patients (mean [SD] age, 62.4 [9.8] years). Of these, 17 (55%) developed CIM. Muscle excitability measurements on Day 10 discriminated between patients who developed CIM and those who did not, with a diagnostic precision of 90% (AUC 0.908; 95% CI 0.799-1.000; sensitivity 1.000; specificity 0.714). On Days 1 and 2, muscle excitability parameters also discriminated between the two groups with 73% (AUC 0.734; 95% CI 0.550-0.919; sensitivity 0.562; specificity 0.857) and 82% (AUC 0.820; CI 0.652-0.903; sensitivity 0.750; specificity 0.923) diagnostic precision, respectively. All critically ill COVID-19 patients showed signs of muscle membrane depolarization compared with healthy subjects, but in patients who developed CIM muscle membrane depolarization on Days 1, 2 and 10 was more pronounced than in patients who did not develop CIM.

CONCLUSIONS

This study reports a 55% prevalence of definite CIM in critically ill COVID-19 patients. Furthermore, the results confirm that muscle excitability measurements may serve as an alternative method for CIM diagnosis and support its use as a tool for early diagnosis and monitoring the development of CIM.

The myokine Fibcd1 is an endogenous determinant of myofiber size and mitigates cancer-induced myofiber atrophy

Decline in skeletal muscle cell size (myofiber atrophy) is a key feature of cancer-induced wasting (cachexia). In particular, atrophy of the diaphragm, the major muscle responsible for breathing, is an important determinant of cancer-associated mortality. However, therapeutic options are limited. Here, we have used Drosophila transgenic screening to identify muscle-secreted factors (myokines) that act as paracrine regulators of myofiber growth. Subsequent testing in mouse myotubes revealed that mouse Fibcd1 is an evolutionary-conserved myokine that preserves myofiber size via ERK signaling. Local administration of recombinant Fibcd1 (rFibcd1) ameliorates cachexia-induced myofiber atrophy in the diaphragm of mice bearing patient-derived melanoma xenografts and LLC carcinomas. Moreover, rFibcd1 impedes cachexia-associated transcriptional changes in the diaphragm. Fibcd1-induced signaling appears to be muscle selective because rFibcd1 increases ERK activity in myotubes but not in several cancer cell lines tested. We propose that rFibcd1 may help reinstate myofiber size in the diaphragm of patients with cancer cachexia.

High-Intensity Inspiratory Muscle Training Improves Scalene and Sternocleidomastoid Muscle Oxygenation Parameters in Patients With Weaning Difficulties: A Randomized Controlled Trial

Background

Critically ill patients who have difficulties weaning from the mechanical ventilator are prone to develop respiratory muscle weakness. Inspiratory muscle training (IMT) can improve respiratory muscle strength. Whether IMT can improve scalene and sternocleidomastoid muscle oxygenation parameters is unknown.

Aim

To compare changes in muscle oxygenation parameters of scalene and sternocleidomastoid inspiratory muscles during a standardized task between patients with weaning difficulties who received either high-intensity IMT (intervention) or sham low-intensity IMT (control).

Method

Forty-one patients performed daily IMT sessions (4 sets, 6–10 breaths) until weaning success or for 28 consecutive days. The training load was progressively adjusted in the intervention group (n = 22) to the highest tolerable load, whilst the control group (n = 19) kept training at 10% of their baseline maximal inspiratory pressure (PImax). Breathing characteristics (i.e., work and power of breathing, PoB), respiratory muscle function [i.e., PImax and forced vital capacity (FVC)] were measured during a standardized loaded breathing task against a load of 30% of baseline PImax before and after the IMT period. In addition, during the same loaded breathing task, absolute mean and nadir changes from baseline in local scalene and sternocleidomastoid muscle oxygen saturation index (Δ%StiO2) (an index of oxygen extraction) and nadir Δ%StiO2 normalized for the PoB were measured by near-infrared spectroscopy.

Results

At post measures, only the intervention group improved mean PoB compared to pre measures (Pre: 0.42 ± 0.33 watts, Post: 0.63 ± 0.51watts, p-value &lt; 0.01). At post measures, both groups significantly improved nadir scalene muscles StiO2% normalized for the mean PoB (ΔStiOnadir%/watt) compared to pre measurements and the improvement was not significant different between groups (p-value = 0.40). However, at post measures, nadir sternocleidomastoid muscle StiO2% normalized for the mean PoB (ΔStiOnadir%/watt) was significantly greater improved in the intervention group (mean difference: +18.4, 95%CI: −1.4; 38.1) compared to the control group (mean difference: +3.7, 95%CI: −18.7; 26.0, between group p-value &lt; 0.01). Both groups significantly improved PImax (Intervention: +15 ± 13 cmH2O p-value &lt; 0.01, Control: +13 ± 15 cmH2O p-value &lt; 0.01). FVC only significantly improved in the intervention group (+0.33 ± 0.31 L p &lt; 0.01) report also change in control group.

Conclusion

This exploratory study suggests that high-intensity IMT induces greater improvements in scalene and sternocleidomastoid muscle oxygenation parameters attributed for oxygen delivery, utilization and oxygen saturation index compared to low-intensity IMT in patients with weaning difficulties.

Intensive care unit-acquired weakness: Questions the clinician should ask

Intensive care unit (ICU)-acquired weakness (ICU-AW) is defined as clinically detected weakness in critically ill patients in whom there is no plausible etiology other than critical illness. Using electrophysiological methods, patients with ICU-AW are classified in three subcategories: critical illness polyneuropathy, critical illness myopathy and critical illness neuromyopathy. ICU-AW is a frequent complication occurring in critical ill patients. Risk factors include illness severity and organ failure, age, hyperglycemia, parenteral nutrition, drugs and immobility. Due to short- and long-term complications, ICU-AW results in longer hospital stay and increased mortality. Its management is essentially preventive avoiding modifiable risk factors, especially duration of sedation and immobilization that should be as short as possible. Pharmacological approaches have been studied but none have proven efficacy. In the present review, we propose practical questions that the clinician should ask in case of acquired weakness during ICU stay: when to suspect ICU-AW, what risk factors should be identified, how to diagnose ICU-AW, what is the prognosis and how can recovery be improved?

Inspiratory response and side-effects to rapid bilateral magnetic phrenic nerve stimulation using differently shaped coils: implications for stimulation-assisted mechanical ventilation

BACKGROUND

Rapid magnetic stimulation (RMS) of the phrenic nerves may serve to attenuate diaphragm atrophy during mechanical ventilation. With different coil shapes and stimulation location, inspiratory responses and side-effects may differ. This study aimed to compare the inspiratory and sensory responses of three different RMS-coils either used bilaterally on the neck or on the chest, and to determine if ventilation over 10 min can be achieved without muscle fatigue and coils overheating.

METHODS

Healthy participants underwent bilateral anterior 1-s RMS on the neck (RMS_BAMPS) (N = 14) with three different pairs of magnetic coils (parabolic, D-shape, butterfly) at 15, 20, 25 and 30 Hz stimulator-frequency and 20% stimulator-output with + 10% increments. The D-shape coil with individual optimal stimulation settings was then used to ventilate participants (N = 11) for up to 10 min. Anterior RMS on the chest (RMS_aMS) (N = 8) was conducted on an optional visit. Airflow was assessed via pneumotach and transdiaphragmatic pressure via oesophageal and gastric balloon catheters. Perception of air hunger, pain, discomfort and paresthesia were measured with a numerical scale.

RESULTS

Inspiration was induced via RMS_BAMPS in 86% of participants with all coils and via RMS_aMS in only one participant with the parabolic coil. All coils produced similar inspiratory and sensory responses during RMS_BAMPS with the butterfly coil needing higher stimulator-output, which resulted in significantly larger discomfort ratings at maximal inspiratory responses. Ten of 11 participants achieved 10 min of ventilation without decreases in minute ventilation (15.7 ± 4.6 L/min).

CONCLUSIONS

RMS_BAMPS was more effective than RMS_aMS, and could temporarily ventilate humans seemingly without development of muscular fatigue. Trial registration This study was registered on clinicaltrials.gov (NCT04176744).

Acute reduction of erector spinae muscle cross-sectional area is associated with ICU-AW and worse prognosis in patients with mechanical ventilation in the ICU: A prospective observational study

BACKGROUND

To investigate the values of erector spinae muscle cross-sectional area (ESMcsa) loss for diagnosing intensive care unit-acquired weakness (ICU-AW) and predicting the 60-day survival status in patients with mechanical ventilation.

METHODS

Patients who were admitted into the intensive care unit (ICU) and received invasive mechanical ventilation therapy from June 2018 to June 2020 were selected. And they were divided into an ICU-AW group and a non-ICU-AW group, which were compared based on the ESMcsa and The British Medical Research Council muscle strength score (MRC-score) on the 1st and 7th day of ICU admission. The receiver operating characteristic curve was employed to measure the values of the ESMcsa Loss and ESMcsa Loss Ratio on the 7th day in order to diagnose ICU-AW in patients with mechanical ventilation. The survival curves of the patients were plotted to analyze the ESMcsa Loss Ratio values for predicting the 60-day survival status.

RESULTS

A total of 104 patients were enrolled, they were divided into the ICU-AW group (n = 56) and the non-ICU-AW group (n = 48). The mechanical ventilation time, ICU stay time, and hospital stay time of the ICU-AW group were all significantly higher than those of the non-ICU-AW group. On the 1st day, no significant difference in the ESMcsa or MRC-score between the 2 groups of patients was observed. On the 7th day, the ESMcsa and MRC-score of the ICU-AW group were significantly lower than those of the non-ICU-AW group. The ESMcsa Loss and ESMcsa Loss Ratio were both significantly negatively correlated with the MRC-score. The ESMcsa Loss and ESMcsa Loss Ratio on the 7th day were both valuable for the prediction of ICU-AW in patients with mechanical ventilation (areas under the receiver operating characteristic curve = 0.904, 0.835, and 0.889, P < .001). The survival rate of the patients in the high- and low-ESMcsa Loss Ratio groups were 60.0% and 80.0% (P < .05).

CONCLUSIONS

As suggested by the ESMcsa Loss Ratios of the patients with mechanical ventilation on the 7th day of ICU admission, it offers a desirable objective indicator for the diagnosis of ICU-AW, and provides certain values for predicting the 60-day survival status of patients with mechanical ventilation in the ICU.

Dysphagia Severity and Management in Patients with COVID-19

COVID-19 has resulted in unprecedented numbers of patients treated at intensive care units (ICUs). Dysphagia is a key concern in critical illness survivors. We investigated the severity of dysphagia in COVID-19 and the need to adapt practices to provide efficient care. We reviewed the literature on COVID-19, post-critical-illness dysphagia, and dysphagia and tracheostomy guidelines during the pandemic. Critically ill COVID-19 patients present a high incidence of dysphagia, aggravated by respiratory distress, deconditioning, and neurological complications. Mechanical ventilation (MV), delirium, sedation and weakness are worse in COVID-19 than in other etiologies of critical care. In awake patients, respiratory compromise impairs breathing-swallowing-coughing coordination. Tracheostomy reduces laryngopharyngeal trauma, sedation, delirium, ICU stay and improves swallowing rehabilitation. Tracheostomy weaning and swallowing evaluation is complex in COVID-19 due to respiratory instability and a team discussion will guide adaptations. Patients assessed in the ICU were 67% recommended to be nil by mouth (were aspirating). Two months following hospital discharge, 83% of those who had undergone tracheostomy were managing a normal diet. Severely ill COVID-19 patients are expected to regain swallow function. Dysphagia care is based on adaptation of practices to the patients' multiple impairments.

Out of Control: The Role of the Ubiquitin Proteasome System in Skeletal Muscle during Inflammation

The majority of critically ill intensive care unit (ICU) patients with severe sepsis develop ICU-acquired weakness (ICUAW) characterized by loss of muscle mass, reduction in myofiber size and decreased muscle strength leading to persisting physical impairment. This phenotype results from a dysregulated protein homeostasis with increased protein degradation and decreased protein synthesis, eventually causing a decrease in muscle structural proteins. The ubiquitin proteasome system (UPS) is the predominant protein-degrading system in muscle that is activated during diverse muscle atrophy conditions, e.g., inflammation. The specificity of UPS-mediated protein degradation is assured by E3 ubiquitin ligases, such as atrogin-1 and MuRF1, which target structural and contractile proteins, proteins involved in energy metabolism and transcription factors for UPS-dependent degradation. Although the regulation of activity and function of E3 ubiquitin ligases in inflammation-induced muscle atrophy is well perceived, the contribution of the proteasome to muscle atrophy during inflammation is still elusive. During inflammation, a shift from standard- to immunoproteasome was described; however, to which extent this contributes to muscle wasting and whether this changes targeting of specific muscular proteins is not well described. This review summarizes the function of the main proinflammatory cytokines and acute phase response proteins and their signaling pathways in inflammation-induced muscle atrophy with a focus on UPS-mediated protein degradation in muscle during sepsis. The regulation and target-specificity of the main E3 ubiquitin ligases in muscle atrophy and their mode of action on myofibrillar proteins will be reported. The function of the standard- and immunoproteasome in inflammation-induced muscle atrophy will be described and the effects of proteasome-inhibitors as treatment strategies will be discussed.

Assessment of magnetic flux density properties of electromagnetic noninvasive phrenic nerve stimulations for environmental safety in an ICU environment

Diaphragm weakness affects up to 60% of ventilated patients leading to muscle atrophy, reduction of muscle fiber force via muscle fiber injuries and prolonged weaning from mechanical ventilation. Electromagnetic stimulation of the phrenic nerve can induce contractions of the diaphragm and potentially prevent and treat loss of muscular function. Recommended safety distance of electromagnetic coils is 1 m. The aim of this study was to investigate the magnetic flux density in a typical intensive care unit (ICU) setting. Simulation of magnetic flux density generated by a butterfly coil was performed in a Berlin ICU training center with testing of potential disturbance and heating of medical equipment. Approximate safety distances to surrounding medical ICU equipment were additionally measured in an ICU training center in Bern. Magnetic flux density declined exponentially with advancing distance from the stimulation coil. Above a coil distance of 300 mm with stimulation of 100% power the signal could not be distinguished from the surrounding magnetic background noise. Electromagnetic stimulation of the phrenic nerve for diaphragm contraction in an intensive care unit setting seems to be safe and feasible from a technical point of view with a distance above 300 mm to ICU equipment from the stimulation coil.

Skeletal muscle weakness in older adults home-restricted due to COVID-19 pandemic: a role for full-body in-bed gym and functional electrical stimulation

Persons suffering with systemic neuromuscular disorders or chronic organ failures, spend less time for daily physical activity, aggravating their mobility impairments. From 2020, patients at risk are also older adults, who, though negative for the SARS-Cov-2 infection, suffer with a fatigue syndrome due to home restriction/quarantine. Besides eventual psycological managements, it could be useful to offer to these patients a rehabilitation workouts easy to learn and to independently repeat at home (Full-Body In-Bed Gym). Inspired by the proven capability to recover skeletal muscle contractility and strength by home-based volitional exercises and functional electrical stimulation (FES), we suggest for this fatigue syndrome a 10–20 min long daily routine of easy and safe physical exercises that may recover from muscle weakness the main 400 skeletal muscles used for every-day activities. Leg muscles could be trained also by an adjunctive neuro-muscular electrical stimulation (NMES) in frail old persons. Many of the exercises could be performed in bed (Full-Body in-Bed Gym), thus hospitalized patients can learn this light training before leaving the hospital. Full-Body in-Bed Gym is, indeed, an extension of well-established cardiovascular-ventilation rehabilitation training performed by patients after heavy surgery. Blood pressure readings, monitored before and after daily routine of Full-Body in-Bed Gym, demonstrate a transient decrease in peripheral resistance due to increased blood flow to major body muscles. Continued regularly, Full-Body in-Bed Gym may help maintaining independence of frail people, including those suffering with the fatigue syndrome related to the restrictions/quarantine imposed to the general population during the COVID-19 pandemic.

German version of the Chelsea Critical Care Physical Assessment Tool (CPAx-GE): translation, cross-cultural adaptation, validity, and reliability

PURPOSE

To translate and cross-culturally adapt the Chelsea Critical Care Physical Assessment tool from English to German (CPAx-GE) and to examine its validity and reliability.

MATERIALS AND METHODS

Following a forward-backward translation including an expert round table discussion, the measurement properties of the CPAx-GE were explored in critically ill, mechanically ventilated adults. We investigated construct, cross-sectional, and cross-cultural validity of the CPAx-GE with other measurement instruments at pre-specified timepoints, analysed relative reliability with intraclass correlation coefficients (ICCs) and determined absolute agreement with the Bland-Altman plots.

RESULTS

Consensus for the translated CPAx-GE was reached. Validity was excellent with >80% of the pre-specified hypotheses accepted at baseline, critical care, and hospital discharge. Interrater reliability was high (ICCs > 0.8) across all visits. Limit of agreement ranged from -2 to 2 points. Error of measurement was small, floor, and ceiling effects limited.

CONCLUSIONS

The CPAx-GE demonstrated excellent construct, cross-sectional, and cross-cultural validity as well as high interrater reliability in critically ill adults with prolonged mechanical ventilation at baseline, critical care, and hospital discharge. Consequently, the CPAx-GE can be assumed equal to the original and recommended in the German-speaking area to assess physical function and activity of critically ill adults across the critical care and hospital stay. Trial registration: German Clinical Trials Register (DRKS) identification number: DRKS00012983 (https://www.drks.de/drks_web/navigate.do?navigationId=trial.HTML&TRIAL_ID=DRKS00012983), registered on 20 September 2017, first patient enrolled on 21 November 2017.Implications for rehabilitationEarly rehabilitation of critically ill patients is recommended to prevent and treat the subsequent functional disability, but a suitable measurement instrument for the German-speaking area is lacking.The translated, cross-culturally adapted German CPAx demonstrated excellent validity and reliability in assessing physical function and activity in critically ill adults.Cross-sectional validity of the CPAx has been newly established and allows the use of this tool at clinically relevant time-points in the course of a critical illness.The CPAx-GE can therefore be used in clinical practice by German-speaking therapists to assess physical function and activity during early rehabilitation in the ICU and hospital.

Identifying Subjects at Risk for Diaphragm Atrophy During Mechanical Ventilation Using Routinely Available Clinical Data

BACKGROUND

Diaphragmatic respiratory effort during mechanical ventilation is an important determinant of patient outcome, but direct measurement of diaphragmatic contractility requires specialized instrumentation and technical expertise. We sought to determine whether routinely collected clinical variables can predict diaphragmatic contractility and stratify the risk of diaphragm atrophy.

METHODS

We conducted a secondary analysis of a prospective cohort study on diaphragm ultrasound in mechanically ventilated subjects. Clinical variables, such as breathing frequency, ventilator settings, and blood gases, were recorded longitudinally. Machine learning techniques were used to identify variables predicting diaphragm contractility and stratifying the risk of diaphragm atrophy (> 10% decrease in thickness from baseline). Performance of the variables was evaluated in mixed-effects logistic regression and random-effects tree models using the area under the receiver operating characteristic curve.

RESULTS

Measurements were available for 761 study days in 191 subjects, of whom 73 (38%) developed diaphragm atrophy. No routinely collected clinical variable, alone or in combination, could accurately predict either diaphragm contractility or the development of diaphragm atrophy (model area under the receiver operating characteristic curve 0.63-0.75). The risk of diaphragm atrophy was not significantly different according to the presence or absence of patient-triggered breaths (38.3% vs 38.6%; odds ratio 1.01, 95% CI 0.05-2.03). Diaphragm thickening fraction < 15% during either of the first 2 d of the study was associated with a higher risk of atrophy (44.6% vs 26.1%; odds ratio 2.28, 95% CI 1.05-4.95).

CONCLUSIONS

Diaphragmatic contractility and the risk of diaphragm atrophy could not be reliably determined from routinely collected clinical variables and ventilator settings. A single measurement of diaphragm thickening fraction measured within 48 h of initiating mechanical ventilation can be used to stratify the risk of diaphragm atrophy during mechanical ventilation.

To contrast and reverse skeletal muscle weakness by Full-Body In-Bed Gym in chronic COVID-19 pandemic syndrome

Mobility-impaired persons, either very old or younger but suffering with systemic neuromuscular disorders or chronic organ failures, spend small amounts of time for daily physical activity, contributing to aggravate their poor mobility by resting muscle atrophy. Sooner or later the limitations to their mobility enforce them to bed and to more frequent hospitalizations. We include among these patients at risk those who are negative for the SARS-COV-2 infection, but suffering with COVID-19 pandemic syndrome. Beside managements of psychological symptoms, it is mandatory to offer to the last group physical rehabilitation approaches easy to learn and self-managed at home. Inspired by the proven capability to recover skeletal muscle contractility and strength by home-based volitional exercises and functional electrical stimulation, we suggest also for chronic COVID-19 pandemic syndrome a 10-20 min long daily routine of easy and safe physical exercises that can activate, and recover from weakness, the main 400 skeletal muscles used for every-day mobility activities. Persons can do many of them in bed (Full-Body in-Bed Gym), and hospitalized patients can learn this light training before leaving the hospital. It is, indeed, an extension of well-established cardiovascular-respiratory rehabilitation training performed after heavy surgical interventions. Blood pressure readings, monitored before and after daily routine, demonstrate a transient decrease in peripheral resistance due to increased blood flow of many muscles. Continued regularly, Full-Body in-Bed Gym may help maintaining independence of frail people, including those suffering with the COVID-19 pandemic syndrome.

Gerta Vrbová, a guide and a friend for a generation of neuro-myologists - Her scientific legacies and relations with colleagues

Gerta Sidonová - Vrbová, (Trnava, Slovakia, November 28, 1926 - London, UK, October 2, 2020) has been a key neuroscientist, who for almost half a century has contributed important findings and hypotheses on the relationships between motoneurons and skeletal muscle fibers, in particular on the differentiation and extent of plasticity of the peculiar characteristics of the different types of fibers present in mammalian muscles. This issue, Ejtm 31 (1), 2021, opens with the personal obituary authored by Dirk Pette, who remember his lifelong collaboration with Gerta, describing the many molecular and metabolic events that occur by changing the pattern of activation of adult muscle fibers through neuromuscular low frequency electrical stimulation. To honor the many scientific legacies of Gerta Vrbová and her impact on a generation of researchers studying myology and managements of neuromuscular disorders I add here additional examples of Gerta's scientific heritage and of her relations with colleagues.

To contrast and reverse skeletal muscle weakness by Full-Body In-Bed Gym in chronic COVID-19 pandemic syndrome

Mobility-impaired persons, either very old or younger but suffering with systemic neuromuscular disorders or chronic organ failures, spend small amounts of time for daily physical activity, contributing to aggravate their poor mobility by resting muscle atrophy. Sooner or later the limitations to their mobility enforce them to bed and to more frequent hospitalizations. We include among these patients at risk those who are negative for the SARS-COV-2 infection, but suffering with COVID-19 pandemic syndrome. Beside managements of psychological symptoms, it is mandatory to offer to the last group physical rehabilitation approaches easy to learn and self-managed at home. Inspired by the proven capability to recover skeletal muscle contractility and strength by home-based volitional exercises and functional electrical stimulation, we suggest also for chronic COVID-19 pandemic syndrome a 10–20 min long daily routine of easy and safe physical exercises that can activate, and recover from weakness, the main 400 skeletal muscles used for every-day mobility activities. Persons can do many of them in bed (Full-Body in-Bed Gym), and hospitalized patients can learn this light training before leaving the hospital. It is, indeed, an extension of well-established cardiovascular-respiratory rehabilitation training performed after heavy surgical interventions. Blood pressure readings, monitored before and after daily routine, demonstrate a transient decrease in peripheral resistance due to increased blood flow of many muscles. Continued regularly, Full-Body in-Bed Gym may help maintaining independence of frail people, including those suffering with the COVID-19 pandemic syndrome.

Diaphragmatic muscle thickness in older people with and without sarcopenia

BACKGROUND

Studies in mice have suggested that sarcopenic animals may have atrophic diaphragmatic muscles; however, to date, no clinical studies are available.

AIMS

To investigate whether the diaphragmatic thickness is affected in older patients with sarcopenia and if this is associated with impaired respiratory functions.

METHODS

Thirty sarcopenic and 30 non-sarcopenic elderly patients aged over 65 were included. All patients underwent comprehensive geriatric assessment. The diagnosis of sarcopenia was made according to the criteria of the European Working Group on Sarcopenia in Older People. Ultrasonographic evaluations of the patients were carried out by an experienced radiologist. Diaphragmatic thickness was measured in three positions: end of deep inspiration, quiet breathing, end of forced expiration. Peak expiratory flow (PEF) rate was evaluated by a peak flow meter.

RESULTS

The mean age of the patients was 77 ± 6 years, and 58% were females. Diaphragmatic thickness in three different positions (deep inspiration [2.3 mm (min-max: 1.3-4.1) vs. 2.5 mm (min-max: 1.9-4.9)], quiet breathing [1.8 mm (min-max: 1.0-2.8) vs. 2.00 mm (min-max: 1.3-3.9)] and end of forced expiration [1.1 mm (min-max: 0.7-2.5) vs. 1.5 mm (min-max: 0.5-3.4)]) were found to be thinner in sarcopenic patients compared to non-sarcopenics (p = 0.02, p = 0.02, p < 0.01, respectively). Also, PEF rate results were lower in patients with sarcopenia (245 L/min [min-max: 150-500] vs. 310 L/min [min-max: 220-610], p < 0.01). Diaphragmatic muscle thicknesses in all three positions were independently associated with sarcopenia status of the participants.

CONCLUSIONS

Our results suggest that sarcopenia in older people may be associated with reduced diaphragmatic muscle thickness and respiratory functions. Findings are needed to be confirmed in further multicenter studies with big sample sizes.

A Pilot Study of Pharyngeal Electrical Stimulation for Orally Intubated ICU Patients with Dysphagia

OBJECTIVE

Dysphagia is a common disorder in neurological and non-neurological intensive care unit (ICU) patients and can lead to aspiration pneumonia, prolonged ventilation, and delayed extubation. Dysphagia is an independent predictor of increased mortality. In dysphagic stroke patients with tracheotomy, the use of pharyngeal electric stimulation (PES), an emerging technique to treat dysphagia, has been shown to improve airway protection and shorten time to decannulation. The objective of this study was to determine whether patients who receive PES have a lower prevalence of pneumonia and frequency of reintubation.

DESIGN

Secondary analysis of a non-blinded interventional subject sample from a large clinical study with a historical age, pathology, and severity-matched control group.

SETTING

ICU of a tertiary care medical center.

PATIENTS

In this pilot non-blinded study, a group of 15 intubated patients in a general and a neurologic ICU received PES while orally intubated during ICU stay. A control group (n = 25) matched for age, type, and region of pathology, and severity of illness expressed by Simplified Acute Physiology Score and Therapeutic Intervention Scoring System was used to compare for pneumonia and need for reintubation.

MAIN RESULTS

Patients treated with PES had significantly lower prevalence of pneumonia (4 vs 21, p = 0.00046) and frequency of reintubation (0 vs 6, p = 0.046) when compared to controls.

CONCLUSION

Although limited by its small size and non-blinded design, this is the first study demonstrating the benefits of PES in ICU patients still orally intubated, thus offering a potential new method to reduce morbidity, mortality, and economic burden in a mixed ICU population. In order to further investigate and strengthen our findings, a statistically powered, randomized controlled study is recommended.

Gerta Vrbová, a guide and a friend for a generation of neuro-myologists – Her scientific legacies and relations with colleagues

Gerta Sidonová - Vrbová, (Trnava, Slovakia, November 28, 1926 - London, UK, October 2, 2020) has been a key neuroscientist, who for almost half a century has contributed important findings and hypotheses on the relationships between motoneurons and skeletal muscle fibers, in particular on the differentiation and extent of plasticity of the peculiar characteristics of the different types of fibers present in mammalian muscles. This issue, Ejtm 31 (1), 2021, opens with the personal obituary authored by Dirk Pette, who remember his lifelong collaboration with Gerta, describing the many molecular and metabolic events that occur by changing the pattern of activation of adult muscle fibers through neuromuscular low frequency electrical stimulation. To honor the many scientific legacies of Gerta Vrbová and her impact on a generation of researchers studying myology and managements of neuromuscular disorders I add here additional examples of Gerta’s scientific heritage and of her relations with colleagues.

COVID-19-associated acute respiratory distress syndrome (CARDS): Current knowledge on pathophysiology and ICU treatment - A narrative review

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) induces coronavirus-19 disease (COVID-19) and is a major health concern. Following two SARS-CoV-2 pandemic “waves,” intensive care unit (ICU) specialists are treating a large number of COVID19-associated acute respiratory distress syndrome (ARDS) patients. From a pathophysiological perspective, prominent mechanisms of COVID19-associated ARDS (CARDS) include severe pulmonary infiltration/edema and inflammation leading to impaired alveolar homeostasis, alteration of pulmonary physiology resulting in pulmonary fibrosis, endothelial inflammation (endotheliitis), vascular thrombosis, and immune cell activation.

Although the syndrome ARDS serves as an umbrella term, distinct, i.e., CARDS-specific pathomechanisms and comorbidities can be noted (e.g., virus-induced endotheliitis associated with thromboembolism) and some aspects of CARDS can be considered ARDS “atypical.” Importantly, specific evidence-based medical interventions for CARDS (with the potential exception of corticosteroid use) are currently unavailable, limiting treatment efforts to mostly supportive ICU care.

In this article, we will discuss the underlying pulmonary pathophysiology and the clinical management of CARDS. In addition, we will outline current and potential future treatment approaches.

PREVENTION OF RESPIRATORY MUSCLE DYSFUNCTION DUE TO DIAPHRAGM ATROPHY IN CHILDREN WITH RESPIRATORY FAILURE

The aim of the study was to determine whether diaphragm-protective mechanical ventilation can prevent diaphragm atrophy in children with respiratory failure. Materials and methods. We complete the prospective single-center cohort study. Data analysis included 82 patients 1 month - 18 years old, divided into I group (lung-protective MV) and II group (diaphragm-protective in addition to lung-protective MV). Patients were divided into age subgroups. Stages of the study: 1st day (d1), 3rd (d3), 5th (d5), 7th (d7), 9th (d9), 28th (d28). We studied changes in diaphragm thickness at the end of exhalation and compared them with these indicators at patient`s admission to the study (baseline). Primary endpoint was length of stay in ICU, secondary endpoints were complications (prolonged MV). Results are described as arithmetic mean (X) and standard deviation (σ) with level of significance p. Results. There were significant differences in length of stay in ICU among patients of the 1st and 5th age subgroups: in 1st age subgroup this data was in 1.3 times lower in II group, compared with I group (p <0,05); in 5th age subgroup the situation was the opposite - length of stay in ICU was in 1.4 times higher in II group, compared with I group (p<0.05). There were no patients who required lifelong mechanical ventilation in any of the groups. Changes in the thickness of the diaphragm, which indicate its atrophy, were the most significant among patients of the first, second, third and fourth age subgroups and the severity of atrophy was higher among patients of group I, compared with patients of group II. Conclusions. Diaphragm-protective mechanical ventilation significantly prevents diaphragm atrophy in children with respiratory failure in 2nd, 4th, and 5th age subgroups. Providing goal-directed diaphragm-protective MV might reduce the length of stay in ICU among patients of 1st and 5th age subgroups. There were no observed complications like lifelong mechanical ventilation in both patient`s group.

Ultrasonographic assessment of parasternal intercostal muscles during mechanical ventilation

Although mechanical ventilation is a lifesaving treatment, abundant evidence indicates that its prolonged use (1 week or more) promotes respiratory muscle weakness due to both contractile dysfunction and atrophy. Along with the diaphragm, the intercostal muscles are one of the most important groups of respiratory muscles. In recent years, muscular ultrasound has become a useful bedside tool for the clinician to identify patients with respiratory muscle dysfunction related to critical illness and/or invasive mechanical ventilation. Images obtained over the course of illness can document changes in muscle dimension and can be used to estimate changes in function. Recent evidence suggests the clinical usefulness of ultrasound imaging in the assessment of intercostal muscle function. In this narrative review, we summarize the current literature on ultrasound imaging of the parasternal intercostal muscles as used to assess the extent of muscle activation and muscle weakness and its potential impact during discontinuation of mechanical ventilation. In addition, we proposed a practical flowchart based on recent evidence and experience of our group that can be applied during the weaning phase. This approach integrates multiple predictive parameters of weaning success with respiratory muscle ultrasound.

Respiratory Muscle Performance Screening for Infectious Disease Management Following COVID-19: A Highly Pressurized Situation

The 2019-2020 coronavirus pandemic elucidated how a single highly infectious virus can overburden health care systems of even highly economically developed nations. A leading contributor to these concerning outcomes is a lack of available intensive care unit (ICU) beds and mechanical ventilation support. Poorer health is associated with a higher risk for severe respiratory complications from the coronavirus. We hypothesize that impaired respiratory muscle performance is an underappreciated factor contributing to poor outcomes unfolding during the coronavirus pandemic. Although impaired respiratory muscle performance is considered to be rare, it is more frequently encountered in patients with poorer health, in particular obesity. However, measures of respiratory muscle performance are not routinely performed in clinical practice, including those with symptoms such as dyspnea. The purpose of this article is to discuss the potential role of respiratory muscle performance from the perspective of the coronavirus pandemic. We also provide a theoretical patient management model to screen for impaired respiratory muscle performance and intervention, if identified, with the goal of unburdening health care systems during future pandemic crises.

Neuregulin-1β Protects the Rat Diaphragm during Sepsis against Oxidative Stress and Inflammation by Activating the PI3K/Akt Pathway

Sepsis-induced diaphragm dysfunction (SIDD) which is mainly characterized by decrease in diaphragmatic contractility has been identified to cause great harms to patients. Therefore, there is an important and pressing need to find effective treatments for improving SIDD. In addition, acetylcholinesterase (AChE) activity is a vital property of the diaphragm, so we evaluated both diaphragmatic contractility and AChE activity. Though neuregulin-1β (NRG-1β) is known to exert organ-protective effects in some inflammatory diseases, little is known about the potential of NRG-1β therapy in the diaphragm during sepsis. Our study was aimed at exploring the effects of NRG-1β application on diaphragmatic contractility and AChE activity during sepsis. Proinflammatory cytokines, muscle injury biomarkers in serum, contractile force, AChE activity, proinflammatory cytokines, oxidative parameters, histological condition, terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) staining, and expression of phosphoinositide 3-kinase (PI3K)/protein kinase B (PKB/Akt) signaling proteins in the diaphragm were measured and compared between nonseptic and septic groups with or without NRG-1β treatment. In vitro, the effects of NRG-1β on reactive oxygen species (ROS) production in the lipopolysaccharide- (LPS-) stimulated L6 rat muscle skeletal cells with or without the Akt inhibitor MK-2206 were detected. NRG-1β inhibited proinflammatory cytokine release and muscle injury biomarkers soaring in serum and improved the sepsis-induced diaphragm dysfunction and AChE activity decrease significantly during sepsis. Meanwhile, the inflammatory response, oxidative stress, pathological impairment, and cell apoptosis in the diaphragm were mitigated by NRG-1β. And NRG-1β activated the PI3K/Akt signaling in the diaphragm of septic rats. Elevated ROS production in the LPS-stimulated L6 rat skeletal muscle cells was reduced after treatment with NRG-1β, while MK-2206 blocked these effects of NRG-1β. In conclusion, our findings underlined that NRG-1β could reduce circulating levels of proinflammatory cytokines in rats with sepsis, adjust diaphragmatic proinflammatory cytokine level, mitigate diaphragmatic oxidative injury, and lessen diaphragm cell apoptosis, thereby improving diaphragmatic function, and play a role in diaphragmatic protection by activating PI3K/Akt signaling.

Physical Activity Intolerance and Cardiorespiratory Dysfunction in Patients with Moderate-to-Severe Traumatic Brain Injury

Moderate-to-severe traumatic brain injury (TBI) is a chronic health condition with multi-systemic effects. Survivors face significant long-term functional limitations, including physical activity intolerance and disordered sleep. Persistent cardiorespiratory dysfunction is a potentially modifiable yet often overlooked major contributor to the alarmingly high long-term morbidity and mortality rates in these patients. This narrative review was developed through systematic and non-systematic searches for research relating cardiorespiratory function to moderate-to-severe TBI. The literature reveals patients who have survived moderate-to-severe TBI have ~ 25-35% reduction in maximal aerobic capacity 6-18 months post-injury, resting pulmonary capacity parameters that are reduced 25-40% for weeks to years post-injury, increased sedentary behavior, and elevated risk of cardiorespiratory-related morbidity and mortality. Synthesis of data from other patient populations reveals that cardiorespiratory dysfunction is likely a consequence of ventilator-induced diaphragmatic dysfunction (VIDD), which is not currently addressed in TBI management. Thus, cardiopulmonary exercise testing should be routinely performed in this patient population and those with cardiorespiratory deficits should be further evaluated for diaphragmatic dysfunction. Lack of targeted treatment for underlying cardiorespiratory dysfunction, including VIDD, likely contributes to physical activity intolerance and poor functional outcomes in these patients. Interventional studies have demonstrated that short-term exercise training programs are effective in patients with moderate-to-severe TBI, though improvement is variable. Inspiratory muscle training is beneficial in other patient populations with diaphragmatic dysfunction, and may be valuable for patients with TBI who have been mechanically ventilated. Thus, clinicians with expertise in cardiorespiratory fitness assessment and exercise training interventions should be included in patient management for individuals with moderate-to-severe TBI.

Is Mitochondrial Oxidative Stress the Key Contributor to Diaphragm Atrophy and Dysfunction in Critically Ill Patients?

Diaphragm dysfunction is prevalent in the progress of respiratory dysfunction in various critical illnesses. Respiratory muscle weakness may result in insufficient ventilation, coughing reflection suppression, pulmonary infection, and difficulty in weaning off respirators. All of these further induce respiratory dysfunction and even threaten the patients' survival. The potential mechanisms of diaphragm atrophy and dysfunction include impairment of myofiber protein anabolism, enhancement of myofiber protein degradation, release of inflammatory mediators, imbalance of metabolic hormones, myonuclear apoptosis, autophagy, and oxidative stress. Among these contributors, mitochondrial oxidative stress is strongly implicated to play a key role in the process as it modulates diaphragm protein synthesis and degradation, induces protein oxidation and functional alteration, enhances apoptosis and autophagy, reduces mitochondrial energy supply, and is regulated by inflammatory cytokines via related signaling molecules. This review aims to provide a concise overview of pathological mechanisms of diaphragmatic dysfunction in critically ill patients, with special emphasis on the role and modulating mechanisms of mitochondrial oxidative stress.

Physiopathological mechanisms of diaphragmatic dysfunction associated with mechanical ventilation

Ventilator-induced diaphragm dysfunction (VIDD) is the loss of diaphragmatic muscle strength'related to of mechanical ventilation, noticed during the first day or 48hours after initiating controlled mechanical ventilation. This alteration has been related to disruption on the insulin growth factor/phosphoinositol 3-kinase/kinase B protein pathway (IGF/PI3K/AKT), in addition to an overexpression of FOXO, expression of NF-kB signaling, increase function of muscular ubiquitin ligase and activation of caspasa-3. VIDD has a negative impact on quality of life, duration of mechanical ventilation, and hospitalization stance and cost. More studies are necessary to understated the process and impact of VIDD. This is a narrative review of non-systematic literature, aiming to explain the molecular pathways involved in VIDD.

Respective contribution of intensive care unit-acquired limb muscle and severe diaphragm weakness on weaning outcome and mortality: a post hoc analysis of two cohorts

Background

Intensive care unit (ICU)-acquired weakness (ICU-AW) and ICU-acquired diaphragm dysfunction (ICU-DD) occur frequently in mechanically ventilated (MV) patients. It is unknown whether they have different risk factors and different impacts on outcome. This study was designed to (1) describe the respective risk factors associated with ICU-AW and severe ICU-DD and (2) evaluate the respective impact of ICU-AW and severe ICU-DD on outcome.

Methods

Post hoc analysis of two prospective cohort studies conducted in two ICUs. In patients mechanically ventilated for at least 24 h undergoing a first spontaneous breathing trial, severe ICU-DD was defined as diaphragm twitch pressure < 7 cmH₂O and ICU-AW was defined as Medical Research Council Score < 48.

Results

One hundred sixteen patients were assessed. Factors independently associated with severe ICU-DD were age, longer duration of MV, and exposure to sufentanil, and those factors associated with ICU-AW were longer duration of MV and exposure to norepinephrine. Severe ICU-DD (OR 3.56, p = 0.008), but not ICU-AW, was independently associated with weaning failure (59%). ICU-AW (OR 4.30, p = 0.033), but not severe ICU-DD, was associated with ICU mortality. Weaning failure and mortality rate were higher in patients with both severe ICU-DD and ICU-AW (86% and 39%, respectively) than in patients with either severe ICU-DD (64% and 0%) or ICU-AW (63% and 13%).

Conclusion

Severe ICU-DD and ICU-AW have different risk factors and different impacts on weaning failure and mortality. The impact of the combination of ICU-DD and ICU-AW is more pronounced than their individual impact.

Respective contribution of intensive care unit-acquired limb muscle and severe diaphragm weakness on weaning outcome and mortality: a post hoc analysis of two cohorts

BACKGROUND

Intensive care unit (ICU)-acquired weakness (ICU-AW) and ICU-acquired diaphragm dysfunction (ICU-DD) occur frequently in mechanically ventilated (MV) patients. It is unknown whether they have different risk factors and different impacts on outcome. This study was designed to (1) describe the respective risk factors associated with ICU-AW and severe ICU-DD and (2) evaluate the respective impact of ICU-AW and severe ICU-DD on outcome.

METHODS

Post hoc analysis of two prospective cohort studies conducted in two ICUs. In patients mechanically ventilated for at least 24 h undergoing a first spontaneous breathing trial, severe ICU-DD was defined as diaphragm twitch pressure < 7 cmH₂O and ICU-AW was defined as Medical Research Council Score < 48.

RESULTS

One hundred sixteen patients were assessed. Factors independently associated with severe ICU-DD were age, longer duration of MV, and exposure to sufentanil, and those factors associated with ICU-AW were longer duration of MV and exposure to norepinephrine. Severe ICU-DD (OR 3.56, p = 0.008), but not ICU-AW, was independently associated with weaning failure (59%). ICU-AW (OR 4.30, p = 0.033), but not severe ICU-DD, was associated with ICU mortality. Weaning failure and mortality rate were higher in patients with both severe ICU-DD and ICU-AW (86% and 39%, respectively) than in patients with either severe ICU-DD (64% and 0%) or ICU-AW (63% and 13%).

CONCLUSION

Severe ICU-DD and ICU-AW have different risk factors and different impacts on weaning failure and mortality. The impact of the combination of ICU-DD and ICU-AW is more pronounced than their individual impact.

Respective contribution of intensive care unit-acquired limb muscle and severe diaphragm weakness on weaning outcome and mortality: a post hoc analysis of two cohorts

BACKGROUND

Intensive care unit (ICU)-acquired weakness (ICU-AW) and ICU-acquired diaphragm dysfunction (ICU-DD) occur frequently in mechanically ventilated (MV) patients. It is unknown whether they have different risk factors and different impacts on outcome. This study was designed to (1) describe the respective risk factors associated with ICU-AW and severe ICU-DD and (2) evaluate the respective impact of ICU-AW and severe ICU-DD on outcome.

METHODS

Post hoc analysis of two prospective cohort studies conducted in two ICUs. In patients mechanically ventilated for at least 24 h undergoing a first spontaneous breathing trial, severe ICU-DD was defined as diaphragm twitch pressure < 7 cmH₂O and ICU-AW was defined as Medical Research Council Score < 48.

RESULTS

One hundred sixteen patients were assessed. Factors independently associated with severe ICU-DD were age, longer duration of MV, and exposure to sufentanil, and those factors associated with ICU-AW were longer duration of MV and exposure to norepinephrine. Severe ICU-DD (OR 3.56, p = 0.008), but not ICU-AW, was independently associated with weaning failure (59%). ICU-AW (OR 4.30, p = 0.033), but not severe ICU-DD, was associated with ICU mortality. Weaning failure and mortality rate were higher in patients with both severe ICU-DD and ICU-AW (86% and 39%, respectively) than in patients with either severe ICU-DD (64% and 0%) or ICU-AW (63% and 13%).

CONCLUSION

Severe ICU-DD and ICU-AW have different risk factors and different impacts on weaning failure and mortality. The impact of the combination of ICU-DD and ICU-AW is more pronounced than their individual impact.

Effects of exercise preconditioning and HSP72 on diaphragm muscle function during mechanical ventilation

BACKGROUND

Mechanical ventilation (MV) is a life-saving measure for patients in respiratory failure. However, prolonged MV results in significant diaphragm atrophy and contractile dysfunction, a condition referred to as ventilator-induced diaphragm dysfunction (VIDD). While there are currently no clinically approved countermeasures to prevent VIDD, increased expression of heat shock protein 72 (HSP72) has been demonstrated to attenuate inactivity-induced muscle wasting. HSP72 elicits cytoprotection via inhibition of NF-κB and FoxO transcriptional activity, which contribute to VIDD. In addition, exercise-induced prevention of VIDD is characterized by an increase in the concentration of HSP72 in the diaphragm. Therefore, we tested the hypothesis that increased HSP72 expression is required for the exercise-induced prevention of VIDD. We also determined whether increasing the abundance of HSP72 in the diaphragm, independent of exercise, is sufficient to prevent VIDD.

METHODS

Cause and effect was determined by inhibiting the endurance exercise-induced increase in HSP72 in the diaphragm of exercise trained animals exposed to prolonged MV via administration of an antisense oligonucleotide targeting HSP72. Additional experiments were performed to determine if increasing HSP72 in the diaphragm via genetic (rAAV-HSP72) or pharmacological (BGP-15) overexpression is sufficient to prevent VIDD.

RESULTS

Our results demonstrate that the exercise-induced increase in HSP72 protein abundance is required for the protective effects of exercise against VIDD. Moreover, both rAAV-HSP72 and BGP-15-induced overexpression of HSP72 were sufficient to prevent VIDD. In addition, modification of HSP72 in the diaphragm is inversely related to the expression of NF-κB and FoxO target genes.

CONCLUSIONS

HSP72 overexpression in the diaphragm is an effective intervention to prevent MV-induced oxidative stress and the transcriptional activity of NF-κB and FoxO. Therefore, overexpression of HSP72 in the diaphragm is a potential therapeutic target to protect against VIDD.