Critical illness polyneuropathy and myopathy 20 years later. No man's land? No, it is our land!

Potential relationship between cuproptosis and sepsis-acquired weakness: an intermediate role for mitochondria

Sepsis is defined as a life-threatening organ dysfunction caused by a dysregulated host response to infection. Skeletal muscle atrophy due to critical illness is a common phenomenon in the intensive care unit (ICU) and is referred to as ICU-acquired weakness (ICU-AW). The occurrence of ICU-AW in patients with sepsis is known as sepsis-acquired weakness (SAW). Furthermore, it is well known that maintaining normal muscle function closely relates to mitochondrial homeostasis. Once mitochondrial function is impaired, both muscle quality and function are affected. Copper plays a key role in mitochondrial homeostasis as a transition metal that regulates the function and stability of various enzymes. Copper is also involved in oxidation-reduction reactions, and intracellular copper overload causes oxidative stress and induces cell death. Previous studies have shown that excess intracellular copper induces cell death by targeting lipid-acylated proteins that regulate the mitochondrial tricarboxylic acid (TCA) cycle, which differs from the known canonical mechanisms of regulated cell death. Furthermore, inhibitors of cell death, such as apoptosis, necroptosis, pyroptosis and ferroptosis, are not effective in preventing copper-induced cell death. This new form of cell death has been termed "Cuproptosis"; however, the mechanism by which copper-induced cell death is involved in SAW remains unclear. In this paper, we review the possible relationship between cuproptosis and SAW. Cuproptosis may be involved in regulating the pathological mechanisms of SAW through mitochondria-related signaling pathways, mitochondria-related ferroptosis mechanisms, and mitochondria-related genes, and to provide new ideas for further investigations into the mechanism of SAW.

A Cross-Sectional Study of the Impact of ICU-Acquired Weakness: Prevalence, Associations, and Severity

Background and objective ICU-acquired weakness (ICU-AW) refers to a group of neuromuscular lesions that can develop in the ICU. It leads to decreased physical function, increased in-ICU and in-hospital mortality, and increased healthcare costs. Given its high prevalence and significant impact on patient outcomes, it is essential to have a deeper understanding of ICU-AW. In light of this, this study aimed to ascertain the prevalence, associations, and severity of ICU-AW at a tertiary hospital in the Kingdom of Saudi Arabia (KSA) and to evaluate physician awareness of this condition. Methods A cross-sectional study was conducted in the ICU of Al Madina General Hospital, Medina, KSA, from April 22 to August 22, 2022, involving patients who were 18 years or older and met the inclusion criteria (n=101). The overall muscle strength was assessed daily by using the Medical Research Council (MRC) scale for muscle strength. ICU-AW was identified in patients who experienced a decline in their MRC-Sum Score (MRC-SS) during their ICU stay. Results A total of 101 patients were enrolled in the study. The incidence of ICU-AW was 16.8% (n=17), with 23.5% exhibiting significant weakness and 76.5% having severe weakness. Post hoc comparisons showed that females had a higher incidence of ICU-AW. Fisher's exact test revealed a statistically significant relationship between ICU-AW and the longer duration of ICU stay (p=0.001), use of mechanical ventilation (p=0.034), and low hemoglobin levels (p=0.037). Conclusions ICU-AW was observed in 16.8% (n=17) of patients in our cohort, highlighting the significance of this condition. The study revealed a noteworthy correlation between ICU-AW and female sex, extended ICU stays, mechanical ventilation, and anemia.

Effects of neuromuscular electrical stimulation therapy on physical function in patients with COVID-19 associated pneumonia: Study protocol of a randomized controlled trial

Purpose

Neuromuscular electrical stimulation (NMES) has been considered as a promising approach for the early rehabilitation of patients during and/or after intensive care unit (ICU) stay. The overall objective of this study is to evaluate the NMES effectiveness to counteract the post-ICU impairment in physical function of COVID-19 patients. The specific aim of this manuscript is to describe the study design, protocol, content of interventions, primary and secondary outcomes and to discuss the clinical rehabilitation impact of the expected experimental results.

Methods

This prospective, randomized, controlled, parallel-group, single-blind trial will include 80 patients who had undergone mechanical or non-invasive ventilation following pneumonia-induced respiratory failure. Patients are randomized to a control group (routine physical therapy for 3 weeks) or a NMES group (routine physical therapy plus NMES of quadriceps and gastrocnemius muscles for 3 weeks). The primary outcome is physical performance assessed through the Short Physical Performance Battery (SPPB). Secondary outcomes include independence level, perceived fatigue, muscle strength, rectus femoris thickness, and walking performance. The SPBB and walking performance are assessed once (after the intervention), while all other outcomes are assessed twice (before and after the intervention).

Conclusion

NMES is a simple and non-invasive technique for muscle strengthening that is usually well tolerated, does not produce adverse effects, requires no or little cooperation from patients and is quite inexpensive. Therefore, proving the effectiveness of NMES therapy for physical and muscle function in COVID-19 patients could support its systematic incorporation in post-ICU rehabilitation protocols of patients presenting with post-intensive care syndrome.

Using ultrasound to examine muscle mass in preterm infants at term-equivalent age

The aim of this study was to compare the skeletal muscle thickness of three different muscles and muscle groups in 44 preterm infants studied at term-equivalent age and 44 full-term controls: the biceps brachii, quadriceps femoris, and anterior tibial. The study was carried out at the Careggi University Hospital, Florence, Italy, from January 2018 to December 2019. We assumed that impaired muscle thickness in premature infants would be correlated with exposure to risk factors in the postnatal period. When the premature babies reached term-equivalent age, they were statistically significantly thinner and shorter and had a lower head circumference and lower body mass index than the full-term controls. The muscle thicknesses in the proximal and distal districts were statistically significantly smaller in prematurely born than term-born infants. The skeletal muscle thickness was related to the revised Clinical Risk Index for Babies score and days of invasive mechanical ventilation.Conclusion: Our data show that at term-equivalent age the premature babies had lower skeletal muscle mass acquisition than the full-term controls. This was particularly due to critical conditions at birth and the subsequent duration of invasive mechanical ventilation. What is Known: • The deleterious effects of prolonged mechanical ventilation on skeletal muscle function have been reported by adult intensive care studies. • Ultrasound imagines of fat and muscle thickness have been used in neonatology, as the method is safe, portable, and noninvasive. What is New: • Premature babies studied at term-equivalent age had lower muscle acquisition, but similar subcutaneous fat thickness, to full-term controls. • A high revised Clinical Risk Index for Babies score at birth, and prolonged invasive mechanical ventilation, was associated with skeletal muscle impairment.

ICU-acquired weakness

Critically ill patients often acquire neuropathy and/or myopathy labeled ICU-acquired weakness. The current insights into incidence, pathophysiology, diagnostic tools, risk factors, short- and long-term consequences and management of ICU-acquired weakness are narratively reviewed. PubMed was searched for combinations of “neuropathy”, “myopathy”, “neuromyopathy”, or “weakness” with “critical illness”, “critically ill”, “ICU”, “PICU”, “sepsis” or “burn”. ICU-acquired weakness affects limb and respiratory muscles with a widely varying prevalence depending on the study population. Pathophysiology remains incompletely understood but comprises complex structural/functional alterations within myofibers and neurons. Clinical and electrophysiological tools are used for diagnosis, each with advantages and limitations. Risk factors include age, weight, comorbidities, illness severity, organ failure, exposure to drugs negatively affecting myofibers and neurons, immobility and other intensive care-related factors. ICU-acquired weakness increases risk of in-ICU, in-hospital and long-term mortality, duration of mechanical ventilation and of hospitalization and augments healthcare-related costs, increases likelihood of prolonged care in rehabilitation centers and reduces physical function and quality of life in the long term. RCTs have shown preventive impact of avoiding hyperglycemia, of omitting early parenteral nutrition use and of minimizing sedation. Results of studies investigating the impact of early mobilization, neuromuscular electrical stimulation and of pharmacological interventions were inconsistent, with recent systematic reviews/meta-analyses revealing no or only low-quality evidence for benefit. ICU-acquired weakness predisposes to adverse short- and long-term outcomes. Only a few preventive, but no therapeutic, strategies exist. Further mechanistic research is needed to identify new targets for interventions to be tested in adequately powered RCTs.

Neuromuscular electrical stimulation in critically ill traumatic brain injury patients attenuates muscle atrophy, neurophysiological disorders, and weakness: a randomized controlled trial

Background

Critically ill traumatic brain injury (TBI) patients experience extensive muscle damage during their stay in the intensive care unit. Neuromuscular electrical stimulation (NMES) has been considered a promising treatment to reduce the functional and clinical impacts of this. However, the time needed for NMES to produce effects over the muscles is still unclear. This study primarily aimed to assess the time needed and effects of an NMES protocol on muscle architecture, neuromuscular electrophysiological disorder (NED), and muscle strength, and secondarily, to evaluate the effects on plasma systemic inflammation, catabolic responses, and clinical outcomes.

Methods

We performed a randomized clinical trial in critically ill TBI patients. The control group received only conventional physiotherapy, while the NMES group additionally underwent daily NMES for 14 days in the lower limb muscles. Participants were assessed at baseline and on days 3, 7, and 14 of their stay in the intensive care unit. The primary outcomes were assessed with muscle ultrasound, neuromuscular electrophysiology, and evoked peak force, and the secondary outcomes with plasma cytokines, matrix metalloproteinases, and clinical outcomes.

Results

Sixty participants were randomized, and twenty completed the trial from each group. After 14 days, the control group presented a significant reduction in muscle thickness of tibialis anterior and rectus femoris, mean of - 0.33 mm (- 14%) and - 0.49 mm (- 21%), p < 0.0001, respectively, while muscle thickness was preserved in the NMES group. The control group presented a higher incidence of NED: 47% vs. 0% in the NMES group, p < 0.0001, risk ratio of 16, and the NMES group demonstrated an increase in the evoked peak force (2.34 kg/f, p < 0.0001), in contrast to the control group (- 1.55 kg/f, p < 0.0001). The time needed for the NMES protocol to prevent muscle architecture disorders and treat weakness was at least 7 days, and 14 days to treat NED. The secondary outcomes exhibited less precise results, with confidence intervals that spanned worthwhile or trivial effects.

Conclusions

NMES applied daily for fourteen consecutive days reduced muscle atrophy, the incidence of NED, and muscle weakness in critically ill TBI patients. At least 7 days of NMES were required to elicit the first significant results.

Trial registration

The trial was registered at ensaiosclinicos.gov.br under protocol RBR-8kdrbz on 17 January 2016.

Risk Factors Associated With Peripheral Neuropathy in Heart Failure Patients Candidates for Transplantation

INTRODUCTION

Peripheral neuropathy can affect patients with heart failure, though its prevalence is unknown. After heart transplantation, it can influence the postoperative course and quality of life, but screening for neuromuscular disease is not routinely performed.

OBJECTIVE

The aim of this study was to identify the factors associated with neuropathy in a population of patients with heart failure who are candidates for heart transplantation.

STUDY DESIGN

Data regarding patients' clinical history, including recent hospitalizations, were collected. All patients underwent a complete neurological examination and a neurophysiological protocol including nerve conduction studies and concentric needle electromyography.

RESULTS

Thirty-two patients were included in the study, and neuropathy was diagnosed in 10 (31.3%). Neuropathy was associated with the number of admissions ( P = .023; odds ratio [OR]: 1.96) and the total number of days of hospitalization in the year prior to inclusion in the study ( P = .010; OR: 1.03). The majority of hospitalizations occurred in the step-down unit (85%), with acute heart failure the leading cause of admission (42%).

CONCLUSIONS

This study shows that neuropathy is frequent in patients with advanced heart failure and that hospitalization for cardiac care, also in the absence of intensive care, is a marker of high risk of neurologic damage. These data can help physicians in selecting and managing candidates for transplantation and can guide decisions on the best immunosuppressive regimen or rehabilitation strategy.

Pulmonary and Physical Rehabilitation in Critically Ill Patients

Some patients admitted to the intensive care unit (ICU) because of an acute illness, complicated surgery, or multiple traumas develop muscle weakness affecting the limbs and respiratory muscles during acute care in the ICU. This condition is referred to as ICU-acquired weakness (ICUAW), and can be evoked by critical illness polyneuropathy (CIP), critical illness myopathy (CIM), or critical illness polyneuromyopathy (CIPNM). ICUAW is diagnosed using the Medical Research Council (MRC) sum score based on bedside manual muscle testing in cooperative patients. The MRC sum score is the sum of the strengths of the 12 regions on both sides of the upper and lower limbs. ICUAW is diagnosed when the MRC score is less than 48 points. However, some patients require electrodiagnostic studies, such as a nerve conduction study, electromyography, and direct muscle stimulation, to differentiate between CIP and CIM. Pulmonary rehabilitation in the ICU can be divided into modalities intended to remove retained airway secretions and exercise therapies intended to improve respiratory function. Physical rehabilitation, including early mobilization, positioning, and limb exercises, attenuates the weakness that occurs during critical care. To perform mobilization in mechanically ventilated patients, pretreatment by removing secretions is necessary. It is also important to increase the strength of respiratory muscles and to perform lung recruitment to improve mobilization in patients who are weaned from the ventilator. For these reasons, pulmonary rehabilitation is important in addition to physical therapy. Early recognition of CIP, CIM, and CIPNM and early rehabilitation in the ICU might improve patients’ functional recovery and outcomes.

Deltoid muscle morphometry as an index of impaired skeletal muscularity in neonatal intensive care

We hypothesised that extremely premature infants would have decreased muscle mass at term-corrected age compared to term-born infants and that the degree of reduced muscle mass acquisition would correlate with the duration of invasive mechanical ventilation. The MRI brain scans of infants admitted in the neonatal unit at King's College Hospital between 1 January 2010 and 1 June 2016 were retrospectively reviewed. The coronal cross-sectional area of the left deltoid muscle (DCSA) was measured in 17 infants born < 28 weeks of gestation and in 20 infants born at term. The prematurely born infants had a median (IQR) gestation age of 25 weeks (24-27) and the term infants 40 weeks (38-41). The duration of invasive mechanical ventilation for the prematurely born infants was 39 days (14-62) and that for the term infants 4 days (2-5), p < 0.001. DCSA was smaller in prematurely born infants (median 189, IQR 176-223 mm²) compared to term-born infants (median 302, IQR 236-389 mm²), p < 0.001. DCSA was related to gestation age (r = 0.545, p = 0.001), weight z-score at MRI (r = 0.658, p < 0.001) and days of invasive mechanical ventilation (r = - 0.583, p < 0.001). In conclusion, extremely premature infants studied at term had a lower muscle mass compared to term-born infants.

CONCLUSION

Our results suggest that prolonged mechanical ventilation in infants admitted in neonatal intensive care is associated with reduced skeletal muscle mass acquisition. What is Known: • Prolonged mechanical ventilation in adult intensive care patients has been associated with skeletal muscle dysfunction and atrophy. • The cross-sectional area of the deltoid muscle has been used to evaluate muscle atrophy in infants with a previous branchial plexus birth injury. What is New: • Premature infants studied at term exhibit lower cross-sectional area of the deltoid muscle than their term counterparts. • Prolonged mechanical ventilation could be associated with skeletal muscle impairment.

ICU-acquired weakness: should medical sovereignty belong to any specialist?

ICU-acquired weakness (ICUAW), including critical illness polyneuropathy, critical illness myopathy, and critical illness polyneuropathy and myopathy, is a frequent disabling disorder in ICU subjects. Research has predominantly been performed by intensivists, whose efforts have permitted the diagnosis of ICUAW early during an ICU stay and understanding of several of the pathophysiological and clinical aspects of this disorder. Despite important progress, the therapeutic strategies are unsatisfactory and issues such as functional outcomes and long-term recovery remain unclear. Studies involving multiple specialists should be planned to better differentiate the ICUAW types and provide proper functional outcome measures and follow-up. A more strict collaboration among specialists interested in ICUAW, in particular physiatrists, is desirable to plan proper care pathways after ICU discharge and to better meet the health needs of subjects with ICUAW.

The ICM research agenda on intensive care unit-acquired weakness

We present areas of uncertainty concerning intensive care unit-acquired weakness (ICUAW) and identify areas for future research. Age, pre-ICU functional and cognitive state, concurrent illness, frailty, and health trajectories impact outcomes and should be assessed to stratify patients. In the ICU, early assessment of limb and diaphragm muscle strength and function using nonvolitional tests may be useful, but comparison with established methods of global and specific muscle strength and physical function and determination of their reliability and normal values would be important to advance these techniques. Serial measurements of limb and respiratory muscle strength, and systematic screening for dysphagia, would be helpful to clarify if and how weakness of these muscle groups is independently associated with outcome. ICUAW, delirium, and sedatives and analgesics may interact with each other, amplifying the effects of each individual factor. Reduced mobility in patients with hypoactive delirium needs investigations into dysfunction of central and peripheral nervous system motor pathways. Interventional nutritional studies should include muscle mass, strength, and physical function as outcomes, and prioritize elucidation of mechanisms. At follow-up, ICU survivors may suffer from prolonged muscle weakness and wasting and other physical impairments, as well as fatigue without demonstrable weakness on examination. Further studies should evaluate the prevalence and severity of fatigue in ICU survivors and define its association with psychiatric disorders, pain, cognitive impairment, and axonal loss. Finally, methodological issues, including accounting for baseline status, handling of missing data, and inclusion of patient-centered outcome measures should be addressed in future studies.