Critical illness polyneuropathy. A 2-year follow-up study in 19 severe cases

Identification and validation of oxidative stress-related genes in sepsis-induced myopathy

BACKGROUND

Sepsis-induced myopathy (SIM) a complication of sepsis that results in prolonged mechanical ventilation, long-term functional disability, and increased patient mortality. This study was performed to identify potential key oxidative stress-related genes (OS-genes) as biomarkers for the diagnosis of SIM using bioinformatics.

METHODS

The GSE13205 was obtained from the Gene Expression Omnibus (GEO) database, including 13 SIM samples and 8 healthy samples, and the differentially expressed genes (DEGs) were identified by limma package in R language. Simultaneously, we searched for the genes related to oxidative stress in the Gene Ontology (GO) database. The intersection of the genes selected from the GO database and the genes from the GSE13205 was considered as OS-genes of SIM, where the differential genes were regarded as OS-DEGs. OS-DEGs were analyzed using GO enrichment, Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways, and protein-protein interaction (PPI) networks. Hub genes in OS-DEGs were selected based on degree, and diagnostic genes were further screened by gene expression and receiver operating characteristic (ROC) curve. Finally, a miRNA-gene network of diagnostic genes was constructed.

RESULTS

A total of 1089 DEGs were screened from the GSE13205, and 453 OS-genes were identified from the GO database. The overlapping DEGs and OS-genes constituted 25 OS-DEGs, including 15 significantly upregulated and 10 significantly downregulated genes. The top 10 hub genes, including CD36, GPX3, NQO1, GSR, TP53, IDH1, BCL2, HMOX1, JAK2, and FOXO1, were screened. Furthermore, 5 diagnostic genes were identified: CD36, GPX3, NQO1, GSR, and TP53. The ROC analysis showed that the respective area under the curves (AUCs) of CD36, GPX3, NQO1, GSR, and TP53 were 0.990, 0.981, 0.971, 0.971, and 0.971, which meant these genes had very high diagnostic values of SIM. Finally, based on these 5 diagnostic genes, we found that miR-124-3p and miR-16-5p may be potential targets for the treatment of SIM.

CONCLUSIONS

The results of this study suggest that OS-genes might play an important role in SIM. CD36, GPX3, NQO1, GSR, and TP53 have potential as specific biomarkers for the diagnosis of SIM.

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.

Early diagnosis leading to improvement of critical illness polyneuropathy associated with severe Staphylococcus aureus infection in a patient on hemodialysis

Critical illness polyneuropathy (CIP) is a very rare complication of sepsis and multi-organ failure. Herein, we report the first case of CIP reported in a patient on maintenance hemodialysis, who improved with rehabilitation. A 55-year-old male patient was emergently admitted with fever and altered consciousness and diagnosed with bacterial meningitis based on cerebral spinal fluid and cranial magnetic resonance imaging findings. Methicillin-susceptible Staphylococcus aureus was detected in blood and cerebral spinal fluid cultures. Despite treatment with appropriate antibiotics, blood cultures were positive for 9 days and serum C-reactive protein (CRP) levels were persistently elevated. Magnetic resonance imaging of hands and feet to determine infection origin revealed osteomyelitis in several fingers and toes, which required the amputation of 14 necrotic fingers and toes. Thereafter, blood cultures became negative and CRP levels declined. However, flaccid paralysis was noted in both upper and lower extremities during sepsis treatment. Nerve conduction studies showed peripheral axonal disorder in motor and sensory nerves, and CIP was determined as the cause of paralysis based on the fulfillment of all four CIP diagnostic criteria. The patient's muscle strength improved with early and appropriate medical treatment and physical therapy, and he was discharged home 147 days after admission. Prolonged high-level inflammation is a cause of CIP. Patients on hemodialysis, who are potentially immunosuppressed and vulnerable to infection, are at high risk for CIP. In patients on maintenance hemodialysis who develop flaccid paralysis during treatment for severe infection, CIP should be considered for early diagnosis and intervention.

Recovery and long term functional outcome in people with critical illness polyneuropathy and myopathy: a scoping review

BACKGROUND

Intensive care unit acquired weakness (ICUAW), embraces an array of disorders labeled "critical illness polyneuropathy" (CIP), "critical illness myopathy" (CIM) or "critical illness polyneuromyopathy" (CIPNM). Several studies have addressed the various characteristics of ICUAW, but the recovery is still unclear.

OBJECTIVE

The present review investigated the recovery and the long-term functional outcome of subjects with ICUAW, whether the types of ICUAW have different outcomes and whether there is any supporting evidence.

METHODS

Literature search was performed from MEDLINE/PubMed, CINAHL, EMBASE, PeDro, Web of Science and Scopus. Inclusion criteria were: i) sample size including five or more subjects; ii) subjects who suffered from ICUAW and/or CIP, CIM and CIP/CIM; iii) ICUAW ascertained by EMG. Follow-ups longer than one year were defined as long-term.

RESULTS

Twenty-nine studies met the inclusion criteria. In total, 788 subjects with ICUAW were enrolled: 159 (20.1%) died and 588 (74.6%) were followed. Of all the included patients, 613 (77.7%) had CIP, 82 (10.4%) CIM and 56 (7.1%) CIP/CIM. Overall, 70.3% of the subjects with ICUAW fully recovered. Seven (24.1%) studies had a follow-up longer than 1 year (range 2-8) with 173 (21.9%) subjects enrolled globally and 108 followed. Of these subjects, 88.8% gained full recovery. Most of the studies did not use proper functional scales and only 4 and 3 studies employed the Barthel scale and the Functional Independence Measure (FIM) scale. Differentiation between the types of ICUAW was performed in 7 studies, but only 3 studies reported that subjects with CIM had a better prognosis and earlier recovery than subjects with CIP/CIM.

CONCLUSIONS

Subjects with ICUAW could achieve good recovery and could improve at follow-up. However, the quality of the published studies due to short follow-ups and the paucity of defined outcome measures require confirms.

High-dose intravenous immunoglobulins as a therapeutic option in critical illness polyneuropathy accompanying SARS-CoV-2 infection: A case-based review of the literature (Review)

The still ongoing COVID-19 pandemic has exposed the medical community to a number of major challenges. A significant number of patients require admission to intensive care unit (ICU) services due to severe respiratory, thrombotic and septic complications and require long-term hospitalization. Neuromuscular weakness is a common complication in critically ill patients who are treated in ICUs and are mechanically ventilated. This complication is frequently caused by critical illness myopathy (CIM) or critical illness polyneuropathy (CIP) and leads to difficulty in weaning from the ventilator. It is thought to represent an important neurologic manifestation of the systemic inflammatory response syndrome (SIRS). COVID-19 infection is known to trigger strong immune dysregulation, with an intense cytokine storm, as a result, the frequency of CIP is expected to be higher in this setting. The mainstay in the diagnosis of this entity beside the high level of clinical awareness is the electrophysiological examination that provides evidence of axonal motor and sensory polyneuropathy. The present article presents the case of a 54-year-old woman with severe COVID 19 infection who developed neuromuscular weakness, which turned out to be secondary to CIP and was treated successfully with a high dose of human intravenous immunoglobulins. Related to this case, we reviewed the relevant literature data regarding the epidemiology, pathophysiology and clinical features of this important complication and discussed also the treatment options and prognosis.

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.

Critical Illness Neuromyopathy Complicating Cardiac Surgery

Critical illness neuromyopathy (CINM) is a sporadically reported disease in the setting of an intensive care unit developing in the process of managing a critical illness. The disease primarily affects the motor and sensory axons and results in severe limb weakness rendering ventilator weaning extremely difficult. We report a case of CINM after cardiac valve surgery. Quadriplegia developed after the operation and resolved slowly over the following 2 months. The patient was discharged home free of neurologic symptoms.

Critical illness myopathy in a cervical spine-injured patient

Neuromuscular weakness acquired in the intensive care unit (ICU) causes significant impairment in critically ill patients. The spectrum of critical illness neuromuscular disease includes critical illness myopathy, critical illness polyneuropathy or both, and occurs in approximately one-third of patients admitted to the ICU and those who are ventilated for at least 7 days. Recognized risk factors include sepsis, systemic inflammatory response syndrome, multi-organ failure, neuromuscular blocking agents and corticosteroids, however the absence of predisposing factors should not preclude critical illness neuromuscular disease. A 23-year-old male suffered a cervical spine injury and was admitted to the ICU. Two weeks post admission, he lost all power in his upper limbs, neck and face. Nerve conduction studies and needle electromyography were performed 4 weeks and 3 months after the injury, suggesting that myopathy was the likely cause of weakness. The definitive diagnosis of critical illness myopathy was based on muscle biopsy demonstrating myosin filament loss. Evaluation of new-onset weakness in ICU patients is essential to distinguish neurological causes from complications of critical illness. Signs and symptoms of critical illness neuromuscular disease must be identified early to encourage recovery, promote rehabilitation, and reduce morbidity and mortality.

The impact of extended bed rest on the musculoskeletal system in the critical care environment

Prolonged immobility is harmful with rapid reductions in muscle mass, bone mineral density and impairment in other body systems evident within the first week of bed rest which is further exacerbated in individuals with critical illness. Our understanding of the aetiology and secondary consequences of prolonged immobilization in the critically ill is improving with recent and ongoing research to establish the cause, effect, and best treatment options. This review aims to describe the current literature on bed rest models for examining immobilization-induced changes in the musculoskeletal system and pathophysiology of immobilisation in critical illness including examination of intracellular signalling processes involved. Finally, the review examines the current barriers to early activity and mobilization and potential rehabilitation strategies, which are being, investigated which may reverse the effects of prolonged bed rest. Addressing the deleterious effects of immobilization is a major step in treatment and prevention of the public health issue, that is, critical illness survivorship.

Muscle atrophy in intensive care unit patients

Introduction:

The muscle atrophy is one of the most important and frequent problems observed in patients in Intensive Care Units. The term describes the disorder in the structure and in the function of the muscle while incidence rates range from 25-90 % in patients with prolonged hospitalization.

Purpose:

This is a review containing all data related to the issue of muscle atrophy and is especially referred to its causes and risk factors. The importance of early diagnosis and early mobilization are also highlighted in the study.

Material and methods:

a literature review was performed on valid databases such as Scopus, PubMed, Cinhal for the period 2000-2013 in English language. The following keywords were used: loss of muscle mass, ICU patients, immobilization, bed rest.

Results:

From the review is concluded that bed rest and immobilization in order to reduce total energy costs, are the main causes for the appearance of the problem. The results of the reduction of the muscle mass mainly affect the musculoskeletal, cardiovascular and respiratory system. The administration of the cortisone, the immobility, the sepsis and hyperglycemia are included in the risk factors. The prevention is the primary therapeutic agent and this is achieved due to the early mobilization of the patients, the use of neuromuscular electrical stimulation and the avoidance of exposure to risk factors.

Conclusions:

The prevention of muscle atrophy is a primary goal of treatment for the patients in the ICU, because it reduces the incidence of the disease, reduces the time spent in ICU and finally improves the quality of patients’ life.

Long-term recovery In critical illness myopathy is complete, contrary to polyneuropathy

INTRODUCTION

Muscle weakness in critically ill patients after discharge varies. It is not known whether the electrophysiological distinction between critical illness myopathy (CIM) and critical illness polyneuropathy (CIP) during the early part of a patient's stay in the intensive care unit (ICU) predicts long-term prognosis.

METHODS

This was a prospective cohort study of mechanically ventilated ICU patients undergoing conventional nerve conduction studies and direct muscle stimulation in addition to neurological examination during their ICU stay and 1 year after ICU discharge.

RESULTS

Twenty-six patients (7 ICU controls, 8 CIM patients, and 11 CIM/CIP patients) were evaluated 1 year after discharge from the ICU. Eighty-eight percent (n = 7) of CIM patients recovered within 1 year compared with 55% (n = 6) of CIM/CIP patients. Thirty-six percent (n = 4) of CIM/CIP patients still needed assistance during their daily routine (P = 0.005).

CONCLUSIONS

Early electrophysiological testing predicts long-term outcome in ICU survivors. CIM has a significantly better prognosis than CIM/CIP.

Intensive care unit-related generalized neuromuscular weakness due to critical illness polyneuropathy/myopathy in critically ill patients

Thirty to fifty percent of critically ill patients admitted to the intensive care unit suffer from generalized neuromuscular weakness due to critical illness polyneuropathy, critical illness myopathy, or a combination of them, thus prolonging mechanical ventilation and their intensive care unit stay. A distinction between these syndromes and other neuromuscular abnormalities beginning either before or after ICU admission is necessary. These intensive care unit-related diseases are associated with both elevated mortality rates and increased morbidity rates. Generally, over 50 % of patients will completely recover. Most of them recover after 4-12 weeks, but some patients have been reported to keep on suffering from muscle weakness for at least 4 months. Prevention has a key role in the management of critical illness neuromuscular disorders, as no specific therapy has been suggested. Either prevention or aggressive treatment of sepsis can prevent critical illness polyneuropathy and critical illness myopathy. The dose and duration of the administration of neuromuscular blocking drugs should be limited, and their concurrent administration with corticosteroids should be avoided. Intensive insulin therapy has also been proven to reduce their incidence. Finally, early mobilization via active exercise or electrical muscle stimulation plays a significant role in their prevention.

Neurologic Implications of Critical Illness and Organ Dysfunction

Critical illness has consequences for the nervous system. Patients experiencing critical illness are at risk for common global neurologic disturbances, such as delirium, long-term cognitive dysfunction, ICU-acquired weakness, sleep disturbances, recurrent seizures, and coma. In addition, complications related to specific organ dysfunction may be anticipated. Cardiovascular disease presents the possibility for CNS injury after cardiac arrest, sequelae of endocarditis, aberrancies of blood flow autoregulation, and malperfusion. Respiratory disease is known to cause short-term effects of hypoxia and long-term effects after ARDS. Sepsis encephalopathy and sickness behavior syndrome are early signs of infection in patients. In addition, commonly encountered organ dysfunction including uremia, hepatic failure, endocrine, and metabolic disturbances present with neurologic findings which may manifest in the critically ill patient as well.

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

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

Long-term functional outcome and health status of patients with critical illness polyneuromyopathy

OBJECTIVE

The aim of this study was to investigate the long-term functional outcome and health status of patients with critical illness polyneuromyopathy (CIPNM).

METHOD AND SUBJECTS

One hundred and twenty-four consecutive survival intensive care unit patients admitted to a neuro-rehabilitation Unit from January 2003 to December 2007 were identified. Patients with proven CIPNM by the electromyography were prospectively followed. The Barthel and modified Rankin Scales (mRS) were administered to all patients at baseline, discharge and follow-up. The SF-36 questionnaire was administered to ascertain health status. Each patient underwent an individually tailored rehabilitation therapy.

RESULTS

Forty-two subjects (23M, 19F, mean age 58.4 ± 13.9) were enrolled. Of these, 30 patients were diagnosed electrophysiologically with CIP, six with critical illness myopathy (CIM) and six with a finding combination of CIP and CIM (CIP/CIM) subtype. The mean Barthel scores at baseline, discharge and follow-up were 16.7 ± 8.6, 81.7 ± 16.4 and 86.7 ± 15.9 (P < 0.001) and the median mRS scores were 5 (IQR: 5-5), 3 (IQR: 0-5) and 1 (IQR: 0-5). The mean length of neuro-rehabilitation stay was 76.2 ± 28.1 days. The SF-36 questionnaire administered at follow-up (mean 31.7 ± 15.8 months), showed significantly lower values compared to Italian normative.

CONCLUSION

ICU patients with CIPNM treated in a neuro-rehabilitation setting resulted in a good functional outcome. Despite complete recovery, patients with CIPNM experienced difficulties in health status.

Critical illness polyneuropathy and myopathy in the intensive care unit

Critical illness polyneuropathy (CIP) and critical illness myopathy (CIM) are major complications that occur in severely ill patients who require intensive care treatment. CIP and CIM affect the limb and respiratory muscles, and, as a consequence, they characteristically complicate weaning from the ventilator, increase the length of stay on the intensive care unit, and prolong physical rehabilitation. The basic pathophysiology of both disorders is complex and involves metabolic, inflammatory and bioenergetic alterations. It is unclear at present whether CIP and CIM are distinct entities, or whether they just represent different 'organ' manifestations of a common pathophysiological mechanism. This article provides an overview of the clinical and diagnostic features of CIP and CIM and discusses current pathophysiological and therapeutic concepts relating to these neuromuscular disorders.

A framework for diagnosing and classifying intensive care unit-acquired weakness

Neuromuscular dysfunction is prevalent in critically ill patients, is associated with worse short-term outcomes, and is a determinant of long-term disability in intensive care unit survivors. Diagnosis is made with the help of clinical, electrophysiological, and morphological observations; however, the lack of a consistent nomenclature remains a barrier to research. We propose a simple framework for diagnosing and classifying neuromuscular disorders acquired in critical illness.

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

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

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

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

Inactivation of sodium channels underlies reversible neuropathy during critical illness in rats

Neuropathy and myopathy can cause weakness during critical illness. To determine whether reduced excitability of peripheral nerves, rather than degeneration, is the mechanism underlying acute neuropathy in critically ill patients, we prospectively followed patients during the acute phase of critical illness and early recovery and assessed nerve conduction. During the period of early recovery from critical illness, patients recovered from neuropathy within days. This rapidly reversible neuropathy has not to our knowledge been previously described in critically ill patients and may be a novel type of neuropathy. In vivo intracellular recordings from dorsal root axons in septic rats revealed reduced action potential amplitude, demonstrating that reduced excitability of nerve was the mechanism underlying neuropathy. When action potentials were triggered by hyperpolarizing pulses, their amplitudes largely recovered, indicating that inactivation of sodium channels was an important contributor to reduced excitability. There was no depolarization of axon resting potential in septic rats, which ruled out a contribution of resting potential to the increased inactivation of sodium channels. Our data suggest that a hyperpolarized shift in the voltage dependence of sodium channel inactivation causes increased sodium inactivation and reduced excitability. Acquired sodium channelopathy may be the mechanism underlying acute neuropathy in critically ill patients.

What patients think about ICU follow-up services: a qualitative study

Introduction

UK policy recommendations advocate the use of intensive care unit (ICU) follow-up services to help detect and treat patients' physical and emotional problems after hospital discharge and as a means of service evaluation. This study explores patients' perceptions and experiences of these services.

Methods

Thirty-four former ICU patients were recruited throughout the UK, using maximum variation sampling to achieve as broad a range of experiences of the ICU as possible. Participants were interviewed at home by a qualitative researcher unconnected to their hospital care. Interviews were recorded and transcribed for analysis. We report a qualitative thematic analysis of patients' experiences of ICU follow up.

Results

Former patients said they valued ICU follow-up services, which had made an important contribution to their physical, emotional and psychological recovery in terms of continuity of care, receiving information, gaining expert reassurance and giving feedback to ICU staff. Continuity of care included having tests and being monitored, referrals to other specialists and ICU follow-up appointments soon after hospital discharge. Information about physical, emotional and psychological recovery was particularly important to patients, as was information that helped them make sense of their ICU experience. Those without access to ICU follow-up care often felt abandoned or disappointed because they had no opportunity to be monitored, referred or get more information.

Conclusions

Former patients value having ICU follow-up services but many found that their healthcare needs were unmet because hospitals were unable to provide the aftercare they required. Most participants were aware of the financial constraints on the health system. Although they valued ICU follow-up care, they did not want it to continue indefinitely, with many of them declining appointment invitations when they themselves felt they no longer needed them.

Clinical review: Critical illness polyneuropathy and myopathy

Critical illness polyneuropathy (CIP) and myopathy (CIM) are major complications of severe critical illness and its management. CIP/CIM prolongs weaning from mechanical ventilation and physical rehabilitation since both limb and respiratory muscles can be affected. Among many risk factors implicated, sepsis, systemic inflammatory response syndrome, and multiple organ failure appear to play a crucial role in CIP/CIM. This review focuses on epidemiology, diagnostic challenges, the current understanding of pathophysiology, risk factors, important clinical consequences, and potential interventions to reduce the incidence of CIP/CIM. CIP/CIM is associated with increased hospital and intensive care unit (ICU) stays and increased mortality rates. Recently, it was shown in a single centre that intensive insulin therapy significantly reduced the electrophysiological incidence of CIP/CIM and the need for prolonged mechanical ventilation in patients in a medical or surgical ICU for at least 1 week. The electrophysiological diagnosis was limited by the fact that muscle membrane inexcitability was not detected. These results have yet to be confirmed in a larger patient population. One of the main risks of this therapy is hypoglycemia. Also, conflicting evidence concerning the neuromuscular effects of corticosteroids exists. A systematic review of the available literature on the optimal approach for preventing CIP/CIM seems warranted.

Neuromuscular complications in the intensive care unit: critical illness polyneuromyopathy

Critical illness polyneuromyopathy, a complication of critical illness, is a primary axonal degeneration of motor and sensory fibers that leads to skeletal muscle weakness. It significantly contributes to the unexplained difficulty in weaning from mechanical ventilation and to their prolonged rehabilitation and poor quality of life after discharge. This article will discuss the diagnosis of critical illness polyneuromyopathy, identify risk factors, review several pathomechanisms that have been proposed, and discuss the implications for practice.

Critical illness polyneuropathy and myopathy: clinical features, risk factors and prognosis

Acquired neuromuscular weakness due to critical illness polyneuropathy and myopathy (CIPNM) frequently develops in patients hospitalized in the intensive care unit for more than 1 week. CIPNM may present with muscle weakness and failure to wean from mechanical ventilation, but is discovered more often and earlier by electrophysiological examination. In this review, the incidence, clinical and electrophysiological features, differential diagnosis and prognosis of CIPNM will be described. Risk factors for CIPNM are sepsis or systemic inflammatory response syndrome and the severity of multi-organ failure. Presence of CIPNM is associated with higher mortality rate, prolonged duration of mechanical ventilation and prolonged rehabilitation. The majority of survivors with CIPNM have persistent functional disabilities and a reduced quality of life. There is need for new therapeutic strategies to prevent or minimize CIPNM in critically ill patients.

A national survey of intensive care follow-up clinics

Intensive care follow-up clinics allow extended review of survivors of critical illness. However, the current provision of intensive care follow-up clinics in the UK is unknown. We performed a survey of intensive care follow-up clinic practice in the UK. A questionnaire was sent to 298 intensive care units in the UK to determine the number of follow-up clinics and details of current follow-up practice. Responses were received from 266 intensive care units, an 89% response rate. Eighty units (30%) ran a follow-up clinic. Only 47 (59%) of these clinics were funded. Of those intensive care units without a follow-up clinic, 158 (88%) cited 'financial constraints' as the reason. Over half of the follow-up clinics (44 clinics, 55%) were nurse-led, and the majority (56 clinics, 77%) only routinely review patients treated on the intensive care unit for 3 or 4 days or longer. Nearly half of the follow-up clinics (39 clinics, 49%) have pre-negotiated access to at least one other out-patient service.

Approach to neuromuscular disorders in the intensive care unit

Neuromuscular disorders increasingly are recognized as a complication in patients in the intensive care unit (ICU) and represent a common cause of prolonged ventilator dependency. The distinct syndromes of critical illness myopathy, prolonged neuromuscular blockade, and critical illness polyneuropathy (CIP) may arise as a consequence of sepsis, multi-organ failure, and exposure to various medications—notably, intravenous corticosteroids and neuromuscular blocking agents—but the pathophysiology of these disorders remains poorly understood. More than one syndrome may occur simultaneously, and the distinctions may be difficult in a particular patient, but a specific diagnosis usually can be established after careful clinical, electrodiagnostic, and, when necessary, histological evaluation. For example, asthmatics requiring treatment with corticosteroids and neuromuscular blocking agents may develop an acute myopathy characterized by generalized weakness, preserved eye movements, elevated creatine kinase levels, and myopathic motor units on electromyography (EMG). Muscle biopsy demonstrates distinctive features of thick (myosin) filament loss on ultrastructural studies. Conversely, those with a prolonged ICU course that is complicated by episodes of sepsis with failure to wean from the ventilator, distal or generalized flaccid limb weakness, and areflexia probably have CIP. EMG in these patients demonstrates reduced or absent motor and sensory potentials with neurogenic motor units. Prolonged neuromuscular blockade most commonly occurs in patients with renal failure who have received prolonged infusions of neuromuscular blockers. There is severe flaccid, areflexic paralysis with normal sensation, facial weakness, and ophthalmoparesis that persists for days or weeks after the neuromuscular blockers have been discontinued. Repetitive nerve stimulation shows a decrement of the compound muscle action potential and, in most cases, establishes a disorder of neuromuscular transmission. With the recent epidemic of West Nile virus infection, a clinical syndrome of acute flaccid paralysis with several features indistinguishable from poliomyelitis has emerged. This article critically examines the clinical, electrophysiological, and pathological features of these and other acute neuromuscular syndromes that arise in the context of ICU care and summarizes the current understanding of the pathophysiology and treatment of these disorders.

Neuromuscular manifestations of critical illness

Critical illness, more precisely defined as the systemic inflammatory response syndrome (SIRS), occurs in 20%-50% of patients who have been on mechanical ventilation for more than 1 week in an intensive care unit. Critical illness polyneuropathy (CIP) and myopathy (CIM), singly or in combination, occur commonly in these patients and present as limb weakness and difficulty in weaning from the ventilator. Critical illness myopathy can be subdivided into thick-filament (myosin) loss, cachectic myopathy, acute rhabdomyolysis, and acute necrotizing myopathy of intensive care. SIRS is the predominant underlying factor in CIP and is likely a factor in CIM even though the effects of neuromuscular blocking agents and steroids predominate in CIM. Identification and characterization of the polyneuropathy and myopathy depend upon neurological examination, electrophysiological studies, measurement of serum creatine kinase, and, if features suggest a myopathy, muscle biopsy. The information is valuable in deciding treatment and prognosis.

Neuromuscular sequelae of critical illness

PURPOSE OF REVIEW

To investigate the impact of critical illness polyneuropathy and critical illness myopathy on short-term and long-term patient outcome.

RECENT FINDINGS

In the acute-care setting, critical illness polyneuropathy and critical illness myopathy are important causes of acute paralysis in critically ill comatose patients, and may cause inappropriately pessimistic prognoses. Duration of weaning from artificial ventilation is 2 to 7 times greater in patients with critical illness polyneuropathy than in patients without critical illness polyneuropathy. After intensive care unit and hospital discharge, many patients diagnosed with critical illness polyneuropathy or critical illness myopathy are reported to complain of profound muscle weakness. Chronic disability was a common finding among them. Complete functional recovery with patients regaining the ability to breathe spontaneously and to walk independently was reported in 180 of 263 patients (68.4%); severe disability with tetraparesis, tetraplegia, or paraplegia was reported in 74 patients (28.1%). Persisting milder disabilities were common even in patients with complete functional recovery, and included reduced or absent deep tendon reflexes, stocking and glove sensory loss, muscle atrophy, painful hyperesthesia, and foot drop. An association of critical illness polyneuropathy and critical illness myopathy with increased intensive care unit and hospital mortality has been demonstrated only in selected intensive care unit populations; data are insufficient to demonstrate any association with long-term mortality.

SUMMARY

Intensive care unit-acquired critical illness polyneuropathy and critical illness myopathy influence the evaluation of acutely ill comatose patients and may instigate unreasonably pessimistic prognosis. Critical illness polyneuropathy and critical illness myopathy are an important cause of difficult weaning of patients from the ventilator and of persisting muscle weakness and disability after intensive care unit discharge.

Effect of critical illness polyneuropathy on the withdrawal from mechanical ventilation and the length of stay in septic patients*

OBJECTIVES

No previous study has demonstrated whether critical illness polyneuropathy itself lengthens mechanical ventilation or whether this prolonged duration of ventilatory support is explained by concomitant risk factors for weaning failure. Our objectives were to evaluate the impact of critical illness polyneuropathy on the length of mechanical ventilation after controlling for coexisting risk factors for weaning failure and to assess the impact of critical illness polyneuropathy on the length of the stay in a cohort of septic patients.

DESIGN

Prospective cohort study.

SETTING

Intensive care unit of a tertiary hospital.

PATIENTS

All patients with severe sepsis or septic shock who required mechanical ventilation for > or =7 days who were considered ready to discontinue mechanical ventilation.

INTERVENTIONS

Patients underwent a neurophysiologic evaluation at onset of weaning from mechanical ventilation.

MEASUREMENTS AND MAIN RESULTS

Sixty-four critically ill septic patients were enrolled, and 34 developed critical illness polyneuropathy (53.1%; 95% confidence interval, 40.2-65.7%). Length of mechanical ventilation was significantly higher in patients who had developed critical illness polyneuropathy (median 34 days vs. 14 days, p < .001). The duration of the weaning period was also significantly greater in patients with critical illness polyneuropathy (median 15 days vs. 2 days, p < .001) even though factors suspected to influence the weaning process did not differ between these two groups. Multiple logistic regression analysis indicated that critical illness polyneuropathy was the only risk factor independently associated with weaning failure (odds ratio, 15.4; 95% confidence interval, 4.55, 52.3; p < .001). Lengths of intensive care unit and hospital stays were significantly higher in patients with critical illness polyneuropathy.

CONCLUSIONS

In critically ill septic patients, critical illness polyneuropathy significantly increases the duration of mechanical ventilation and prolongs the lengths of intensive care unit and hospital stays.

Combination of histopathological and electromyographic patterns can help to evaluate functional outcome of critical ill patients with neuromuscular weakness syndromes

Introduction

The aim of the study was to describe patterns of neuromuscular weakness using a combination of electromyography and histology, and to evaluate functional outcome in patients following complicated cardiovascular surgery.

Methods

Fifteen adults requiring long-term mechanical ventilation (>15 days) following cardiovascular surgery associated with postoperative complications were prospectively included. Electrophysiological and histological analyses (muscle and nerve) were performed when failure to wean from mechanical ventilation associated with peripheral neuromuscular weakness was noticed. Functional disability was evaluated 12 months after surgery.

Results

Six patients had a predominantly axonal neuropathy, six presented with myopathy, and three patients had a combination of axonal neuropathy and myopathy. All of them presented with acute tetraparesis and failure to wean from mechanical ventilation. All of the study patients who received corticosteroids exhibited a myopathic pattern (with or without axonopathic changes) but never an axonopathic pattern only. Only two of the eight survivors at 12 months were not ambulatory. These two patients had no detectable compound muscle action potential on electrophysiological examination.

Conclusion

The combination of electromyographic evaluation and neuromuscular histological abnormalities could help to identify the type and severity of neuromuscular weakness, in turn helping to evaluate the patient's potential functional prognosis.

Disorders of the respiratory muscles

The act of breathing depends on coordinated activity of the respiratory muscles to generate subatmospheric pressure. This action is compromised by disease states affecting anatomical sites ranging from the cerebral cortex to the alveolar sac. Weakness of the respiratory muscles can dominate the clinical manifestations in the later stages of several primary neurologic and neuromuscular disorders in a manner unique to each disease state. Structural abnormalities of the thoracic cage, such as scoliosis or flail chest, interfere with the action of the respiratory muscles-again in a manner unique to each disease state. The hyperinflation that accompanies diseases of the airways interferes with the ability of the respiratory muscles to generate subatmospheric pressure and it increases the load on the respiratory muscles. Impaired respiratory muscle function is the most severe consequence of several newly described syndromes affecting critically ill patients. Research on the respiratory muscles embraces techniques of molecular biology, integrative physiology, and controlled clinical trials. A detailed understanding of disease states affecting the respiratory muscles is necessary for every physician who practices pulmonary medicine or critical care medicine.

Persistent neuromuscular and neurophysiologic abnormalities in long-term survivors of prolonged critical illness

OBJECTIVE

To establish the prevalence, clinical characteristics, and electrophysiologic features of residual neuromuscular dysfunction after prolonged critical illness.

DESIGN

Prospective follow-up study of survivors of prolonged critical illness.

SETTING

A university hospital and two district general hospitals in the UK.

PATIENTS

The study occurred for a period of 5 yrs. All patients during that time who were in the intensive care unit for >28 days were entered in the study.

MEASUREMENTS AND MAIN RESULTS

At follow-up, length of intensive care unit and hospital stay, duration of mechanical ventilation and admission Acute Physiology and Chronic Health Evaluation II score were recorded from the case notes. A clinical history was obtained, a Barthel Index disability score was calculated, and a full neurologic examination was performed. Nerve conduction studies, needle electromyography, single-fiber electromyography and thermal thresholds were performed. A total of 195 patients were identified. There were 86 survivors, of whom 47 could be contacted and 22 consented to be studied. The median time from intensive care unit discharge to follow-up was 43 months (range, 12-57 months). All gave a clear history of severe weakness and functional impairment after hospital discharge and, in all, recovery was prolonged. Motor or sensory deficits were present on clinical examination in 59% of the patients studied. Common peroneal nerve palsy was present in two patients. A total of 21 of 22 (95%) patients had electromyographic evidence of chronic partial denervation at follow-up, findings indicative of a preceding axonal neuropathy. The single-fiber electromyographic studies were also consistent with a preceding motor neuropathy.

CONCLUSION

Severe weakness requiring prolonged rehabilitation and abnormal clinical neurologic findings are extremely common in survivors of protracted critical illness. Neurophysiologic evidence of chronic partial denervation of muscle consistent with previous critical illness polyneuropathy is almost invariable and can be found up to 5 yrs after intensive care unit discharge in >90% of these long-stay patients. Evidence of myopathy is unusual. These findings have important implications for the management and rehabilitation of intensive care survivors.

Critical illness polyneuropathy

Critical illness polyneuropathy (CIP) is a syndrome that was first extensively described in the early 1980s, mainly in patients with failure to wean from mechanical ventilation. The syndrome is further characterized by limb muscle weakness, usually more pronounced distally than proximally, and is often accompanied by atrophy. The facial musculature is often strikingly spared. Reduced or absent deep-tendon reflexes and loss of peripheral sensation to light touch and pin prick often accompany the syndrome. Involvement of the phrenic nerve has been shown to further contribute to delayed weaning from the ventilator in many patients. The electrophysiologic studies are consistent with a predominantly motor and, often to a lesser extent, sensory axonal polyneuropathy. The incidence of CIP is high, with often more than 50% of patients in major medical and surgical critical care units suffering from the syndrome. The systemic inflammatory response syndrome (SIRS) is strongly associated with CIP and, among the multiorgan failure often seen in SIRS, CIP is thought to represent a neurologic manifestation of SIRS. The neurologic effects of SIRS are thought to be mediated by released mediators like cytokines and free radicals, affecting the microcirculation of the central and peripheral nervous system. Examination of the peripheral nervous system is often unreliable, and the only way to establish a definitive diagnosis is by performing electrophysiologic studies. Morbidity and mortality rates are high. If the underlying problem causing sepsis and/or SIRS can be treated successfully, full recovery from CIP can occur. This recovery often occurs in a matter of weeks in milder cases and in months in more severe cases. Knowledge of CIP is essential for intensivists and other specialists who care for critically ill patients. This review summarizes the current available literature on this topic.

Clinical outcomes of critical illness polyneuropathy

It is often difficult to isolate the origin of acute weakness in the critically ill population because of multiple etiologies. Aminoglycosides, corticosteroids, and neuromuscular blockers frequently are implicated as the source of acute weakness. Recently, critical illness polyneuropathy (CIP), a syndrome of unknown etiology, was added to the differential diagnosis. The frequency of CIP is approximately 70% in patients with sepsis. Early studies of CIP, which were mostly retrospective, underestimated its frequency due to the complexity of the diagnosis and unfamiliarity with the syndrome. Prospective studies have explored the causality and clinical outcomes of CIP Clinical outcomes of patients with CIP include difficulty weaning from mechanical ventilation, increased length of stay, prolonged recovery, and an overall mortality rate of 26-71%. The association of CIP with sepsis, multiorgan failure, and drugs is still unclear.

Clinical review: Intensive care follow-up--what has it told us?

The majority of intensive care practitioners, until comparatively recently, was content to discharge surviving patients to the care of referring primary specialty colleagues who would undertake subsequent inpatient and outpatient care. With the exception of mortality statistics from clinical studies, the practitioners were thus denied the opportunity of understanding the full impact of critical illness on a patient and their family. The concept of the intensive care follow-up clinic has developed more recently, and is run commonly on multidisciplinary lines. These clinics serve a number of purposes, but importantly have drawn attention to broader patient-centred outcomes after intensive care. Investigators are just beginning to identify, and in some cases quantify, the postdischarge burden on patient and family; additional useful data have also come from follow-up of specific disease states. The purpose of the present review is to highlight some of the important issues that impact on recovery from critical illness towards an acceptable quality of postdischarge life. We have concentrated on the adult literature, and specifically on studies that inform us about the more general effects of critical illness. Head and spinal injury are thus largely ignored, as the effects of the primary injury overwhelm the effects of 'general' critical illness.

Critical illness polyneuropathy

Critical illness polyneuropathy is a self-limited acute axonal neuropathy that develops during treatment of severely ill patients and remits spontaneously once the critical condition is under control. Clinical manifestations include muscle weakness and atrophy, delayed weaning from the respirator, and prolongation of the mobilization phase. The pathogenesis is not understood in detail but most authors assume that the inflammatory cascade that mediates the systemic inflammatory response and multiple organ failure play a pivotal role. This review summarizes current knowledge of this common neuropathic complication during intensive care treatment.

Neurologic complications in intensive care

Neurologic complications in intensive care occur as the result of critical illness, intensive care therapies and procedures, or medical or surgical conditions; perioperatively; or because of underlying primary neurologic disease. These complications occur at greater frequency and are often unrecognized because critically ill patients are often intubated, sedated, and/or receiving neuromuscular blocking agents. Encephalopathy is the most common neurologic complication in the ICU and is usually multifactorial in origin. Sepsis is associated with the highest incidence of neurologic complications. Neurologic complications are associated with increased disability, longer hospital stay, and increased mortality. This review focuses on neurologic complications that are the result of critical illnesses and intensive care management.