From the Guidelines
Critical illness myopathy (CIM) is a neuromuscular disorder characterized by muscle weakness that develops in critically ill patients, typically during their stay in intensive care units. It primarily affects the limb and respiratory muscles, causing symmetrical weakness and reduced muscle mass. CIM often occurs in patients who have been treated with mechanical ventilation, corticosteroids, and neuromuscular blocking agents, particularly in the context of sepsis, multi-organ failure, or systemic inflammatory response syndrome, as noted in guidelines from the American Thoracic Society 1. The condition develops due to a combination of factors including inflammation, metabolic disturbances, medication side effects, and immobility, which lead to muscle fiber atrophy and dysfunction.
Key Characteristics and Diagnosis
- CIM is associated with intensive care unit–acquired weakness (ICUAW), which may be more common among ICU patients with severe sepsis or those having difficulty being liberated from mechanical ventilation 1.
- Diagnosis typically involves clinical assessment, electromyography, nerve conduction studies, and sometimes muscle biopsy.
- The use of terms like critical illness polyneuropathy, critical illness myopathy, and critical illness myoneuropathy are relevant in this context, highlighting the complexity of neuromuscular disorders in critically ill patients 1.
Treatment and Management
- Treatment focuses on supportive care, early physical rehabilitation, nutritional support, and addressing the underlying critical illness.
- Early mobilization and rehabilitation are crucial for improving outcomes and preventing long-term disability, as emphasized by recent guidelines on positioning and early mobilization in the critically ill 1.
- Therapeutic options such as non-invasive electrical muscle stimulation (NMES) can be beneficial in the early phase of critical illness, promoting active muscle contraction and potentially mitigating muscle atrophy 1.
Outcome and Recovery
- Most patients experience gradual improvement over weeks to months after the acute illness resolves, though recovery can be prolonged and some may have persistent weakness.
- The importance of early intervention and comprehensive management cannot be overstated, given the potential for long-term disability and the impact on morbidity, mortality, and quality of life.
From the Research
Definition of Critical Illness Myopathy
Critical illness myopathy (CIM) is a condition that occurs in critically ill patients, characterized by muscle weakness and difficulty in weaning from the ventilator 2, 3. It is often associated with critical illness polyneuropathy (CIP) and can be subdivided into different types, including thick-filament (myosin) loss, cachectic myopathy, acute rhabdomyolysis, and acute necrotizing myopathy of intensive care 2.
Key Features of Critical Illness Myopathy
- Muscle weakness and difficulty in weaning from the ventilator 2, 3
- Loss of myosin filaments on muscle biopsy 3
- Earlier onset than CIP, with faster recovery 3
- Associated with critical illness, use of steroids, and immobility 3
- Can be diagnosed using clinical, electrophysiological, and muscle biopsy investigations 2, 3
Pathogenesis of Critical Illness Myopathy
- Sepsis and inflammatory mediators play a major role in the development of CIM 4
- Multiple sites of disturbances to the excitation-contraction coupling cascade are possible causes of muscle weakness 4
- Bioenergetic failure is thought to be a relevant pathophysiological mechanism explaining CIM 5
Clinical Consequences of Critical Illness Myopathy
- Prolonged hospital and intensive care unit (ICU) stays 6
- Increased mortality rates 6
- Failed weaning of patients from the ventilator, inappropriate evaluations of comatose patients, and prolonged disability after ICU discharge 5
- Better prognosis than CIP, with differential diagnosis important to predict long-term outcome in ICU patients 5