From the Guidelines
Critical care myopathy is a neuromuscular disorder characterized by muscle weakness that develops in critically ill patients during their stay in intensive care units, typically affecting the limb and respiratory muscles, causing symmetrical weakness and reduced muscle tone, as supported by recent evidence 1. This condition occurs due to multiple factors including systemic inflammation, medication side effects (particularly from corticosteroids and neuromuscular blocking agents), immobility, and metabolic derangements. The pathophysiology involves muscle fiber atrophy, altered excitation-contraction coupling, and mitochondrial dysfunction, as described in the context of intensive care unit-acquired weakness (ICUAW) 1. Some key points to consider in the definition and management of critical care myopathy include:
- The importance of early mobilization in preventing ICUAW and critical care myopathy, as highlighted in recent guidelines 1
- The role of medication side effects, particularly from corticosteroids and neuromuscular blocking agents, in contributing to the development of critical care myopathy, as discussed in earlier studies 1
- The need for supportive treatment, including early physical rehabilitation, nutritional support, and minimizing exposure to triggering medications, to improve outcomes in patients with critical care myopathy
- The potential for prevention strategies, such as judicious use of corticosteroids and neuromuscular blockers, tight glycemic control, and adequate nutritional support, to reduce the risk of critical care myopathy in critically ill patients.
From the Research
Definition of Critical Care Myopathy
Critical Care Myopathy, also known as Intensive Care Unit-acquired myopathy, is a syndrome of widespread muscle weakness and neurological dysfunction that can develop in critically ill patients receiving intensive care 2, 3, 4, 5, 6.
Characteristics
The condition is characterized by protein catabolism, an increase in urinary nitrogen loss, and muscle wasting 2. Muscle biopsies in critically ill patients demonstrate low glutamine levels, low protein/DNA levels, and high concentrations of extracellular water 2.
Subtypes
There are three main subtypes of Critical Care Myopathy:
- Critical illness myopathy
- Myopathy with selective loss of myosin filaments (thick-filament myopathy)
- Acute necrotizing myopathy of intensive care 3, 4 These subtypes can be differentiated based on clinical features and muscle biopsy 2, 3.
Causes and Risk Factors
The exact causes of Critical Care Myopathy are unknown, but it is thought to be a possible neurological manifestation of systemic inflammatory response syndrome 6. The use of corticosteroids and muscle relaxants may trigger some types of ICU myopathy 4. Sepsis, denervation, and muscle membrane inexcitability may also be additional factors 4, 5.
Clinical Importance
The clinical importance of Critical Care Myopathy is still unknown, but it is likely that weakness caused by myopathy prolongs ICU stay and rehabilitation 4. Health professionals working at critical care units should be aware that any ICU patient may develop Critical Care Myopathy 6.