What is the approach to examining and managing muscle weakness in the Intensive Care Unit (ICU)?

From the Guidelines

The approach to examining and managing muscle weakness in the ICU should prioritize early mobilization, as evidenced by the most recent guideline on positioning and early mobilisation in the critically ill by an expert panel 1.

Key Considerations

When examining muscle weakness in the ICU, it is crucial to consider the various etiologies, including prolonged recovery from neuromuscular blocking agents, myasthenia gravis, muscular dystrophy, and critical illness polyneuropathy/myopathy, as outlined in the clinical practice guidelines for sustained neuromuscular blockade in the adult critically ill patient 1.

• Initial evaluation should include a thorough neurological examination focusing on muscle strength grading (0-5 scale), deep tendon reflexes, and sensory testing to distinguish between central, peripheral, and neuromuscular junction disorders.
• Laboratory workup should include creatine kinase, electrolytes, thyroid function, and consideration of nerve conduction studies or electromyography in unclear cases.

Management Strategies

Management of muscle weakness in the ICU involves treating underlying causes, minimizing sedation and neuromuscular blocking agents, maintaining proper glycemic control, correcting electrolyte abnormalities, and implementing early mobilization protocols within 24-48 hours of hemodynamic stability, as supported by the guideline on multimodal rehabilitation for patients with post-intensive care syndrome 1.

• Physical therapy should begin with passive range of motion exercises and progress to active exercises, sitting, standing, and ambulation as tolerated.
• Nutritional support with adequate protein (1.2-2.0 g/kg/day) and caloric intake is essential for muscle preservation.
• Prevention strategies include daily sedation interruptions, spontaneous breathing trials, and minimizing corticosteroid exposure when possible, as recommended by the American Thoracic Society/European Respiratory Society statement on pulmonary rehabilitation 1.

Prioritizing Early Mobilization

Early mobilization is a critical component of managing muscle weakness in the ICU, as it can reduce the risk of intensive care unit-acquired weakness (ICUAW) and improve patient outcomes 1.

• Early mobilization protocols should be implemented within 24-48 hours of hemodynamic stability.
• Physical therapy should be tailored to the individual patient's needs and abilities, with a focus on progressive exercise and mobilization.

From the Research

Approach to Examining Muscle Weakness in ICU

• The approach to examining muscle weakness in the Intensive Care Unit (ICU) involves understanding the various causes of weakness, including previously unrecognised chronic neurological conditions, ICU-acquired weakness, and other possible causes 2.
• Clinicians can use clinical clues to help recognise the causes of weakness and need to understand how patterns of weakness reflect differing causes of reduced consciousness on ICU 2.
• Assessing patients in ICU is challenging due to physical barriers, medication barriers, and cognitive barriers, but a clinical diagnosis is necessary to organise appropriate tests and communicate clearly with patients and ICU colleagues 2.

Diagnosis and Prevention of ICU-Acquired Muscle Weakness

• ICU-acquired muscle weakness can be prevented by early treatment of the underlying disease, goal-directed therapy, restrictive use of immobilizing medications, optimal nutrition, activating ventilatory modes, early rehabilitation, and preventive drug therapy 3.
• The consequences of ICU-acquired muscle weakness depend on the underlying mechanism, and temporary drug-induced weakness may not affect outcome, while severe perioperative acquired weakness can lead to adverse outcomes 3.
• The diagnosis of ICU-acquired weakness involves bedside manual testing of muscle strength and the severity is scored by the Medical Research Council sum score, with additional electrophysiological testing required for differential diagnosis in cases of atypical clinical presentation or evolution 4.

Risk Factors and Outcomes of ICU-Acquired Muscle Weakness

• The main risk factors for ICU-acquired weakness include high severity of illness upon admission, sepsis, multiple organ failure, prolonged immobilization, and hyperglycemia, with older patients having a higher risk 4.
• ICU-acquired weakness is typically symmetrical and affects predominantly proximal limb muscles and respiratory muscles, whereas facial and ocular muscles are often spared 4.
• Weak patients have worse acute outcomes and consume more healthcare resources, with recovery usually occurring within weeks or months, although it may be incomplete with weakness persisting up to 2 years after ICU discharge 4.

Use of Muscular Ultrasound in ICU

• Muscular ultrasound is a valid alternative to other imaging modalities for the assessment of skeletal muscle mass in the ICU setting, allowing visualization and classification of muscle characteristics 5.
• Muscular ultrasound can be used to detect muscle weakness and its potential impact on treatment and prognosis of critically ill patients when combined with biomarkers of muscle catabolism/anabolism and bioenergetic state 5.