What is the best management approach for critical illness myopathy?

Management of Critical Illness Myopathy

Early mobilization initiated within 72 hours of ICU admission combined with neuromuscular electrical stimulation (NMES) for immobile patients represents the cornerstone of critical illness myopathy management, while strictly avoiding prolonged neuromuscular blocking agents and concurrent corticosteroid use. 1

Prevention: The Primary Strategy

Critical illness myopathy has no specific pharmacologic treatment, making prevention paramount. 2, 3

Avoid Known Risk Factors

• Limit neuromuscular blocking agents (NMBAs) to the shortest duration possible - administration beyond 1-2 days substantially increases myopathy risk, particularly when combined with corticosteroids (incidence up to 30%). 4, 5
• Avoid concurrent NMBA and corticosteroid administration - total corticosteroid doses exceeding 1 g methylprednisolone equivalent significantly increase risk. 4
• Monitor neuromuscular blockade with train-of-four monitoring when NMBAs are necessary, adjusting to achieve 1-2 twitches to prevent overdosing. 5, 6
• Consider daily "drug holidays" by stopping NMBAs for several hours and restarting only when necessary, though evidence for reducing myopathy is limited. 4

Early Mobilization Protocol

Begin mobilization within 72 hours of ICU admission after cardiorespiratory and neurological stabilization - this reduces ICU-acquired weakness incidence by 51%, shortens ICU stay by 1.82 days, and hospital stay by 3.90 days. 1

For Unconscious or Sedated Patients:

• Position upright ≥40° upper body elevation when hemodynamically stable to increase lung volumes, stimulate autonomic activity, and reduce cardiac stress. 4, 1
• Implement continuous passive motion (CPM) for 3 hours, three times daily - this reduces fiber atrophy and protein loss more effectively than brief passive stretching. 1
• Use passive cycling with bedside ergometers to allow prolonged mobilization without requiring patient cooperation. 1
• Apply positioning, splinting, passive mobilization and muscle stretching to preserve joint mobility and skeletal muscle length. 4

Neuromuscular Electrical Stimulation (NMES) Parameters:

• Target large muscle groups (quadriceps, hamstrings) with maximal tolerable current intensity. 1
• Start with 4 Hz frequency (non-tetanic) to prevent delayed onset muscle soreness, then progress to 20-25 Hz tetanic contractions. 1
• Use short duty cycles initially: 2 seconds on/2 seconds off. 1
• Gradually increase session duration from 10 to 60 minutes as tolerated. 1
• NMES prevents muscle atrophy, reduces critical illness polyneuromyopathy development, and shortens mechanical ventilation weaning. 1

For Alert, Cooperative Patients - Mobilization Hierarchy:

1. Transferring in bed 1
2. Sitting at edge of bed 1
3. Bed-to-chair transfers 1
4. Standing 1
5. Walking with aids (modified walking frames, tilt tables are safe and feasible) 4, 1
6. Active cycling on bedside ergometers with intensity adjusted to physiological responses 1

Structured Exercise Programs:

• Prescribe 3 sets of 8-10 repetitions at 50-70% of 1 repetition maximum for resistance training daily within patient tolerance. 4, 1
• Implement upper and lower limb training programs for minimum 6 weeks - this improves muscle strength, increases ventilator-free time, and enhances functional outcomes in patients requiring long-term mechanical ventilation. 4, 1
• Add aerobic training and muscle strengthening to routine mobilization - this improves walking distance more than mobilization alone in ventilated patients. 4

Safety Monitoring - Contraindications to Aggressive Mobilization:

Do not aggressively mobilize patients with: 1

• Hemodynamic instability or active resuscitation
• Uncontrolled arrhythmias
• Active myocardial ischemia
• High FiO₂ requirements and high ventilatory support levels
• Increased intracranial pressure

Monitor for these contraindications before each mobilization session. 1

Nutritional Support

• Provide adequate protein delivery at 1.3 g/kg/day combined with physical activity, as critical illness causes marked proteolysis and muscle loss. 1
• Optimize nutrition while avoiding overfeeding - excessive energy delivery is deleterious. 1
• Test for micronutrient status after 6-7 days in ICU, particularly copper, selenium, zinc, and iron levels, especially in patients on continuous renal replacement therapy. 1
• Consider values 20% below laboratory reference as concerning and initiate repletion. 1
• Correct electrolyte abnormalities, particularly hypophosphatemia and hypermagnesemia. 5

Supportive Care for Established Myopathy

Once critical illness myopathy develops, management is entirely supportive: 2, 3

• Continue physical therapy and mobilization as outlined above
• Provide nutritional support with adequate protein
• Conduct daily trials of decreased ventilatory support to facilitate weaning 6
• Address concurrent renal or hepatic dysfunction 5

Critical Timing Considerations

The critical window for intervention is early in the ICU course - electrophysiological changes occur as early as 48 hours after admission and muscle loss is rapid. 1 Mobility programs beginning after ICU discharge have limited impact on mitigating weakness and functional decline. 1

Common Pitfalls

• Do not delay mobilization - waiting until after ICU discharge misses the critical intervention window. 1
• Do not use NMBAs routinely - reserve for absolute necessity only and monitor depth of paralysis to avoid overdosing. 6
• Do not combine corticosteroids with prolonged NMBAs unless absolutely unavoidable. 4
• Weigh mobilization risks against immobility risks - no adverse effects of physical activity on inflammatory status have been demonstrated in critically ill patients. 4