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Related Subjects: |Respiratory Failure |Non-invasive ventilation (NIV) |Intubation and Mechanical Ventilation |Critical illness neuromuscular weaknesss |Haemodialysis |Dobutamine

The most common acquired causes of weakness in the critically ill patient in the intensive care unit are critical illness polyneuropathy and critical illness myopathy

About

• Delays recovery and adds to the morbidity

Risk factors

• Prolonged Mechanical Ventilation: higher risk due to immobility and the effects of sedatives and paralytics.
• Sepsis: Severe infections trigger inflammatory responses that contribute to muscle and nerve damage.
• Use of Corticosteroids: can lead to muscle atrophy and weakness.
• Neuromuscular Blocking Agents: used during mechanical ventilation, can contribute to muscle weakness if used for prolonged periods.
• Immobilization: Lack of movement and prolonged bed rest can lead to muscle wasting and weakness.
• Multiorgan Failure: acute respiratory distress syndrome (ARDS), kidney failure, and liver failure

Types

• Critical Illness Myopathy (CIM): Characterized by muscle fiber atrophy and dysfunction, often associated with the use of corticosteroids and neuromuscular blocking agents. Symptoms: Predominantly affects proximal muscles, leading to difficulty in movement, especially in the upper arms and thighs.
• Critical Illness Polyneuropathy (CIP): Pathophysiology: A diffuse, symmetric neuropathy affecting the peripheral nerves, commonly seen in patients with sepsis or multi-organ failure. Symptoms: Includes limb weakness, loss of deep tendon reflexes, and sensory deficits, primarily affecting the lower limbs.

Causes of weakness in the ITU

Clinical

• Prolonged ITU admission: Severe sepsis or respiratory failure or brain injury
• Slow to wean off ventilator weak respiratory muscles
• Generalised Muscle weakness, reduced reflexes
• Initially flaccid quadriplegia then spastic
• Symmetrical facial weakness may be seen

Differentials

• Guillain Barre syndrome (Axonal or demyelinating)
• Rhabdomyolysis CK > 10,000

Investigations

• FBC, U&E, LFTs, B12, folate
• Creatine Kinase (CK) Levels: Elevated in CIM due to muscle breakdown.
• Nerve Conduction Studies (NCS): reduced conduction velocities in CIP.
• Electromyography (EMG): helps differentiate between CIM and CIP.
• LP if Guillan Barre considered
• Magnetic resonance imaging (MRI) when there is a suspicion of upper motor neuron involvement

Management

• Weaning from Ventilation: Rehabilitation: Early Mobilization Protocols:
• Supportive or focused on a found cause.
• Avoiding Prolonged Use of Neuromuscular Blockers
• Physiotherapy and rehabilitation period
• Good nutrition and care

References