105. ICU Acquired Weakness

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Today we’re talking about a topic that is relevant for all critical care physicians but under-examined: ICU Acquired Weakness. We are joined by two excellent guests to walk through a case and discuss the diagnosis, pathophysiology, prevention, and treatment of ICU Acquired Weakness. Check out our associated infographics and key learning points below.

Meet Our Guests

Jim Devanney is a Physiatrist who just completed a neurocritical care fellowship at BIDMC. He is transitioning to a clinical associate position at University Health Network – University of Toronto where he will be working as a PM&R consultant within the ICU.

Kalaila Pais is a third year internal medicine resident at BIDMC, interested in pulmonary and critical care and medical education and is returning for her third Pulm PEEPs episode.

Key Learning Points

Definition & Clinical Presentation

  • ICU-AW refers to new-onset, generalized muscle weakness that arises during critical illness, not explained by other causes.It typically presents as:
    • Symmetric, proximal > distal weaknessRespiratory muscle involvementPreserved cranial nerve functionNo sensory deficits in myopathy (sensory loss points toward neuropathy)
    • Differential Diagnosis Using Neuroanatomical ApproachAn anatomical approach (central → peripheral) helps localize the etiology weakness
  • CNS: trauma, stroke, encephalitis, seizuresAnterior horn cells: viral myelitis, motor neuron diseasePeripheral nerves: Guillain-Barré, vasculitis, critical illness polyneuropathy (CIP)Neuromuscular junction: myasthenia gravis, botulism, Lamber EatonMuscle: rhabdomyolysis, inflammatory or drug-induced myopathies, critical illness myopathy (CIM)
    • Subtypes of ICU-AW
  • Critical Illness Myopathy (CIM):
    • Muscle dysfunctionEarly onset (within 48 hrs)Sensation intactproximal > distal weakness

  • Critical Illness Polyneuropathy (CIP):
    • Nerve involvementDistal > proximal weakness, sensory deficits

    • Critical Illness Polyneuromyopathy (CIPNM): Combination of both

    Diagnosis

    • Medical Research Council Score (MRC-SS):
      • Score < 48: ICU-AW
      • Score < 36: severe ICU-AW
    • Handgrip dynamometry: <11 kg (men), <7 kg (women)
    • Electrophysiology: EMG/NCS to distinguish CIM vs CIP
    • Muscle ultrasound: bedside monitoring
    • MRI/CT/Muscle biopsy: rarely used due to practical limitation

    Risk Factors

    Modifiable:

    • Hyper/hypoglycemia
    • Electrolyte derangement
    • Parenteral nutrition
    • Immobility
    • Medications (steroids, NM blockers, sedatives, aminoglycosides)

    Non-modifiable:

    • Age, female sex, comorbidities
    • Severity of illness, prolonged ventilation
    • Sepsis, multi-organ failure

     Management & Prevention

    • Prevention is key:
      • Early treatment of sepsis and inflammation
      • Glycemic control
      • Early enteral nutrition
      • Minimize sedation (A-F bundle)
      • Early mobilization and physical therapy
    • NMES (neuromuscular electrical stimulation): emerging therapy, needs more evidence

    Outcomes

    • Short-term: increased LOS, ventilation duration, mortality
    • Long-term: decreased function, discharge to rehab, prolonged recovery

    Final Takeaways

    • Prevention is crucial — start interventions early.
    • Systematic approach to ICU weakness helps rule out dangerous mimics.
    • ICU-AW is common but often under-recognized — awareness and early rehab can significantly impact recovery.

    Infographics

    References and Further Reading


    Clinical Practice Guidelines for the Prevention and Management of Pain, Agitation/­Sedation, Delirium, Immobility, and Sleep Disruption in Adult Patients in the ICU.     Devlin JW, Skrobik Y, Gélinas C, et al. Critical Care Medicine. 2018;46(9):e825-e873. doi:10.1097/CCM.0000000000003299.

    The ABCDEF Bundle: Science and Philosophy of How ICU Liberation Serves Patients and Families. Ely EW. Critical Care Medicine. 2017;45(2):321-330. doi:10.1097/CCM.0000000000002175.

    Caring for Critically Ill Patients With the ABCDEF Bundle: Results of the ICU Liberation Collaborative in Over 15,000 Adults. Pun BT, Balas MC, Barnes-Daly MA, et al. Critical Care Medicine. 2019;47(1):3-14. doi:10.1097/CCM.0000000000003482.

    Delirium in Critical Illness: Clinical Manifestations, Outcomes, and Management. Stollings JL, Kotfis K, Chanques G, et al. Intensive Care Medicine. 2021;47(10):1089-1103. doi:10.1007/s00134-021-06503-1.

    ICU-acquired Weakness. Vanhorebeek I, Latronico N, Van den Berghe G. Intensive Care Medicine. 2020;46(4):637-653. doi:10.1007/s00134-020-05944-4.

    Clinical Review: Intensive Care Unit Acquired Weakness. Hermans G, Van den Berghe G. Critical Care (London, England). 2015;19:274. doi:10.1186/s13054-015-0993-7.

    Best Practices for Conducting Interprofessional Team Rounds to Facilitate Performance of the ICU Liberation (ABCDEF) Bundle. Stollings JL, Devlin JW, Lin JC, et al. Critical Care Medicine. 2020;48(4):562-570. doi:10.1097/CCM.0000000000004197.

    ABCDE and ABCDEF Care Bundles: A Systematic Review of the Implementation Process in Intensive Care Units. Moraes FDS, Marengo LL, Moura MDG, et al. Medicine. 2022;101(25):e29499. doi:10.1097/MD.0000000000029499.

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