105. ICU Acquired Weakness

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. (https://doi.org/10.1097/CCM.000000000...) 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. (https://pubmed.ncbi.nlm.nih.gov/28098628) 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. (https://pubmed.ncbi.nlm.nih.gov/30339549) 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. (https://pubmed.ncbi.nlm.nih.gov/34401939) 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. (https://pubmed.ncbi.nlm.nih.gov/32076765) 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. (https://pubmed.ncbi.nlm.nih.gov/26242743) Hermans G, Van den Berghe G. Critical Ca...