“ICU acquired weakness – is not a storm, but a shadow – eyes that seek can unmask it early”.
Intensive care unit-acquired weakness (ICU-AW) continues to pose a challenge in the management of critically ill patients. As the survival rate improves, the complications that ICU-AW brings can delay weaning from the ventilator, increase ICU and hospital length of stay, and have a significant impact on patient recovery and rehabilitation.1 The prevalence of ICU-AW ranges from 25 to 67%, with a higher incidence in patients with sepsis.2
Recent research has shed light on understanding the pathophysiology of the condition; however, diagnosing this condition at the bedside has significant challenges. Diagnosing ICU-AW requires a high index of suspicion and ruling out other conditions that may cause similar muscle weakness. There is a lack of standardized criteria and guidelines for early diagnosis.
The hand-held dynamometer is considered a tool for screening, whereas the medical research council (MRC) score can aid diagnosis.3,4 However, the use of both tools is limited by the prerequisite of patient cooperation and thus cannot be implemented in patients with sedation or delirium. The use of bedside neuromuscular ultrasound is a promising non-invasive tool for evaluation of diaphragm function and its involvement and assessment of muscle mass and echogenicity in muscles like biceps brachii and quadriceps femoris. Often the diagnosis is delayed and overshadowed by various other high-pressure and acute care priorities.
With consistent physical therapy and treatment of modifiable risk factors, ICU-AW can be prevented and lead to improved outcomes.5 Thus, identifying the condition early is paramount to guiding early rehabilitation strategies. Key strategies for early intervention include early mobilization, neuromuscular electrical stimulation, in-bed cycle ergometry, nutritional optimization, and emerging pharmacological therapies, and other supportive measures. A successful and consistent program requires a multidisciplinary care team involving intensivists, physiotherapists, and nutritionists.
In this issue of IJCCM, study conducted in a Brazilian Tertiary ICU from May 2021 to October 2023 by Delazari LEB et al. addressed this question.6 With ICU-AW affecting 78.4% of the study's 97 participants, this prospective observational study identified a Perme score of ≤9 to be independently associated with the risk of ICU-AW. Being practical and not needing patient cooperation, this score showed a high diagnostic utility (AUC = 0.836, sensitivity 77.1%, specificity 71.4%, positive predictive value 91.4%). Perme score also includes components that are not directly influenced by neuromuscular strength—mental status, pain, and potential impediments to mobility. Also the score was assessed as a single-point measure and may have been affected by various confounding factors like clinical severity and instability due to the primary disease and various barriers to movement.
Though the study population included diverse patient populations (mixed medical-surgical ICU patients), this being a single center study, its generalizability is questionable. Also, the low negative predictive value of 45.5% indicates that a higher Perme score does not reliably rule out ICUAW. Also, its limitation in assessing respiratory muscle functions limits its utility in predicting weaning difficulty. This gap emphasizes the use of other modalities for physiological assessment, such as point-of-care ultrasound (POCUS) or P0.1 for measurement of respiratory muscle strength.
The integration of machine learning models, like the LASSO and Random Forest, further strengthens the study's analytical depth. However, applying these complex algorithms to small datasets reduces their predictive accuracy and clinical applications.
However, the study does highlight the importance of early screening for ICU-AW in critically ill patients and the use of the Perme score as a complementary tool for the same. This will help the intensivists to identify those at risk and adopt a proactive approach to use targeted strategies to improve mobility and muscle rehabilitation, and thus reduce the burden and long-term sequelae of ICU-AW.
What Messages Can We Take from This Study?
The striking prevalence of 78.4% of ICU-AW in the study population signifies that all patients in the ICU should be considered at risk of ICU-AW. A high index of suspicion along with a multidisciplinary approach should be taken to prevent the same and improve outcomes. The lack of a definitive treatment for ICU-AW further signifies the need for early detection and adopting a proactive, integrated approach to mitigate its deleterious effects. The study highlights the need to risk stratify and adopt collaborative strategies to fight against ICU-AW.
The Perme score appears to be a promising tool; however, needs to be validated in wider population groups. It may be used as a clinical bedside tool for screening ICU-AW and not for diagnosis of ICU-AW. Studies with individual component-based assessment of the Perme score may further help analyze the individual factors that can aid detection of ICU-AW. Also, the additive advantage of the score with other diagnostic modalities may be further studied. Being a simple tool, the score can be useful in resource-limited ICUs for early screening of ICU-AW.
Till then, specific assessments of neuromuscular strength may be done with the use of electromyography, and nerve conduction studies, and POCUS. Also, while machine learning tools hold promise for risk stratification, larger cohorts are needed to validate their use and improve their predictive accuracy.
In this era of personalized medicine, high priority should be placed on covering the research gaps in understanding ICU-AW and developing and standardizing simplified tools to enhance early detection of ICU-AW. Further, newer therapies and protocols should be researched to ensure prevention and management in order to reduce its incidence and impact. Post-ICU follow up by a multidisciplinary team can help effective recovery and better outcomes.
Orcid
Gunjan Chanchalani https://orcid.org/0000-0001-8429-8526
Footnotes
Source of support: Nil
Conflict of interest: None
References
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