Muscle and nerve inflammation in intensive care unit-acquired weakness: A systematic translational review

• We summarize current knowledge on inflammation in muscle and nerve tissue in ICU-AW.
• Direct histological evidence of muscle and nerve inflammation in ICU-AW is limited.
• A detrimental role for local inflammation in ICU-AW cannot be established.
• Various inflammatory mediators are present in muscle and nerve tissue in ICU-AW.

BackgroundIntensive care unit-acquired weakness (ICU-AW) is an important complication of critical illness. The main risk factors, sepsis and the systemic inflammatory response syndrome, suggest an inflammatory pathogenesis. In this systematic translational review we summarize current knowledge on inflammation in muscle and nerve tissue in animal models of ICU-AW and in critically ill patients with ICU-AW.MethodsWe conducted a systematic search in the databases of MEDLINE, EMBASE and Web of Science using predefined search and selection criteria. From the included studies we extracted data on study characteristics and on inflammation in muscle and nerve tissue.ResultsThe literature search yielded 349 unique articles, of which 12 animal studies and 20 human studies fulfilled the in- and exclusion criteria. All studies had important shortcomings in methodological quality. In the animal studies, inflammation of muscle tissue was found, represented by cellular infiltration and increased local levels of various inflammatory mediators. In human studies, high levels of various inflammatory mediators were found in muscle and nerve tissue of ICU-AW patients.ConclusionThis systematic translational review suggests a role for local inflammation in ICU-AW, but the available evidence is limited and studies have severe methodological limitations.