The importance of sarcopenia in critically ill patients in intensive care units

Abstract

Skeletal muscles, renowned for their remarkable adaptability, undergo significant mass reduction under catabolic conditions, a phenomenon notably observed during critical illness. Aging, exacerbated by reduced physical activity, accelerates this process, leading to a cascade of health consequences. The term "sarcopenia" has emerged to encapsulate these multifaceted aspects, encompassing diminished muscle strength, mass, and functional capacity. This comprehensive review explores the evolution of the concept of sarcopenia. Irwin Rosenberg's pioneering work 1989 introduced the term, defining it as the age-related loss of muscle mass. Subsequently, Baumgartner in 1998 refined the definition by quantifying sarcopenia as a reduction in appendicular skeletal muscle mass, precisely defined by statistical parameters. The European Working Group on Sarcopenia in the Elderly, in 2018, further advanced our understanding by including muscle strength as a diagnostic criterion. It also underscored the significance of reduced muscle mass in confirming the diagnosis. Severe sarcopenia is marked by the fusion of existing muscle damage and functional impairment, presenting a critical pathological condition. Sarcopenia has garnered official recognition in numerous countries as a distinct muscle disorder, classified under the diagnostic code ICD-10-MC. This review explores the pathophysiological underpinnings of sarcopenia, which can manifest either chronically, often accompanying the aging process, or acutely during hospitalization or prolonged bed rest. A key facet of age-related sarcopenia is the deterioration of type II fast-twitch muscle fibers, crucial for muscle strength and overall performance. Sarcopenia emerges as a syndrome characterized by progressive and generalized loss of skeletal muscle mass and strength. It is inexorably linked with physical disability, diminished quality of life, and, notably, increased mortality rates. Observational studies have indicated a substantial prevalence of sarcopenia among critically ill patients, affecting up to 60% of individuals admitted to intensive care units, especially those requiring mechanical ventilation. In light of these findings, this review aims to provide insights into the epidemiological, pathophysiological, and clinical facets of sarcopenia. We underscore its particular relevance in the context of critically ill patients in intensive care units, examining the profound impact on mortality. Furthermore, we delve into contemporary diagnostic methods for identification and available treatment modalities, aiming to shed light on the complexities of this pervasive and underrecognized condition.