Relationship between intensive care unit-acquired weakness, fatigability and fatigue: What role for the central nervous system?

Abstract

Purpose: To provide a comprehensive review of studies that have investigated fatigue in intensive care unit (ICU) survivors and questions the potential link between intensive care unit-acquired weakness (ICUAW), fatigability and fatigue. We also question whether the central nervous system (CNS) may be the link between these entities.

Material and methods: A narrative review of the literature that investigated fatigue in ICU survivors and review of clinical trials enabling understanding of CNS alterations in response to ICU stays.

Results: Fatigue is a pervasive and debilitating symptom in ICU survivors that can interfere with rehabilitation. Due to the complex pathophysiology of fatigue, more work is required to understand the roles of ICUAW and/or fatigability in fatigue to provide a more holistic understanding of this symptom. While muscle alterations have been well documented in ICU survivors, we believe that CNS alterations developing early during the ICU stay may play a role in fatigue.

Conclusions: Fatigue should be considered and treated in ICU survivors. The causes of fatigue are likely to be specific to the individual. Understanding the role that ICUAW and fatigability may have in fatigue would allow to tailor individual treatment to prevent this persistent symptom and improve quality of life.

Keywords: Central nervous system; Fatigability; Fatigue; Intensive care unit-acquired weakness.