Cortisol Levels as a Measure of Accumulated Physiological Stress in Mechanical Ventilated ICU Patients: the Relationship With Premorbid Frailty, Functional, Cognitive and Psychopathological Impairment in the ICU Survivors

Critical illness is a situation of severe and prolonged stress for patients with mechanical ventilation (MV). Between 40-80% of these patients present the Post-ICU syndrome, a set of physical, cognitive, psychological alterations at hospital discharge. In more than a third of the ICU survivors, these sequelae become chronic being observed months and even years after ICU stay.

The characteristics of the Post-ICU syndrome have been related to different risk factors associated with the critical illness and its management. However, the impact of accumulated physiological stress is still unknown. The physiological response to prolonged stress generates high levels of cortisol that have been related to the loss of muscle tissue, cognitive and psychological alterations in both clinical populations and healthy subjects. The concentration of cortisol in plasma is not a measure of adequate physiological stress due to the dysregulation of the hypothalamic-pituitary-adrenal (HPA) axis during critical illness. Therefore, the objective of this study is to assess the levels of accumulated cortisol in human hair (CHH) during the different stages of the critical illness and its recovery, as well as to explore its relationship with the functional and neuropsychological sequelae observed in the ICU survivors.