This longitudinal, prospective observational study aims to evaluate functional status in critically ill adult patients in the Intensive Care Unit using the Chelsea Critical Care Physical Assessment Tool (CPAx). The primary objective is to analyze CPAx score variation as a potential predictor of clinical outcomes, including mortality and duration of mechanical ventilation. Functional assessments will be performed at intensive care unit (ICU) admission and discharge to monitor changes in physical function and to predict adverse clinical outcomes.

This prospective, longitudinal, and observational study will be conducted at the general ICU of Pedro Ernesto University Hospital (HUPE). Demographic and clinical information at admission will be collected, including age, sex, type of airway at ICU admission, cause of ICU admission, comorbidities, and clinical scores such as Sepsis-related Organ Failure Assessment (SOFA), Simplified Acute Physiology Score III (SAPS III), and Charlson Comorbidity Index. During the ICU stay, data on the use of invasive mechanical ventilation, non-invasive ventilation, high-flow nasal cannula (HFNC), renal replacement therapy, extubation, and reintubation will be recorded. The CPAx will be assessed at ICU admission and discharge. Additionally, total hospital and ICU length of stay, as well as days on mechanical ventilation, will be recorded.The study aims to analyze the variation in CPAx scores as a predictor of adverse clinical outcomes, including mortality and duration of mechanical ventilation.

Inclusion Criteria: All adult patients admitted to the Pedro Ernesto University Hospital (HUPE) General ICU over 18 years of age and with an ICU stay greater than or equal to 48 hours will be included.

Exclusion Criteria:

• Pregnancy
• Inability to record the CPAx score within the first 48 hours of ICU admission or on the day of ICU discharge
• ICU readmission
• Known comorbidities causing generalized weakness, such as neuromuscular or neurological diseases

The general ICU admits both surgical patients and clinical patients, including those with acute illnesses or decompensations of chronic diseases. Participants include both male and female patients.