Evaluating optimal rehabilitation strategies in ICU: study protocol for a multicentre cohort study to assess Physical Activity dosing, Muscle mass, and physICal outcomeS (IPAMICS study).

Background: Many patients who get discharged from the intensive care unit experience physical dysfunction that persists even after discharge. Physical dysfunction is associated with skeletal muscle atrophy and accompanying intensive care unit-acquired weakness in the early stages of intensive care unit admission, and early diagnosis and prevention with early mobilization are crucial. However, the amount of physical activity required for early mobilization remains controversial in critically ill patients. This study aims to reveal the optimal mobilization quantification score dose associated with physical dysfunction after hospital discharge.

Methods: This is a multicenter prospective cohort study planned in 22 facilities; all consecutive patients admitted to the participating facilities between June 2024 and May 2025 will be included. Adult patients on ventilator management for at least 2 days and who will consent to this study will be included. Patients' mobility level and duration will be documented by the mobilization quantification score during their intensive care unit stay, and physical dysfunction will be assessed using muscle mass changes from day one to seven with ultrasonography and the Short-Form 12 Health Survey at 3 months after hospital discharge. The primary outcome is physical dysfunction at 3 months.

Results and conclusion: Mobilization quantification score dose and muscle mass evaluation with ultrasonography will enable the quantification of the early mobilization intervention. This study will lay the foundation for future randomised studies.