Early physical rehabilitation in the ICU and ventilator liberation

Critically ill patients requiring mechanical ventilation are frequently subjected to long periods of physical inactivity, leading to skeletal muscle atrophy and muscle weakness. Disuse muscle atrophy is the result of complex mechanisms, including altered protein turnover and disturbed redox signaling. These ICU-acquired complications are associated with longer duration of mechanical ventilation, prolonged ICU and hospital stays, and poorer functional status at hospital discharge. Similarly, there is growing evidence that continuous mandatory ventilation alters diaphragmatic structure and contractile function and promotes oxidative injury, resulting in a rapid-onset diaphragmatic atrophy and weakness, which most likely delays discontinuing mechanical ventilation. Physical rehabilitation, when started at the onset of mechanical ventilation, has been associated with shorter periods of mechanical ventilation, decreased ICU and hospital stay, and improved physical function at hospital discharge. This review summarizes the impact of both physical inactivity and mechanical ventilation on skeletal and diaphragmatic muscles structure and function. Also reviewed is the growing evidence demonstrating the feasibility and safety of early physical rehabilitation interventions for mechanically ventilated patients, as well as their benefit on patient outcomes.