Past research on PICS has mainly focused on the predictability and prognosis of PICS occurrence in ICU patients. Still, there is currently insufficient research on the role of PICS in the care setting of patients who have stabilized and are transferred to respiratory care units such as Respiratory Care Centers (RCCs) for weaning attempts. To understand the impact of PICS on the respiratory physiology of patients undergoing weaning from prolonged mechanical ventilation, investigators propose a one-year research plan