This study will be conducted at the Beit Rivka geriatric rehabilitation hospital, Petah Tikva. Written informed consent will be obtained from the patient or legal representative. The study will include 60 consecutive patients who meet all inclusion criteria after stabilization of the acute health problems that prompted admission to the referral hospital. Inclusion criteria are as follows: pressure support ventilation (PSV) for at least 48 h, plateau pressure less than 30 cmH2O, PEEP < 6 cmH2O, PaO2/FIO2 ratio > 150 or SaO2 > 94% with FIO2 < than 0.5, pCO2 <55 mm Hg for normal patients and < 65 m Hg for patients with COPD, no requirement for inotropic support, body temperature > 36.50C and < 38.50 C, stable neurological status with Glasgow Coma Score (GCS) > 6, HgB > 8 mg %, systolic blood pressure >90 mg Hg, mean arterial pressure >65 mg Hg, absence of sedative medications and availability of CDS at the time of patient admission or switching to pressure support ventilation (PSV). Patients younger than 60 or older than 85 years of age, patients on chronic ventilatory assistance at home, and patients with decision to limit life-sustaining treatments will be excluded.