Extubation failure can directly worsen patient outcomes. Therefore, the decision to extubate is a critical moment during an intensive care unit (ICU) stay. The decision to extubate is usually made after a weaning readiness test involving spontaneous breathing on a T-piece or low levels of ventilatory assistance. However, extubation failure still occurs in 10 to 20% of patients. The investigators focused on previously reported physiological risk factors, and were able to obtain from common clinical practice: 1) age, 2) underlying cardiovascular disease, 3) underlying respiratory disease or occurrence of pneumonia, 4) rapid shallow breathing index (RSBI), 5) positive fluid balance during the previous 24 hours, 6) the ratio of arterial oxygen partial pressure to fractional inspired oxygen, 7) Glasgow Coma Scale, 8) respiratory tract secretions. The investigators aimed to assess the incidence and risk factors for extubation failure among critically ill patients who passed the 30 min spontaneous breathing test (SBT) using a low level of pressure support (PS) with positive end-expiratory pressure (PEEP), in a prospective multicenter study.