Design: Prospective, randomized, controlled trial, with 2 groups: study (protocol weaning group) and control (clinicians' order weaning group). Setting: Respiratory Intensive Care Unit (RICU). Subjects: Patients >18 yr, noninvasive mechanical ventilation >24 hours. Interventions and measurements: Study group (weaning as the protocol) and control group (weaning as the clinicians' order); recording of clinical variables at admission and during RICU stay, and end-point variables (noninvasive mechanical ventilation day, RICU and hospital stay, RICU mortality. Expected results: the protocol group's noninvasive mechanical ventilation days is less than clinicians' order group.