any mechanically assisted breathing, employing either positive- or negative-pressure devices. Some positive-pressure devices require intubation of the trachea, others require only a mask applied to mouth or nose. For the past several decades, the standard way of ventilating a patient with respiratory failure mechanically has involved intubation of the trachea and either pressure- or volume-limited application of positive pressure to the lungs through an endotracheal tube; currently, the need for intubation in any case is coming into question and many patients experiencing chronic respiratory failure can be adequately ventilated by noninvasive devices. Mechanical ventilation: Treatments