Refers to modes of ventilation where the pressure of the tidal breath is set. E.g. we set the ventilator to deliver a breath pressure of 30 cm H20. Setting the rate is normally mandatory for this method of controlling ventilation. E.g. we set the breath pressure at 30 cm H20 to be delivered at a rate of 14 bpm (breath per minute).
The tidal volume in this mode of ventilation will depend on the lung and chest wall compliance. Indeed the tidal volume might change from breath to breath depending on many factors.