The invention is directed to a ventilation control system and method of powering up a patient ventilator for detecting if a patient is connected to the ventilator when the ventilator is initially powered up prior to input of ventilator settings. The ventilation control system utilizes a user-friendly user interface for the display of patient data and ventilator status, as well as for entering values for ventilation settings to be used to control the ventilator. Values for ventilation settings entered during set up of the ventilator result in the display of only those further ventilation settings that are appropriate in accordance with the earlier entered settings.