This disclosure describes systems and methods for configuring a ventilator to estimate the carinal pressure to minimize the work of breathing due to a breathing tube. A patient's carina is a cartilaginous ridge located at the site of the tracheal bifurcation between the two primary bronchi. An estimated carinal pressure (a pressure estimated to exist at the patient carina) may be determined and used as feedback control for the carinal pressure. According to embodiments, the estimated carinal pressure may be compared to the carinal pressure command to determine an error. The carinal pressure command may be positive end expiratory pressure (PEEP) or some other suitable target pressure. The error between the estimated carinal pressure and the carinal pressure command may then be used as feedback control to achieve the carinal pressure command and thereby to minimize the work of breathing due to the breathing tube.