The present disclosure relates to a system and method for use of acoustic reflectometry information in ventilation devices. The system and method includes a speaker to emit sound waves into an intubated endotracheal tube (“ETT”) and a microphone to detect returning acoustic reflections. In addition, the system and method includes a reflectometry device in communication with a ventilation device for analyzing timings and amplitudes of the returning acoustic reflections to determine a size of a passageway around an ETT tip, location and size of ETT obstructions, and relative movement of the ETT tip within a trachea. The reflectometry device is also configured to determine a resistance parameter representative of resistance to actual flow of air through the ETT based upon a function of the diameter of the ETT, length of the ETT, and percent obstruction of the ETT, where the resistance parameter is used to calculate the tracheal pressure.