Patent ID: 7270128

Claim:
A method for preventing dynamic airway compression during ventilatory support of a patient comprising the steps of: providing an interface to the patient's airway, providing said interface with a supply of breathable gas at a controllable pressure and with an exhaust, determining the patient's respiratory airflow, varying the pressure at the patient interface so as to provide ventilatory support to the patient, from at least the respiratory airflow determining the patient's airway conductance separately during the inspiratory and expiratory portions of at least one respiratory cycle and calculating a measure of the degree of dynamic airway compression as a function of the values of the inspiratory conductance and the expiratory conductance, and servo-controlling the measure of the degree of dynamic airway compression by increasing expiratory pressure if said measure is large or increasing, and reducing expiratory pressure if said measure is small or zero, wherein the measure of the degree of dynamic airway compression is calculated as a function of the difference between the inspiratory conductance and the expiratory conductance, or as a function of the ratio of the inspiratory conductance to the expiratory conductance.