A system for determining a parameter of respiratory mechanics in the presence of an intrinsic positive end-expiratory pressure during a ventilator support of a patient is provided. The system includes a computer system that comprises one or more in physical processors programmed with computer program instructions which, when executed cause the computer system to: determine breath segmentation data from airway flow information of the patient and airway pressure information of the patient； and determine the parameter of respiratory mechanics in the presence of the intrinsic positive end-expiratory pressure using the determined breath segmentation data. The parameter of respiratory mechanics includes one or more of the following: respiratory resistance, respiratory elastance, respiratory compliance, the intrinsic positive end-expiratory pressure, a pressure inside the alveoli, and an equivalent pressure generated by the respiratory muscles of the patient.
