Abstract: A hybrid single-limb patient circuit coupled to an inspiratory port and an expiratory port of a ventilator. The hybrid single-limb patient circuit may include a check valve positioned to direct breathing gases supplied from the inspiratory port in a single direction; a manifold pneumatically coupled to the check valve; a dual-purpose single limb, pneumatically coupled to the manifold and the non-invasive patient interface, to carry breathing gases to the non-invasive patient interface and carry exhaled gases from the non-invasive patient interface; and an exhalation tubing segment, pneumatically coupled to the manifold and the expiratory port, to carry the exhaled gases from the manifold to the expiratory port.

Abstract: Systems and methods for non-invasively estimating intrapleural pressure and muscle pressure are disclosed. The disclosed estimation of intrapleural pressure functions in the presence of a leak and/or leak-compensated flow and does not require a maneuver. In examples, the muscle pressure is represented as a muscle pressure model with model parameters that are unique from breath to breath. An equation of motion relates the muscle pressure, respiratory mechanics, and measured ventilation data (e.g., airway pressure and flow). Based on past measured ventilation data, values for the respiratory mechanics and the model parameters are estimated. Constraints may be set on these values. An intrapleural pressure profile may be generated for past inhalation phases, based on the past measured ventilation data and the estimated model parameters and/or the estimated respiratory mechanics. The estimated respiratory mechanics may be used for real-time estimates of intrapleural pressure with real-time ventilation data.