Abstract: A system and method are configured to monitor respiratory stability and/or effectiveness. A ventilation index is determined that provides an indication of respiratory stability and/or effectiveness. The ventilation index is determined from one or more metrics that indicate deviation of a breathing parameter of a subject from levels that have been observed to be normal or typical for the subject.

Abstract: Gas-pressure-based testing, in some embodiments, features a self-leak-testing module (120) that includes an internal sensor and is configured for measuring, using the sensor, gas leakage (179, 180) from a set of walls that defines respective gas passageways that both exist within the module and are incident to the gas pressure measured. One or more walls of the set may extend outside the module. The module can be configured for deciding, based on a result of the measuring, whether a magnitude of the leakage exceeds a predetermined threshold. A source for applying the pressure may be internal (138) or external (104, 132, 135). Gas pressure based pattern recognition can be used to identify, optionally during treatment and in real time, one or more leak sites responsible for the leakage. The module is implementable as a ventilation monitoring module that measures differential flow of a breathing circuit, the testing serving to prevent cross-contamination of patients.

Abstract: Respiratory insufficiency is detected by classifying preliminary breaths identified through a capnogram as being valid or artifact. Individual breaths are classified as being valid or artifact by determining values of a plurality of breathing parameters for a given breath, inferring a value for a key parameter from the determined values for the plurality of breathing parameters, and comparing the inferred value for the key parameter to a predetermined threshold.

Abstract: A system is configured to perform capnometry/capnography, and/or other compositional analysis on a non-invasively ventilated subject. As such, the system determines amounts of a molecular species of gas (e.g., carbon dioxide, oxygen, etc.) excreted by the subject on a per-breath basis. Determinations of amounts of the molecular species of gas excreted are adjusted to reflect amounts of the molecular species of gas leaked from the non-invasive interface used to communicate with the airway of the subject.

Abstract: A system is configured to determine one or more breathing parameters of a subject, such as one or both of end-tidal carbon dioxide concentration and/or breath rate. The system is configured to make a plurality of preliminary determinations of an individual breathing parameter according to a plurality of different algorithms. A final determination of the breathing parameter is obtained by selecting one of the preliminary determinations based on therapy parameters, gas parameters, and/or other parameters that impact the accuracy and/or precision of the different algorithms.

Abstract: Breaths of a subject are identified based on the concentration of carbon dioxide at or near the airway of the subject. Troughs corresponding to inhalation are identified and plateaus corresponding to exhalation are identified. A breath is identified responsive to a trough being followed by a plateau.

Abstract: Ventilation information may be presented. Output signals may be received that convey information related to one or more breathing parameters of a subject receiving assisted or controlled mechanical ventilation. Based at least in part on the received output signals, volumetric components of a tidal volume of the subject may be determined. The volumetric components may include an alveolar dead space, an effective alveolar tidal volume, and/or other volumetric components. The alveolar dead space is the volume of inspired gas that occupies alveoli but does not take part in oxygen exchange in the lungs of the subject. The effective alveolar tidal volume is the volume of inspired gas that takes part in oxygen exchange in the lungs of the subject. A visual representation that textually or graphically represents the tidal volume, and/or textually or graphically represents the volumetric components separately from each other may be presented via a user interface.

Abstract: A subject interface appliance (10) configured to deliver a breathable substance to a subject. The subject interface appliance includes a primary interface (12) configured to deliver a breathable substance to the subject, and a secondary interface (14) configured to obtain gas samples from the airway of the subject. The secondary interface is resiliently held at a default position with respect to the primary interface. The default position is located such that installation of the primary and secondary interfaces on the subject results in the application of a bias force to the secondary interface that holds the secondary interface in place.

Abstract: Values of components of total carbon dioxide excreted by a subject can be provided. One or more signals may be received conveying information related to a rate of total carbon dioxide excreted by the subject. Based at least in part on the received one or more signals, a first capnometric component and/or a second capnometric component may be determined. The first capnometric component may indicate a rate of metabolic carbon dioxide production. The second capnometric component may indicate a rate of carbon dioxide transfer to or from body compartments of the subject that store carbon dioxide. The first capnometric component and/or the second capnometric component may be presented to a user.

Abstract: A system is configured to monitor the dead space fraction of a subject in a substantially ongoing manner, rather than only updating the dead space fraction of the subject if one or more blood gas parameters of the subject are measured. This may facilitate enhanced control over respiratory therapy being provided to the subject, may inform decisions about care of the subject, and/or may provide other enhancements.

Abstract: Based on a capnometry signal, one or more breathing parameters of a subject are determined that require valid breaths by the subject to be distinguished from anatomical events that cause the CO2 content of gas at or near the airway of the subject to fluctuate. To improve the accuracy of one or more of these determinations, gas at or near the airway of the subject is diluted.

Abstract: Pressure support therapy is provided to a subject. The effectiveness of the provided pressure support therapy is determined and/or the therapy is titrated based on determinations of the concentration of one or more gaseous molecular species in gas exhaled by the subject. The determinations of composition of gas exhaled by the subject are obtained from samples with relatively little distortion caused by dilution of expired gases from gases provided to the airway of the subject as part of the pressure support therapy.

Abstract: Sidestream sampling of gas to determine information related to the composition of gas at or near the airway of a subject is implemented. From such information one or more breathing parameters of subject 12 (e.g., respiratory rate, end-tidal CO2, etc.) are determined, respiratory events (e.g., obstructions, apneas, etc.) are identified, equipment malfunction and/or misuse is identified, and/or functions are performed. To improve the accuracy of one or more of these determinations, information related to pressure at or near the airway of subject is implemented. This information may include detection of pressure at or near a sidestream sampling cell.

Abstract: A system and method that determine the functional residual capacity of a subject in an automated manner. The determination of the functional residual capacity of the subject is made by analyzing the washout and/or wash-in of one or more molecular species present in gas breathed by the subject. The determination of the functional residual capacity can be made without a determination of oxygen consumption.

Abstract: Respiratory insufficiency is detected by classifying preliminary breaths identified through a capnogram as being valid or artifact. Individual breaths are classified as being valid or artifact by determining values of a plurality of breathing parameters for a given breath, inferring a value for a key parameter from the determined values for the plurality of breathing parameters, and comparing the inferred value for the key parameter to a predetermined threshold.