Abstract: The present invention relates to a respiration valve (401) for performing respiration tests on e.g. humans, consisting of at least three ports, a first mouth port (402) and two breathing ports (403, 404). The breathing ports (403, 404) comprise pneumatic pinch valves consisting of a channel (101) with a flexible wall (201) to be used for the flow of material and molded as an integrated part of a surrounding chamber (102). The flexible wall (201) comprises two opposing angularly interconnected wall segments (202) which are angularly connected at interconnection points (203) and which flexible wall (201) is pinched by a pressure from fluid, such as air, introduced into the chamber (102). The cross sectional shape corresponds in one embodiment approximately to a elongated hexagon. The construction of the respiration valve (401) comprising these pneumatic pinch is valves enables a very small, light, hygienic, and safe yet inexpensive construction with a long life expectancy.

Abstract: The present invention discloses a method to compensate for a non-zero mixed venous partial pressure of inert blood soluble gas when determining physical parameter(s) of a patient in successive inert gas rebreathing tests. The method comprises the steps of: obtaining the partial pressure of said inert blood soluble gas inhaled and/or exhaled by said patient in a period prior to said successive rebreathing test; obtaining the partial pressure of said inert blood soluble gas inhaled and/or exhaled by said patient in said successive rebreathing test; determining said physical parameters) using said partial pressure of said inert blood soluble gas inhaled and/or exhaled by said patient and obtained in said period prior to said successive rebreathing test and said partial pressure of said inert blood soluble gas inhaled and/or exhaled by said patient and obtained in said successive rebreathing test. Furthermore the present invention relates to a corresponding system and computer-readable medium.

Abstract: The present invention discloses a method to determine the lung clearance index (LCI) or other indices of ventilation inhomogeneity of the lungs by combining two pulmonary gas exchange techniques; Inert gas rebreathing (IGR) is used for rapid wash-in of the inert tracer gas and for accurate determination of the functional residual capacity (FRC) by gas analysis alone. This is followed by multiple-breath wash-out (MBW) for determination of the cumulative expired volume (VCE) required to clear the inert tracer gas from the lungs, and calculation of the LCI as the ratio between VCE and FRC. The advantages of the method are i) significant reduction of required test time, ii) significant reduction of consumed gas mixture for wash-in of tracer gas, iii) potential for further reduction of the use of tracer gas, and iv) more accurate determination of the FRC by gas dilution alone. Furthermore the present invention relates to a corresponding system and computer-readable medium.