Abstract: A bymixer device and method which provides fast-response, accurate measurements of mixed inspired and/or expired gas fractions in open or closed ventilation circuits and/or in circle circuits used in anesthesia and/or critical care. The bymixer device may include a main flow channel and a bypass flow channel. The bypass flow channel includes a flow-restrictor (e.g, an orifice) that partially blocks the flow of respiratory gas through the bypass flow channel, a mixing chamber positioned upstream of the flow restrictor and a sampling apparatus (e.g., a port for withdrawing samples of gas from said mixing chamber and/or sensor(s) positioned within the mixing chamber).

Abstract: A system and method for determining the volume of oxygen taken up by the lungs of a human or veterinary patient. A closed ventilation circuit is connected to a spirometric device, which contains a quantity of oxygen. As oxygen is taken up by the patient, an equivalent volume of oxygen passes from the spirometric device into the ventilation circuit. The volume of oxygen that moves from the spirometric device may thus be measured as an indication of the volume of oxygen that has been taken up by the patient. In some embodiments, a source of make-up oxygen is connected to the ventilation circuit and the flow of make-up oxygen is adjusted as necessary to maintain a substantially constant volume of oxygen in the spirometric device. The volume of make-up oxygen is measured and serves as an indication of the amount of oxygen taken up by the patient. A valve may be used to close the spirometric device off from the ventilation circuit during all but a part of the ventilation cycle (e.g.

Abstract: Apparatus for producing a light mask for balancing light across a display area of a vehicle instrument cluster comprises a camera, a digitiser and a computer. An image of the display area is obtained and digitized to produce data relating to the illumination levels of the image at a plurality of pixels. The illumination levels are used to calculate an appropriate light mask for the display area on the basis of the transmissive density of the masking ink used and or a reference illumination value relating to the least lit part of the display area which it is desired to illuminate. The light mask comprises an array of dots having a diameter related to the amount of attenuation required in the area in which the dot is located. Up to three masking layers may be provided if a single layer is insufficient to produce the required attenuation with the chosen masking ink. Balanced coverlays can readily be produced, and the number of masking layers required can also be reduced.