Importance

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Abstract

A gas blending system for use with a medical ventilator blends a pressurized gas with ambient air for delivery to the ventilator in response to the ventilator's demand for gas during the gas intake phase of its cycle. The system comprises a demand valve that discharges a flow of the pressurized gas in proportion to the demand applied to its outlet. The demand valve outlet is coupled to a first inlet of a blending valve, a second inlet of which is open to the atmosphere. The blending valve has a blended gas outlet adapted to be coupled to the ventilator. The total demand applied by the ventilator to the blended gas outlet is transmitted to the first and second inlets. A proportioning mechanism in the blending valve adjusts the demand that is transmitted to the demand valve outlet through the blending valve first inlet as a percentage of the total demand applied to the blended gas outlet. The total flow of blended gas from the blended gas outlet is proportional to the total demand applied thereto, while the percentage of pressurized gas in the blended gas flow is proportional to the ratio of the demand applied to the first inlet to the total demand applied to the blended gas outlet. The pressurized gas percentage is determined only by the proportioning mechanism, and is independent of the total applied demand.

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First Claim