Importance

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Abstract

A device for sensing the respiratory air of a patient. The device includes a venturi tube through which the patient inspires and expires, the tube having a constricted midportion. The tube also has an inspiration orifice, an expiration orifice, and a central orifice therebetween. An air mass flow sensor is positioned in the tube. A flow direction housing is attached to the tube and has a channel with an inspiration portion, an expiration portion, and a central portion therebetween. The housing also has an inspiration opening providing communication between the tube inspiration orifice and an end portion of the inspiration channel away from the central channel portion, an expiration opening providing communication between the tube expiration orifice and an end portion of the expiration channel portions away from the central channel portion, and a central opening providing communication between the tube central orifice and the central channel portion. This causes a flow of a portion of the respiratory air which the patient inspires to pass through the tube inspiration orifice and flow through the inspiration channel portion to the housing central opening, and a flow of a portion of the respiratory air which the patient expires to pass through the tube expiration orifice and flow through the expiration channel portion to the housing central opening for return to the venturi tube at the tube constricted portion. A flow direction sensor is positioned in the inspiration channel portion and a flow direction sensor is positioned in the expiration channel portion to produce outputs responsive to the flow of respiratory air through the inspiration and expiration channel portions for determining if the respiratory air flowing through the venturi tube is inspired or expired air.

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First Claim