Importance

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Abstract

An apparatus and method for providing a sample gas flow from an air tube of a patient undergoing automatic ventilation is disclosed. The air tube includes a gas diffusive membrane disposed in a wall of the air tube. The base of a funnel member is disposed to engage the air tube at the membrane, the area of the base substantially equal to the area of the membrane. The funnel member includes a tubular end portion opposite the base which end portion is disposed to be coupled to a sampling tube or gas monitoring equipment. Cross sectional area of the tubular end portion is substantially smaller than the area of the base. A pump in the gas monitoring system is coupled to the tubular end portion and causes a small portion of the gas in the air tube to pass through the membrane into the funnel. The velocity of the sample gas flow through the membrane is lower than the velocity through the tubular end portion but the sample gas flow rate remains constant. The gas diffusive membranes can be non-wettable membranes for rejecting water from entering the sample gas flow. Sampling tubes coupled between the tubular end portion and the gas monitoring system may also comprise water absorbing or water passing materials to eliminate excess water from the gas sample flow.

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First Claim