Abstract: A heat exchanger wherein heat transfer fluid flows through a tube having an integral, substantially continuous hollow helical rib along its length providing a substantially continuous helical flute. The tube is positioned within a chamber connected in an extracorporeal blood circuit such that the blood is caused to flow over the exterior surface of the helically ribbed tube. In the preferred embodiment, the blood flows through a plurality of continuous, restricted area flow paths offering substantially uniform flow impedance to the blood, these restricted flow paths being provided by forming the helically ribbed tube in a helical configuration mounted between an inner cylindrical column and an outer cylindrical shell such that the blood is caused to flow through the plural paths of restricted cross-sectional area provided by the helical flute.

Abstract: A tracheostomy tube having an inflatable cuff, an inflating means including an indicating balloon, and a pressure relief valve to prevent over-inflation of the balloon and the cuff are disclosed.

Abstract: A convexo-concave, saucer-like heart valve vane is floatingly supported in a valve ring between a vane closing support rod, which engages the edge of a concentric recess on the arcuate convex side of the vane, and a vane closing support rod which engages the arcuate concave side of the vane. In its open position, the limiting portion of the convex distal surface of the vane is nearly aligned with the blood stream to maximize the blood flow through the portion of the valve defined by said portion and the adjacent portion of the ring.

Abstract: A relief valve having a main passage normally closed with a main valve member and a vent passage normally closed with a vent valve member, the vent valve member being constructed to open the vent passage upon application of a predetermined pressure into the main valve passage to thereby prevent application of greater than said predetermined pressure to the outlet of the valve is disclosed.

Abstract: A wedge-like seal for use with a tracheotomy tube having an inner cannula and an outer cannula. The seal is integrally formed within the outer end of the inner cannula to provide a tight seal engagement between the inner cannula and the outer cannula as well as between the coupling connector and the inner cannula. Incorporated in the seal is a circular sealing ridge from which depend two frusto-conical shaped sealing surfaces extending in opposite directions from the central ridge. The seal minimizes the force necessary to establish as well as to disengage the sealing contact between the respective tracheotomy tube parts, eliminating possible discomfort to the patient.