Abstract: The need for a venous reservoir in a heart-lung machine is obviated by using a vacuum-purged negative-pressure air filter in the venous return line ahead of the main blood pump. The purging vacuum for the venous air filter can also be used to purge air from the cardiotomy reservoir if a backflow-preventing valve is used on the venous air filter.

Abstract: The efficiency of a hollow fiber wound oxygenator is improved by varying the packing density of the fiber bundle in a direction longitudinal and/or circumferential of the core.

Abstract: Blood mixing in fiber-wound oxygenators is improved by inserting at least one layer of a planar apertured mat between selected layers of wound gas-exchange fibers.

Abstract: Retrograde flow in an extracorporeal blood circuit using a centrifugal blood pump is prevented by passing the blood line through a normally-closed powered occlusion clamp, and opening the clamp in response to powering of the pump or, preferably, in response to the sensing of forward blood flow in the extracorporeal circuit.

Abstract: The need for a venous reservoir in a heart-lung machine is obviated by using a vacuum-purged negative-pressure air filter in the venous return line ahead of the main blood pump. The purging vacuum for the venous air filter can also be used to purge air from the cardiotomy reservoir if a backflow-preventing valve is used on the venous air filter.

Abstract: A heat exchanger, or the heat exchanger component of a multi-function device, comprising a polymeric heat transfer material. The heat exchanger exhibits reduced voltage-induced breakdown of the polymeric material, which can lead to cross-contamination of the two fluids. Either or both of two approaches may be employed. The first approach modifies the polymeric material to increase its resistance to breakdown. The second approach employs at least one electrical bridge between the fluids in the two sides of the heat exchanger, thus placing the two fluids into electrical equilibrium.

Abstract: The need for a venous reservoir in a heart-lung machine is obviated by using a vacuum-purged negative-pressure air filter in the venous return line ahead of the main blood pump. The purging vacuum for the venous air filter can also be used to purge air from the cardiotomy reservoir if a backflow-preventing valve is used on the venous air filter.

Abstract: Waterless temperature control of blood in a blood oxygenator is achieved by providing a non-disposable heater/cooler with a temperature-controlled surface that can be intimately mated with a heat-conducting surface of a disposable blood heat exchanger associated with the oxygenator. Blood flows in a shallow path past the heat-conducting surface so that substantially all of the blood will assume the temperature of the heat-conducting surface as it flows past that surface.

Abstract: Physiological changes in a patient's circulatory system can be detected in real time during open heart surgery by injecting a known amount of a marker substance into the patient's blood prior to surgery, and during surgery continuously concurrently monitoring variations both of the quantity of circulatory fluid in the heart-lung machine's reservoir and of the marker substance concentration in the fluid being pumped through the heart-lung machine. The patient's blood volume can also be continuously computed from the data thus gathered.

Abstract: A softshell blood reservoir incorporates an integral flexible cardiotomy section in which a filter/defoamer unit is supported in a semirigid cage. The reservoir also incorporates a storage section and a mixing section. The three sections can selectively communicate with each other. Cardiotomy blood is supplied to the cardiotomy section, and venous blood is supplied to the mixing section. The storage section holds varying amounts of cardiotomy blood to maintain a constant mixed blood output from the mixing section. Only the filter/defoamer unit and the mixing section need be primed.

Abstract: Blood heat exchanger apparatus with improved heat exchanged capability and improved bonding of micro-conduit heat exchange fibers. The micro-conduit comprises a plurality of elongated fibers, which may be made of a hydrophobic material such as polypropylene or polyethylene. The micro-conduit fibers may be provided as a heat exchanger micro-conduit wrapping material, wherein the micro-conduit fibers are attached to a thin flexible interconnect, such as woven netting, to maintain the fibers at predetermined and substantially parallel alignment with each other. The wrapping material is wrapped about an elongated spindle to provide a generally cylindrical heat exchange core. A shell is placed around the core to contain the heat transfer fluid which passes around the exterior of the fibers. Opposing first and second seals are created by applying potting compound between fibers proximate the spindle's first and second ends respectively.

Abstract: A blood inlet manifold is provided for connection to a first end of a blood heat exchanger including a plurality of hollow conduits arranged in a bundle. A plurality of first ends of the conduits terminate adjacent the first end of the blood heat exchanger and a plurality of second ends of the conduits terminate adjacent a second end of the blood heat exchanger. The blood inlet manifold includes a blood inlet nozzle having an upstream segment and a downstream segment. The upstream segment is connectable to a tube for conveying blood. The blood inlet manifold further includes a generally conical wall member connected to the downstream segment of the blood inlet nozzle and connectable to the first end of the blood heat exchanger. The connection of the blood inlet manifold to the blood heat exchanger defines a chamber between the conical wall member and the first set of ends of the conduits. An interior of the downstream segment of the blood inlet nozzle opens into this chamber.

Abstract: A blood outlet manifold is provided for a membrane-type blood oxygenator made of a plurality of micro-porous fibers. The fibers have first and second ends wound into a generally cylindrical bundle. The blood outlet manifold comprises a generally cylindrical vessel having a first annular wall dimensioned to snugly overly an exterior surface of the oxygenator fiber bundle. The vessel further has a flared portion including a second annular wall radially spaced from an end portion of the exterior surface of the oxygenator fiber bundle adjacent to the second ends of the fibers. An annular blood collection chamber is defined between the exterior surface of the oxygenator fiber bundle and the second annular wall for receiving blood flowing radially outwardly from around the fibers of the oxygenator fiber bundle. A seal is provided between the end portion of the oxygenator fiber bundle and the second annular wall.

Abstract: A transition manifold is provided for use in association with the upper end of a generally cylindrical heat exchanger fiber bundle having a plurality of vertically extending conduits with open upper ends terminating in substantially co-planar fashion. The transition manifold is specially configured for redirecting blood flowing out of the upper end of the heat exchanger fiber bundle radially outwardly around the fibers of a concentric, surrounding oxygenator fiber bundle. The transition manifold includes a generally conical wall member defining a surface which extends at a relatively flat angle with respect to a plane perpendicular to a vertical central axis of the heat exchanger fiber bundle. The surface of the conical wall member diverges away from the upper end of the heat exchanger fiber bundle in a direction moving radially outwardly from the central axis.

Abstract: A generally cylindrical membrane-type fiber bundle blood oxygenator concentrically surrounds a generally cylindrical blood heat exchanger including a fiber bundle made of thousands of polymer material micro-conduits. A heat transfer fluid such as water is introduced into the upper end of the heat exchanger and flows downwardly around the outside surfaces of the micro-conduits to an outlet. Upper and lower seals of urethane potting compound separate the heat transfer fluid from the open ends of the micro-conduits through which blood flows. A transition manifold at the upper end of the heat exchanger directs out flowing blood radially outwardly to the upper end of the oxygenator fiber bundle. The blood flows downwardly around the outside surfaces of the fibers of the oxygenator fiber bundle to a blood outlet manifold that collects the oxygenated blood.

Abstract: A tight, sterile connection between flexible tubing and a connector on a medical device is produced by pre-assembling the tubing and the connector, heat-shrinking the tubing onto the connector, and then sterilizing the connection while maintaining compression of the tubing against the connector.

Abstract: The obstruction of a curved blood manifold window in a blood oxygenator by oxygenation fibers which lie along a chord of a curved window when wound upon the oxygenator core is avoided by recessing the manifold wall portions most closely adjacent the window sufficiently so that the fibers lying on that chord remain sufficiently spaced from those closest wall portions to allow blood flow between those wall portions and the closest fibers.

Abstract: A tight seal is achieved in a blood oxygenator between the potting of the heat exchanger fibers and the rim of the heat exchanger container by extending the potting material over the rim and down, so that when the potting material shrinks during cure, the potting will become prestressed in the sealing direction against an outwardly facing wall of the container. The invention also provides a ring coextensive with the rim and spaced therefrom. The potting extends into the ring. This forms an air gap between the rim and the ring through which potting can extend. As a result, there is no possible leakage path between the blood and the heat exchange medium. Any leak that does occur discharges to atmosphere outside the container.

Abstract: A medical device and method for affecting mass transfer between blood and a fluid. In one application, this mass transfer is an oxygenation of the blood. Generally, a membrane which separates the blood and fluid is moved in a predetermined manner and in a direction which is substantially parallel to that of the primary direction of the flow to augment the mass transfer efficiency/rate. Importantly, this movement of the membrane is relative to the blood mass transfer boundary layer which steepens or increases the oxygen concentration gradient and decreases the thickness of the blood mass transfer boundary layer and thereby improves upon the mass transfer efficiency/rate of oxygen into the blood.

Abstract: An artificial lung is created by taking an animal lung, filling either its circulatory system or its respiratory system with a hardenable liquid, hardening the liquid, then dissolving the natural lung tissue, coating the hardened liquid with a material forming a gas permeable membrane, removing the hardenable fluid, and enclosing the resulting artificial lung structure in a fluid-tight pouch.