Abstract: The present invention relates to a heat exchanger which is specifically adapted for use in connection with blood oxygenators, particularly bubble oxygenators. The core of the heat exchanger is generally cylindrical and closed at both ends. The cylinder is made of thin walled material with good heat exchange properties such as aluminum. The portion of the heat exchanger core which will be exposed to blood is coated with a biocompatible material such as tetrafluoroethylene. The heat exchanger may be connected to a source of heat exchange medium, such as water, through couplings in the top portion of the heat exchanger core. The heat exchange medium is then circulated through the core providing heating or cooling which is capable of heating or cooling blood within a bubble oxygenator. The heat exchanger core is then nested within a suitable receiver.

Abstract: The oxygenater heat exchanger disclosed utilizes a heat transfer tube having several tube legs arranged in closely spaced, parallel relation. A resilient central core fits resiliently within the tube legs and cooperates with spiral ribs on the tube and with the housing to form blood flow spiral passages down around the exterior of each of the tube legs. The blood inlet is positioned to enhance efficient heat exchange.

Abstract: An apparatus for the transfer of one or more substances between a gas and a liquid, for example between an oxygen-containing gas and blood, is disclosed. The apparatus includes a plurality of concentric vessels which define a flow path for the liquid, and which includes along a portion of the path an annular heat exchange chamber having a first end at which the liquid is introduced into the chamber and a second end at which the liquid is conducted from the chamber. A heat exchanger is supported in the heat exchange chamber for conducting a heat exchange fluid in heat exchange relationship with the liquid as the liquid flows through the chamber. Gas in the form of bubbles is introduced into the liquid as the liquid is conducted along the flow path to thereby effect transfer of substances between the gas and the liquid, the gas being introduced upstream of the first end of the heat exchange chamber.

Abstract: A method and apparatus for administering large quantities of blood which has been stored at less than ambient temperatures continuously and rapidly to a patient at physiologically acceptable temperatures and pressures in a short time wherein the blood is continuously directed through a plurality of discrete capillary paths in heat-exchange relationship with a warming medium, the number of said paths being such that the pressure of the blood is not substantially increased, and the blood is rapidly administered directly to a patient.

Abstract: A unitary system incorporates an upper reservoir container having a blood gas separator, a cardiotomy reservoir and a venous reservoir. The upper container is positioned directly above a lower mass transfer container coupled with the venous reservoir by means of a check valve and having a spirally wound flattened tubular transfer membrane. A vacuum is drawn upon an upper portion of the reservoir container which carries a blood gas separator into which aspirated wound site blood is drawn for filtering and collection of blood in the cardiotomy reservoir. The latter is automatically drained via a pressure responsive valve into a venous blood reservoir at the lower portion of the reservoir container and into which venous blood flows for mixing with the filtered cardiotomy blood.

Abstract: Blood oxygenating apparatus having a sampling access device connected to the blood outlet port and a blood inlet port of the apparatus by a sample supply line and return line and means to cause the pressure at the blood outlet port to be sufficient to cause a small continuous flow of blood through the lines and access device.

Abstract: A membrane type blood oxygenator with a microporous membrane separating blood and air channels, the blood in the blood channels flowing downward to cause any accidentally introduced air bubbles to have an increased residence time in the membrane device owing to buoyancy, the blood being at a pressure sufficiently greater than the air pressure to cause passage of air bubbles through the pores of the microporous membrane to the air side prior to being carried out of the device by flowing blood.

Abstract: The device comprises plural oxygenation modules, each of which has at least one member for diffusing oxygen through the blood, and one shutter for shutting off such fluids. The modules communicate with a chamber wherethrough the pipes of a heat exchanger extend, and with a collecting chamber through a layer of an antifoaming material.

Abstract: A blood oxygenator containing a means for combining oxygen-containing gas with liquid blood, the oxygenator having an outer shell portion rotatably joined to a cap portion. Preferably the cap portion includes at least one blood inlet together with an oxygen-containing gas inlet while the outer shell portion contains at least one oxygenated blood outlet and the rotatable joint between said outer shell portion and said cap portion is in venting communication with the exterior of the blood oxygenator.

Abstract: Device useful as a heat exchanger for blood or as an apparatus in which blood may be treated or reacted with selected reactants. Device comprises hollow tubing which has plastic monofilament placed in a generally spiral configuration around its outer surface, said monofilament being in the form of continuous or discontinuous projections or ridges. Strands of wire may be substituted for the plastic monofilament. Hollow tubing having such plastic monofilament or strands of wire is also included.

Abstract: A closed, air-free blood oxygenator assembly having integrated into one self-supporting unit a rigid-shell blood reservoir having an easily visible, concavity which is closed by an attached expansible, flexible membrane which overlies the concavity and forms a variable volume liquid and air-tight blood reservoir, and an attached blood heater, and a hollow fiber membrane oxygenator. The assembly stores, heats, oxygenates and purifies blood by passing oxygen through the lumens of a mat of small diameter gas-permeable hollow fibers supported on a cylindrical core as blood flows over the outside surfaces of the fibers in a small, easy to use, safe, integrated unit which avoids blood contact with ambient air as blood circulates through the assembly during surgery.

Abstract: Blood units and water units for membrane type blood oxygenator in which blood units are separated from water units by oxygen units; oxygen diffuses through membranes of blood units from oxygen units and water units apply pressure to blood units through intervening oxygen units. The blood unit is formed by a frame having a pair of opposing sides and a pair of opposing ends, the ends being imperforate, the sides being formed with flow-through passages for flow of blood from one blood unit to the next and with lateral passages for flow of a portion of the blood into, through and out of the blood unit, there being a semi-permeable membrane affixed to opposite faces of the frame. The water unit comprises a water impermeable, expansible water mattress having rigid end members formed with water flow-through passages for flow of water from one water unit to the next and having lateral passages for flow of a portion of the water into, through and out of the mattress.

Abstract: A blood oxygenator for one time use and discard in medical procedures. The blood oxygenator has a unitary transparent sealed vessel with first and second blood treating stages arranged for series flow. The first stage receives an inflow of blood and oxygen and it has integrated oxygenating and heat exchanging elements that include a plurality of vertical ribs and flutes internested to provide upright thin-film blood and oxygen flow channels. These ribs and flutes surround, by a common wall, a heat exchanger with upright channels for counter-directional coolant flow relative to the blood and oxygen flow. The second stage has integrated blood degassing and defoaming elements including a vertical perforated wall surrounded by a porous foam member with a surrounding reservoir of outflowing degassed and defoamed blood and a vent for free oxygen gas.

Abstract: A blood oxygenator is equipped with a sparger having a passageway formed by two vertically aligned fluid impervious cones, one upright and one inverted, between the bases of which a porous disc is positioned. An oxygen inlet communicates with the porous disc to radially inject oxygen into the passageway from the periphery of the porous disc. The blood is transformed from a liquid to a foam as it rises in the passageway. At the outlet of the sparger an oxygenation chamber includes a serpentine cascade which prolongs contact between the blood and bubbles of gas containing oxygen. The outlet of the cascade empties into a reservoir which has a concave foam filter therein defining a defoaming chamber and a screen having uniform interstices surrounding the foam filter to form a bubble point barrier. The screen prevents undissolved gaseous emboli in the blood from passing from the defoaming chamber toward the arterial outlet of the reservoir.

Abstract: A hollow fiber-type artificial lung having an enclosed heat exchanger comprises a first housing and a second housing connected together coaxially. A gas exchange chamber is defined in the first housing by a pair of spaced walls and a bundle of hollow fibers designed for gas exchange arranged in the first housing and between the pair of walls. The hollow fiber bundle is preferably constricted at the central portion to increase the packing ratio of the hollow fibers. The second housing is connected to the first housing by way of a blood chamber and has a pair of spaced apart walls, and multiple tubes which extend lengthwise between the pair of walls to effect heat exchange between a circulating heat exchange medium and the blood flowing through the multiple tubes.

Abstract: A device for the transfer of one or more substances between a gas and a liquid, the gas being introduced into the liquid in the form of bubbles from which the said substances are transferred to the liquid whereupon the excess gas is removed together with any substances transferred from the liquid to the gas. Characteristic for the device is a narrow annular gap (10), arranged vertically, for the liquid, a gas inlet (20), arranged in close connection to this gap (10), this gas inlet being adapted so that it introduces the gas uniformly distributed along the whole periphery of the gap (10), and means (34,36) for the removal of the excess gas.The device is intended in particular to be used as a so-called oxygenator when the said liquid is blood and the said gas is oxygen or an oxygen mixture. Carbon dioxide from the blood will then be removed together with the excess gas.

Abstract: A blood oxygenating device having an oxygenating chamber and a heat exchange chamber. The oxygenating chamber consists of a bubbler chamber and a mixing chamber. Oxygen is introduced into the bubbler chamber through a porous diffusion means situated near the inlet of the bubbler chamber. Bubbles pass from the bubbler chamber into a mixing chamber which is provided with a plurality of secondary flow-producing deflectors to promote secondary flow of blood bubbles passing therethrough. The secondary flow results in a highly efficient oxygen-carbon dioxide transfer. The blood bubbles are then passed through a heat exchange chamber and a defoaming means prior to exiting the oxygenating device.

Abstract: The oxygenator is used for arterializing blood during open heart surgery. The oxygenator is factory-assembled and sterilized and is of economic and efficient design so that it can serve as a throwaway unit. Blood from the patient is oxygenated as it passes through the center of a tubular sparger with porous walls which supplies oxygen bubbles of the optimum size. The foaming blood is delivered to the top of the main oxygenator body where it is distributed by gravity flow downward across the heat exchanger tubing. The heat exchanger is wound as a flat coil with all connections outside of the oxygenator body. A silicone-coated sponge is located below the heat exchanger so that downwardly flowing foaming blood is defoamed as it passes through the sponge. Carbon dioxide and other gases are vented, and liquid blood gravitates into a tapered arterial reservoir.

Abstract: Blood units and water units for membrane type blood oxygenator in which blood units are separated from water units by oxygen units; oxygen diffuses through membranes of blood units from oxygen units and water units apply pressure to blood units through intervening oxygen units. The blood unit is formed by a frame having a pair of opposing sides and a pair of opposing ends, the ends being imperforate, the sides being formed with flow-through passages for flow of blood from one blood unit to the next and with lateral passages for flow of a portion of the blood into, through and out of the blood unit, three being a semi-permeable membrane affixed to opposite faces of the frame. The water unit comprises a water impermeable, expansible water mattress having rigid end members formed with water flow-through passages for flow of water from one water unit to the next and having lateral passages for flow of a portion of the water into, through and out of the mattress.

Abstract: To supply oxygen to blood and control its carbon dioxide content, the blood is pumped through a silicone rubber tube wound as a helix around an aluminum cylinder. In a typical use, water at 37.degree. C. is pumped through the cylinder to maintain the temperature constant and a gas containing 95% oxygen and 5% carbon dioxide is passed over the silicone rubber tube so that: (1) oxygen passes through the rubber silicone tube to enrich the blood in oxygen; and (2) carbon dioxide is exchanged through the silicone rubber tube between the blood and the outside gas.

Abstract: A blood oxygenating device comprising an oxygenating chamber and a heat exchange chamber, the oxygenating chamber comprising a bubbler chamber and a mixing chamber. Oxygen is introduced into the bubbler chamber through a porous diffusion means situated near the inlet of the bubbler chamber. Bubbles pass from the bubbler chamber into the mixing chamber which is provided with a plurality of secondary flow-producing deflectors to promote secondary flow and rotation of blood bubbles passing therethrough. The secondary flow results in a highly efficient oxygen-carbon dioxide transfer. The blood bubbles are then passed through a heat exchange chamber and a defoaming means prior to exiting the oxygenating device.In a preferred version, blood and oxygen-rich gas are admitted at the top of the device and caused to flow substantially downwardly through a tortuous path which causes at least a portion of the blood bubbles to rotate.

Abstract: A rigid blood oxygenator in which blood and oxygen-rich gas are admitted at the top of the device and caused to flow substantially concurrently downwardly through a tortuous path. During the course of this downward flow, oxygen-rich gas bubbles are formed in the blood and a gas transfer is accomplished according to which the oxygen content of the blood is enriched and carbon dioxide is removed from the blood, which gas transfer is enhanced by the secondary flow induced by the tortuous path. During the course of downward flow, the blood-gas-bubble mixture is also passed around a heat exchange device, which preferably is convoluted so as to form a tortuous path, to bring the blood to a desired temperature. The device is equipped with a defoaming means such that the blood bubbles are converted back into liquid blood, which is then returned to the patient. Vent means are provided for removal of carbon dioxide and other vent gases.

Abstract: An improved blood oxygenator including a first chamber having a plurality of oxygenator tubes disposed therein with each tube having an elongated cross-section. A blood inlet for introducing blood and a oxygen inlet for introducing oxygen gas into the blood are located on the oxygenator such that a mixture of blood and oxygen flows through the tubes where the blood is oxygenated. A blood foam exits from the tubes and then flows through a ring of reticulated polyurethane causing the blood to be further oxygenated. A defoamer is disposed about the first chamber and defoams the blood. The blood is then filtered and collected in a reservoir and can be withdrawn from the oxygenator through a blood outlet port.

Abstract: Apparatus for the transfer of substances between two fluids with the simultaneous tempering of at least one of the fluids. The apparatus includes at least one heat permeable membrane having first and second opposing surfaces for the transfer of heat therethrough. First and second fluid conducting means are provided for conducting a first and second fluid, respectively. Transfer means are provided for transferring substances between the first and second fluids. The second fluid conducting means conducts the second fluid along the first surface of the heat permeable membrane and third fluid conducting means are providing for conducting a third fluid along the second surface of the heat permeable membrane for tempering the second fluid. According to the preferred embodiment, the transfer means may comprise either means for directly mixing the first fluid into the second fluid or may comprise a semipermeable membrane for diffusing substances therethrough between the first and second fluids.

Abstract: There is disclosed a blood oxygenating device having an oxygenating chamber and a heat exchange chamber. The oxygenating chamber consists of a bubbler chamber and a mixing chamber. Oxygen is introduced into the bubbler chamber through a porous diffusion means situated near the inlet of the bubbler chamber. Bubbles pass from the bubbler chamber into a mixing chamber which is provided with a plurality of secondary flow-producing deflectors to promote secondary flow of blood bubbles passing therethrough. The secondary flow results in a highly efficient oxygen-carbon dioxide transfer. The blood bubbles are then passed through a heat exchange chamber and a defoaming means prior to exiting the oxygenating device.

Abstract: An apparatus for the oxygenation of blood has a housing centered on an upright axis and an oxygenation chamber below the housing which has a tube formed thereon which extends upwardly and passes coaxially through the housing, the chamber communicating therewith through the tube. Provided in the housing is a microporous shell which surrounds the tube and defines with it a defoaming chamber into which the tube feeds, the shell also defining with the housing a reservoir for the oxygenated blood. A heat exchanger is provided in the oxygenation chamber surrounding a flow-directing body, while a vertically disposed oxygen inlet pipe having a diffusion nozzle is provided in the bottom of the chamber with a pair of blood inlet pipes flanking the oxygen pipe and forming an angle therewith.

Abstract: A membrane device having particular utility as a blood oxygenator is disclosed. The device comprises a housing having an oxygen inlet and outlet, a blood inlet and outlet, and a water inlet and outlet. A plurality of blood modules and water modules are arranged in a predetermined configuration in the housing. Each of the blood modules is in flow communication with the blood inlet and outlet on the housing and defines a flow path for the blood through the housing and across each of the blood modules. The water modules are in flow communication with the water inlet and outlet on the housing and define a flow path for the water through the housing and across each of the water modules. The blood modules and water modules are arranged and configured in a specific and predetermined configuration so as to form a pathway for introducing oxygen between adjacent modules.

Abstract: An oxygenator for blood employs a unique and inexpensive, tubular, finned heat exchanger, one type utilizing a spirally wound plate attached to the tube, and another type comprising longitudinal fins. The oxygenator provides a fairly uniform oxygen saturation which permits better control over the oxygen content in a patient's blood. Also, elevated inlet oxygen pressures can be reduced, and this lessens the possibility of embolii due to cavitation effects when CO.sub.2 is released by the blood following oxygenation.A preferred form of a sparger for inlet oxygen to the blood is made of a porous, hydrophobic plastic material such as high density polyethylene.

Abstract: A blood oxygenating device of the type having an oxygenating chamber, a settling chamber, and a heat exchange chamber. A bubbler assembly within the oxygenating chamber including a housing with blood and oxygen inlet means, an outlet opening for blood bubbles which extends 360 degrees around the bubbler assembly housing, and a continuous closed passageway therebetween for effecting optimum oxygen-carbon dioxide exchange. Blood bubbles pass from the outlet means through a defoamer unit for debubbling. A defoamer support member on the outside of the bubbler assembly housing supports the defoamer unit and affords an open passageway for blood bubbles to flow from the outlet means downwardly adjacent the outside of the bubbler assembly housing into the defoamer unit. The blood, after passing through the defoamer unit, flows first into the settling chamber and then along a divided annular path through the heat exchange chamber for the transfer of heat thereto.

Abstract: An apparatus and method for the diffusion of substances between two fluids. The apparatus comprises at least one semipermeable membrane having first and second opposing surfaces, first conducting means for conducting a first fluid along the first surface of the membrane, and second conducting means for conducting a second fluid along a second surface of the membrane. The membrane is permeable to a portion of the first fluid so that at least a part of the portion of the first fluid is diffused through the membrane into the second fluid during conduction of the first and second fluids along the opposing surfaces of the membrane. Mixing means are provided for directly mixing the first fluid into the second fluid after conduction of the first fluid along the first surface of the membrane. In the preferred embodiment, this mixing means comprises apertures at the downstream end of the membrane for introducing the first fluid directly into the second fluid flowing on the opposite side of the membrane.

Abstract: Making temperature measurements of blood inside a disposable, sterilized medical device by providing receptacles in the walls of the device for receiving temperature-sensitive probes, the receptacles including a tubular heat-conductive member, extending through a wall of the device and being sealed to the wall, and a cylindrical body having protuberances extending radially for cooperating with slots in a temperature-sensitive probe.

Abstract: Diffusing gas into and out of a liquid at a uniform rate by distributing a foam consisting of bubbles with liquid walls surrounding the gas through elongated passages defined by a corrugated surface adjacent to a smooth surface, while simultaneously providing for indirect heat - exchange of the blood foam while the foam is within the elongated passages.

Abstract: Sturdily mounting a disposable medical device by rotatably attaching a back plate to a back brace, biasing the back plate toward the medical device and employing a camming means on the back plate cooperating with a tab on the device to rotate the plate away from the device as the device is initially slid onto the mount and to return the plate to lock the device in place when the device is slid fully onto the mount.

Abstract: A blood oxygenator with an oxygen filter in the oxygen inlet chamber, featuring in a particular aspect elevating the filter above the diffuser plug of the oxygenator.

Abstract: A bubble oxygenator having a generally cubic exterior housing with a gas dispersion system having a one-way valve that prevents the backflow of blood into the oxygen supply. At one end of the oxygenator housing is a generally vertically extending bubble chamber having a movable wall to vary the flow capacity of the oxygenator. Formed separately from the bubble or oxygenating chamber is a generally horizontally extending bubble collection chamber in the top of the cubic housing. The bubble collection chamber is formed by a rectangular envelope shaped, defoaming mesh and filter assembly. A planar temperature controlled ramp receives debubbled blood from the bubble collection chamber and directs it in planar fashion downwardly toward the reservoir.

Abstract: A bubble oxygenator having a generally cubic exterior housing with a gas dispersion system having a one-way valve that prevents the backflow of blood into the oxygen supply. At one end of the oxygenator housing is a generally vertically extending bubble chamber having a movable wall to vary the flow capacity of the oxygenator. Formed separately from the bubble or oxygenating chamber is a generally horizontally extending bubble collection chamber in the top of the cubic housing. The bubble collection chamber is formed by a rectangular envelope shaped, defoaming mesh and filter assembly. A planar temperature controlled ramp receives debubbled blood from the bubble collection chamber and directs it in planar fashion downwardly toward the reservoir.

Abstract: An artificial lung provided with a built-in heat exchanger comprising an outer cylindrical member, an inner cylindrical member and an intermediate cylindrical member disposed between said outer and inner cylindrical members.A plurality of tubes are disposed within said inner cylindrical member through which a heat exchange medium is adapted to pass. The supply of oxygen to the blood is carried out within the inner cylindrical member while heat exchange is performed between the blood and the heat exchange medium.

Abstract: A blood oxygenator having two separable components one of which is disposable and the other of which is reusable and sterilizable. The disposable portion of the oxygenator is multichambered and provides an oxygenating chamber, a defoaming chamber and an arterial reservoir constructed so that blood will flow sequentially therethrough. The reusable member is constructed in the form of a cover for the oxygenator and has depending therefrom a heat exchanger for maintaining the temperature of the blood, the heat exchanger projecting telescopically into the oxygenating chamber. Defoaming is assisted by a cellular foam material rolled into a generally cylindrical configuration and having abutting faces which are bias cut so that the line formed by the abutting faces is not coaxial with the blood flow path.

Abstract: Blood oxygenator of the membrane type in which a semi-permeable membrane (by which is meant a membrane that is permeable to gas but not to aqueous liquid) separates the blood from the oxygen but allows diffusion of oxygen into the blood and of carbon dioxide from the blood into the stream of gas; such blood oxygenator being characterized by a plurality of oxygen, water and blood units, each blood unit having a frame which together with semi-permeable membranes forms a blood cavity, the blood entering each such unit from one side, crossing the blood cavity and exiting on the other side, such blood units being isolated from the water units such that leakage of water into the blood units is precluded. Also applicable to oxygenators in which membranes of blood units are permeable to water and small molecules but not to large molecules or particles of the blood.

Abstract: A blood treatment apparatus having within a sealed housing a chamber for mixing oxygen and blood, a column of packed beads through which the mixture of oxygen and blood passes to cause oxygenation of the blood, a blood defoamer through which the oxygenated blood must pass, a reservoir into which the defoamed blood passes and a heat-exchanger which occupies a substantial portion of the lower region of the reservoir. The heat-exchanger comprises a stacked array of spirally wound coils being connected at each of its ends to a manifold which is external of the sealed housing. The configuration of the various components and of the walls of the sealed housing are such that the coils provide high heat-exchange effectiveness by optimizing the size and uniformity of the spacing between coils through which the blood must pass.

Abstract: A blood oxygenator having two separable components one of which is disposable and the other of which is reusable and sterilizable. The disposable portion of the oxygenator is multichambered and provides an oxygenating chamber, a defoaming chamber and an arterial reservoir constructed so that blood will flow sequentially therethrough. The reusable member is constructed in the form of a cover for the oxygenator and has depending therefrom a heat exchanger for maintaining the temperature of the blood, the heat exchanger projecting telescopically into the oxygenating chamber. Defoaming is assisted by a cellular foam material rolled into a generally cylindrical configuration and having abutting faces which are bias cut so that the line formed by the abutting faces is not coaxial with the blood flow path.

Abstract: A purification device for utilizing a gas to purify a liquid, principally useable as an artificial lung, and employs a simple mixing tube so as to assure the mixing of a purification gas with the liquid, with the liquid and gas mixture exiting from the mixing tube into a housing carrying gas separation means in the form of a filter with the purified liquid flowing through the housing in reverse direction to liquid flow in the mixing tube and being collected at one end of the housing while the separated gas is vented from the opposite end of the housing. The housing carries a heat exchange device for maintaining the purified liquid at a predetermined temperature as it exits from the purification device. A pump is provided for pumping the purified liquid from the housing. In order that the housing will not be pumped dry, there is provided a float valve arrangement for controlling flow of the purified liquid out of the housing.

Abstract: A blood oxygenator includes a heat exchanger wherein heat transfer fluid flows through a tube which is ribbed along its length. 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 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 constructing the tube with an integral, substantially continuous, hollow, helical rib, and 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 blood oxygenator includes a heat exchanger wherein heat transfer fluid flows through an aluminum tube having an intergral, 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 anodized 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.