Abstract: An engine structure and mechanism that operates on various combustion processes in a two-stroke-cycle without supplemental cooling or lubrication comprises an axial assembly of cylindrical modules and twin, double-harmonic cams that operate with opposed pistons in each cylinder through fully captured rolling contact bearings. The engine may comprise one or more pairs of axially symmetric cylinder modules which with their opposed pistons perform perfectly balanced reciprocating and rotary motions at all loads and speeds. The opposed pistons are double-acting, performing a two-stroke engine power cycle on facing ends and induction and scavenge air compression on their outside ends, all within the same cylinder bore.

Abstract: A probe for use within a catheter is disclosed. The probe transducer portion is constructed of a crystal hollow cylinder with an inside lead attached to the inner surface of the crystal cylinder. One end of the outside lead is positioned close to the outer surface, in a plane tangential to the outer surface, and is coupled to the outer surface of the crystal cylinder by a thin sputtered layer of conductive material. The probe transducer also includes a layer of acoustically absorbing material on the proximal end of the crystal, and layer of acoustically coupling material on the distal end of the crystal cylinder. The transducer element simultaneously generates an axially oriented signal beam at one frequency and a radially oriented signal beam at 2 different frequency. The signal beams are analyzed to calculate the blood flow area and the blood flow velocity, the product of which is the blood flow rate.

Abstract: A system for measuring fluid flow within a conduit, such as blood flow from the heart, includes a heating element that is driven so as to apply heat to the fluid at an upstream position as a series of periodic heat signals. A temperature sensor located downstream measures a local temperature of the fluid and generates an electrical fluid temperature signal corresponding to the local temperature. This signal is then applied to a dispersive filter, which outputs a pulse-like signal in the presence of each periodic heat signal. Fluid flow is then calculated by a processor as a function of the area under an estimated impulse response curve for the channel in which the fluid flows. Each periodic heat signal is preferably sinusoidal and has an instantaneous frequency that varies substantially continuously between a first frequency and a second frequency over a pre-determined active input signal period.

Abstract: An improved integral flow-through injectate delivery system comprises fluid flow means having a proximal and a distal end. The proximal end comprises a first port having fluid inlet means for connecting the flow means to a source of fluid injectate and a second port adapted to be connected to a syringe means. The distal end of the fluid flow means is adapted to be connected to a fluid delivery means for delivering the injectate to the patient and the syringe means is adapted to direct injectate fluid from the injectate source through the fluid inlet and the fluid flow means to the fluid delivery means. A first check valve is in fluid-flow communication with the fluid inlet means and the fluid flow means and a second check valve means is in fluid-flow communication with the fluid flow means and the fluid delivery means. A sensing means is disposed within the fluid flow means at its distal end for sensing a characteristic of fluid flowing therethrough, usually temperature.

Abstract: A probe for use within a catheter is disclosed. The probe transducer portion is constructed of a crystal hollow cylinder with an inside lead attached to the inner surface of the crystal cylinder. One end of the outside lead is positioned close to the outer surface, in a plane tangential to the outer surface, and is coupled to the outer surface of the crystal cylinder by a thin sputtered layer of conductive material. The probe transducer also includes a layer of acoustically absorbing material on the proximal end of the crystal, and layer of acoustically coupling material on the distal end of the crystal cylinder. The transducer element simultaneously generates an axially oriented signal beam at one frequency and a radially oriented signal beam at 2 different frequency. The signal beams are analyzed to calculate the blood flow area and the blood flow velocity, the product of which is the blood flow rate.

Abstract: A device including an integrally formed membrane oxygenator and heat exchange device positioned in a single housing. The device includes a thermally conductive body formed with a plurality of blood pathways on its surface, and a gas permeable membrane, or membranes positioned in the housing in substantial contact with the heat exchange body to cover or lie within a portion of each of the pathways. The membrane defines a gas pathway separate from the blood pathway through which a gas is directed. The blood is directed through the individual blood pathways. The device also includes various ports and passageways for delivering the blood to the individual channels, and for collecting and removing the blood from the device.

Abstract: A membrane oxygenator designed to provide blood flow evenly across a gas permeable membrane in a direction substantially perpendicular to the longitudinal direction of the gas permeable membrane. In particular, the present invention is directed to a membrane oxygenator wherein the blood is distributed substantially evenly and at a substantially constant velocity, in a cross-wise direction across the gas permeable membrane. In accordance with a preferred embodiment, the membrane is a bundle of gas permeable hollow fibers with the blood being distributed in a direction substantially perpendicular to the longitudinal direction of the individual hollow fiber membranes.

Abstract: Methods and apparatus for eliminating the effects of electrosurgical interference on continuous, heat-based cardiac output measurements employing several procedures, including the steps of (1) supplying power via an isolation transformer and carrier frequency to a catheter-mounted heating element; (2) measuring the voltage and current on the primary side of the isolation transformer; (3) determining the voltage and current on the secondary side of the transformer on the basis of the measured primary side voltage and current; and (4) calculating the power delivered to and resistance of the catheter-mounted heater on the basis of the secondary voltage and current. A heater power waveform generated with this process will be substantially free of electrical interference due to electrosurgical devices. Then, a system transfer function may be produced via signal processing techniques which involve cross-correlating the heater power waveform with the blood temperature waveform.

Abstract: A cardiac output probe assembly is disclosed wherein the assembly includes a chest tube which carries a cardiac output probe therein. The chest tube includes a main lumen for draining fluids from the thoracic cavity of the chest and a secondary lumen which carries leads attached to the probe. The probe is attached to the pulmonary artery or aorta vessel with detachable tines and/or sutures. The tines are uniquely configured to ensure that good contact between the probe and vessel is maintained. When cardiac output monitoring is complete, a pulling force is applied to the probe leads extending out through a proximal end of the tube. The pulling force detaches the tines and sutures, releasing the probe from connection with the vessel. Further withdrawal of the leads through the tube retracts the probe within the tube, where it is housed until the tube is removed from the thoracic cavity.

Abstract: A low priming volume centrifugal pump comprising a disc shaped impeller having opposite faces and an inlet hole centrally disposed therein. The impeller has flow channels disposed on at least one of the faces of the impeller which radiate outward from said inlet hole. The volume of the flow channels is small relative to the total impeller envelope volume providing for efficient momentum transfer with a minimum of turbulence and backflow Thus, priming volume is reduced and flow within the pump is more efficient. The pump can be used as stand alone device, or it can be integrated with a blood oxygenator into a common housing.

Abstract: A catheter for measuring the temperature of a fluid in a living body comprising an elongated tube having at least one lumen extending longitudinally within the tube and an opening in a peripheral wall of the tube. A thermistor mounting body mounts a thermistor in the lumen adjacent the opening. The thermistor mounting body defines a cavity at the opening which opens radially outwardly, and the thermistor is partially within the mounting body and projects from the mounting body into the cavity. There is at least one conductor in the tube with at least a region of the conductor being in the lumen and extending along the lumen to the thermistor. The region of the conductor is electrically coupled to the thermistor. The region of the conductor extends longitudinally of the lumen from a location in the lumen proximally of the thermistor to a location at which the conductor is electrically coupled to the thermistor.

Abstract: A low priming volume integrated centrifugal pump and membrane oxygenator comprising a housing containing a mass transfer bed comprising gas permeable hollow membrane fibers placed circumferentially in a ring around an impeller. The mass transfer bed is formed by a multiple wrap of a fiber ribbon comprising at least two layers of fibers bonded in precise orientation with fibers in alternate layers are positioned in line with the opening between fibers in the layers above and below. Adhesion means ensure precise orientation of the fibers. Priming volume is further reduced by a small impeller flow channel volume.

Abstract: A method of sequentially analyzing various body conditions with a plurality of probes is disclosed. Also disclosed, is a catheter which can be used to practice the method. The catheter has several independent lumens extending longitudinally therethrough for accepting probes and for introducing fluid therethrough and into a body cavity. The catheter outer body has a cross-sectional maximum outer dimension. The first lumen is circular in cross-section, and has a cross-sectional dimension of approximately half the maximum outer dimension of the catheter body. The first lumen is capable of accepting various probes, as well as allowing simultaneous fluid flow through the lumen. The second lumen is crescent-shaped in cross-section and occupies at least a quarter of an arc around the cross-section of the catheter body. The large cross-section of the second lumen allows for a high fluid flow rate through the lumen.

Abstract: There is disclosed herein a method of obtaining certain information about the blood pressure of a given patient by means of a particular blood pressure technique, specifically by means of oscillometry, in which the pressurizable pressure transducing bladder located adjacent and cooperating with a particular artery of the patient, is used in combination with means for pressurizing the bladder in a controlled way in order to provide the desired information. The particular artery used is the patient's supraorbital artery which is readily accessible in a specific area just above the eyebrow of substantially all patients. There is also disclosed herein a blood pressure transducing bladder assembly which is specifically designed to easily access the supraorbital artery of substantially all patients using the eyebrow and nose of each patient as a frame of reference.

Abstract: A device including an integrally formed membrane oxygenator and heat exchange device positioned in a single housing. The device includes a thermally conductive body formed with a plurality of blood pathways on its surface, and a gas permeable membrane, or membranes positioned in the housing in substantial contact with the heat exchange body to cover or lie within a portion of each of the pathways. The membrane defines a gas pathway separate from the blood pathway through which a gas is directed. The blood is directed through the individual blood pathways. The device also includes various ports and passageways for delivering the blood to the individual channels, and for collecting and removing the blood from the device.

Abstract: A blood oxygenation system includes an oxygenator for oxygenating blood and a heat exchanger for regulating blood temperature. The heat exchanger includes a heat exchange coil that provides a flow path for a heat exchange media, the heat exchange coil is configured to define a heat exchange zone, and the oxygenator is disposed in heat transfer relationship with the heat exchange zone in order to transfer heat between the heat exchange coil and the oxygenator. The heat exchange coil may at least partially circumscribe the oxygenator and, preferably, be helically shaped and disposed coaxially over a membrane oxygenator. In one embodiment, single or multiple hollow fiber strands are wound onto a small diameter center core so that the fiber segments provide spiralling helical blood-flow pathways which increase oxygen/carbon dioxide exchange by secondary flow paths.

Abstract: A catheter for monitoring heart function comprises a catheter tube having a plurality of lumens. The catheter includes an inflatable balloon at a distal tip of the catheter tube for positioning the catheter in a wedged position within a pulmonary artery within the heart of a patient. Dual injectate ports are formed in a side wall of the catheter tube. Each port communicates with a respective injectate lumen carried in the catheter tube. When inserted into the heart of a patient, either the first or second injectate port is positioned within the desired distance from the tricuspid valve for thermodilution depending upon the size of the heart. Thermodilution to obtain cardiac output and/or right heart ejection fraction is implemented by injecting injectate through the lumen associated with the port properly positioned relative the tricuspid valve and discharged through the corresponding port.

Abstract: A system is provided for weighing and monitoring flow from multiple fluid sources into a flow system wherein incoming fluid is received in a weighing bag attached to a control system for monitoring the amount of fluid passed through the weighing bag and for preventing admission of air into the flow system. An alarm attached to the weighing bag warns when fluid in the weighing bag is approaching empty, so that the fluid in the weighing bag can be replenished from the fluid source before the weighing bag runs dry. If fluid in the weighing bag is not replenished, the system automatically shuts down.The fluid pump can be absolutely calibrated using the controlled admission of known amounts of fluid into the weighing bag so that the amount of fluid introduced into the flow system through the weighing bag can be calculated automatically.

Abstract: A method and system for adaptively controlled withdrawal/infusion of a fluid, such as blood, to or from a fluid source, such as a blood vessel. An adaptive flow rate limit is established and periodically adjusted during the course of withdrawal/infusion so as to maximize and optimize the withdrawal/infusion rate while, at the same time, providing for rapid corrective adjustments in flow rate responsive to early indications of flow disruption, such as occlusion or collapse of the blood vessel during blood withdrawal. The method and system of the invention is particularly applicable to automated apheresis systems.

Abstract: A defoaming device for separating foam and bubbles from a liquid, such as blood, is disclosed. The device can be used in conjunction with a medical device, such as a membrane oxygenator, for separating air from blood while minimizing blood contact with the antifoam agent used in the device. In a first embodiment, the device includes a reservoir and a filtering material that does not contain any antifoaming agent. This filtering material is positioned in a lower portion of the reservoir to separate foam and bubbles from the liquid. An element containing an antifoaming agent is positioned in the reservoir above the maximum surface fluid level therein and receives the foam and bubbles that rise from the filtering material. Contact of the liquid with the antifoaming agent is substantially avoided. In a second embodiment, an element containing an antifoaming agent is positioned in the reservoir within the fluid therein.