Abstract: An improved sensing electrode assembly for testing for a constituent in blood is provided. An electrode assembly exhibits a decreased time to reach stable operation by virtue of having the assembly pretreated by applying thereto a liquid containing blood derived albumin.

Abstract: A chemically sensitive field effect device has its chemically selective system exposed to the material being investigated. The device is driven by a time varying, typically sinusoidal, current source. A protected reference electrode is also in contact with the body under investigation, and is biased at a predetermined DC level relative to the chemically sensitive field effect device.

Abstract: Negative pressure to accelerate flashback is formed by selective deformation of an elastomeric bladder. The bladder and a next adjacent cam means are enclosed in a housing, penetrated by a slide or roller engaging the cam surface. As the slide or roller moves along the cam surface, the bladder is selectively deformed first to close, then to evacuate distally and then to reopen at a negative differential pressure.

Abstract: In the formation of a chemically sensitive field effect device, prior to formation of the gate membrane, an aluminum pad is disposed over the gate, and a polyimide layer is disposed thereover. Photoresist and etching steps produce openings in the polyimide to form a gridwork which is anchored to the device on the periphery of the gate. The aluminum layer is etched completely away, forming a void defined by the suspended polyimide mesh on one side, and the gate insulator on the other. Polymeric membrane is formed in the void by insertion in liquid form.

Abstract: A polarographic sensor for blood oxygen monitoring is defined by respective anode and cathode electrode wires fixedly maintained in conventional fashion. The end cross sections of the wires are carried on a surface, and overlying this surface is a capillary pore ultrafiltration membrane. The microscopic capillary pores, which have diameters less than 12 micrometers each, pass water therethrough and thus allow the blood, which passes on the side of the membrane opposite the anode and cathode, to act as its own electrolyte.

Abstract: A pair of compressible, hinged opposing arms enclose a bladder chamber, which in turn is coupled to the catheter. As the arms are compressed together, successive pivot fulcra close, in turn first pinching and closing, and then opening the bladder to create negative differential pressure against the catheter, and promoting flashback.

Abstract: A device for simulating the pressure readings obtained from the arm of a living subject whose blood pressure levels are being determined by an oscillometric blood pressure monitor, includes a pulse pressure chamber for generating pressure pulses at a rate equivalent to a preselected pulse rate. The input to the pressure chamber is attached to the pressure cuff of the monitor and the output is connected to the pressure transducer of the monitor. In order to balance the pressure across the chamber and to apply the full cuff pressure to the monitor transducer, a normally-open valve is connected across the pressure chamber. This valve, however, is closed when the chamber creates a pressure pulse so that the pulse is added to the applied cuff pressure at the monitor transducer. A processor generates electrical signals that control the amplitude of the pressure pulses created by the chamber, depending on preselected values for simulated systolic, mean arterial and diastolic pressures.

Abstract: An adaptive monitor and method for rapidly determining blood pressure, selects an initial cuff pressure to be applied to an artery of the test subject and then measures the amplitude of pressure pulses caused by the pumping of blood by the subject's heart. The cuff pressure is incrementally increased while the pulse amplitudes are monitored in order to obtain blood pressure readings by the oscillometric method. If the pulse amplitudes decrease for increases in pressure above the initial value, it is taken as an indication that mean arterial pressure is below the initial cuff pressure. Thus the cuff pressure is substantially decreased to a new initial value and the process is restarted.

Abstract: In the formation of a chemically sensitive field effect device, prior to formation of the gate membrane, an aluminum pad is disposed over the gate, and a polyimide layer is disposed thereover. Photoresist and etching steps produce openings in the polyimide to form a gridwork which is anchored to the device on the periphery of the gate. The aluminum layer is etched completely away, forming a void defined by the suspended polyimide mesh on one side, and the gate insulator on the other. Polymeric membrane is formed in the void by insertion in liquid form.

Abstract: Semiconductor chips carrying chemically sensitive field effect devices are encapsulated by tape automated bonding techniques, wherein one tape layer has a beam lead pattern disposed thereon which terminates in the chip bonding pad pattern over an opening in the tape. A tape layer for sealably covering the beam lead pattern and the chip has openings which are respectively coincident with the chemically selective membrane systems of the field effect devices.

Abstract: A cardiac output computer which measures cardiac output by the indicator method involving the estimation of the area under either a thermodilution of a luminous transmission curve with automatic bolus detection. Evaluation of the area under the curve is made relative to a true baseline and is independent of, in the case of thermodilution, blood temperature as of the time the bolus is injected into the patient. A series of blood temperature samples are read and stored with the magnitude of each successive signal compared to the one received immediately before. As soon as a plurality of successive comparisons, preferably five, of six successively acquired blood temperatures indicate monotonically decreasing blood temperature values, a test for monotonicity is confirmed, with the highest temperature of the six being designated as the baseline. Once the test is confirmed the computer proceeds to evaluate the area under the curve.

Abstract: A pulmonary monitor for measuring a complex set of variables utilizing a group of three pushbuttons arranged to operate in a hierarchical pattern for facilitating operator control of the functions of the monitor.

Abstract: A thermodilution catheter assembly for use in determining cardiac output includes a special connector for joining the catheter to the output computer. Catheter size indicator links housed in the connector automatically communicate the size of the catheter to the computer when the connection is made. As an optional feature, the connector additionally includes means to automatically energize the computer when the connection is made.

Abstract: Provided is a method as well as apparatus for a catheter catheter-balloon assembly wherein the catheter balloon is mounted on the catheter by means of adhesive and, in the preferred mode, an annular internal rib protrusion of the catheter balloon is provided for forming a sharply defined boundary of adhesive thereby aiding in the even and symmetrical inflation of the catheter balloon.

Abstract: A pneumotachograph including a housing having first and second ports which, during the course of respiration, alternate as input and output ports and which provide a path for generally linear flow of the respiratory gases. A pair of pitot tubes are disposed along the top of the path and are positioned generally at right angles thereto. A pair of baffles or flow deflectors are disposed in the path in alignment with the axes of the pitot tubes. Each of the baffles is positioned at an angle of approximately 45.degree. to the axis of its associated pitot tube and to the path of flow. The baffles may be held in the flow path by a rigid connection or alternatively, they may be retained there by a resilient connection such that the pitot tube measurement is linearized.In another embodiment, the baffles may actually be merged into a single baffle thus leaving an annular opening between itself and the housing with the opening of the gap being approximately the same distance as the distance between the pair of tubes.

Abstract: A system for encapsulating semiconductor chips, such as chips carrying chemical sensitive field-effect devices, includes lamination of a sheet of dry film photoresist material onto the surface of the chip, placement of a photomask over the chip in a predetermined alignment, and then exposure of the photomask to light so that light passes through certain light-transmitting portions of the mask onto the chip. The photoresist material is then developed to remove the material from over the gate regions of each of the field-effect devices to define windows in the material through which the gate regions are exposed. Chemical sensitive membrane systems may then be applied to the windows of the devices to cover the gate regions.

Abstract: A pair of toroidally wound cores are maintained in a generally parallel, vertical, spaced apart relationship by a tubular insulating member passing through the toroid centers. The tubular member insulates the windings from a coupling loop which passes through the tube and which closes outside the toroidal windings. One winding is the primary of the isolation circuit, connecting the source of signals through a FET device to ground, and the other winding is secondary winding, which is also connected to ground through a FET, and which is coupled to a utilization device through a low pass filter. The FET devices are synchronously pulsed at a frequency above the signal frequency and the filter pass band.

Abstract: A seal for limiting access of bacteria through a side arm of a stopcock such as that used in apparatus for monitoring pressure in a human blood vessel. The seal has a generally cylindrical body, an open end of which slides over the side arm. A portion of the body seals against the side arm exterior wall. The other end of the seal forms a cap through which a syringe nose may penetrate to establish fluid communication between the syringe and the side arm lumen. The interior of the seal body includes a recess for a Luer lock fitting which may exist on the end of the side arm, and an annular spacer projecting from the inside of the body to provide a surface against which the end of the side arm can abut to prevent the inserted syringe nose from bottoming on the end of the stopcock arm during use. A slit in the capped end of the seal facilitates insertion of the syringe nose. The slit is surrounded by a recess to guide the syringe nose into the slit.

Abstract: A liquid infusion catheter assembly comprises a hub and a first hollow catheter connected at its proximal end, and being in fluid communication with, the hub. This catheter has at least one fluid outlet opening. A second hollow catheter, extending from, but being out of fluid communication with, the hub surrounds the first catheter with a space therebetween. This second catheter extends distally farther than the first catheter and has at least one hole through its surface where it surrounds the first catheter, and has a fluid outlet opening in the portion extending beyond the first catheter.

Abstract: A vented filtration device comprising a closed, flexible and compressible housing having a liquid inlet and a liquid outlet. The housing includes an internal passage connecting the inlet and the outlet. A liquid filter assembly is disposed within the passage between the inlet and outlet thereby defining an upstream pressure section between the inlet and the filter and a downstream pressure section between the filter and the outlet. This assembly includes a flexible, porous bacteria retentive filter membrane, a flexible, porous support material overlying one surface of the filter membrane and a frame having at least one large central opening overlying the opposite surface of the filter membrane. A gas vent located in the housing communicating with the upstream pressure section of the passage is adapted to allow gas but not liquid to pass from the upstream section out of the housing.