Abstract: The exhalation valve includes a valve housing with a valve seat having an annular shoulder, and a valve poppet having a face with a corresponding annular groove. A soft flexible diaphragm seal disposed between the face of the valve poppet and the valve seat provides a suspended soft seal, ensuring perpendicularity in the valve seal for improved accuracy of valve operation. An annular permanent magnet and an annular magnetic ring are disposed around and spaced apart from a magnetic body to define an air gap in which an electromagnetic coil is disposed. The electromagnetic coil is connected to a control mechanism by a flexible circuit connector that is sufficiently slack that provides minimal force transverse to the longitudinal axis of the valve.

Abstract: A method and apparatus for performing scoring analysis of the pathological sleep events of apnea, hypopnea and desaturation of a patient from a sampled data set of only three sensor signals, namely, airflow, heart rate and oxygen saturation. The data source is either currently sensed data or previously recorded data. A microprocessor provides the display, printing, input and output channels, operator interface and computation capability for the system. Specialized programs direct the analysis and operation thereof.

Abstract: An improved electromagnetic shield for a photodetector which uses a wire mesh screen laminated to an insulating layer. A portion of the wire mesh screen and laminated layer sandwich can then be cut out to provide an individual electromagnetic shield. The sandwich combination is flexible, and can be easily wrapped around the photodetector. Preferably, an adhesive is on one side of the insulating layer, to allow the wrapped combination to adhere to the photodetector.

Abstract: A carbon dioxide indicator in an exhaust port of a resuscitator assembly. The carbon dioxide indicator is preferably in a removable insert for ease of maintenance and replacement. Breath-to-breath indications are provided by either exposing the indicator to the ambient air at the exhaust port, or diverting a portion of the fresh air or gases provided to the patient.

Abstract: A method and apparatus for conserving power in a medical diagnostic apparatus by using a sleep mode during a monitoring state. The invention monitors physiological parameters of the patient and enters a sleep mode only after they have been stable for a predetermined period of time. The apparatus is periodically awakened from the sleep mode to take additional measurements and to ascertain that the stability of the physiological parameters has not changed.

Abstract: An apparatus and method for controlling the output of an oxygen concentrator wherein an oxygen concentrator indicator is comprised of an oxygen sensor monitor and circuit board which receives a gas sample from the concentrator, the oxygen concentrator indicator circuit board converts the concentration of oxygen to a DC voltage range from 0 to 1 volt corresponding to 0% to 100% oxygen. A plurality of set-point amplifiers accept the voltage and feed the voltage to a logic block where the voltage is analyzed to insure that only one of a plurality of solid state relays or switches is energized at a time. A plurality of taps on an AC motor winding are selectively energized by the solid state relays to drive the oxygen concentrator at a pre-determined rate in response to the concentration of oxygen generated by the concentrator.

Abstract: The present invention provides an improved method and apparatus for more accurately calculating and measuring vital information such as oxygen saturation and pulse rate when an ECG signal is not available. Instead of using an ECG R-wave as a trigger to overlay optical pulses, a virtual trigger is generated based on the heart rate and used to overlay optical pulse data. The optical information from a number of periods is added together, with the beginning of each period being determined by the issuance of the virtual trigger. In this way, the maximum and minimum of the optical signal should be lined up with each other in each period and added together to give a cumulative maximum and minimum. This enables precise identification of the maximum and minimum of the signal, and thus allows calculation of the oxygen saturation at that point.

Abstract: An intrauterine pulse oximetry apparatus and method are provided to measure fetal blood oxygen saturation at sites in a preferred region on the fetus. The sensor of the apparatus is attached to a stiff cable which can be inserted into the uterus past the presenting part and transcervical region of the fetus. The cable may have visual and tactile markings by which the user, without seeing or feeling the sensor, can guide it to an appropriate site on the fetus.

Abstract: A presenting part fetal pulse oximeter sensor with a securing mechanism for providing tension to a hook or other securing mechanism penetrating the fetal scalp. In one embodiment, a sensor can be secured to the presenting part of the fetus by means of a suture or a hook which penetrates the fetus' scalp. If a suture is used, the ends of the suture are wrapped around a securing member, such as a bar, attached to the back of the sensor. By tying the suture ends around this securing member, the sensor is pressed up against the fetus' scalp and retained in place by virtue of tension provided in the suture between the securing member and the portion of the suture penetrating the fetus' scalp.

Abstract: Pairs of signal input leads with a low level signal imposed across them usually have noise induced by stray coupling capacitance which is typically unequal. This results in an unfavorable signal to noise ratio. Adding enough capacitance to the lead having the least capacitance, thereby equalizing the coupling capacitances to the noise services thereof, tends to reduces the noise effect considerably. This is accomplished by changing the relative sizes of the anode and/or cathode of a corresponding sensor device. The noise effect is further reduced by a negative feedback process which comprises extracting the induced noise component from the leads, inverting the noise component, and coupling the inverted noise component back to the input leads.

Abstract: The present invention provides a method and apparatus for adapting to noise sources affecting a pulse oximeter. Various available frequencies are evaluated to determine their respective noise levels and one is selected to act as the operating demultiplexer frequency. During normal operation of the pulse oximeter, the various available demultiplexer frequencies are periodically scanned to determine which has the lowest associated noise. The noise level associated with the operating frequency is used to determine the signal-to-noise ratio of the pulse oximeter signals and thereby qualify certain signals from the pulse oximeter. Those pulses associated with a signal-to-noise ratio below a predetermined threshold are rejected and excluded from use in calculating blood oxygen saturation.

Abstract: A heat exchanger medium which can be incorporated into a heat and moisture exchanger. The heat exchanger medium includes an elongate sheet of spunbonded olefin. The sheet has a longitudinal axis, a front and back surface and first and second edges generally parallel to the longitudinal axis of the sheet. The sheet may be covered with a hydrophilic coating and a desiccant.

Abstract: A conformable sensor which uses a flexible substrate, preferably a polyester strip is disclosed. The emitter and detector are mounted on one portion of the strip with conductive traces connecting to them. The second portion of the strip is folded over to cover the emitter and detector and traces, with openings for the emitter and detector. A conductive coating is applied to the strip to provide shielding from electromagnetic interference. Preferably, a second portion of the strip, which folds over the first portion, also has a Faraday shield covering the opening over the detector. The detector and emitter semiconductor chip die (rather than use encapsulated chips) may be mounted directly on the polyester strip so that it is in contact with one of the conductive traces.

Abstract: An apparatus for measuring the concentration of blood constituents in which the architecture of the electronic processor reduces the amount of controller processing time required for tasks such as data acquisition and generation of system control signals. A demodulator is coupled to a probe for converting a first electrical signal to digital data. An interface is coupled to the demodulator for receiving the digital data and generating interrupts when a first amount of the digital data has been received. A buffer memory is coupled to the interface for storing the digital data. A controller having a controller memory (in specific embodiments, a CPU having a CPU memory) is also coupled to the buffer memory. The controller transfers the digital data from the buffer memory to the controller memory in response to the interrupts. The controller then processes the digital data to calculate the blood oxygen concentration.

Abstract: A connector for a medical sensor is provided. The connector includes a number of contacts, and includes an electronic device for encoding a characteristic of the medical sensor. The electronic device is insertable into the connector. This simplifies the design of a sensor, which no longer needs to include a calibration element. In addition, the sensor can be made more cheaply, which is especially important for disposable sensors.

Abstract: Motion compensation is based on analysis of intensity signals received by detectors, without separately measuring a motion signal, without providing feedback to cancel the motion signal and without attempting to mathematically eliminate the motion signal. Instead, the present invention mathematically recognizes the presence of the motion signal and recognizes a few key characteristics of the motion signal and makes corresponding assumptions. First, it is recognized that the motion/noise in each wavelength signal is proportional. Second, it is assumed that the blood pulse signal is not affected by motion.

Abstract: An apparatus for controlling the pressure of a respiratory gas delivered to a patient includes a phase detection circuit for determining the inhalation and exhalation phases of a patient's respiratory cycle. More particularly, a valving apparatus for controlling air flow within the breathing circuit which is connected to the phase detection circuit.

Abstract: A lock mechanism for a built-in connector (2) fixed in a casing (10) constituting the main body of a diagnostic apparatus, etc., to an external plug (3) connected to a cable of a measurement sensor, etc. The built-in connector (2) is fixed inside the open portion of a panel (11) of the casing (10) of the apparatus, and shutters (4; 6; 7) for closing the open portion (13) are arranged in front of the built-in connector (2) in such a fashion as to form an opening (12) for receiving the plug (3) between the front of the connector and the shutters (4; 6; 7). The plug is locked when its rear portion is engaged with notches (41, 61, 71) formed in the shutters.