Abstract: A CO.sub.2 monitor which has a reusable portion and a disposable portion is disclosed. The disposable portion includes an airway sensor for connecting between a ventilator output and an endotracheal tube. The airway sensor has ports on opposite sides. In one port a disposable infrared light source is inserted with wire contacts extending to the exterior of the airway sensor body. The reusable portion is a detector module which includes a detector and an amplifier. The detector module attaches to the airway sensor so that the detector is disposed in the second port and so that contacts in the detector module communicate with the wire contacts of the light source. The detector module may be removed from the airway sensor without removing the light source from the airway sensor.

Abstract: A pulse oximeter which modifies the alarm condition when motion is detected. Basically, if the lack of a pulse is determined to be as a result of motion artifact, the generation of an alarm is postponed. In addition, the display indicates that motion is present and that the last reading is questionable due to the presence of motion. The invention also determines if motion artifact is present from the pulse oximeter detector signal itself. The ratio of the positive and negative peaks of the derivative of the pulse signal are compared to a motion/blood pulse threshold.

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 compact pulse oximetry system which separates the combined signal into its respective AC and DC components. By separating the signal into AC and DC components, a smaller order bit A/D converter may be used while still maintaining signal accuracy. Instead of using the combined signal to calculate the oxygen saturation content, the system microprocessor computes the Ratio of Ratios using the derivative of the separated AC component of the diffused signal to calculate the oxygen saturation of the measured fluid. To calculate the Ratio of Ratios, a ratio of the derivative value of the separated AC component is used. Instead of taking a single sample between the peak and valley of the signal, the oximeter system samples each value. To decrease the effect of system noise, a linear regression is performed over each sample.

Abstract: An electronic processor for calculating in vivo blood oxygenation concentration levels using pulsed light that eliminates both requirements for comparing photosensor signal amplitudes with analog/digital circuit dynamic ranges and also adjusting electronic processor parameters. The invention uses monolithic a/d converters with expanded capacity and a microcontroller/processor with a pulse control module to synchronize switching in an oversampling demodulator with pulsing of light sources to overcome prior circuitry limitations that consumed substantial central processor capacity.

Abstract: A graphics coprocessor adapter with hardware support for horizontal scrolling is disclosed. A graphics processor provides both a row address with a RAS signal and a column address with a CAS signal to two banks of video RAMs. Both banks are provided with the same scrolling column address signal. Translating logic intercepts the column address signal for the static plane RAM bank and translates it into a fixed value. Thus, a single column address signal can control both the scrolling and static planes.

Abstract: A method and apparatus for a simple pulse oximeter measurement of an area of the body with a small amount of blood vessels by using a counterirritant to profuse the blood and then apply a modern oximeter probe is disclosed. The counterirritant is either applied to the skin immediately before attaching the probe, or, preferably, is contained in an adhesive pad which couples the probe to the skin.

Abstract: A sensor placement and retention mechanism for use with fetal sensor sites beyond the user's reach are disclosed. The preferred embodiment of this invention is a fetal pulse oximetry sensor having an active face through which a light source and a light detector operate. The sensor includes a handle that facilitates placement of the active face at a sensor site in a preferred region beyond the transcervical region and beyond the reach of the user. A pair of electrodes--one disposed against the fetus' skin and one exposed to the amniotic fluid--are used to confirm that the sensor is firmly in place on the fetus. In an optional sensor retention feature, a self-inflating bladder presses the active face of the sensor against the fetus' skin to optically couple the sensor with the tissue at the sensor site.

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.

Abstract: An agent gas analyzer that will determine the types and measure simultaneously the concentrations of a plurality of agent gases in a respiratory gas stream of an anesthetized patient, with the analyzer self-determining the agent gas types and concentrations each time gas measurements are made.

Abstract: A first light emitting element directs light through a first region of tissue, a second light emitting element directs light through a second region of tissue that is spatially distinct from the first region of tissue, and a photodetector detects light traveling through the first and second regions. First and second oxygen saturation values are calculated from the amount of light detected from the first and second regions of tissue, respectively. A difference calculating unit calculates a difference value which represents how much the first oxygen saturation value differs from the second oxygen saturation value, and a comparator compares the difference value to a threshold value. A threshold indicating signal is provided when the difference value has a selected mathematical relationship (e.g., less than or equal) to the threshold value.

Abstract: A pulse oximeter sensor that is designed to surround an appendage of the patient, such as a finger, toe or foot is disclosed. The sensor has a reusable member which preferably includes a photodetector. A disposable, flexible member preferably contains the photoemitter and can be wrapped around the patient's appendage to secure it to the appendage and the reusable member. When secured, the photoemitter and photodetector end up on opposite sides of the appendage. The disposable member connects to the reusable member to establish electrical contact. The reusable member is connected to a cable which can be plugged into a sensor monitoring system.

Abstract: A method and apparatus are is disclosed for determining whether respiratory gas is present in a gaseous sample. The sample is brought into contact with an indicator which yields an indication within a diagnostically effective period of time of the presence in the sample of carbon dioxide in concentration of at least 2% while an indication of the presence of carbon dioxide or other trace acidic gas in a sample of ambient air is delayed beyond a predetermined period of time. The method and apparatus of the present invention have particular utility in determining the correct placement of an endotracheal catheter in a patient or in the direction of apnea.

Abstract: A method is disclosed for determining whether respiratory gas is present in a gaseous sample by which the sample is brought into contact with an indicator which yields an indication within a diagnostically effective period of time of the presence in the sample of carbon dioxide in concentration of at least 2% while an indication of the presence of carbon dioxide in a sample of ambient air would be delayed beyond a predetermined period of time. The method has particular utility in determining the correct placement of an endotracheal catheter in a patient or in the detection of apnea.

Abstract: A fetal pulse oximetry probe has clusters of light-transmissive bumps over the light source and the light detector on the surface of the probe. The probe is usually attached to the fetus' head. The clusters part the fetal hair and penetrate other light-attenuating organic materials on the head. The clusters thus transmit a more intense light signal. To reduce the amount of signal shunting between them, the clusters also may be separated by additional opaque (light-shielding) bumps.

Abstract: A method and apparatus for improving the calculation of oxygen saturation by non-invasive pulse oximeters during transient conditions. Transient conditions introduce artifactual errors into the detected optical signal because of changes in transmittance of the light with localized blood volume changes and as the average background oxygen saturation level of the patient's blood changes. The invention relates to correcting the detected optical pulses by linear interpolation and rate of change techniques or by selective frequency filtering and compensating the detected optical signal using the filtered signal to provide accurate estimates of oxygen saturation during transient conditions.

Abstract: An apparatus for use in measuring fetal blood flow characteristics. The apparatus includes a non-invasive pulse oximetry probe that is inserted into the uterus between the fetus and the uterine wall. The probe is deformable and is positively attached to the fetal tissue surface using a vacuum pump which causes the probe to deform from a pre-set curvature to the curvature of the fetal tissue surface and to form a gasket-type seal with the fetal tissue surface. The probe is manually inserted into the uterus using a curved insertion tool, and is shaped to fit through a slightly dilated cervix. In a preferred embodiment, the probe includes fetal and maternal ECG sensors and additional sensing devices, and is provided with apparatus for improving the efficiency of the pulse oximetry optics.

Abstract: A method and apparatus for improving the calculation of oxygen saturation and other blood constituents by non-invasive pulse oximeters. The method and apparatus permit more accurate determination of blood flow by collecting time-measures of the absorption signal at two or more wavelengths and processing the collected time-measure to obtain composite pulsatile flow data from which artifacts have been filtered. The processing may occur in the time domain or in the frequency domain. In the preferred time domain embodiment, successive portions of periodic information are weighted and added together in synchrony to obtain the composite pulse information. In the preferred frequency domain embodiment, the time-measure in Fourier transformed into its spectral components to form the composite information.

Abstract: A non-invasive, electro-optical sensor probe and a method for its use are disclosed. The sensor probe measures light extinction during transillumination of a portion of blood-perfused tissue. A malleable layer makes the sensor particularly well-suited for attachment to a central site, such as the patient's tongue, cheek, gum or lip, to provide accurate oxygen saturation and pulse rate readings for patients with lowered or inconsistent peripheral circulation.