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 arterial oxygen concentration.
Abstract:
A network or telemetry system (10) which allows virtual services at the application or presentation layer to communicate with other virtual services without regard to the physical interconnections. Each message, called a parcel, includes the information to be transmitted along with a virtual address header. The parcel is provided to a gateway (12, 26), which inserts the parcel without modification into a packet with address information for the physical through session layers in the packet header. The packet is then transmitted to another network node (62, 64, 66, 68, 70, 72) which receives and delivers the unmodified parcel to the addressed destination virtual service. A number of parcels from the same or different virtual services can be packed into a signal packet (712) for transmission from the gateway in cases where these parcels are all directed to virtual services at the same destination node. Once a session is established, such as between a gateway and a workstation, virtual services at the gateway node and the workstation can communicate with each other without requiring a lot of header overhead for each transmission.
Abstract:
A method and apparatus for measuring and correlating a patient's heart activity with optical detection of the patient's blood flow. The method and apparatus permit more accurate determination of blood flow characteristics such as oxygen saturation and pulse rate. In a preferred embodiment, the heart activity is detected by monitoring the patient's EKG waveform (100), and the blood flow is detected by a non-invasive pulse oximeter (200). The occurrence of the R wave portion of the EKG signal is detected and the time delay by which an arterial pulse follows the R wave is determined to establish a time window in which an arterial is to be expected. The established time window provides the oximeter (200) with a parameter enabling the oximeter (200) to analyze the blood flow only when it is likely to present an arterial blood pulse for waveform analysis. The invention also includes means for adjusting the polarity of the detected EKG signal (160) to obtain a preselected uniform upgoing or downgoing polarity.
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:
Reactive azo dyes, hydrogels, dye films (9) prepared therefrom, and sensing elements incorporating such films are disclosed. The sensing elements are useful, e.g., in body fluid analyzing devices, where they are capable of providing accurate information on the pH or pCO2 of fluids such as blood.
Abstract:
The present invention provides a medical sensor for detecting a blood characteristic. The sensor includes a transducer for producing an analog signal related to the blood characteristic. The analog signal is converted into a transmission signal which is in amplitude-independent form for transmission to a remote analyzer. In one embodiment, a current-to-frequency converter converts a signal from a pulse oximeter sensor into a frequency signal which can be transmitted over a transmission line to a remote pulse oximeter.
Abstract:
The present invention provides an encoding mechanism for a medical sensor which uses a modulated signal to provide the coded data to a remote analyser. The modulated signal could be, for instance, a pulse width modulated signal or a frequency modulated signal. This signal is amplitude independent and thus provides a significant amount of noise immunity.
Abstract:
A pulse oximeter sensor (410) with a light source optimized for low oxygen saturation ranges and for maximizing the immunity to perturbation induced artifact. Preferably, a red (112) and an infrared light source (114) are used, with the red light source (112) having a mean wavelength between 700-790 nm. The infrared light source (114) can have a mean wavelength as in prior art devices used on patients with high saturation. The sensor of the present invention is further optimized by arranging the spacing between the light emitter (112, 114) and light detectors (116) to minimize the sensitivity to perturbation induced artifact. The present invention optimizes the chosen wavelengths to achieve a closer matching of the absorption and scattering coefficient products for the red and IR light sources. This optimization gives robust readings in the presence of perturbation artifacts including force variations, tissue variations and variations in the oxygen saturation itself.
Abstract:
A fetal pulse oximetry probe (200) has clusters of light-transmissive bumps (100, 300) over the light source (110) and the light detector (120) on the surface of the probe. The probe is usually attached to the fetus's 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 the signal shunting between them, the clusters also may be separated by additional opaque (light-shielding) bumps (190).
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.