Abstract: Present embodiments include providing an initial estimate of a value representative of a blood flow characteristic at a current timestep, and determining a probability distribution of transition, wherein the probability distribution of transition includes potential values of the blood flow characteristic at the current timestep with associated probabilities of occurrence based solely on the initial estimate. Present embodiments further include obtaining an initial measurement of the blood flow characteristic, and determining a probability distribution of measured values, wherein the probability distribution of measured values includes potential values of the blood flow characteristic at the current timestep with associated probabilities of occurrence based on the initial measurement.

Abstract: The present invention provides a memory chip for use in an oximeter sensor, or an associated adapter or connector circuit. The memory chip allows the storing of patient related data, such as patient trending data or a patient ID, to provide enhanced capabilities for the oximeter sensor. In addition to providing unique data to store in such a memory, the present invention include unique uses of the data stored in such a memory.

Abstract: A method and a system for ensemble averaging signals in a pulse oximeter, including receiving first and second electromagnetic radiation signals from a blood perfused tissue portion corresponding to two different wavelengths of light, obtaining an assessment of the signal quality of the electromagnetic signals, selecting weights for an ensemble averager using the assessment of signal quality, and ensemble averaging the electromagnetic signals using the ensemble averager.

Abstract: A pulse oximeter method and apparatus which provides (1) a notch filter at a distance between a modulation frequency and a common multiple of commonly used power line frequencies (50, 60, 100 and 120) and also (2) a demodulation frequency greater than a highest pulse rate of a person and lower than any harmonic of 50, 60, 100 or 120 Hz, to filter ambient light interference, while choosing an optimum demodulation frequency that avoids interference from the notch filter or from harmonics of the line interference. Also, ambient light for any low frequency interference, such as power line interference, is measured both before and after each of the light emitter wavelengths and the average of the ambient light is then subtracted from the detected signal.

Abstract: A pulse oximeter sensor comprising an emitter and a detector disposed on a substrate layer with a thinned portion between the emitter and the detector. A partially transparent covering layer covers the substrate layer and comprises a corresponding thinned portion. The thinned portions attenuate light shunted via the substrate layer and the partially transparent covering layer from the emitter to the detector, and may be configured such that less than 10% of the light detectable by the detector is shunted light.

Abstract: A pulse oximeter sensor with a light source optimized for low oxygen saturation ranges and for maximizing the immunity to perturbation induced artifact. Preferably, a red and an infrared light source are used, with the red light source having a mean wavelength between 700-790 nm. The infrared light source 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 and light detectors 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 pulse oximeter sensor having an emitter(s) and a detector, with a layer having a first portion of the emitter and a second portion of layer over the detector is provided. A barrier is included between the first and second portions of the overlying layer to substantially block radiation of the wavelengths emitted by the emitter(s). Preferably, the barrier reduces the radiation shunted to less than 10% of the radiation detected, and more preferably to less than 1% of the radiation detected.

Abstract: A pulse oximeter sensor comprising an emitter and a detector coupled to a substrate layer and a partially opaque layer located on a patient contact side of the sensor and covering the emitter. The partially opaque layer is configured to attenuate light shunted via the partially opaque layer from the emitter to the detector, and may be configured such that less than 10% of the light detected by the detector is shunted light.

Abstract: A pulse oximeter sensor with a light source optimized for low oxygen saturation ranges and for maximizing the immunity to perturbation induced artifact. Preferably, a red and an infrared light source are used, with the red light source having a mean wavelength between 700-790 nm. The infrared light source 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 and light detectors 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 pulse oximeter sensor comprising a light emitter and a detector disposed on a substrate layer with a plurality of perforations or variations in thickness between the light emitter and the detector. The plurality of perforations or variations in thickness blocks or scatters light shunted via the substrate layer from the light emitter to the detector, and may be configured such that less than 10% of the light detectable by the detector is shunted light.

Abstract: A pulse oximeter sensor comprising an emitter and a detector disposed on a substrate layer with a thinned portion between the emitter and the detector. A partially transparent covering layer covers the substrate layer and comprises a corresponding thinned portion. The thinned portions attenuate light shunted via the substrate layer and the partially transparent covering layer from the emitter to the detector, and may be configured such that less than 10% of the light detectable by the detector is shunted light.

Abstract: A pulse oximeter sensor comprising an emitter and a detector disposed on a substrate layer with a thinned portion between the emitter and the detector. A partially transparent covering layer covers the substrate layer and comprises a corresponding thinned portion. The thinned portions attenuate light shunted via the substrate layer and the partially transparent covering layer from the emitter to the detector, and may be configured such that less than 10% of the light detectable by the detector is shunted light.

Abstract: A pulse oximeter with drive lines for driving red and IR LEDs, and a drive circuit for driving those drive lines. A processor controls the drive circuit using a red zero output line and an IR zero output line directly connected between the processor and the drive circuit. This allows a control signal to directly control the turning off of either the red or IR drive transistors to prevent forward current flow through the red and IR LEDs by overriding the ongoing programmable logic state machine control of the drive transistors. The effects of crosstalk and capacitive coupling are reduced as a result.

Abstract: A pulse oximeter sensor comprising an emitter and a detector disposed on a substrate layer with a thinned portion between the emitter and the detector. A partially transparent covering layer covers the substrate layer and comprises a corresponding thinned portion. The thinned portions attenuate light shunted via the substrate layer and the partially transparent covering layer from the emitter to the detector, and may be configured such that less than 10% of the light detectable by the detector is shunted light.

Abstract: The present invention provides a device and method to efficiently turn light from an optical fiber around a corner while avoiding the frustrated-TIR loss that would occur if the fiber were bent. The invention uses non-imaging optics which efficiently deal with beam divergence half-angles less than 90°. By recognizing that most light from a fiber optic source will have a divergence half-angle of less than 90 degrees, a practical solution is achieved using non-imaging optics.

Abstract: A pulse oximeter sensor comprising an emitter and a detector disposed on a substrate layer with a thinned portion between the emitter and the detector. A partially transparent covering layer covers the substrate layer and comprises a corresponding thinned portion. The thinned portions attenuate light shunted via the substrate layer and the partially transparent covering layer from the emitter to the detector, and may be configured such that less than 10% of the light detectable by the detector is shunted light.

Abstract: There is provided a pulse oximeter circuit including a feedback circuit configured to receive a digital output signal of a multi-bit sigma-delta modulator and generate a pulse width modulated signal (PWM). The PWM signal is directed to a first switching circuit and a D flip-flop. The first switching circuit provides a first or second reference voltage as a feedback signal to the multi-bit sigma-delta modulator. The D flip-flop generates a sample and hold signal. The sample and hold signal controls a second switching circuit coupled to the input of the multi-bit sigma-delta modulator.

Abstract: A method and a system for ensemble averaging signals in a pulse oximeter, including receiving first and second electromagnetic radiation signals from a blood perfused tissue portion corresponding to two different wavelengths of light, obtaining an assessment of the signal quality of the electromagnetic signals, selecting weights for an ensemble averager using the assessment of signal quality, and ensemble averaging the electromagnetic signals using the ensemble averager.

Abstract: Low power techniques for sensing cardiac pulses in a signal from a sensor are provided. A pulse detection block senses the sensor signal and determines its signal-to-noise ratio. After comparing the signal-to-noise ratio to a threshold, the drive current of light emitting elements in the sensor is dynamically adjusted to reduce power consumption while maintaining the signal-to-noise ratio at an adequate level. The signal component of the sensor signal can be measured by identifying systolic transitions. The systolic transitions are detected using a maximum and minimum derivative averaging scheme. The moving minimum and the moving maximum are compared to the scaled sum of the moving minimum and moving maximum to identify the systolic transitions. Once the signal component has been identified, the signal component is compared to a noise component to calculate the signal-to-noise ratio.

Abstract: There is provided a pulse oximeter circuit including a feedback circuit configured to receive a digital output signal of a multi-bit sigma-delta modulator and generate a pulse width modulated signal (PWM). The PWM signal is directed to a first switching circuit and a D flip-flop. The first switching circuit provides a first or second reference voltage as a feedback signal to the multi-bit sigma-delta modulator. The D flip-flop generates a sample and hold signal. The sample and hold signal controls a second switching circuit coupled to the input of the multi-bit sigma-delta modulator.