Abstract: In a system for measuring a physiological parameter using at least one wavelength of electromagnetic energy transmitted through living tissue, a method for determining an operational status of the system. The method includes receiving a data signal from at least one sensor, determining whether the received data signal is representative of the physiological parameter by sensing whether the at least one sensor is secured to the living tissue, and generating a status signal representative of the operational status of the system based on that determination. The determination includes measuring an output level corresponding to the at least one wavelength. The determination may also include analyzing a spectrum corresponding to the at least one wavelength to determine a percentage of energy contained in a subset of the spectrum, or monitoring an amplitude of the data signal for a given interval.

Abstract: The use of two separate ensemble averagers for processing a detected waveform for use in calculating oxygen saturation and a pulse rate. The ensemble averager used for calculating oxygen saturation operates on a signal which has been normalized, while the ensemble averager for the pulse rate calculation operates on a signal which has not been normalized. The metrics chosen for the two paths through the two ensemble averagers can be varied to optimize the ensemble averaging for oxygen saturation or pulse rate calculations.

Abstract: A method and a device for determining the quality of signal used for measuring a physiological parameter. One embodiment of the present invention is directed towards a pulse oximeter, where the measured physiological parameter includes a patient's pulse rate and blood oxygen saturation. The signal quality, which is indicative of the accuracy and reliability of the measured physiological parameter, is calculated by combining a plurality of signal quality indicators, each of which is an indicator of a quality of the measured signal. The value of the signal quality metric is compared to a threshold and based on this comparison various decisions are made by the medical device. One decision is directed towards deciding whether or not to display the measured physiological parameter, to ensure that only accurate measured values are displayed. Another decision is directed towards providing feedback to guide the clinician to adjust the location of the sensor to a more suitable tissue location.

Abstract: A method and apparatus for reducing the effects of noise on a system for measuring physiological parameters, such as, for example, a pulse oximeter. The method and apparatus of the invention take into account the physical limitations on various physiological parameters being monitored when weighting and averaging a series of measurements. Varying weights are assigned different measurements, measurements are rejected, and the averaging period is adjusted according to the reliability of the measurements. Similarly, calculated values derived from analyzing the measurements are also assigned varying weights and averaged over adjustable periods. More specifically, a general class of filters such as, for example, Kalman filters, is employed in processing the measurements and calculated values. The filters use mathematical models which describe how the physiological parameters change in time, and how these parameters relate to measurement in a noisy environment.

Abstract: A method and apparatus for reducing the effects of noise on a system for measuring physiological parameters, such as, for example, a pulse oximeter. The method and apparatus of the invention take into account the physical limitations on various physiological parameters being monitored when weighting and averaging a series of measurements. Varying weights are assigned different measurements, measurements are rejected, and the averaging period is adjusted according to the reliability of the measurements. Similarly, calculated values derived from analyzing the measurements are also assigned varying weights and averaged over adjustable periods. More specifically, a general class of filters such as, for example, Kalman filters, is employed in processing the measurements and calculated values. The filters use mathematical models which describe how the physiological parameters change in time, and how these parameters relate to measurement in a noisy environment.

Abstract: A method and apparatus for reducing the effects of noise on a system for measuring physiological parameters, such as, for example, a pulse oximeter. The method and apparatus of the invention take into account the physical limitations on various physiological parameters being monitored when weighting and averaging a series of measurements. Varying weights are assigned different measurements, measurements are rejected, and the averaging period is adjusted according to the reliability of the measurements. Similarly, calculated values derived from analyzing the measurements are also assigned varying weights and averaged over adjustable periods. More specifically, a general class of filters such as, for example, Kalman filters, is employed in processing the measurements and calculated values. The filters use mathematical models which describe how the physiological parameters change in time, and how these parameters relate to measurement in a noisy environment.

Abstract: A method and apparatus for reducing the effects of noise on a system for measuring physiological parameters, such as, for example, a pulse oximeter. The method and apparatus of the invention take into account the physical limitations on various physiological parameters being monitored when weighting and averaging a series of measurements. Varying weights are assigned different measurements, measurements are rejected, and the averaging period is adjusted according to the reliability of the measurements. Similarly, calculated values derived from analyzing the measurements are also assigned varying weights and averaged over adjustable periods. More specifically, a general class of filters such as, for example, Kalman filters, is employed in processing the measurements and calculated values. The filters use mathematical models which describe how the physiological parameters change in time, and how these parameters relate to measurement in a noisy environment.

Abstract: A method for determining whether a sensor is coupled to a tissue sample is described. The sensor is operable to generate a detector signal indicative of absorption of electromagnetic radiation by the tissue sample. A plurality of metric values corresponding to the detector signal are generated. A neural net is employed with the metric values to determine whether the sensor is coupled to the tissue sample.

Abstract: A method and apparatus for controlling alarms in medical diagnostic apparatus where an alarm is generated when a measured value for a physiological parameter passes a threshold. The method determines both the amount of time the measured value is past the threshold, and the amount by which the threshold is passed. The alarm is inhibited based upon a combination of (1) the amount of time and (2) how much past the threshold the measured value is. Preferably, the combination is an integral or some function of an integral.

Abstract: A method and apparatus for reducing the effects of noise on a system for measuring physiological parameters, such as, for example, a pulse oximeter. The method and apparatus of the invention take into account the physical limitations on various physiological parameters being monitored when weighting and averaging a series of measurements. Varying weights are assigned different measurements, measurements are rejected, and the averaging period is adjusted according to the reliability of the measurements. Similarly, calculated values derived from analyzing the measurements are also assigned varying weights and averaged over adjustable periods. More specifically, a general class of filters such as, for example, Kalman filters, is employed in processing the measurements and calculated values. The filters use mathematical models which describe how the physiological parameters change in time, and how these parameters relate to measurement in a noisy environment.

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: 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.