WO2005087100A1 - Pulse oximeter with alternate heart-rate determination - Google Patents

Pulse oximeter with alternate heart-rate determination Download PDF

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Publication number
WO2005087100A1
WO2005087100A1 PCT/US2005/007293 US2005007293W WO2005087100A1 WO 2005087100 A1 WO2005087100 A1 WO 2005087100A1 US 2005007293 W US2005007293 W US 2005007293W WO 2005087100 A1 WO2005087100 A1 WO 2005087100A1
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Prior art keywords
pulse
heart rate
rate
period
qualified
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PCT/US2005/007293
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French (fr)
Inventor
Clark R. Baker, Jr.
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Nellcor Puritan Bennett Incorporated
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Application filed by Nellcor Puritan Bennett Incorporated filed Critical Nellcor Puritan Bennett Incorporated
Priority to EP05724772A priority Critical patent/EP1729635A1/en
Priority to CA002557945A priority patent/CA2557945A1/en
Priority to MXPA06010317A priority patent/MXPA06010317A/en
Priority to AU2005221642A priority patent/AU2005221642A1/en
Priority to JP2007502888A priority patent/JP2007527770A/en
Publication of WO2005087100A1 publication Critical patent/WO2005087100A1/en

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    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B5/00—Measuring for diagnostic purposes; Identification of persons
    • A61B5/02—Detecting, measuring or recording pulse, heart rate, blood pressure or blood flow; Combined pulse/heart-rate/blood pressure determination; Evaluating a cardiovascular condition not otherwise provided for, e.g. using combinations of techniques provided for in this group with electrocardiography or electroauscultation; Heart catheters for measuring blood pressure
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B5/00—Measuring for diagnostic purposes; Identification of persons
    • A61B5/02—Detecting, measuring or recording pulse, heart rate, blood pressure or blood flow; Combined pulse/heart-rate/blood pressure determination; Evaluating a cardiovascular condition not otherwise provided for, e.g. using combinations of techniques provided for in this group with electrocardiography or electroauscultation; Heart catheters for measuring blood pressure
    • A61B5/024—Detecting, measuring or recording pulse rate or heart rate
    • A61B5/02416—Detecting, measuring or recording pulse rate or heart rate using photoplethysmograph signals, e.g. generated by infrared radiation
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B5/00—Measuring for diagnostic purposes; Identification of persons
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B5/00—Measuring for diagnostic purposes; Identification of persons
    • A61B5/02—Detecting, measuring or recording pulse, heart rate, blood pressure or blood flow; Combined pulse/heart-rate/blood pressure determination; Evaluating a cardiovascular condition not otherwise provided for, e.g. using combinations of techniques provided for in this group with electrocardiography or electroauscultation; Heart catheters for measuring blood pressure
    • A61B5/024—Detecting, measuring or recording pulse rate or heart rate

Definitions

  • the present invention relates to oximeters, and in particular to determining a pulse rate by multiple mechanisms in a detected waveform from a pulse oximeter.
  • Pulse oximetry is typically used to measure various blood chemistry characteristics including, but not limited to, the blood-oxygen saturation of hemoglobin in arterial blood, the volume of individual blood pulsations supplying the tissue, and the rate of blood pulsations corresponding to each heartbeat of a patient.
  • Measurement of these characteristics has been accomplished by use of a non-invasive sensor which scatters light through a portion of the patient's tissue where blood perfuses the tissue, and photoelectrically senses the absorption of light in such tissue. The amount of light absorbed at various wavelengths is then used to calculate the amount of blood constituent being measured.
  • the light scattered through the tissue is selected to be of one or more wavelengths that are absorbed by the blood in an amount representative of the amount of the blood constituent present in the blood.
  • the amount of transmitted light scattered through the tissue will vary in accordance with the changing amount of blood constituent in the tissue and the related light absorption.
  • Known non-invasive sensors include devices that are secured to a portion of the body, such as a finger, an ear or the scalp. In animals and humans, the tissue of these body portions is perfused with blood and the tissue surface is readily accessible to the sensor.
  • 6,083,172, No. 5,853,364 and No. 6,411,833 show multiple methods of calculating a pulse rate in a pulse oximeter, with a "best rate” module which arbitrates between the pulse rate calculations to select a best rate based on confidence levels associated with each. The confidence levels are calculated using various metrics to determine the reliability of the different pulse rate calculations.
  • Patent No. 5,524,631 shows a fetal heart rate monitor that uses multiple parallel filter paths to identify the fetal heart rate, and uses a figure of merit operation to weight the different heart rate estimates.
  • N-100 The N-100 technology, dating to around 1985, accepted or rejected pulses based on pulse history of the size of pulses, pulse shape, expected time to occur (frequency) and ratio of R/IR. In particular, the N-100 found pulses by looking for a signal maximum, followed by a point of maximum negative slope, then a minimum. The processing was done in a state machine referred to as "munch.” Each maximum was not qualified until the signal passed below a noise threshold, referred to as a noise gate. This acted as an adaptive filter since the noise gate level was set by feedback from a subsequent processing step to adapt to different expected signal amplitudes.
  • the pulses are then accepted or rejected in a "Level3" process which was a filter which adapts to changing signals by comparing the amplitude, period and ratio-of-ratios (ratio of Red to IR, with Red and IR being expressed as a ratio of AC to DC) of a new pulse to the mean of values in a history buffer, then determining if the difference is within a confidence level. If the new pulse was accepted, the history buffer was updated with the values for the new pulse.
  • the level3 process acted as an adaptive bandpass filter with center-frequency and bandwidth (confidence limits) being adapted by feedback from the output of the filter.
  • the N-200 improved on the N-100 since it could be synchronized with an ECG, and included ECG filtering.
  • the N-200 also added interpolation to compensate for baseline shift between the time of measuring the pulse maximum and minimum.
  • the N-200 included other filtering features as well, such as a "boxcar" filter which computed the mean of a varying number of signal samples.
  • the N-200 after various filtering and scaling steps, applies the digitized signals to a "boxcar” filter, which computes the mean of N samples, where N is set by feedback from a subsequent processing step according to the filtered heart rate. New samples are averaged into the boxcar filter, while the oldest samples are dropped.
  • the boxcar length (N) is used to set three parameters: a pulse threshold, absolute minimum pulse and small pulse.
  • An ensemble-averaging (a.k.a "slider”) filter then produces a weighted average of the new samples and the previous ensemble-averaged sample from one pulse-period earlier.
  • the samples are then passed to a "munch” state machine and a noise gate, like the N-100.
  • An interpolation feature is added to the N- 100 process, to compensate for changes in the baseline level. Since the minimum and maximum occur at different times, a changing baseline may increase or decrease the minimum and not the maximum, or vice-versa.
  • End averaging is an integral part of C-Lock, which is NELLCOR's trademark for the process of averaging samples from multiple pulses together to form a composite pulse. This process is also known as “cardiac-gated averaging.” It requires a “trigger” event to mark the start of each pulse.
  • the present invention is a pulse oximeter which determines multiple heart rates, and selects between them based on the metrics of only one of the heart rate calculations.
  • a primary heart rate calculation method is selected, and is used unless its metrics indicate questionable accuracy, in which case an alternative rate calculation is available and is used instead.
  • the primary heart rate calculation method does not use an ensemble averaged waveform, while the alternative heart rate calculation does use an ensemble averaged waveform.
  • the alternative heart rate calculation is used if the primary calculation has disqualified its most recently detected pulse.
  • FIG. 1 is a block diagram of an oximetry system incorporating an embodiment of the invention.
  • Fig. 2 is a diagram of the software processing blocks of an oximeter including an embodiment of the present invention.
  • Fig. 3 is a context diagram of the pulse rate calculation subsystem.
  • DETAILED DESCRIPTION OF THE INVENTION Fig. 1 illustrates an embodiment of an oximetry system incorporating the present invention.
  • a sensor 10 includes red and infrared LEDs and a photodetector. These are connected by a cable 12 to a board 14.
  • LED drive current is provided by an LED drive interface 16.
  • the received photocurrent from the sensor is provided to an I-V interface 18.
  • the IR and red voltages are then provided to a sigma-delta interface 20 incorporating the present invention.
  • the output of sigma-delta interface 20 is provided to a microcontroller 22 which includes a 10-bit A/D converter.
  • Controller 22 includes flash memory for a program, and EEPROM memory for data.
  • the processor also includes a controller chip 24 connected to a flash memory 26. Finally, a clock 28 is used and an interface 30 to a digital calibration in the sensor 10 is provided. A separate host 32 receives the processed information, as well as receiving an analog signal on a line 34 for providing an analog display.
  • Signal metrics are measured and used to determine filter weighting.
  • Signal metrics are things that indicate if a pulse is likely a plethysmograph or noise, such as frequency (is it in the range of a human heart rate), shape (is it shaped like a heart pulse), rise time, etc.
  • a similar technique was used in the Nellcor N200, described in the background of this application.
  • the new design adds a number of different features and variations, such as the use of two ensemble averagers as claimed in the present invention.
  • A. Signal Conditioning The digitized red and IR signals are received and are conditioned in this block by (1) taking the 1st derivative to get rid of baseline shift, (2) low pass filtering with fixed coefficients, and (3) dividing by a DC value to preserve the ratio.
  • the function of the Signal Conditioning subsystem is to emphasize the higher frequencies that occur in the human plethysmograph and to attenuate low frequencies in which motion artifact is usually concentrated.
  • the Signal Conditioning subsystem selects its filter coefficients (wide or narrow band) based on hardware characteristics identified during initialization.
  • Inputs - digitized red and IR signals Outputs - Pre-processed red and IR signals B.
  • Pulse Identification and Qualification The low pass filtered and digitized red and IR signals are provided to this block to identify pulses, and qualify them as likely arterial pulses. This is done using a pre- trained neural net, and is primarily done on the IR signal. The pulse is identified by examining its amplitude, shape and frequency, just as was done in the Nellcor N-100. An input to this block is the average pulse period from block D. This function is similar to the N-100, which changed the upfront qualification using the pulse rate. The output indicates the degree of arrhythmia and individual pulse quality.
  • This block calculates the average pulse period from the pulses received. Inputs - Qualified pulse periods and age. Outputs - Average pulse period. El . Lowpass Filter and Ensemble Averaging - Block El low pass filters and ensemble averages the signal conditioned by block A, and normalized by block C, for the pulse rate identification. The weights for the low pass filter are determined by the Signal Metrics block C. The signal is also ensemble averaged (this attenuates frequencies other than those of interest near the pulse rate and its harmonics), with the ensemble averaging filter weights also determined by Signal Metrics block C. Less weight is assigned if the signal is flagged as degraded.
  • More weight is assigned if the signal is flagged as arrhythmic because ensemble-averaging is not appropriate during arrhythmia. Red and IR are processed separately, but with the same filtering weights. The filtering is delayed approximately one second to allow the signal metrics to be calculated first.
  • the filters use continuously variable weights. If samples are not to be ensemble-averaged, then the weighting for the previous filtered samples is set to zero in the weighted average, and the new samples are still processed through the code. This block tracks the age of the signal - the accumulated amount of filtering (sum of response times and delays in processing). Too old a result will be flagged (if good pulses haven't been detected for awhile).
  • Lowpass Filter and Ensemble Averaging - Block E2 low pass filters and ensemble averages the signal conditioned by block A, for the pulse rate identification.
  • the weights for the low pass filter are determined by the Signal Metrics block C.
  • the signal is also ensemble averaged (this attenuates frequencies other than those of interest near the pulse rate and its harmonics), with the ensemble averaging filter weights also determined by Signal Metrics block C. Less weight is assigned if the signal is flagged as degraded. More weight is assigned if the signal is flagged as arrhythmic since filtering is not appropriate during arrhythmia. Red and IR are processed separately. The process of this block is delayed approximately one second to allow the signal metrics to be calculated first.
  • the filters use continuously variable weights.
  • the weighting for the previous filtered samples is set to zero in the weighted average, and the new samples are still processed through the code. This block tracks the age of the signal - the accumulated amount of filtering (sum of response times and delays in processing). Too old a result will be flagged (if good pulses haven't been detected for awhile).
  • Filtered Pulse Identification and Qualification This block identifies and qualifies pulse periods from the filtered waveforms, and its results are used only when a pulse is disqualified by block B.
  • Inputs (1) filtered red and IR signals and age, (2) average pulse period, (3) hardware ID or noise floor, (4) kind of sensor.
  • Venous Pulsation - Block K receives as inputs the pre-processed red and IR signal and age from Block A, and pulse rate and provides an indication of venous pulsation as an output.
  • This subsystem produces an IR fundamental waveform in the time domain using a single-tooth comb filter which is output to the Ensemble Averaging filters.
  • the Pulse Lost and Sensor Off Detection subsystem uses a pre-trained neural net to determine whether the sensor is off the patient.
  • the inputs to the neural net are metrics that quantify several aspects of the behavior of the IR and Red values over the last several seconds. Samples are ignored by many of the oximetry algorithm's subsystems while the Signal State is not either Pulse Present or Sensor Maybe Off. The values of the Signal State variable are: "Pulse Present, Disconnect, Pulse Lost, Sensor Maybe Off, and Sensor Off.”
  • the subsystem averages qualified pulse periods from the Pulse Identification and Qualification subsystem. It outputs the average period and the corresponding pulse rate.
  • the oximetry algorithm contains two instances of this subsystem.
  • the first instance receives input from the Pulse Identification and Qualification instance whose input waveform have been processed by the Signal Conditioning subsystem, then lowpass filtered, but not ensemble averaged, by the Ensemble Averaging subsystem.
  • the second instance of the Pulse Rate Calculation subsystem receives input from two instances of the Pulse Identification and Qualification subsystem, the one described above and a second instance that receives input that has been ensemble averaged.
  • Pulse Period Source One instance of the subsystem receives qualified pulse periods from two sources. The subsystem selects which of these two sources to use for its pulse rate calculation based solely on analysis of only one source, the "primary" source.
  • the oximetry algorithm designates the Pulse Identification and Qualification instance that does NOT receive ensemble-averaged waveforms as the primary source, and designates the other Pulse Identification and Qualification instance as the "alternate" source of qualified pulse periods. Qualified pulse periods from the alternate source are only used if the most recent pulse from the primary source was rejected. When a qualified pulse period is received from the primary source, it is always used to update the pulse-rate calculation, and will prevent qualified pulse periods from the alternate source from being used until the primary source once again rejects a pulse period.
  • the subsystem uses a Qualified_Pulse_Period, it updates its average pulse period, Avg_Pe ⁇ od, using a pulse-based, variable-weight IIR filter, then computes its Rate output from Avg Period.
  • k Consecutive Qualified I max(
  • x bound(min(-4 vg_Period t - ⁇ , Qualif ⁇ ed_Pulse_Period), 3 A seconds, 2 secom seconds 4.
  • l ⁇ Rate Age > 10 seconds, x min(x * Rate Age 1 10 seconds, 0.3) 5.
  • Rate_Age Rate Age + k * (Qualified _Period_Age - Rate Age)
  • r is the pulse rate corresponding to Qualified _Pulse Period, in BPM the réelle ! subscript denotes the previous qualified pulse.
  • ⁇ t is the oximetry algorithm's sample interval in seconds 60 / ⁇ t is the number of samples per minute
  • x is a filter weight that targets a 7-second response time for typical adult pulse rates.
  • k is the final filter weight, based on both x and the differences between consecutive values of r,. During the first few pulses, k is increased to at least 1 / Total Qualified so that the initial qualified pulses will be weighted equally.
  • Consecutive _Qualified is the number of consecutive qualified pulses, and Total Qualified is the total number of pulses qualified since the subsystem was reinitialized. Both Consecutive jQualified and Total Qualified are incremented each time a Qualified Pulse Period is used, before k is calculated. Consecutive Qualified is set to zero when a pulse is rejected by the pulse-period source currently in use.
  • the update formula for Avg Period is a geometric average of Avg Period, and Qualified _Pulse Period. Geometric averaging helps to keep the subsystem responsive to large pulses-to-pulse period variations, and large, sustained changes in pulse rate.
  • Rate Age is incremented every sample, whether or not Rate is updated.
  • Fig. 3 is a context diagram of the pulse rate calculation subsystem.
  • the subsystem updates its Avg_Period and Rate outputs from Qualified_Pulse_Periods. It uses Qualified Pulse Periods from the Alternative _Period_Source only if it last received a Notify Pulse Rejected from the primary source. It updates its Rate Age output based on Qualified Period Age. When Rate is updated, the subsystem sets its Pulse Rate ⁇ pdated flag. The Reinitialize input tells the subsystem to reinitialize itself. Increment _Rate Age notifies the subsystem to increment its Rate Age every sample once Rate is initialized.

Abstract

A pulse oximeter which determines multiple heart rates, and selects between them based on the metrics of only one of the heart rate calculations. A primary heart rate calculation method is selected, and is used unless its metrics indicate questionable accuracy, in which case an alternative rate calculation is available and is used instead.

Description

PULSE OXIMETER WITH ALTERNATE HEART-RATE DETERMINATION BACKGROUND OF THE INVENTION The present invention relates to oximeters, and in particular to determining a pulse rate by multiple mechanisms in a detected waveform from a pulse oximeter. Pulse oximetry is typically used to measure various blood chemistry characteristics including, but not limited to, the blood-oxygen saturation of hemoglobin in arterial blood, the volume of individual blood pulsations supplying the tissue, and the rate of blood pulsations corresponding to each heartbeat of a patient. Measurement of these characteristics has been accomplished by use of a non-invasive sensor which scatters light through a portion of the patient's tissue where blood perfuses the tissue, and photoelectrically senses the absorption of light in such tissue. The amount of light absorbed at various wavelengths is then used to calculate the amount of blood constituent being measured.
The light scattered through the tissue is selected to be of one or more wavelengths that are absorbed by the blood in an amount representative of the amount of the blood constituent present in the blood. The amount of transmitted light scattered through the tissue will vary in accordance with the changing amount of blood constituent in the tissue and the related light absorption. For measuring blood oxygen level, such sensors have typically been provided with a light source that is adapted to generate light of at least two different wavelengths, and with photodetectors sensitive to both of those wavelengths, in accordance with known techniques for measuring blood oxygen saturation. Known non-invasive sensors include devices that are secured to a portion of the body, such as a finger, an ear or the scalp. In animals and humans, the tissue of these body portions is perfused with blood and the tissue surface is readily accessible to the sensor. Patents No. 6,083,172, No. 5,853,364 and No. 6,411,833 show multiple methods of calculating a pulse rate in a pulse oximeter, with a "best rate" module which arbitrates between the pulse rate calculations to select a best rate based on confidence levels associated with each. The confidence levels are calculated using various metrics to determine the reliability of the different pulse rate calculations. Also, Patent No. 5,524,631 shows a fetal heart rate monitor that uses multiple parallel filter paths to identify the fetal heart rate, and uses a figure of merit operation to weight the different heart rate estimates.
N-100. The N-100 technology, dating to around 1985, accepted or rejected pulses based on pulse history of the size of pulses, pulse shape, expected time to occur (frequency) and ratio of R/IR. In particular, the N-100 found pulses by looking for a signal maximum, followed by a point of maximum negative slope, then a minimum. The processing was done in a state machine referred to as "munch." Each maximum was not qualified until the signal passed below a noise threshold, referred to as a noise gate. This acted as an adaptive filter since the noise gate level was set by feedback from a subsequent processing step to adapt to different expected signal amplitudes. The pulses are then accepted or rejected in a "Level3" process which was a filter which adapts to changing signals by comparing the amplitude, period and ratio-of-ratios (ratio of Red to IR, with Red and IR being expressed as a ratio of AC to DC) of a new pulse to the mean of values in a history buffer, then determining if the difference is within a confidence level. If the new pulse was accepted, the history buffer was updated with the values for the new pulse. The level3 process acted as an adaptive bandpass filter with center-frequency and bandwidth (confidence limits) being adapted by feedback from the output of the filter.
N-200. The N-200 improved on the N-100 since it could be synchronized with an ECG, and included ECG filtering. The N-200 also added interpolation to compensate for baseline shift between the time of measuring the pulse maximum and minimum. The N-200 included other filtering features as well, such as a "boxcar" filter which computed the mean of a varying number of signal samples.
The N-200, after various filtering and scaling steps, applies the digitized signals to a "boxcar" filter, which computes the mean of N samples, where N is set by feedback from a subsequent processing step according to the filtered heart rate. New samples are averaged into the boxcar filter, while the oldest samples are dropped. The boxcar length (N) is used to set three parameters: a pulse threshold, absolute minimum pulse and small pulse. An ensemble-averaging (a.k.a "slider") filter then produces a weighted average of the new samples and the previous ensemble-averaged sample from one pulse-period earlier. The samples are then passed to a "munch" state machine and a noise gate, like the N-100. An interpolation feature is added to the N- 100 process, to compensate for changes in the baseline level. Since the minimum and maximum occur at different times, a changing baseline may increase or decrease the minimum and not the maximum, or vice-versa.
"Ensemble averaging" is an integral part of C-Lock, which is NELLCOR's trademark for the process of averaging samples from multiple pulses together to form a composite pulse. This process is also known as "cardiac-gated averaging." It requires a "trigger" event to mark the start of each pulse.
BRIEF SUMMARY OF THE INVENTION The present invention is a pulse oximeter which determines multiple heart rates, and selects between them based on the metrics of only one of the heart rate calculations. A primary heart rate calculation method is selected, and is used unless its metrics indicate questionable accuracy, in which case an alternative rate calculation is available and is used instead.
In one embodiment, the primary heart rate calculation method does not use an ensemble averaged waveform, while the alternative heart rate calculation does use an ensemble averaged waveform. The alternative heart rate calculation is used if the primary calculation has disqualified its most recently detected pulse.
BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a block diagram of an oximetry system incorporating an embodiment of the invention. Fig. 2 is a diagram of the software processing blocks of an oximeter including an embodiment of the present invention.
Fig. 3 is a context diagram of the pulse rate calculation subsystem. DETAILED DESCRIPTION OF THE INVENTION Fig. 1 illustrates an embodiment of an oximetry system incorporating the present invention. A sensor 10 includes red and infrared LEDs and a photodetector. These are connected by a cable 12 to a board 14. LED drive current is provided by an LED drive interface 16. The received photocurrent from the sensor is provided to an I-V interface 18. The IR and red voltages are then provided to a sigma-delta interface 20 incorporating the present invention. The output of sigma-delta interface 20 is provided to a microcontroller 22 which includes a 10-bit A/D converter. Controller 22 includes flash memory for a program, and EEPROM memory for data. The processor also includes a controller chip 24 connected to a flash memory 26. Finally, a clock 28 is used and an interface 30 to a digital calibration in the sensor 10 is provided. A separate host 32 receives the processed information, as well as receiving an analog signal on a line 34 for providing an analog display.
Design Summary The design of the present invention is intended to deal with unwanted noise. Signal metrics are measured and used to determine filter weighting. Signal metrics are things that indicate if a pulse is likely a plethysmograph or noise, such as frequency (is it in the range of a human heart rate), shape (is it shaped like a heart pulse), rise time, etc. A similar technique was used in the Nellcor N200, described in the background of this application. The new design adds a number of different features and variations, such as the use of two ensemble averagers as claimed in the present invention.
Details of the architecture are shown in the diagram of Fig. 2. This design calculates both the oxygen saturation, and the pulse rate, which are described separately below. I. Oxygen Saturation Calculation. A. Signal Conditioning - The digitized red and IR signals are received and are conditioned in this block by (1) taking the 1st derivative to get rid of baseline shift, (2) low pass filtering with fixed coefficients, and (3) dividing by a DC value to preserve the ratio. The function of the Signal Conditioning subsystem is to emphasize the higher frequencies that occur in the human plethysmograph and to attenuate low frequencies in which motion artifact is usually concentrated. The Signal Conditioning subsystem selects its filter coefficients (wide or narrow band) based on hardware characteristics identified during initialization.
Inputs - digitized red and IR signals Outputs - Pre-processed red and IR signals B. Pulse Identification and Qualification - The low pass filtered and digitized red and IR signals are provided to this block to identify pulses, and qualify them as likely arterial pulses. This is done using a pre- trained neural net, and is primarily done on the IR signal. The pulse is identified by examining its amplitude, shape and frequency, just as was done in the Nellcor N-100. An input to this block is the average pulse period from block D. This function is similar to the N-100, which changed the upfront qualification using the pulse rate. The output indicates the degree of arrhythmia and individual pulse quality. Inputs - (1) Pre-processed red and IR signals, (2) Ave. pulse period, (3) Lowpass Waveforms from the low pass filter.
Outputs - (1) Degree of arrhythmia, (2) pulse amplitude variations, (3) individual pulse quality, (4) Pulse beep notification, (5) qualified pulse periods and age. C. Compute Signal Quality Metrics - This block determines the pulse shape (derivative skew), period variability, pulse amplitude and variability, Ratio of Ratios variability, and frequency content relative to pulse rate. Inputs - (1) raw digitized red and IR signals, (2) degree of arrhythmia, individual pulse quality, pulse amplitude variation (3) pre-processed red and IR signals, (4) average pulse period. Outputs - (1) Lowpass and ensemble averaging filter weights, (2) metrics for sensor off detector, (3) Normalized Pre-processed waveforms, (4) percent modulation. D. Average Pulse Periods. This block calculates the average pulse period from the pulses received. Inputs - Qualified pulse periods and age. Outputs - Average pulse period. El . Lowpass Filter and Ensemble Averaging - Block El low pass filters and ensemble averages the signal conditioned by block A, and normalized by block C, for the pulse rate identification. The weights for the low pass filter are determined by the Signal Metrics block C. The signal is also ensemble averaged (this attenuates frequencies other than those of interest near the pulse rate and its harmonics), with the ensemble averaging filter weights also determined by Signal Metrics block C. Less weight is assigned if the signal is flagged as degraded. More weight is assigned if the signal is flagged as arrhythmic because ensemble-averaging is not appropriate during arrhythmia. Red and IR are processed separately, but with the same filtering weights. The filtering is delayed approximately one second to allow the signal metrics to be calculated first.
The filters use continuously variable weights. If samples are not to be ensemble-averaged, then the weighting for the previous filtered samples is set to zero in the weighted average, and the new samples are still processed through the code. This block tracks the age of the signal - the accumulated amount of filtering (sum of response times and delays in processing). Too old a result will be flagged (if good pulses haven't been detected for awhile). Inputs - (1) normalized pre-processed red and IR signals, (2) average pulse period, (3) low pass filter weights and ensemble averaging filter weights, (4) ECG triggers, if available, (5) IR fundamental, for zero-crossing triggers. Outputs - (1) filtered red and IR signals, (2) age. F. Estimate Filtered Waveform Correlation and Calculate Averaging Weight - this uses a noise metric similar to that used in the N100 and N200 described above, and doesn't use feedback. The variable weighting for the filter is controlled by the ratio-of-ratios variance. The effect of this variable-weight filtering is that the ratio-of-ratios changes slowly as artifact increases and changes quickly as artifact decreases. The subsystem has two response modes. Filtering in the Fast Mode targets an age metric of 3 seconds. The target age is 5 seconds in Normal Mode. In Fast Mode, the minimum weighting of the current value is clipped at a higher level. In other words, a low weight is assigned to the newest ratio-of-ratios calculation if there is noise present, and a high weight if no noise is present.
Inputs - (1) filtered red and IR signals and age, (2) calibration coefficients, (3) response mode (user speed settings).
Outputs - averaging weight for ratio-of-ratios calculation.
H. Calculate Saturation - Saturation is calculated using an algorithm with the calibration coefficients and averaged ratio of ratios.
Inputs - (1) Averaged Ratio-of-Ratios, (2) calibration coefficients.
Outputs - Saturation.
II. Pulse Rate Calculation.
E2. Lowpass Filter and Ensemble Averaging - Block E2 low pass filters and ensemble averages the signal conditioned by block A, for the pulse rate identification. The weights for the low pass filter are determined by the Signal Metrics block C. The signal is also ensemble averaged (this attenuates frequencies other than those of interest near the pulse rate and its harmonics), with the ensemble averaging filter weights also determined by Signal Metrics block C. Less weight is assigned if the signal is flagged as degraded. More weight is assigned if the signal is flagged as arrhythmic since filtering is not appropriate during arrhythmia. Red and IR are processed separately. The process of this block is delayed approximately one second to allow the signal metrics to be calculated first. The filters use continuously variable weights. If samples are not to be ensemble-averaged, then the weighting for the previous filtered samples is set to zero in the weighted average, and the new samples are still processed through the code. This block tracks the age of the signal - the accumulated amount of filtering (sum of response times and delays in processing). Too old a result will be flagged (if good pulses haven't been detected for awhile).
Inputs - (1) pre-processed red and IR signals, (2) average pulse period, (3) Lowpass filter weights and ensemble averaging filter weights, (4) ECG triggers, if available, (5) IR fundamental, for zero-crossing triggers. Outputs - (1) filtered red and IR signals, (2) age.
I. Filtered Pulse Identification and Qualification - This block identifies and qualifies pulse periods from the filtered waveforms, and its results are used only when a pulse is disqualified by block B. Inputs - (1) filtered red and IR signals and age, (2) average pulse period, (3) hardware ID or noise floor, (4) kind of sensor.
Outputs - qualified pulse periods and age.
J. Average Pulse Periods and Calculate Pulse Rate - This block calculates the pulse rate and average pulse period.
Inputs - Qualified pulse periods and age Outputs - (1) average pulse period, (2) pulse rate.
III. Venous Pulsation
K. Detect Venous Pulsation - Block K receives as inputs the pre-processed red and IR signal and age from Block A, and pulse rate and provides an indication of venous pulsation as an output. This subsystem produces an IR fundamental waveform in the time domain using a single-tooth comb filter which is output to the Ensemble Averaging filters. Inputs - (1) filtered red and IR signals and age, (2) pulse rate. Outputs - Venous Pulsation Indication, IR fundamental
IV. Sensor Off
L. Detect Sensor-Off and Loss of Pulse Amplitude - The Pulse Lost and Sensor Off Detection subsystem uses a pre-trained neural net to determine whether the sensor is off the patient. The inputs to the neural net are metrics that quantify several aspects of the behavior of the IR and Red values over the last several seconds. Samples are ignored by many of the oximetry algorithm's subsystems while the Signal State is not either Pulse Present or Sensor Maybe Off. The values of the Signal State variable are: "Pulse Present, Disconnect, Pulse Lost, Sensor Maybe Off, and Sensor Off."
Inputs - (1) metrics, (2) front-end servo settings and ID
Outputs - Signal state including sensor-off indication
Pulse Rate Calculation subsystem
The subsystem averages qualified pulse periods from the Pulse Identification and Qualification subsystem. It outputs the average period and the corresponding pulse rate.
The oximetry algorithm contains two instances of this subsystem. The first instance receives input from the Pulse Identification and Qualification instance whose input waveform have been processed by the Signal Conditioning subsystem, then lowpass filtered, but not ensemble averaged, by the Ensemble Averaging subsystem. The second instance of the Pulse Rate Calculation subsystem receives input from two instances of the Pulse Identification and Qualification subsystem, the one described above and a second instance that receives input that has been ensemble averaged.
Selection of Pulse Period Source One instance of the subsystem receives qualified pulse periods from two sources. The subsystem selects which of these two sources to use for its pulse rate calculation based solely on analysis of only one source, the "primary" source. The oximetry algorithm designates the Pulse Identification and Qualification instance that does NOT receive ensemble-averaged waveforms as the primary source, and designates the other Pulse Identification and Qualification instance as the "alternate" source of qualified pulse periods. Qualified pulse periods from the alternate source are only used if the most recent pulse from the primary source was rejected. When a qualified pulse period is received from the primary source, it is always used to update the pulse-rate calculation, and will prevent qualified pulse periods from the alternate source from being used until the primary source once again rejects a pulse period.
Calculation of Average Pulse Period and Pulse-Rate Estimate
When the subsystem uses a Qualified_Pulse_Period, it updates its average pulse period, Avg_Peήod, using a pulse-based, variable-weight IIR filter, then computes its Rate output from Avg Period. The steps for this filtering operation are: 1. r, = (60 / Δt) / Qualified _Pulse_Period 2. k= Consecutive Qualified I max(|r, - r,.ι|, |r,.ι - r,.2|, |r,.2 - r,.3|, 1.0) 3. x = bound(min(-4 vg_Periodt -\, Qualifιed_Pulse_Period), 3A seconds, 2 secom seconds 4. lϊ Rate Age > 10 seconds, x = min(x * Rate Age 1 10 seconds, 0.3) 5. k = max(l / Total Qualified, min(&, x)) 6. If Avg Period, .\ o 0 Avg_Periodt = Avg_Periodt -\ * (Qualified Pulse Period I Avg_Periodt . f 7. If Avg Periodt -ι = 0 Avg_Period, = Qualified Pulse Period 8. Rate = (60 / Δt) / Avg_Periodt 9. Rate_Age = Rate Age + k * (Qualified _Period_Age - Rate Age) where: r, is the pulse rate corresponding to Qualified _Pulse Period, in BPM the „! subscript denotes the previous qualified pulse. Δt is the oximetry algorithm's sample interval in seconds 60 / Δt is the number of samples per minute x is a filter weight that targets a 7-second response time for typical adult pulse rates. k is the final filter weight, based on both x and the differences between consecutive values of r,. During the first few pulses, k is increased to at least 1 / Total Qualified so that the initial qualified pulses will be weighted equally.
Consecutive _Qualified is the number of consecutive qualified pulses, and Total Qualified is the total number of pulses qualified since the subsystem was reinitialized. Both Consecutive jQualified and Total Qualified are incremented each time a Qualified Pulse Period is used, before k is calculated. Consecutive Qualified is set to zero when a pulse is rejected by the pulse-period source currently in use.
The update formula for Avg Period,, in step 6 above, is a geometric average of Avg Period, and Qualified _Pulse Period. Geometric averaging helps to keep the subsystem responsive to large pulses-to-pulse period variations, and large, sustained changes in pulse rate.
Once Rate is initialized to a non-zero value, Rate Age is incremented every sample, whether or not Rate is updated.
Context Diagram
Fig. 3 is a context diagram of the pulse rate calculation subsystem. The subsystem updates its Avg_Period and Rate outputs from Qualified_Pulse_Periods. It uses Qualified Pulse Periods from the Alternative _Period_Source only if it last received a Notify Pulse Rejected from the primary source. It updates its Rate Age output based on Qualified Period Age. When Rate is updated, the subsystem sets its Pulse Rate ϋpdated flag. The Reinitialize input tells the subsystem to reinitialize itself. Increment _Rate Age notifies the subsystem to increment its Rate Age every sample once Rate is initialized.

Claims

WHAT IS CLAIMED IS:
1. A method for determining a heart rate in a pulse oximeter comprising: determining a first heart rate from a pulse oximetry signal using a first method; determining a second heart rate from a pulse oximetry signal using a second method; evaluating a reliability of said first heart rate using metrics applied to said first method; using said first heart rate when said metrics indicate said first method is reliable; and using said second heart rate when said metrics indicate that said first heart rate is unreliable.
2. The method of claim 1 further comprising determining that said first heart rate is unreliable when said metrics indicate that a most recent pulse is rejected.
3. The method of claim 1 wherein said first method does not use an ensemble averaged waveform, and said second method does use an ensemble averaged waveform.
4. The method of claim 1 wherein determining a first and second heart rate each comprise determining a pulse period, and further comprising: converting a pulse period used into a rate.
5. A pulse oximeter which determines a heart rate, comprising: a first heart rate calculator for determining a first heart rate from a pulse oximetry signal using a first method; a second heart rate calculator for determining a second heart rate from a pulse oximetry signal using a second method; an evaluator configured to determine the reliability of said first heart rate using metrics applied to said first method; and a selector configured to use said first heart rate when said metrics indicate said first method is reliable, and to use said second heart rate when said metrics indicate that said first heart rate is unreliable.
6. The pulse oximeter of claim 5 wherein said selector determines that said first heart rate is unreliable when said metrics indicate that a most recent pulse is rejected.
7. The pulse oximeter of claim 5 wherein said first heart rate calculator does not use an ensemble averaged waveform, and said second heart rate calculator does use an ensemble averaged waveform.
PCT/US2005/007293 2004-03-08 2005-03-07 Pulse oximeter with alternate heart-rate determination WO2005087100A1 (en)

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Families Citing this family (60)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US7016715B2 (en) 2003-01-13 2006-03-21 Nellcorpuritan Bennett Incorporated Selection of preset filter parameters based on signal quality
US8611977B2 (en) * 2004-03-08 2013-12-17 Covidien Lp Method and apparatus for optical detection of mixed venous and arterial blood pulsation in tissue
US7534212B2 (en) * 2004-03-08 2009-05-19 Nellcor Puritan Bennett Llc Pulse oximeter with alternate heart-rate determination
US7194293B2 (en) 2004-03-08 2007-03-20 Nellcor Puritan Bennett Incorporated Selection of ensemble averaging weights for a pulse oximeter based on signal quality metrics
US20080208009A1 (en) * 2004-07-09 2008-08-28 Dror Shklarski Wearable Device, System and Method for Measuring Vital Parameters
US7392075B2 (en) 2005-03-03 2008-06-24 Nellcor Puritan Bennett Incorporated Method for enhancing pulse oximetry calculations in the presence of correlated artifacts
US20070100220A1 (en) * 2005-10-28 2007-05-03 Baker Clark R Jr Adjusting parameters used in pulse oximetry analysis
US7706852B2 (en) 2006-01-30 2010-04-27 Nellcor Puritan Bennett Llc System and method for detection of unstable oxygen saturation
US8308641B2 (en) * 2006-02-28 2012-11-13 Koninklijke Philips Electronics N.V. Biometric monitor with electronics disposed on or in a neck collar
US8123695B2 (en) * 2006-09-27 2012-02-28 Nellcor Puritan Bennett Llc Method and apparatus for detection of venous pulsation
US7922665B2 (en) * 2006-09-28 2011-04-12 Nellcor Puritan Bennett Llc System and method for pulse rate calculation using a scheme for alternate weighting
US7680522B2 (en) 2006-09-29 2010-03-16 Nellcor Puritan Bennett Llc Method and apparatus for detecting misapplied sensors
US8109882B2 (en) 2007-03-09 2012-02-07 Nellcor Puritan Bennett Llc System and method for venous pulsation detection using near infrared wavelengths
US8229530B2 (en) 2007-03-09 2012-07-24 Nellcor Puritan Bennett Llc System and method for detection of venous pulsation
US8221326B2 (en) 2007-03-09 2012-07-17 Nellcor Puritan Bennett Llc Detection of oximetry sensor sites based on waveform characteristics
US20080262326A1 (en) * 2007-04-19 2008-10-23 Starr Life Sciences Corp. Signal Processing Method and Apparatus for Processing a Physiologic Signal such as a Photoplethysmography Signal
US8827917B2 (en) * 2008-06-30 2014-09-09 Nelleor Puritan Bennett Ireland Systems and methods for artifact detection in signals
US8862194B2 (en) 2008-06-30 2014-10-14 Covidien Lp Method for improved oxygen saturation estimation in the presence of noise
US8077297B2 (en) 2008-06-30 2011-12-13 Nellcor Puritan Bennett Ireland Methods and systems for discriminating bands in scalograms
US8295567B2 (en) 2008-06-30 2012-10-23 Nellcor Puritan Bennett Ireland Systems and methods for ridge selection in scalograms of signals
JP5234078B2 (en) 2010-09-29 2013-07-10 株式会社デンソー Pulse wave analysis device and blood pressure estimation device
US8721557B2 (en) 2011-02-18 2014-05-13 Covidien Lp Pattern of cuff inflation and deflation for non-invasive blood pressure measurement
US9072433B2 (en) 2011-02-18 2015-07-07 Covidien Lp Method and apparatus for noninvasive blood pressure measurement using pulse oximetry
US8897860B2 (en) 2011-03-25 2014-11-25 Zoll Medical Corporation Selection of optimal channel for rate determination
US9370308B2 (en) 2012-05-01 2016-06-21 Nellcor Puritan Bennett Ireland Angle distribution technique for analyzing a physiological sensor signal
US9259186B2 (en) 2012-09-11 2016-02-16 Covidien Lp Methods and systems for determining noise information from a physiological signal
US8868148B2 (en) 2012-09-11 2014-10-21 Covidien Lp Methods and systems for qualifying physiological values based on segments of a physiological signal
US9247887B2 (en) 2012-09-11 2016-02-02 Covidien Lp Methods and systems for determining physiological information based on low and high frequency components
US9161723B2 (en) 2012-09-11 2015-10-20 Covidien Lp Methods and systems for qualifying calculated values based on multiple difference signals
US9149232B2 (en) 2012-09-11 2015-10-06 Covidien Lp Methods and systems for qualifying calculated values based on state transitions
US9226670B2 (en) 2012-09-11 2016-01-05 Covidien Lp Methods and systems for determining physiological information based on statistical regression analysis
US9186110B2 (en) 2012-09-11 2015-11-17 Covidien Lp Methods and systems for qualifying calculated values based on a statistical metric
US9155478B2 (en) 2012-09-11 2015-10-13 Covidien Lp Methods and systems for determining an algorithm setting based on a difference signal
US9392976B2 (en) 2012-09-11 2016-07-19 Covidien Lp Methods and systems for determining physiological information based on a combined autocorrelation sequence
US20140073949A1 (en) * 2012-09-11 2014-03-13 Nellcor Puritan Bennett Llc Methods and systems for determining physiological information based on failure information
US9357936B2 (en) 2012-09-11 2016-06-07 Covidien Lp Methods and systems for determining physiological information based on a correlation matrix
US9192310B2 (en) 2012-09-11 2015-11-24 Covidien Lp Methods and systems for qualifying a calculated value based on baseline and deviation information
US9314209B2 (en) 2012-09-11 2016-04-19 Covidien Lp Methods and systems for determining physiological information based on a correlation sequence
US9119598B2 (en) 2012-09-11 2015-09-01 Covidien Lp Methods and systems for determining physiological information using reference waveforms
US9220423B2 (en) 2012-09-11 2015-12-29 Covidien Lp Methods and systems for qualifying a calculated value based on differently sized sorted difference signals
US9149196B2 (en) 2012-09-11 2015-10-06 Covidien Lp Methods and systems for determining an algorithm setting based on a difference signal
US9186101B2 (en) 2012-09-11 2015-11-17 Covidien Lp Methods and systems for qualifying a correlation lag value based on a correlation value at a different lag
US9241670B2 (en) 2012-09-11 2016-01-26 Covidien Lp Methods and systems for conditioning physiological information using a normalization technique
US9186076B2 (en) 2012-09-11 2015-11-17 Covidien Lp Methods and systems for qualifying a correlation lag value based on skewness
US9339235B2 (en) 2012-09-11 2016-05-17 Covidien Lp Methods and systems for determining signal-to-noise information from a physiological signal
US9392974B2 (en) 2012-09-11 2016-07-19 Covidien Lp Methods and systems for qualifying physiological values based on segments from a cross-correlation sequence
US9186108B2 (en) 2012-09-11 2015-11-17 Covidien Lp Methods and systems for determining an algorithm setting based on a skew metric
US9186109B2 (en) 2012-09-11 2015-11-17 Covidien Lp Methods and systems for qualifying physiological values based on metrics
JP5991100B2 (en) 2012-09-13 2016-09-14 オムロンヘルスケア株式会社 Pulse measuring device, pulse measuring method, and pulse measuring program
US10292594B2 (en) 2013-03-15 2019-05-21 Rochester Institute Of Technology Method and system for contactless detection of cardiac activity
US10342466B2 (en) 2015-03-24 2019-07-09 Covidien Lp Regional saturation system with ensemble averaging
JP6052332B2 (en) * 2015-04-28 2016-12-27 セイコーエプソン株式会社 Pulse wave meter, signal processing method, and program
US11617538B2 (en) 2016-03-14 2023-04-04 Zoll Medical Corporation Proximity based processing systems and methods
WO2018014246A1 (en) * 2016-07-20 2018-01-25 深圳市汇顶科技股份有限公司 Earphone and interactive system
TWI657794B (en) 2017-01-09 2019-05-01 財團法人工業技術研究院 Physiological information detecting apparatus and physiological information detecting method using the same are provided
US10646707B2 (en) 2017-11-30 2020-05-12 Zoll Medical Corporation Medical devices with rapid sensor recovery
AU2019231059B2 (en) * 2018-03-06 2021-05-27 Nippon Telegraph And Telephone Corporation Heartbeat rate calculation device and method
US10960213B2 (en) 2018-03-12 2021-03-30 Zoll Medical Corporation Verification of cardiac arrhythmia prior to therapeutic stimulation
CA3038097A1 (en) * 2019-03-26 2020-09-26 Roland SABBAGH Systems and methods for assessment and management of congestive heart failure
US20230225621A1 (en) * 2022-01-20 2023-07-20 Guy P. Curtis System and method for evaluating cardiac pumping function

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5524631A (en) 1994-10-13 1996-06-11 The United States Of America As Represented By The Administrator Of The National Aeronautics And Space Administration Passive fetal heart rate monitoring apparatus and method with enhanced fetal heart beat discrimination
US5853364A (en) 1995-08-07 1998-12-29 Nellcor Puritan Bennett, Inc. Method and apparatus for estimating physiological parameters using model-based adaptive filtering
US20020072660A1 (en) * 1999-03-25 2002-06-13 Diab Mohamed K. Pulse oximeter probe-off detector

Family Cites Families (198)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3638640A (en) * 1967-11-01 1972-02-01 Robert F Shaw Oximeter and method for in vivo determination of oxygen saturation in blood using three or more different wavelengths
US4938218A (en) 1983-08-30 1990-07-03 Nellcor Incorporated Perinatal pulse oximetry sensor
US4714341A (en) 1984-02-23 1987-12-22 Minolta Camera Kabushiki Kaisha Multi-wavelength oximeter having a means for disregarding a poor signal
JPS61209634A (en) * 1984-11-02 1986-09-17 シチズン時計株式会社 Pulse measuring device
US4911167A (en) * 1985-06-07 1990-03-27 Nellcor Incorporated Method and apparatus for detecting optical pulses
US4936679A (en) 1985-11-12 1990-06-26 Becton, Dickinson And Company Optical fiber transducer driving and measuring circuit and method for using same
US4913150A (en) * 1986-08-18 1990-04-03 Physio-Control Corporation Method and apparatus for the automatic calibration of signals employed in oximetry
US4805623A (en) * 1987-09-04 1989-02-21 Vander Corporation Spectrophotometric method for quantitatively determining the concentration of a dilute component in a light- or other radiation-scattering environment
US4807631A (en) * 1987-10-09 1989-02-28 Critikon, Inc. Pulse oximetry system
EP0315040B1 (en) 1987-11-02 1993-01-27 Sumitomo Electric Industries Limited Bio-photosensor
JPH0288041A (en) 1988-09-24 1990-03-28 Misawahoomu Sogo Kenkyusho:Kk Finger tip pulse wave sensor
US4972331A (en) 1989-02-06 1990-11-20 Nim, Inc. Phase modulated spectrophotometry
US5564417A (en) 1991-01-24 1996-10-15 Non-Invasive Technology, Inc. Pathlength corrected oximeter and the like
US5873821A (en) * 1992-05-18 1999-02-23 Non-Invasive Technology, Inc. Lateralization spectrophotometer
CA1331483C (en) 1988-11-02 1994-08-16 Britton Chance User-wearable hemoglobinometer for measuring the metabolic condition of a subject
US5122974A (en) 1989-02-06 1992-06-16 Nim, Inc. Phase modulated spectrophotometry
EP0374668A3 (en) * 1988-12-16 1992-02-05 A.W. Faber - Castell GmbH & Co. Fluorescent marking fluid
US5119815A (en) 1988-12-21 1992-06-09 Nim, Incorporated Apparatus for determining the concentration of a tissue pigment of known absorbance, in vivo, using the decay characteristics of scintered electromagnetic radiation
US5553614A (en) 1988-12-21 1996-09-10 Non-Invasive Technology, Inc. Examination of biological tissue using frequency domain spectroscopy
US5028787A (en) 1989-01-19 1991-07-02 Futrex, Inc. Non-invasive measurement of blood glucose
US6183414B1 (en) 1999-04-26 2001-02-06 Michael S. Wysor Technique for restoring plasticity to tissues of a male or female organ
US6708048B1 (en) * 1989-02-06 2004-03-16 Non-Invasive Technology, Inc. Phase modulation spectrophotometric apparatus
US5483646A (en) * 1989-09-29 1996-01-09 Kabushiki Kaisha Toshiba Memory access control method and system for realizing the same
US5190038A (en) * 1989-11-01 1993-03-02 Novametrix Medical Systems, Inc. Pulse oximeter with improved accuracy and response time
DE3938759A1 (en) * 1989-11-23 1991-05-29 Philips Patentverwaltung NON-INVASIVE OXIMETER ARRANGEMENT
US6266546B1 (en) 1990-10-06 2001-07-24 In-Line Diagnostics Corporation System for noninvasive hematocrit monitoring
US6246894B1 (en) 1993-02-01 2001-06-12 In-Line Diagnostics Corporation System and method for measuring blood urea nitrogen, blood osmolarity, plasma free hemoglobin and tissue water content
US6681128B2 (en) * 1990-10-06 2004-01-20 Hema Metrics, Inc. System for noninvasive hematocrit monitoring
US5372136A (en) 1990-10-06 1994-12-13 Noninvasive Medical Technology Corporation System and method for noninvasive hematocrit monitoring
MX9702434A (en) * 1991-03-07 1998-05-31 Masimo Corp Signal processing apparatus.
US5632272A (en) 1991-03-07 1997-05-27 Masimo Corporation Signal processing apparatus
EP0574509B1 (en) * 1991-03-07 1999-09-15 Masimo Corporation Signal processing apparatus and method
US6580086B1 (en) 1999-08-26 2003-06-17 Masimo Corporation Shielded optical probe and method
US5995855A (en) 1998-02-11 1999-11-30 Masimo Corporation Pulse oximetry sensor adapter
US5638818A (en) 1991-03-21 1997-06-17 Masimo Corporation Low noise optical probe
DE4138702A1 (en) * 1991-03-22 1992-09-24 Madaus Medizin Elektronik METHOD AND DEVICE FOR THE DIAGNOSIS AND QUANTITATIVE ANALYSIS OF APNOE AND FOR THE SIMULTANEOUS DETERMINATION OF OTHER DISEASES
US6549795B1 (en) * 1991-05-16 2003-04-15 Non-Invasive Technology, Inc. Spectrophotometer for tissue examination
US5365934A (en) * 1991-06-28 1994-11-22 Life Fitness Apparatus and method for measuring heart rate
US5246003A (en) 1991-08-28 1993-09-21 Nellcor Incorporated Disposable pulse oximeter sensor
US5247931A (en) 1991-09-16 1993-09-28 Mine Safety Appliances Company Diagnostic sensor clasp utilizing a slot, pivot and spring hinge mechanism
ATE171027T1 (en) 1992-01-25 1998-09-15 Alsthom Cge Alcatel METHOD FOR FACILITATING THE OPERATION OF TERMINAL DEVICES IN TELEVISION SYSTEMS
US5385143A (en) * 1992-02-06 1995-01-31 Nihon Kohden Corporation Apparatus for measuring predetermined data of living tissue
US5297548A (en) * 1992-02-07 1994-03-29 Ohmeda Inc. Arterial blood monitoring probe
US5263244A (en) * 1992-04-17 1993-11-23 Gould Inc. Method of making a flexible printed circuit sensor assembly for detecting optical pulses
JP3170866B2 (en) 1992-04-24 2001-05-28 株式会社ノーリツ 1 can 2 circuit type instant heating type heat exchanger
EP0572684B1 (en) * 1992-05-15 1996-07-03 Hewlett-Packard GmbH Medical sensor
US6785568B2 (en) 1992-05-18 2004-08-31 Non-Invasive Technology Inc. Transcranial examination of the brain
US5355880A (en) * 1992-07-06 1994-10-18 Sandia Corporation Reliable noninvasive measurement of blood gases
US20050062609A9 (en) 1992-08-19 2005-03-24 Lynn Lawrence A. Pulse oximetry relational alarm system for early recognition of instability and catastrophic occurrences
US5680857A (en) 1992-08-28 1997-10-28 Spacelabs Medical, Inc. Alignment guide system for transmissive pulse oximetry sensors
US9215979B2 (en) 1992-11-17 2015-12-22 Robert Bosch Healthcare Systems, Inc. Multi-user remote health monitoring system
CA2109017A1 (en) 1992-12-16 1994-06-17 Donald M. Smith Method and apparatus for the intermittent delivery of oxygen therapy to a person
CA2160252C (en) 1993-04-12 2004-06-22 Robert R. Steuer System and method for noninvasive hematocrit monitoring
US5485847A (en) * 1993-10-08 1996-01-23 Nellcor Puritan Bennett Incorporated Pulse oximeter using a virtual trigger for heart rate synchronization
EP0684575A4 (en) * 1993-12-14 1997-05-14 Mochida Pharm Co Ltd Medical measuring apparatus.
US5645059A (en) 1993-12-17 1997-07-08 Nellcor Incorporated Medical sensor with modulated encoding scheme
JP3464697B2 (en) 1993-12-21 2003-11-10 興和株式会社 Oxygen saturation meter
US5995859A (en) 1994-02-14 1999-11-30 Nihon Kohden Corporation Method and apparatus for accurately measuring the saturated oxygen in arterial blood by substantially eliminating noise from the measurement signal
US6371921B1 (en) 1994-04-15 2002-04-16 Masimo Corporation System and method of determining whether to recalibrate a blood pressure monitor
DE4423597C1 (en) * 1994-07-06 1995-08-10 Hewlett Packard Gmbh Pulsoximetric ear sensor
US5797840A (en) 1994-09-14 1998-08-25 Ramot University Authority For Applied Research & Industrial Development Ltd. Apparatus and method for time dependent power spectrum analysis of physiological signals
US5692503A (en) 1995-03-10 1997-12-02 Kuenstner; J. Todd Method for noninvasive (in-vivo) total hemoglobin, oxyhemogolobin, deoxyhemoglobin, carboxyhemoglobin and methemoglobin concentration determination
JPH08322811A (en) * 1995-05-30 1996-12-10 Nippon Colin Co Ltd Automatic sphygmomanometer
US7035697B1 (en) * 1995-05-30 2006-04-25 Roy-G-Biv Corporation Access control systems and methods for motion control
US5758644A (en) 1995-06-07 1998-06-02 Masimo Corporation Manual and automatic probe calibration
US5645060A (en) 1995-06-14 1997-07-08 Nellcor Puritan Bennett Incorporated Method and apparatus for removing artifact and noise from pulse oximetry
US5995856A (en) 1995-11-22 1999-11-30 Nellcor, Incorporated Non-contact optical monitoring of physiological parameters
SE9600322L (en) 1996-01-30 1997-07-31 Hoek Instr Ab Sensor for pulse oximetry with fiber optic signal transmission
DE59704665D1 (en) * 1996-04-01 2001-10-25 Linde Medical Sensors Ag Basel DETECTION OF INTERFERENCE SIGNALS IN PULSOXYMETRIC MEASUREMENT
US6163715A (en) 1996-07-17 2000-12-19 Criticare Systems, Inc. Direct to digital oximeter and method for calculating oxygenation levels
US5842981A (en) 1996-07-17 1998-12-01 Criticare Systems, Inc. Direct to digital oximeter
US20060217774A1 (en) 1996-08-19 2006-09-28 Mower Morton M Cardiac contractile augmentation device and method therefor
US6120460A (en) 1996-09-04 2000-09-19 Abreu; Marcio Marc Method and apparatus for signal acquisition, processing and transmission for evaluation of bodily functions
US6544193B2 (en) 1996-09-04 2003-04-08 Marcio Marc Abreu Noninvasive measurement of chemical substances
US5830139A (en) 1996-09-04 1998-11-03 Abreu; Marcio M. Tonometer system for measuring intraocular pressure by applanation and/or indentation
US5871442A (en) * 1996-09-10 1999-02-16 International Diagnostics Technologies, Inc. Photonic molecular probe
US6081742A (en) 1996-09-10 2000-06-27 Seiko Epson Corporation Organism state measuring device and relaxation instructing device
US6018673A (en) * 1996-10-10 2000-01-25 Nellcor Puritan Bennett Incorporated Motion compatible sensor for non-invasive optical blood analysis
US5830136A (en) 1996-10-31 1998-11-03 Nellcor Puritan Bennett Incorporated Gel pad optical sensor
US6487439B1 (en) 1997-03-17 2002-11-26 Victor N. Skladnev Glove-mounted hybrid probe for tissue type recognition
WO1998042251A1 (en) 1997-03-21 1998-10-01 Nellcor Puritan Bennett Inc. Method and apparatus for harmonically filtering data
JP3763480B2 (en) * 1997-03-21 2006-04-05 ネルコー・ピューリタン・ベネット・インコーポレイテッド Method and apparatus for measuring pulse rate and saturation
DE69725621T2 (en) 1997-03-21 2004-08-19 Nellcor Puritan Bennett Inc., Pleasanton METHOD AND DEVICE FOR ADAPTIVE AVERAGE VALUING OF DATA SIGNALS
AUPO676397A0 (en) 1997-05-13 1997-06-05 Dunlop, Colin Method and apparatus for monitoring haemodynamic function
BR9810143A (en) 1997-06-17 2001-11-27 Respironics Inc Fetal oximetry system and sensor
AU7934498A (en) * 1997-06-27 1999-01-19 Toa Medical Electronics Co., Ltd. Living body inspecting apparatus and noninvasive blood analyzer using the same
FI973454A (en) 1997-08-22 1999-02-23 Instrumentarium Oy A resilient device in a measuring sensor for observing the properties of living tissue
US6035223A (en) * 1997-11-19 2000-03-07 Nellcor Puritan Bennett Inc. Method and apparatus for determining the state of an oximetry sensor
EP0864293B1 (en) 1997-12-22 1999-08-04 Hewlett-Packard Company Telemetry system, in particular for medical purposes
JP3567319B2 (en) 1997-12-26 2004-09-22 日本光電工業株式会社 Probe for pulse oximeter
ATE416668T1 (en) * 1998-02-05 2008-12-15 Hema Metrics Inc METHOD AND DEVICE FOR NON-INVASIVE OBSERVATION OF BLOOD COMPONENTS
JP3576851B2 (en) * 1998-03-23 2004-10-13 キヤノン株式会社 Liquid crystal display, video camera
US6662030B2 (en) * 1998-05-18 2003-12-09 Abbott Laboratories Non-invasive sensor having controllable temperature feature
EP0904727B1 (en) * 1998-06-05 2000-10-18 Hewlett-Packard Company Pulse rate and heart rate coincidence detection for pulse oximetry
IL124787A0 (en) 1998-06-07 1999-01-26 Itamar Medical C M 1997 Ltd Pressure applicator devices particularly useful for non-invasive detection of medical conditions
US5920263A (en) 1998-06-11 1999-07-06 Ohmeda, Inc. De-escalation of alarm priorities in medical devices
AU4634799A (en) 1998-07-04 2000-01-24 Whitland Research Limited Non-invasive measurement of blood analytes
US7400918B2 (en) 1998-07-04 2008-07-15 Edwards Lifesciences Measurement of blood oxygen saturation
WO2000009004A2 (en) * 1998-08-13 2000-02-24 Whitland Research Limited Optical device
JP2000083933A (en) * 1998-07-17 2000-03-28 Nippon Koden Corp Instrument for measuring concentration of light absorptive material in vital tissue
US6671526B1 (en) 1998-07-17 2003-12-30 Nihon Kohden Corporation Probe and apparatus for determining concentration of light-absorbing materials in living tissue
US6949081B1 (en) 1998-08-26 2005-09-27 Non-Invasive Technology, Inc. Sensing and interactive drug delivery
US6064898A (en) * 1998-09-21 2000-05-16 Essential Medical Devices Non-invasive blood component analyzer
US6606511B1 (en) 1999-01-07 2003-08-12 Masimo Corporation Pulse oximetry pulse indicator
US6684090B2 (en) * 1999-01-07 2004-01-27 Masimo Corporation Pulse oximetry data confidence indicator
US6658276B2 (en) 1999-01-25 2003-12-02 Masimo Corporation Pulse oximeter user interface
CA2684695C (en) * 1999-01-25 2012-11-06 Masimo Corporation Universal/upgrading pulse oximeter
US6438399B1 (en) 1999-02-16 2002-08-20 The Children's Hospital Of Philadelphia Multi-wavelength frequency domain near-infrared cerebral oximeter
US6675029B2 (en) * 1999-07-22 2004-01-06 Sensys Medical, Inc. Apparatus and method for quantification of tissue hydration using diffuse reflectance spectroscopy
US7904139B2 (en) * 1999-08-26 2011-03-08 Non-Invasive Technology Inc. Optical examination of biological tissue using non-contact irradiation and detection
US6618042B1 (en) * 1999-10-28 2003-09-09 Gateway, Inc. Display brightness control method and apparatus for conserving battery power
US20050154370A1 (en) 1999-10-29 2005-07-14 Medtronic, Inc. Methods and systems for providing therapies into the pericardial space
JP2001149349A (en) * 1999-11-26 2001-06-05 Nippon Koden Corp Sensor for living body
US6415236B2 (en) 1999-11-30 2002-07-02 Nihon Kohden Corporation Apparatus for determining concentrations of hemoglobins
US6622095B2 (en) 1999-11-30 2003-09-16 Nihon Kohden Corporation Apparatus for determining concentrations of hemoglobins
US6408198B1 (en) 1999-12-17 2002-06-18 Datex-Ohmeda, Inc. Method and system for improving photoplethysmographic analyte measurements by de-weighting motion-contaminated data
US7464040B2 (en) * 1999-12-18 2008-12-09 Raymond Anthony Joao Apparatus and method for processing and/or for providing healthcare information and/or healthcare-related information
US7490048B2 (en) * 1999-12-18 2009-02-10 Raymond Anthony Joao Apparatus and method for processing and/or for providing healthcare information and/or healthcare-related information
EP2308374B1 (en) 1999-12-22 2012-07-18 Orsense Ltd. A method of optical measurements for determining various parameters of the patient's blood
US6419671B1 (en) 1999-12-23 2002-07-16 Visx, Incorporated Optical feedback system for vision correction
US6594513B1 (en) 2000-01-12 2003-07-15 Paul D. Jobsis Method and apparatus for determining oxygen saturation of blood in body organs
IL135077A0 (en) * 2000-03-15 2001-05-20 Orsense Ltd A probe for use in non-invasive measurements of blood related parameters
PT2322085E (en) 2000-04-17 2014-06-23 Covidien Lp Pulse oximeter sensor with piece-wise function
US6449501B1 (en) 2000-05-26 2002-09-10 Ob Scientific, Inc. Pulse oximeter with signal sonification
US20020023140A1 (en) * 2000-06-08 2002-02-21 Hile John K. Electronic document delivery system
US6889153B2 (en) * 2001-08-09 2005-05-03 Thomas Dietiker System and method for a self-calibrating non-invasive sensor
US6591123B2 (en) 2000-08-31 2003-07-08 Mallinckrodt Inc. Oximeter sensor with digital memory recording sensor data
IL138683A0 (en) * 2000-09-25 2001-10-31 Vital Medical Ltd Apparatus and method for monitoring tissue vitality parameters
IL138884A (en) * 2000-10-05 2006-07-05 Conmed Corp Pulse oximeter and a method of its operation
US6466809B1 (en) 2000-11-02 2002-10-15 Datex-Ohmeda, Inc. Oximeter sensor having laminated housing with flat patient interface surface
US6501974B2 (en) 2001-01-22 2002-12-31 Datex-Ohmeda, Inc. Compensation of human variability in pulse oximetry
US7239902B2 (en) 2001-03-16 2007-07-03 Nellor Puritan Bennett Incorporated Device and method for monitoring body fluid and electrolyte disorders
US6606509B2 (en) 2001-03-16 2003-08-12 Nellcor Puritan Bennett Incorporated Method and apparatus for improving the accuracy of noninvasive hematocrit measurements
US6591122B2 (en) 2001-03-16 2003-07-08 Nellcor Puritan Bennett Incorporated Device and method for monitoring body fluid and electrolyte disorders
US6898451B2 (en) * 2001-03-21 2005-05-24 Minformed, L.L.C. Non-invasive blood analyte measuring system and method utilizing optical absorption
US6862091B2 (en) * 2001-04-11 2005-03-01 Inlight Solutions, Inc. Illumination device and method for spectroscopic analysis
US7083593B2 (en) 2001-04-18 2006-08-01 Advanced Bionics Corporation Programmable implantable pump with accessory reservoirs and multiple independent lumen catheter
WO2002085191A2 (en) * 2001-04-19 2002-10-31 O'mara Sean T Pulse oximetry device and method
US20020156354A1 (en) 2001-04-20 2002-10-24 Larson Eric Russell Pulse oximetry sensor with improved spring
ATE369787T1 (en) 2001-06-20 2007-09-15 Purdue Research Foundation PRESSURE CUFF WITH BODY ILLUMINATION FOR USE IN OPTICAL NON-INVASIVE MEASUREMENT OF BLOOD PARAMETERS
SG126677A1 (en) 2001-06-26 2006-11-29 Meng Ting Choon Method and device for measuring blood sugar level
US6697658B2 (en) * 2001-07-02 2004-02-24 Masimo Corporation Low power pulse oximeter
DE10139379A1 (en) * 2001-08-10 2003-03-06 Siemens Ag Inductive motion sensor has sensor coils beside permanent magnet field generator
US6654621B2 (en) 2001-08-29 2003-11-25 Bci, Inc. Finger oximeter with finger grip suspension system
US6668183B2 (en) 2001-09-11 2003-12-23 Datex-Ohmeda, Inc. Diode detection circuit
IL145445A (en) * 2001-09-13 2006-12-31 Conmed Corp Signal processing method and device for signal-to-noise improvement
US7162306B2 (en) * 2001-11-19 2007-01-09 Medtronic Physio - Control Corp. Internal medical device communication bus
JP3709836B2 (en) 2001-11-20 2005-10-26 コニカミノルタセンシング株式会社 Blood component measuring device
US6856125B2 (en) * 2001-12-12 2005-02-15 Lifescan, Inc. Biosensor apparatus and method with sample type and volume detection
JP2003194714A (en) 2001-12-28 2003-07-09 Omega Wave Kk Measuring apparatus for blood amount in living-body tissue
JP2003210438A (en) 2002-01-22 2003-07-29 Tyco Healthcare Japan Inc Adapter for oximeter
US6822564B2 (en) * 2002-01-24 2004-11-23 Masimo Corporation Parallel measurement alarm processor
DE60315596T2 (en) 2002-01-31 2008-05-15 Loughborough University Enterprises Ltd., Loughborough VENOUS PULSE OXIMETRY
WO2003068070A1 (en) * 2002-02-14 2003-08-21 Toshinori Kato Apparatus for evaluating biological function
US6993377B2 (en) 2002-02-22 2006-01-31 The Board Of Trustees Of The University Of Arkansas Method for diagnosing heart disease, predicting sudden death, and analyzing treatment response using multifractal analysis
DE60332094D1 (en) * 2002-02-22 2010-05-27 Masimo Corp ACTIVE PULSE SPECTROPHOTOMETRY
WO2003073924A1 (en) 2002-03-01 2003-09-12 Terry Beaumont Ear canal sensing device
US6863652B2 (en) * 2002-03-13 2005-03-08 Draeger Medical Systems, Inc. Power conserving adaptive control system for generating signal in portable medical devices
DE10213692B4 (en) 2002-03-27 2013-05-23 Weinmann Diagnostics Gmbh & Co. Kg Method for controlling a device and device for measuring ingredients in the blood
AU2003226171B2 (en) * 2002-04-01 2009-01-15 Covidien Lp System and method of assessment of arousal, pain and stress during anesthesia and sedation
US6690958B1 (en) * 2002-05-07 2004-02-10 Nostix Llc Ultrasound-guided near infrared spectrophotometer
US6711425B1 (en) * 2002-05-28 2004-03-23 Ob Scientific, Inc. Pulse oximeter with calibration stabilization
JP4040913B2 (en) 2002-06-07 2008-01-30 株式会社パルメディカル Noninvasive arteriovenous oxygen saturation measuring device
US6909912B2 (en) 2002-06-20 2005-06-21 University Of Florida Non-invasive perfusion monitor and system, specially configured oximeter probes, methods of using same, and covers for probes
US7024235B2 (en) * 2002-06-20 2006-04-04 University Of Florida Research Foundation, Inc. Specially configured nasal pulse oximeter/photoplethysmography probes, and combined nasal probe/cannula, selectively with sampler for capnography, and covering sleeves for same
AU2003242975B2 (en) * 2002-07-15 2008-04-17 Itamar Medical Ltd. Body surface probe, apparatus and method for non-invasively detecting medical conditions
JP2004113353A (en) 2002-09-25 2004-04-15 Citizen Watch Co Ltd Blood analyzer
WO2004047631A2 (en) * 2002-11-22 2004-06-10 Masimo Laboratories, Inc. Blood parameter measurement system
JP3944448B2 (en) 2002-12-18 2007-07-11 浜松ホトニクス株式会社 Blood measuring device
US7006856B2 (en) * 2003-01-10 2006-02-28 Nellcor Puritan Bennett Incorporated Signal quality metrics design for qualifying data for a physiological monitor
US7025730B2 (en) * 2003-01-10 2006-04-11 Medtronic, Inc. System and method for automatically monitoring and delivering therapy for sleep-related disordered breathing
US7016715B2 (en) * 2003-01-13 2006-03-21 Nellcorpuritan Bennett Incorporated Selection of preset filter parameters based on signal quality
JP4284674B2 (en) 2003-01-31 2009-06-24 日本光電工業株式会社 Absorbent concentration measuring device in blood
WO2004069046A1 (en) 2003-02-05 2004-08-19 Philips Intellectual Property & Standards Gmbh Finger medical sensor
JP2004248819A (en) 2003-02-19 2004-09-09 Citizen Watch Co Ltd Blood analyzer
EP1628571B1 (en) 2003-02-27 2011-08-24 Nellcor Puritan Bennett Ireland Method and system for analysing and processing photoplethysmogram signals using wavelet transform analysis
JP2004290545A (en) 2003-03-28 2004-10-21 Citizen Watch Co Ltd Blood analyzer
US6947780B2 (en) 2003-03-31 2005-09-20 Dolphin Medical, Inc. Auditory alarms for physiological data monitoring
CA2522006C (en) 2003-04-10 2013-05-28 Vivometrics, Inc. Systems and methods for respiratory event detection
US6944488B2 (en) 2003-04-30 2005-09-13 Medtronic, Inc. Normalization method for a chronically implanted optical sensor
KR100571811B1 (en) * 2003-05-09 2006-04-17 삼성전자주식회사 Ear type measurement apparatus for bio signal
US7717112B2 (en) 2003-06-04 2010-05-18 Jianguo Sun Positive airway pressure therapy management module
US7047056B2 (en) 2003-06-25 2006-05-16 Nellcor Puritan Bennett Incorporated Hat-based oximeter sensor
US7455643B1 (en) 2003-07-07 2008-11-25 Nellcor Puritan Bennett Ireland Continuous non-invasive blood pressure measurement apparatus and methods providing automatic recalibration
US8602986B2 (en) 2003-08-20 2013-12-10 Koninklijke Philips N.V. System and method for detecting signal artifacts
EP1675501B1 (en) 2003-09-12 2013-09-04 Or-Nim Medical Ltd. Noninvasive optical monitoring of region of interest
US7379769B2 (en) * 2003-09-30 2008-05-27 Sunnybrook Health Sciences Center Hybrid imaging method to monitor medical device delivery and patient support for use in the method
US7373193B2 (en) * 2003-11-07 2008-05-13 Masimo Corporation Pulse oximetry data capture system
US20050113651A1 (en) * 2003-11-26 2005-05-26 Confirma, Inc. Apparatus and method for surgical planning and treatment monitoring
US20050267346A1 (en) 2004-01-30 2005-12-01 3Wave Optics, Llc Non-invasive blood component measurement system
WO2005077260A1 (en) 2004-02-12 2005-08-25 Biopeak Corporation Non-invasive method and apparatus for determining a physiological parameter
US7162288B2 (en) * 2004-02-25 2007-01-09 Nellcor Purtain Bennett Incorporated Techniques for detecting heart pulses and reducing power consumption in sensors
US7534212B2 (en) * 2004-03-08 2009-05-19 Nellcor Puritan Bennett Llc Pulse oximeter with alternate heart-rate determination
US7277741B2 (en) 2004-03-09 2007-10-02 Nellcor Puritan Bennett Incorporated Pulse oximetry motion artifact rejection using near infrared absorption by water
US20050228248A1 (en) 2004-04-07 2005-10-13 Thomas Dietiker Clip-type sensor having integrated biasing and cushioning means
US7551950B2 (en) * 2004-06-29 2009-06-23 O2 Medtech, Inc,. Optical apparatus and method of use for non-invasive tomographic scan of biological tissues
US7343186B2 (en) * 2004-07-07 2008-03-11 Masimo Laboratories, Inc. Multi-wavelength physiological monitor
US7548771B2 (en) 2005-03-31 2009-06-16 Nellcor Puritan Bennett Llc Pulse oximetry sensor and technique for using the same on a distal region of a patient's digit

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5524631A (en) 1994-10-13 1996-06-11 The United States Of America As Represented By The Administrator Of The National Aeronautics And Space Administration Passive fetal heart rate monitoring apparatus and method with enhanced fetal heart beat discrimination
US5853364A (en) 1995-08-07 1998-12-29 Nellcor Puritan Bennett, Inc. Method and apparatus for estimating physiological parameters using model-based adaptive filtering
US6083172A (en) 1995-08-07 2000-07-04 Nellcor Puritan Bennett Incorporated Method and apparatus for estimating physiological parameters using model-based adaptive filtering
US6411833B1 (en) 1995-08-07 2002-06-25 Nellcor Puritan Bennett Incorporated Method and apparatus for estimating physiological parameters using model-based adaptive filtering
US20020072660A1 (en) * 1999-03-25 2002-06-13 Diab Mohamed K. Pulse oximeter probe-off detector

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
REUSS J L ET AL: "Period domain analysis in fetal pulse oximetry", SECOND JOINT EMBS-BMES CONFERENCE 2002. CONFERENCE PROCEEDINGS. 24TH. ANNUAL INTERNATIONAL CONFERENCE OF THE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL FALL MEETING OF THE BIOMEDICAL ENGINEERINGSOCIETY. HOUSTON, TX,, vol. VOL. 1 OF 3. CONF. 24, 23 October 2002 (2002-10-23), pages 1742 - 1743, XP010620304, ISBN: 0-7803-7612-9 *

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