Respiration processor

• US 10,595,747 B2
• Filed: 08/04/2017
• Issued: 03/24/2020
• Est. Priority Date: 10/16/2009
• Status: Active Grant

• Current Assignee: Masimo Corporation
• Original Assignee: Masimo Corporation
• Inventors: Al-Ali, Ammar, Weber, Walter M., Majmudar, Anmol B., Sierra, Gilberto, Lee, Sung Uk, Diab, Mohamed, Telfort, Valery G., Pelletier, Marc, Popov, Boris
• Primary Examiner(s): Jang, Christian
• Application Number:
  US15/669,201
• Publication Number:
  US 20180014752A1
• Time in Patent Office: 963 Days
• CPC Class Codes: A61B 5/08 Detecting, measuring or recording devices for evaluating the respiratory organs A61B5/0205 takes precedence
• CPC Class Codes: A61B 5/0816 Measuring devices for examining respiratory frequency measuring frequency of electric signals G01R23/00
• CPC Class Codes: A61B 5/7221 Determining signal validity, reliability or quality A61B5/7207 and A61B5/7217 take precedence
• CPC Class Codes: A61B 5/7257 using Fourier transforms
• CPC Class Codes: A61B 7/003 Detecting lung or respiration noise

Abstract

Respiratory rate can be calculated from an acoustic input signal using time domain and frequency domain techniques. Confidence in the calculated respiratory rate can also be calculated using time domain and frequency domain techniques. Overall respiratory rate and confidence values can be obtained from the time and frequency domain calculations. The overall respiratory rate and confidence values can be output for presentation to a clinician.

Claims

1. A system for monitoring respiration of a patient using a signal received from a physiological sensor adapted to be coupled with the patient, the system comprising:

a signal filter configured to;

receive an acoustic signal from an acoustic sensor adapted to be coupled to a patient, and

filter the acoustic signal to generate a filtered output signal;

a high gain stage configured to generate a first amplified output signal from the filtered output signal by amplifying the filtered output signal with a first gain level;

a low gain stage configured to generate a second amplified output signal from the filtered output signal by amplifying the filtered output signal with a second gain level lower than the first gain level; and

one or more hardware processors configured to;

responsive to a magnitude of the first amplified output signal satisfying a first threshold, select one of the first amplified output signal or the second amplified output signal to be a selected signal for further processing,

determine first respiratory rates from a first domain representation of the selected signal and second respiratory rates from a second domain representation of the selected signal, the first domain representation being different from the second domain representation,

assign first confidence values to the first respiratory rates using one or more of (i) a calculation of a spectral density of energy in the first domain representation, (ii) a calculation of a harmonic energy in the first domain representation, (iii) a comparison of local maximums in the first domain representation and one or more magnitude thresholds, or (iv) a comparison of maximum frequency components in the first domain representation and one or more frequency thresholds,

assign second confidence values to the second respiratory rates using the second domain representation,

determine overall respiratory rates from the first respiratory rates and the second respiratory rates using the first confidence values and the second confidence values, and

output at least some of the overall respiratory rates in real time to a display for presentation on the display.

2. The system of claim 1, wherein

at a first time, the first amplified output signal is selected by the one or more hardware processors to be the selected signal, and

at a second time subsequent to the first time, the one or more hardware processors is configured to, responsive to the magnitude of the first amplified output signal satisfying the first threshold, switch from selecting the first amplified output signal to be the selected signal to selecting the second amplified output signal to be the selected signal so that the second amplified output signal is subsequently used for determining the overall respiratory rates rather than the first amplified output signal.

3. The system of claim 1, wherein the one or more hardware processors is configured to, responsive to a magnitude of the second amplified output signal satisfying a second threshold, determine that the second amplified output signal is not indicative of a valid clinical data sample and output an indication denoting that the second amplified output signal is not indicative of the valid clinical data sample.

4. The system of claim 1, wherein when the first amplified output signal is selected by the one or more hardware processors to be the selected signal, the one or more hardware processors is configured to not determine any respiratory rates from the second amplified output signal.

5. The system of claim 1, wherein the first domain representation is a time domain representation of the selected signal, and the second domain representation is a frequency domain representation of the selected signal.

6. The system of claim 1, wherein the first domain representation is a frequency domain representation of the selected signal, and the second domain representation is a time domain representation of the selected signal.

7. The system of claim 1, wherein the one or more hardware processors is configured to assign the first confidence values to the first respiratory rates using the calculation of the spectral density of energy in the first domain representation.

8. The system of claim 1, wherein the one or more hardware processors is configured to assign the first confidence values to the first respiratory rates using the calculation of the harmonic energy in the first domain representation.

9. The system of claim 1, wherein the one or more hardware processors is configured to assign the first confidence values to the first respiratory rates using (iii) the comparison of the local maximums in the first domain representation and the one or more magnitude thresholds or (iv) the comparison of the maximum frequency components in the first domain representation and the one or more frequency thresholds.

10. The system of claim 1, further comprising a housing configured to support the signal filter, the high gain stage, the low gain stage, and the one or more hardware processors.

11. The system of claim 1, wherein the one or more hardware processors is configured to determine the overall respiratory rates by selecting, using the first confidence values and the second confidence values, a subset of the first respiratory rates and the second respiratory rates to be the overall respiratory rates.

12. The system of claim 1, wherein the one or more hardware processors is configured to:

determine third respiratory rates from a third domain representation of the selected signal, the third domain representation being different from the first domain representation and derived from a shorter time window of the selected signal than the second domain representation;

assign third confidence values to the third respiratory rates; and

determine the overall respiratory rates further from the third respiratory rates and the third confidence values.

13. The system of claim 1, further comprising the acoustic sensor, the acoustic sensor comprising a piezoelectric device.

14. The system of claim 1, wherein the acoustic signal comprises a first range of frequencies and a second range of frequencies different from the first range of frequencies, and the signal filter is configured to attenuate the first range of frequencies and pass the second range of frequencies without attenuation to generate the filter output signal.

15. A method for monitoring respiration of a patient using a signal received from a physiological sensor coupled with the patient, the method comprising:

detecting, using an acoustic sensor coupled to a patient, an acoustic signal;

filtering, using a signal filter, the acoustic signal to generate a filtered output signal;

generating, using first electronic circuitry, a first amplified output signal from the filtered output signal by amplifying the filtered output signal with a first gain level;

generating, using second electronic circuitry, a second amplified output signal from the filtered output signal by amplifying the filtered output signal with a second gain level lower than the first gain level;

selecting, using one or more hardware processors, one of the first amplified output signal or the second amplified output signal to be a selected signal for further processing;

determining, using the one or more hardware processors, first respiratory rates from a time domain representation of the selected signal and second respiratory rates from a frequency domain representation of the selected signal;

determining, using the one or more hardware processors, first confidence values for the first respiratory rates, the first confidence values being indicative of one or more features of local maximums in the time domain representation;

determining, using the one or more hardware processors, second confidence values for the second respiratory rates using the frequency domain representation;

determining, using the one or more hardware processors, overall respiratory rates from the first respiratory rates and the second respiratory rates using the first confidence values and the second confidence values; and

displaying, on a display, at least some of the overall respiratory rates in real time.

16. The method of claim 15, further comprising:

when the selected signal is the first amplified output signal, determining that a magnitude of the first amplified output signal satisfies a threshold; and

in response to determining that the magnitude of the first amplified output signal satisfies the threshold, switching, with the one or more hardware processors, from selecting the first amplified output signal to be the selected signal to selecting the second amplified output signal to be the selected signal so that the second amplified output signal is subsequently used for determining the overall respiratory rates rather than the first amplified output signal.

17. The method of claim 15, wherein the one or more features comprises magnitudes of the local maximums.

18. The method of claim 15, wherein the one or more features comprises maximum frequency components in frequency spectrums of the local maximums.

19. The method of claim 15, wherein the one or more features comprises frequency spectral densities of energy in frequency spectrums of the local maximums.

20. The method of claim 15, wherein said determining the overall respiratory rates comprises selecting the overall respiratory rates from the first respiratory rates and the second respiratory rates according at least to trends in the first confidence values and the second confidence values.

21. The method of claim 15, further comprising:

determining, with the one or more hardware processors, third respiratory rates from another frequency domain representation of the selected signal, the another frequency domain representation being derived from a shorter time window of the selected signal than the frequency domain representation; and

determining, using the one or more hardware processors, third confidence values for the third respiratory rates from the another frequency domain representation,

wherein said determining the overall respiratory rates comprises determining the overall respiratory rates further from the third respiratory rates and the third confidence values.