Non-invasive monitoring of respiratory rate, heart rate and apnea

Abstract

A method and apparatus for estimating a respiratory rate of a patient. The method comprises the steps of recording respiratory sounds of the patient, deriving a plurality of respiratory rates from the recorded sounds using a plurality of respiratory rate estimating methods and applying a heuristic to the plurality of derived respiratory rates, the heuristic selecting one of the derived respiratory rates. The selected respiratory rate is the estimated respiratory rate. The apparatus comprises at least one sensor recording respiratory sounds of the patient, a plurality of respiratory rate processors, each of the processors comprising a respiratory rate calculating method, a heuristic means for selecting one of the calculated respiratory rates and a display means for displaying the selected respiratory as the estimated respiratory rate.

1 - 20 . (canceled) 
     
     
         21 . A method for estimating a respiratory rate of a patient, the method comprising:
 receiving respiratory sound data from at least one acoustic sensor, the respiratory sound data representing respiratory sounds of a patient;   deriving a plurality of respiratory rates from the respiratory sound data with a processor using a plurality of different respiratory rate estimating methods, wherein the plurality of different respiratory rate estimating methods comprises at least one time domain method and at least one frequency domain method; and   determining an estimated respiratory rate based at least in part on the plurality of respiratory rates; and   outputting the estimated respiratory rate.   
     
     
         22 . The method of  claim 21 , wherein the at least one time domain method comprises determining a first respiratory rate of the plurality of respiratory rates using a time domain representation of the respiratory sound data, and the at least one frequency domain method comprises determining a second respiratory rate of the plurality of respiratory rates using a frequency domain representation of the respiratory sound data. 
     
     
         23 . The method of  claim 21 , wherein the at least one time domain method comprises determining a first envelope of the respiratory sound data in a time domain representation of the respiratory sound data and deriving a first respiratory rate of the plurality of respiratory rates based at least on a frequency of the first envelope or a period of the first envelope. 
     
     
         24 . The method of  claim 23 , wherein the at least one frequency domain method comprises determining a second envelope of the respiratory sound data in a frequency domain representation of the respiratory sound data and deriving a second respiratory rate of the plurality of respiratory rates based at least on a frequency of the second envelope or a period of the second envelope. 
     
     
         25 . The method of  claim 21 , wherein the at least one frequency domain method comprises determining a second envelope of the respiratory sound data in a frequency domain representation of the respiratory sound data and deriving a second respiratory rate of the plurality of respiratory rates based at least on a frequency of the second envelope or a period of the second envelope. 
     
     
         26 . The method of  claim 21 , wherein the estimated respiratory rate comprises one of the plurality of respiratory rates. 
     
     
         27 . The method of  claim 21 , wherein said determining the estimated respiratory rate comprises determining the estimated respiratory rate based at least on a comparison between a previously estimated respiratory rate and the plurality of respiratory rates. 
     
     
         28 . The method of  claim 21 , wherein at least some of the same set of samples of the respiratory sound data are used to derive a first respiratory rate of the plurality of respiratory rates and a second respiratory rate of the plurality of respiratory rates, the first respiratory rate derived using the at least one time domain method and the second respiratory rate derived using the at least one frequency domain method. 
     
     
         29 . The method of  claim 21 , wherein the at least one acoustic sensor comprises one acoustic sensor. 
     
     
         30 . The method of  claim 21 , wherein the at least one acoustic sensor is coupled to a neck of the patient. 
     
     
         31 . An apparatus for estimating a respiratory rate of a patient, the apparatus comprising:
 an input configured to receive respiratory sound data from at least one acoustic sensor, the respiratory sound data representing respiratory sounds of a patient; and   a processor configured to:
 derive a plurality of respiratory rates from the respiratory sound data using a plurality of different respiratory rate estimating methods, wherein the plurality of different respiratory rate estimating methods comprises at least one time domain method and at least one frequency domain method; 
 determine an estimated respiratory rate based at least on the plurality of respiratory rates; and 
 output the estimated respiratory rate. 
   
     
     
         32 . The apparatus of  claim 31 , wherein the at least one time domain method comprises determining a first respiratory rate of the plurality of respiratory rates using a time domain representation of the respiratory sound data, and the at least one frequency domain method comprises determining a second respiratory rate of the plurality of respiratory rates using a frequency domain representation of the respiratory sound data. 
     
     
         33 . The apparatus of  claim 31 , wherein the at least one time domain method comprises determining a first envelope of the respiratory sound data in a time domain representation of the respiratory sound data and deriving a first respiratory rate of the plurality of respiratory rates based at least on a frequency of the first envelope or a period of the first envelope. 
     
     
         34 . The apparatus of  claim 33 , wherein the at least one frequency domain method comprises determining a second envelope of the respiratory sound data in a frequency domain representation of the respiratory sound data and deriving a second respiratory rate of the plurality of respiratory rates based at least on a frequency of the second envelope or a period of the second envelope. 
     
     
         35 . The apparatus of  claim 31 , wherein the at least one frequency domain method comprises determining a second envelope of the respiratory sound data in a frequency domain representation of the respiratory sound data and deriving a second respiratory rate of the plurality of respiratory rates based at least on a frequency of the second envelope or a period of the second envelope. 
     
     
         36 . The apparatus of  claim 31 , wherein the estimated respiratory rate comprises one of the plurality of respiratory rates. 
     
     
         37 . The apparatus of  claim 31 , wherein the processor is configured to determine the estimated respiratory rate based at least on a comparison between a previously estimated respiratory rate and the plurality of respiratory rates. 
     
     
         38 . The apparatus of  claim 31 , wherein the processor is configured to use at least some of the same set of samples of the respiratory sound data to derive a first respiratory rate of the plurality of respiratory rates and a second respiratory rate of the plurality of respiratory rates, the first respiratory rate derived using the at least one time domain method and the second respiratory rate derived using the at least one frequency domain method. 
     
     
         39 . The apparatus of  claim 31 , wherein the at least one acoustic sensor comprises one acoustic sensor. 
     
     
         40 . The apparatus of  claim 31 , wherein the at least one acoustic sensor is coupled to a neck of the patient.