Signal processing techniques for aiding the interpretation of respiration signals

Abstract

According to embodiments, a respiration signal may be processed to normalize respiratory feature values in order to improve and/or simplify the interpretation and subsequent analysis of the signal. Data indicative of a signal may be received at a sensor and may be used to generate a respiration signal. Signal peaks in the respiration signal may be identified and signal peak thresholds may be determined. The identified signal peaks may be adjusted based on the signal peak threshold values to normalize the respiration signal.

What is claimed: 
     
         1 . A method for processing a physiological signal, comprising:
 receiving, using a processor, the physiological signal;   generating, using the processor, a wavelet transform based at least in part on the physiological signal, wherein the wavelet transform comprises phase information;   identifying, using the processor, phase values corresponding to respiration based at least in part on the wavelet transform; and   generating, using the processor, a substantially sinusoidal function based at least in part on the phase values, wherein the substantially sinusoidal function is indicative of respiration phase.   
     
     
         2 . The method of  claim 1 , wherein the substantially sinusoidal function comprises normalized height values. 
     
     
         3 . The method of  claim 1 , wherein identifying the phase values comprises identifying a respiration ridge based at least in part on the wavelet transform. 
     
     
         4 . The method of  claim 3 , wherein the respiration ridge comprises local phase values as a function of time. 
     
     
         5 . The method of  claim 1 , wherein generating the sinusoidal function comprises determining the cosine or sine of the phase values. 
     
     
         6 . The method of  claim 1 , wherein generating the sinusoidal function comprises determining an inverse wavelet transform of the phase values as a function of time. 
     
     
         7 . The method of  claim 1 , further comprising determining a respiration parameter based at least in part on the substantially sinusoidal function. 
     
     
         8 . The method of  claim 1 , further comprising generating a display based at least in part on the substantially sinusoidal function. 
     
     
         9 . The method of  claim 8 , wherein the display comprises a bar graph. 
     
     
         10 . The method of  claim 1 , wherein the physiological signal is a photoplethysmograph signal. 
     
     
         11 . A system for processing a physiological signal, comprising:
 a processor configured to perform operations comprising:
 receiving the physiological signal; 
 generating a wavelet transform based at least in part on the physiological signal, wherein the wavelet transform comprises phase information; 
 identifying phase values corresponding to respiration based at least in part on the wavelet transform; and 
 generating a substantially sinusoidal function based at least in part on the phase values, wherein the substantially sinusoidal function is indicative of respiration phase. 
   
     
     
         12 . The system of  claim 11 , wherein the substantially sinusoidal function comprises normalized height values. 
     
     
         13 . The system of  claim 11 , wherein identifying the phase values comprises identifying a respiration ridge based at least in part on the wavelet transform. 
     
     
         14 . The system of  claim 13 , wherein the respiration ridge comprises local phase values as a function of time. 
     
     
         15 . The system of  claim 11 , wherein generating the sinusoidal function comprises determining the cosine or sine of the phase values. 
     
     
         16 . The system of  claim 11 , wherein generating the sinusoidal function comprises determining an inverse wavelet transform of the phase values as a function of time. 
     
     
         17 . The system of  claim 11 , wherein the processor is configured to perform operations further comprising determining a respiration parameter based at least in part on the substantially sinusoidal function. 
     
     
         18 . The system of  claim 11 , wherein the processor is configured to perform operations further comprising generating a display based at least in part on the substantially sinusoidal function. 
     
     
         19 . The system of  claim 18 , wherein the display comprises a bar graph. 
     
     
         20 . The system of  claim 11 , wherein the physiological signal is a photoplethysmograph signal. 
     
     
         21 . A method for processing a respiration signal, comprising:
 obtaining, using a processor, the respiration signal;   determining, using the processor, one or more signal thresholds for the respiration signal based at least in part on the respiration signal;   identifying, using the processor, one or more portions of the respiration signal that exceed at least one of the one or more signal thresholds;   selectively adjusting, using the processor, the amplitude of the respiration signal based at least in part on the identified one or more portions to generate an adjusted respiration signal, wherein the amplitude of at least one peak in the respiration signal is adjusted; and   determining, using the processor, a respiration parameter based at least in part on the adjusted respiration signal.   
     
     
         22 . The method of  claim 21 , wherein the one or more signal thresholds comprise an upper threshold and a lower threshold, wherein selectively adjusting comprises reducing the amplitude of the at least one peak, and wherein at least one other peak below the lower threshold remains unadjusted.