Apparatus with automatic respiration monitoring and display

Abstract

A respiratory device is provided with a display showing a respiration signal related to a breathing pattern of a patient. This signal is derived from the difference between a sensed signal indicative of the respiration and airflow generated by the device and a baseline signal. The parameter is adjusted so that the respiration signal is restricted to a predetermined dynamic range. A short term average of the respiration signal (taken over about 0.5 seconds) and a long term average of respiration signals (taken over about 12 seconds) are calculated based on the CPAP measure. These averages are used to monitor the dynamic change in the respiration signal. If a large variation in either average is detected, the baseline is set to a value selected to rapidly reduce the respiration signal to a lower offset.

1 - 30 . (canceled)  
   
   
       31 . An improvement for a display having a predetermined display range and operative to display a signal whose baseline varies, said baseline varying sufficiently to cause the signal to go beyond said display range in the absence of adjustment of the signal baseline, comprising a first averager used to determine a long-term average of said signal, a second averager used to determine a short-term average of said signal, and a display adjusting circuit for adjusting the baseline of said signal in accordance with said long-term and short-term averages to restrict said signal to said predetermined display range.  
   
   
       32 . An improvement for a display in accordance with  claim 31  wherein said short-term average is used to adjust said baseline only if the difference between said long-term average and the current baseline does not exceed a threshold value.  
   
   
       33 . An improvement for a display in accordance with  claim 32  wherein each of said averages is used to adjust said baseline only if the difference between it and the current baseline exceeds a threshold value.  
   
   
       34 . An improvement for a display in accordance with  claim 31  wherein each of said averages is used to adjust said baseline only if the difference between it and the current baseline exceeds a threshold value.  
   
   
       35 . A display unit having a predetermined display range for displaying a signal whose baseline varies, said baseline varying sufficiently to cause the signal to go beyond said display range in the absence of adjustment of the signal baseline, comprising an averaging circuit that operates on said signal to derive short-term and long-term averages thereof, and a circuit for adjusting the baseline of said signal in accordance with said long-term and short-term averages to restrict said signal to said predetermined display range, said adjusting circuit operating to adjust said signal in accordance with said long-term average in response to one set of conditions and to adjust said signal in accordance with said short-term average in response to another set of conditions.  
   
   
       36 . A display unit in accordance with  claim 35  wherein said short-term average is used to adjust said baseline only if the difference between said long-term average and the current baseline does not exceed a threshold value.  
   
   
       37 . A display unit in accordance with  claim 36  wherein each of said averages is used to adjust said baseline only if the difference between it and the current baseline exceeds a threshold value.  
   
   
       38 . A display unit in accordance with  claim 35  wherein each of said averages is used to adjust said baseline only if the difference between it and the current baseline exceeds a threshold value.  
   
   
       39 . A display unit having a predetermined display range for displaying a signal whose baseline varies, said baseline varying sufficiently to cause the signal to go beyond said display range in the absence of adjustment of the signal baseline, comprising a control unit for (a) determining long-term and short-term averages of said signal, (b) comparing said long-term average to the current baseline of said signal and changing said baseline in accordance with said long-term average if the difference between the current baseline and said long-term average is equal to or greater than a predetermined value; and (c) if said difference is less than said predetermined value, then comparing said short-term average to the current baseline and changing said baseline in accordance with said short-term average if the difference between the current baseline and said short-term average is greater than a predetermined value.  
   
   
       40 . A display unit in accordance with  claim 39  wherein said long-term average is calculated over a period of about twelve seconds.  
   
   
       41 . A display unit in accordance with  claim 39  wherein said short-term average is calculated over a period of about 0.5 seconds.  
   
   
       42 . A method for presenting a signal on a display having a predetermined display range, the method comprising the steps of: 
 determining a short-term average of said signal and a long-term average of said signal;    comparing the current baseline of the signal used for the display to said long-term average and if the difference between said current baseline and said long-term average is equal to or greater than a predetermined value, then changing said baseline to said long-term average; and    if the difference between the current baseline of the signal used for the display and said long-term average is less than said predetermined value, then comparing the current baseline of the signal used for the display to said short-term average and if the difference between said current baseline and said short-term average is greater than a predetermined value, then changing said baseline to said short-term average.    
   
   
       43 . A method in accordance with  claim 42  wherein said long-term average is calculated over a period of about twelve seconds.  
   
   
       44 . A method in accordance with  claim 42  wherein said short-term average is calculated over a period of about 0.5 seconds.