Detection of asynchrony

Abstract

A controller or processor(s) implements detection of respiratory related conditions, such as asynchrony, associated with use of a respiratory treatment apparatus or ventilator. Based on data derived from sensor signals associated with the respiratory treatment, the detector may evaluate a feature set of detection values to determine whether or not an asynchrony occurs in a breath of the patient's respiratory cycle such as by comparing the values against a set of thresholds. Different events may also be identified based on the particular feature set and threshold(s) involved in the detection processing. Automated determination of feature sets may also be implemented to design different asynchrony event classifiers. The methodologies may be implemented by computers or by respiratory treatment apparatus. The detection of such asynchrony events can then also serve as part of control logic for automated adjustments to the control parameters of the respiratory treatment generated by the respiratory treatment apparatus.

1 . A respiratory treatment apparatus for estimating respiratory resistance and compliance based on measures of flow and pressure comprising:
 one or more sensors to generate signals representative of flow and pressure; and   a processor, coupled with the one or more sensors, the processor being configured to control:
 detecting a portion of expiration of a breathing cycle from data of the flow signal; and 
 calculating a resistance value and compliance value with flow, pressure and volume measures that correspond to the detected portion of expiration. 
   
     
     
         2 . The respiratory treatment apparatus of  claim 1  wherein the detected portion of expiration begins at an expiration cycle and ends when an expired tidal volume for the expiration cycle exceeds a limit in a range of about 85 to 90 percent. 
     
     
         3 . The respiratory treatment apparatus of  claim 2  wherein the calculating comprises a multiple linear regression process with data representing the flow, pressure and volume measures. 
     
     
         4 . The respiratory treatment apparatus of  claim 3  wherein the resistance value and compliance value are calculated in a breath-by-breath process. 
     
     
         5 . The respiratory treatment apparatus of  claim 2  wherein the processor is further configured to control an assessment of accuracy of the calculated resistance and compliance values. 
     
     
         6 . The respiratory treatment apparatus of  claim 5  wherein the assessment of accuracy comprises calculating a coefficient of determination and comparing it to a threshold. 
     
     
         7 . The respiratory treatment apparatus of  claim 1  wherein the processor is further configured to control determining a PEEP control parameter based on a plurality of compliance values determined by the calculating of the processor. 
     
     
         8 . The respiratory treatment apparatus of  claim 7  wherein the processor controls a repeated change to a preset PEEP control parameter during which a plurality of pressure and flow measures are determined, and wherein the plurality of compliance values are determined based on the plurality of pressure and flow measures. 
     
     
         9 . The respiratory treatment apparatus of  claim 8  wherein the determining of the PEEP control parameter comprises detecting an inflection point from data representing the plurality of compliance values. 
     
     
         10 . The respiratory treatment apparatus of  claim 1  wherein the processor is further configured to control determining a maximum pressure support limit based on a plurality of compliance values determined by the calculating of the processor. 
     
     
         11 . The respiratory treatment apparatus of  claim 10  wherein the processor controls a repeated change to a preset PEEP control parameter during which a plurality of pressure and flow measures are determined, and wherein the plurality of compliance values are determined based on the plurality of pressure and flow measures. 
     
     
         12 . The respiratory treatment apparatus of  claim 8  wherein the determining of the maximum pressure support limit comprises detecting an inflection point from data representing the plurality of compliance values. 
     
     
         13 . The respiratory treatment apparatus of  claim 4  further comprising a flow generator, coupled with the processor, to generate a flow of breathable gas at pressures above atmospheric to a patient interface based on control signals from the processor. 
     
     
         14 . A method for estimating respiratory resistance and compliance based on measures of flow and pressure comprising:
 generating, with one or more sensors, signals representative of flow and pressure; and   detecting, in a processor, a portion of expiration of a breathing cycle from data of the flow signal; and   calculating, in the processor, a resistance value and compliance value with flow, pressure and volume measures that correspond to the detected portion of expiration.   
     
     
         15 . The method of  claim 14  wherein the detected portion of expiration begins at an expiration cycle and ends when an expired tidal volume for the expiration cycle exceeds a limit in a range of about 85 to 90 percent. 
     
     
         16 . The method of  claim 15  wherein the calculating comprises a multiple linear regression process with data representing the flow, pressure and volume measures. 
     
     
         17 . The method of  claim 16  wherein the resistance value and compliance value are calculated in a breath-by-breath process. 
     
     
         18 . The method of  claim 15  wherein the processor is further configured to control an assessment of accuracy of the calculated resistance and compliance values. 
     
     
         19 . The method of  claim 18  wherein the assessment of accuracy comprises calculating a coefficient of determination and comparing it to a threshold. 
     
     
         20 . The method of  claim 14  further comprising, determining, in the processor a PEEP control parameter based on a plurality of compliance values determined by the calculating of the processor. 
     
     
         21 . The method of  claim 20 , further comprising, repeatedly, changing, in the processor, a preset PEEP control parameter during which a plurality of pressure and flow measures are determined, and wherein the plurality of compliance values are determined based on the plurality of pressure and flow measures. 
     
     
         22 . The method of  claim 21  wherein the determining of the PEEP control parameter comprises detecting an inflection point from data representing the plurality of compliance values. 
     
     
         23 . The method of  claim 14 , further comprising, determining, in the processor, a maximum pressure support limit based on a plurality of compliance values determined by the calculating of the resistance value and compliance value. 
     
     
         24 . The method of  claim 23  further comprising repeatedly changing a preset PEEP control parameter during which a plurality of pressure and flow measures are determined, and wherein the plurality of compliance values are determined based on the plurality of pressure and flow measures. 
     
     
         25 . The method of  claim 21  wherein the determining of the maximum pressure support limit comprises detecting an inflection point from data representing the plurality of compliance values. 
     
     
         26 . The method of  claim 17  further comprising controlling, with the processor, a flow generator to generate a flow of breathable gas at pressures above atmospheric to a patient interface. 
     
     
         27 . The method of  claim 14  further comprising controlling, with the processor, an operation of a flow generator based on the calculated resistance value and compliance value.