Volume depletion detection

Abstract

Detection of volume depletion, particularly after an incidence of volume overload is disclosed. Various methods, systems, and devices are disclosed that sense and analyze a physiological parameter related to a patient's fluid level in order to warn patients of potentially dangerous volume depletion conditions while minimizing false notifications.

1 . A method of detecting volume depletion in a patient comprising:
 measuring a physiological parameter indicative of a patient's fluid volume to determine measured values;   calculating long term averages and short term averages of the measured values;   comparing the short term averages to the long term averages to determine the presence of a volume overload condition; and   comparing the short term averages to the long term averages to determine the presence of a volume depletion condition after determining the presence of the volume overload condition.   
     
     
         2 . A method according to  claim 1 , wherein the physiological parameter measured includes blood pressure. 
     
     
         3 . A method according to  claim 2 , wherein the blood pressure being measured includes one of at least right ventricular systolic pressure (RVSP) and right ventricular diastolic pressures (RVDP), estimated pulmonary artery diastolic pressure (ePAD). 
     
     
         4 . A method according to  claim 1 , wherein the detection of the volume overload condition includes determining whether the values of a predetermined number of consecutive short term averages exceed the values of associated long term averages. 
     
     
         5 . A method according to  claim 4 , wherein the detection of the volume depletion condition includes determining whether the values of a predetermined number of consecutive long term averages exceed the values of associated long term averages following the detection of the volume overload condition. 
     
     
         6 . A method according to  claim 5 , wherein the consecutive averages following the detection of the volume overload condition all fall within a predetermined amount of time. 
     
     
         7 . A method according to  claim 5 , wherein the detection of the volume depletion condition includes determining whether the values of the long term averages exceed the values of the associated short term averages by a threshold level. 
     
     
         8 . A method according to  claim 5 , further including determining the threshold amount based on an amounts by which the short term averages deviate from the long term averages before the detection of the volume overload condition. 
     
     
         9 . A method according to  claim 1 , wherein the short term averages and long term averages used in each comparison are based on values measured up until the same point in time. 
     
     
         10 . A method according to  claim 1 , further including notifying the patient after the detection of volume depletion.