Advanced thoracic fluid monitoring capability with impedance

Abstract

Advanced thoracic fluid monitoring capabilities using impedance are disclosed. An implantable medical device used for detection of changes in impedance in a patient can have means for measuring impedances of the patient in a supine position and in an upright position. Impedance differences can be generated which correspond to a diurnal delta value showing impedance differences between the supine and upright positions.

1 . A computer-readable medium programmed with instructions for performing a method in an implantable medical device, the medium comprising instructions for causing a programmable processor to:
 measure impedances of a patient in a supine position;   measure impedances of the patient in an upright position; and   generate a diurnal delta corresponding to impedance differences between the supine and upright positions.   
     
     
         2 . A medium according to  claim 1 , further comprising instructions to reset certain impedance data after receipt of a reset input. 
     
     
         3 . A medium according to  claim 1 , wherein an alarm is initiated if the supine position impedance measurements drop below a threshold. 
     
     
         4 . A medium according to  claim 1 , wherein an alarm is initiated if the upright position impedance measurements drop below a threshold. 
     
     
         5 . A medium according to  claim 1 , further comprising instructions to detect when the patient is in the supine position. 
     
     
         6 . A medium according to  claim 1 , further comprising instructions to wait a predetermined time limit before measuring impedances when the patient is first detected in the supine position. 
     
     
         7 . A medium according to  claim 1 , further comprising instructions to determine whether the diurnal delta values are increasing or decreasing over time. 
     
     
         8 . A medium according to  claim 1 , further comprising instructions to determine whether a predetermined time limit has elapsed during which the delta value was increasing or decreasing.