Patent ID: 8282562

Claim:
A method for use with an implantable medical device for implant within a patient, said method comprising: determining, using a fluid perfusion transfer rate determination system, a fluid perfusion transfer rate representative of transfer of fluids from heart-to-lung within a patient; and controlling, using a cardiopulmonary fluid transfer rate-based controller, at least one device function in response to the fluid perfusion transfer rate; wherein determining a fluid perfusion transfer rate comprises: measuring values representative of electrical admittance through at least a portion of the lungs; identifying a first set of values measured while the patient is in a sleep posture; determining a first exponential time-constant (k 1 ) based on the first set of values; and equating the first exponential time-constant (k 1 ) with the rate of transfer of fluids from heart-to-lung within the patient; wherein determining a first exponential time-constant (k 1 ) comprises fitting a curve of the form: Adm( u,t )= DC+A *(1 −u )*(1−exp(− k 1 *t )) to the values measured, wherein “DC” represents a minimum detected admittance during the period, “A” represents a maximum detected admittance during the period minus DC, and u=0 for admittance data collected while the patient is in a sleep posture for a sufficient amount of time for admittance to increase significantly.