System and method for monitoring cardiopulmonary fluid transfer rates using an implantable medical device

A method for use with an implantable medical device for implant within a patient, said method comprising:

• determining, using a lymphatic fluid excretion rate determination system, a lymphatic fluid excretion rate representative of transfer of fluids from lung-to-lymphatic system;
• and
• controlling, using a cardiopulmonary fluid transfer rate-based controller, at least one device function in response to the lymphatic fluid excretion rate;
• wherein determining a lymphatic fluid excretion rate comprises:
• measuring values representative of electrical admittance through at least a portion of the lungs;
• identifying a second set of values measured while patient is not in a sleep posture;
• determining a second exponential time-constant (k2) based on the second set of values;
• and
• equating the second exponential time-constant (k2) with the rate of fluids from lung-to-lymphatic system within the patient;
• wherein determining the second exponential time-constants (k2) includes fitting a curve of the form:
• Adm(u,t)=DC+A*u*exp(−k2*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=1 for admittance data collected during a subsequent time interval while the patient is not in a sleep posture for a sufficient amount of time for admittance to decrease significantly.

A method for use with an implantable medical device for implant within a patient, the method comprising:

• determining, using a cardiopulmonary fluid transfer rate determination system, a cardiopulmonary fluid transfer rate within the patient, wherein the cardiopulmonary fluid transfer rate includes both a fluid transfer rate from heart-to-lung and a fluid transfer rate from lung-to-lymphatic system:
• and
• controlling, using a cardiopulmonary fluid transfer rate-based controller, at least one device function in response to the cardiopulmonary fluid transfer rate;
• wherein determining the cardiopulmonary fluid transfer rates includes:
• measuring a set of values representative of electrical admittance through at least a portion of the lungs during at least one twenty-four hour period;
• determining a first exponential time-constant (k1) based on values detected while the patient is in a sleep posture;
• determining a second exponential time-constant (k2) based on values detected while the patient is not in a sleep posture;
• equating the first exponential time-constant (k1) with the rate of transfer of fluids from the heart-to-lung;
• and
• equating the second exponential time-constant (k2) with the rate of transfer of fluids from the lung-to-lymphatic system;
• wherein determining the first and second exponential time-constants (k1, k2) includes fitting a curve of the form:
• Adm(u,t)=DC+A*(1−u)*(1−exp(−k1*t))+A*u*exp(−k2*t)
• to the values measured throughout the twenty-four hour period, 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 and u=1 for admittance data collected during a subsequent time interval while the patient is not in a sleep posture for a sufficient amount of time for admittance to decrease significantly.

A system for use with an implantable medical device for implant within a patient, the system comprising:

• a fluid perfusion transfer rate determination system operative to determine a fluid perfusion transfer rate representative of transfer of fluids from heart-to-lung within a patient;
• and
• a cardiopulmonary fluid transfer rate-based controller operative to control at least one device function based on to the fluid perfusion transfer rate;
• wherein the fluid perfusion transfer rate determination system is operative to:
• measure values representative of electrical admittance through at least a portion of the lungs;
• identify a first set of values measured while the patient is in a sleep posture;
• determine a first exponential time-constant (k1) based on the first set of values;
• and
• equate the first exponential time-constant (k1) with the rate of transfer of fluids from heart-to-lung within the patient;
• wherein to determine a first exponential time-constant (k1), the fluid perfusion transfer rate determination system is further operative to fit a curve of the form:
• Adm(u,t)=DC+A*(1−u)*(1−exp(−k1*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.

A system for use with an implantable medical device for implant within a patient, said system comprising:

• a lymphatic fluid excretion rate determination system operative to determine a lymphatic fluid excretion rate representative of transfer of fluids from lung-to-lymphatic system within the patient;
• and
• a cardiopulmonary fluid transfer rate-based controller operative to control at least one device function based on the lymphatic fluid excretion rate;
• wherein the lymphatic fluid excretion rate determination system is operative to:
• measure values representative of electrical admittance through at least a portion of the lungs;
• identify a second set of values measured while patient is not in a sleep posture;
• determine a second exponential time-constant (k2) based on the second set of values;
• and
• equate the second exponential time-constant (k2) with the rate of fluids from lung-to-lymphatic system within the patient;
• wherein, to determine a second exponential time-constant (k2), the lymphatic fluid excretion rate determination system is further operative to fit a curve of the form:
• Adm(u,t)=DC+A*u*exp(−k2*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=1 for admittance data collected during a subsequent time interval while the patient is not in a sleep posture for a sufficient amount of time for admittance to decrease significantly.

A system for use with an implantable medical device for implant within a patient, said system comprising:

• a cardiopulmonary fluid transfer rate determination system operative to determine at least one of a fluid transfer rate from heart-to-lung and a fluid transfer rate from lung-to-lymphatic system;
• and
• a cardiopulmonary fluid transfer rate-based controller operative to control at least one device function based on a cardiopulmonary fluid transfer rate
• wherein the cardiopulmonary fluid transfer rate determination system is operative to:
• measure a set of values representative of electrical admittance through at least a portion of the lungs during at least one twenty-four hour period;
• determine a first exponential time-constant (k1) based on values detected while the patient is in a sleep posture;
• determine a second exponential time-constant (k2) based on values detected while the patient is not in a sleep posture;
• equate the first exponential time-constant (k1) with the rate of transfer of fluids from the heart-to-lung;
• and
• equate the second exponential time-constant (k2) with the rate of transfer of fluids from the lung-to-lymphatic system;
• wherein, to determine the first and second exponential time-constants (k1, k2), the cardiopulmonary fluid transfer rate determination system is further operative to fit a curve of the form:
• Adm(u,t)=DC+A*(1−u)*(1−exp(−k1*t))+A*u*exp(−k2*t)
• to the values measured throughout the twenty-four hour period, 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 and u=1 for admittance data collected during a subsequent time interval while the patient is not in a sleep posture for a sufficient amount of time for admittance to decrease significantly.