CRITERIA FOR MONITORING INTRATHORACIC IMPEDANCE

• US 20090270746A1
• Filed: 07/07/2009
• Published: 10/29/2009
• Est. Priority Date: 11/07/2005
• Status: Active Grant

• Current Assignee: Pacesetter Incorporated (Abbott Laboratories)
• Original Assignee: Pacesetter Incorporated (Abbott Laboratories)
• Inventors: Min, Xiaoyi
• Granted Patent: US 8,452,389 B2
• Time in Patent Office: Days
• US Class Current: 600/508
• CPC Class Codes: A61B 5/02028 Determining haemodynamic parameters not otherwise provided for, e.g. cardiac contractility or left ventricular ejection fraction
• CPC Class Codes: A61B 5/0205 Simultaneously evaluating both cardiovascular conditions and different types of body conditions, e.g. heart and respiratory condition
• CPC Class Codes: A61B 5/053 Measuring electrical impedance or conductance of a portion of the body
• CPC Class Codes: A61B 5/0538 invasively, e.g. using a catheter
• CPC Class Codes: A61B 5/4878 Evaluating oedema
• CPC Class Codes: A61N 1/36521 the parameter being derived from measurement of an electrical impedance
• CPC Class Codes: A61N 1/3702 Physiological parameters A61N1/365 takes precedence; evoked response A61N1/371
• CPC Class Codes: A61N 1/3943 for threshold determination
• CPC Class Codes: A61N 1/39622 Pacing therapy

Abstract

An exemplary method includes providing information (e.g., a left atrial pressure, a NYHA class, echocardiographic information, etc.), based at least in part on the information, determining a weight and, based at least in part on the weight, determining a threshold for use in intrathoracic impedance monitoring. Such an exemplary method may include comparing an intrathoracic impedance to the threshold, comparing an intrathoracic impedance change to the threshold, or comparing a product of intrathoracic impedance and time to the threshold. Various exemplary methods, devices, systems, etc., are disclosed.

Claims

1. An implantable device comprising:

a processor;

an impedance measuring circuit operably connected to the processor; and

control logic operable in conjunction with the processor to;

acquire a NYHA class for a patient,

determine a weight based on the NYHA class,

calculate a threshold based at least in part on the weight, and

compare the threshold to one or more of an intrathoracic impedance, a change in intrathoracic impedance, and a product of intrathoracic impedance and time.

2. The device of claim 1 wherein the control logic is further operable in conjunction with the processor to decide, based on the comparison, whether to trigger a pulmonary edema alarm.

3. The device of claim 1 wherein the impedance measuring circuit is operative to measure intracardiac impedance.

4. The device of claim 1 wherein the product has units of ohms-days.

5. The device of claim 1 wherein the threshold pertains to pulmonary edema occurring in a period of less than one day.

6. The device of claim 1 wherein the threshold pertains to pulmonary edema occurring over a period of more than one day.

7. The device of claim 1 wherein the threshold pertains to pulmonary edema associated with an increase in dry lung weight.

8. The device of claim 1 wherein the threshold comprises a percentage decrease in intrathoracic impedance from a base value or baseline.

9. A system comprising:

means for acquiring a NYHA class for a patient; and

means for determining a threshold for use in intrathoracic impedance monitoring based at least in part on the NYHA class.

10. The system of claim 9 further comprising means for comparing an intrathoracic impedance to the threshold.

11. The system of claim 9 further comprising means for comparing an intrathoracic impedance change to the threshold.

12. The system of claim 9 wherein the means for determining a threshold comprises means for determining a value pertaining to pulmonary edema occurring in a period of less than one day.

13. The system of claim 9 wherein the means for determining a threshold comprises means for determining a value pertaining to pulmonary edema occurring over a period of more than one day.