METHODS FOR DETECTING AND MONITORING SLEEP DISORDERED BREATHING USING AN IMPLANTABLE MEDICAL DEVICE

• US 20090171220A1
• Filed: 12/30/2008
• Published: 07/02/2009
• Est. Priority Date: 09/28/2005
• Status: Active Grant

• Current Assignee: Medtronic Incorporated (Medtronic Plc)
• Original Assignee: Medtronic Incorporated (Medtronic Plc)
• Inventors: Bennett, Tommy D., Kjellstrom, Barbro M., Cho, Yong Kyun
• Granted Patent: US 7,988,635 B2
• Time in Patent Office: Days
• US Class Current: 600/483
• CPC Class Codes: A61B 5/0215 by means inserted into the body catheters A61M25/00
• CPC Class Codes: A61B 5/283 Invasive
• CPC Class Codes: A61B 5/4818 Sleep apnoea
• CPC Class Codes: A61B 5/7239 using differentiation including higher order derivatives

Abstract

A method of identifying sleep disordered breathing (SDB) in a patient includes monitoring a hemodynamic pressure, deriving high, middle, and low values representative of the distribution of the hemodynamic pressure over a storage interval, measuring a ratio of a lower range to a full range of the hemodynamic pressure based on the derived high, middle, and low values, and using the ratio to determine whether the patient has experienced an SDB episode. Certain embodiments of the invention compare the ratio to a threshold value to identify the occurrence of an SDB episode, while other embodiments of the invention identify the occurrence of an SDB episode by monitoring for a simultaneous increase in both the ratio and the full range of the hemodynamic pressure. In certain other embodiments of the invention, activity level and/or duration criteria may be employed to confirm the occurrence of an SDB episode detected using the ratio.

Claims

1. A method of identifying sleep disordered breathing (SDB) in a patient, the method comprising:

measuring a hemodynamic pressure over a period of time;

monitoring an activity level signal of a patient over the period of time;

measuring a phase difference between the hemodynamic pressure and activity level signals; and

identifying the presence of SDB if the phase difference is greater than a threshold amount.

2. The method of claim 1 wherein the phase difference is measured by a correlation coefficient.

3. The method of claim 1 wherein the phase difference is measured by comparing a derivative of the hemodynamic pressure to a derivative of the activity level signal and identifying when the derivatives are of the same polarity.

4. A method of identifying sleep disordered breathing (SDB) in a patient, the method comprising:

measuring a hemodynamic pressure signal over a period of time;

monitoring an activity level signal of a patient over the period of time;

classifying the activity level as being low when below a predetermined activity level; and

during a period when activity level is classified as low, identifying the presence of SDB when a change in the hemodynamic pressure signal is greater than a threshold.

5. The method of claim 4 wherein the change in the hemodynamic pressure signal is a decrease of greater than a predetermined threshold.