System and method for detecting circadian states using an implantable medical device
US7207947B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Jan 10, 2003 |
| Grant date | Apr 24, 2007 |
| Priority date | — |
| Expiry date | Mar 9, 2024 |
Classification
- Technology area (CPC A)Human Necessities
- CPC primaryA61N1/36542
- WIPO fieldMedical technology
- WIPO sectorInstruments
Abstract
Techniques are provided for detecting the circadian state of a patient using an implantable medical device based on selected blood carbon dioxide (CO2) parameters. In one example, the implantable device tracks changes in end tidal CO2 (etCO2) levels and changes in maximum variations of pCO2 levels per breathing cycle (ΔcycleCO2) over the course of the day and determines the circadian state based thereon. It has been found that average etCO2 levels are generally highest and average ΔcycleCO2 levels are generally lowest while a patient is asleep and opposite while a patient is awake. Hence, by tracking changes in average etCO2 and ΔcycleCO2 levels over the course of the day, circadian states can be detected. Minute ventilation and activity levels are used to assist in the determination of the circadian state. Additional techniques are directed to detecting the stage of sleep.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.