Surgery: light – thermal – and electrical application – Light – thermal – and electrical application – Electrical therapeutic systems
Reexamination Certificate
1999-10-21
2002-09-10
Schaetzle, Kennedy (Department: 3762)
Surgery: light, thermal, and electrical application
Light, thermal, and electrical application
Electrical therapeutic systems
C600S595000
Reexamination Certificate
active
06449508
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to determination of activity levels for living beings wearing or having implantable medical devices and particularly to how to determine appropriate values for such activity levels using accelerometer output signal.
BACKGROUND OF THE INVENTION
A wide assortment of body-implantable medical devices may employ activity level signals for a) maintaining records of patient activity, or for b) providing input to devices that deliver therapy. For example, a cardiac pacemaker can adjust a pacing rate in response to higher levels of indicated patient activity, assuming that cardiac demand will respond to the activity and that increasing the pacing rate will fulfill that demand better. Activity levels can be useful for diagnostic purposes too, and having a record of patient activity can provide a window into the state of that patient's state of health.
Examples of activity sensors from the prior art are described in, The following U.S. Patents; Schaldach U.S. Pat. No. 5,215,084, Alt, et al., U.S. Pat. No. 5,649,968, Mann et al., U.S. Pat. Nos. 5,040,535 and 4,940,053, Meyerson et al., U.S. Pat. No. 5,179,974, and Alt, U.S. Pat. No. 5,031,614, all incorporated herein by this reference in their entireties.
Each type of activity signal in the art has strengths and weaknesses relative to accuracy in tracking cardiac demand. Much development work has gone into multisensor systems of which the U.S. Pat. No. 5,562,711 to Yerich, is an example. This patent is also incorporated herein by this reference in its entirety.
There is certainly a need for more refinement in the activity signals available and how to best process them, especially as the art moves from piezocrystal activity crystal sensors to accelerometers.
SUMMARY OF THE INVENTION
Generally we take a plurality of thresholds and apply them to what amount to or may be copies of the accelerometer output signal. From these we get a plurality of different activity counts from the same accelerometer output signal. We then weight them according to a sensitivity setting and combine the count values to establish the preferred count value. We can store this value for recording the patient activity level or use it for diagnostic purposes, or for therapy alteration purposes as in, changing the pacing rate, for example.
We cyclically change the accelerometer circuitry's sensitivity for each short period (we prefer two second periods) to one of (preferably) three settings that are based on the programmed activity threshold. The activity counts obtained at each sensitivity setting will be weighted such that activity counts obtained at less sensitive levels will be more heavily weighted. These activity counts are then combined to create a sensor count value. This value is used to determine the Target Rate. If the current pacing rate, called the Sensor Rate is above (below) the Target Rate, the Sensor Rate will decelerate (accelerate) towards the Target Rate. The acceleration and deceleration of the Sensor Rate towards the target rate is represented by the smoothing of the acceleration/deceleration shown in block
47
of FIG.
3
.
REFERENCES:
patent: 4374382 (1983-02-01), Markowitz
patent: 4476868 (1984-10-01), Thompson
patent: 4485813 (1984-12-01), Anderson
patent: 4556063 (1985-12-01), Thompson
patent: 4940053 (1990-07-01), Mann
patent: 5031614 (1991-07-01), Alt
patent: 5040535 (1991-08-01), Mann
patent: 5052388 (1991-10-01), Sivula
patent: 5127404 (1992-07-01), Wyborny
patent: 5179974 (1993-01-01), Taniguchi
patent: 5215084 (1993-06-01), Schaldach
patent: 5243979 (1993-09-01), Stein et al.
patent: 5562711 (1996-10-01), Yerich
patent: 5635640 (1997-06-01), Geen
patent: 5649968 (1997-07-01), Alt
patent: 5674258 (1997-10-01), Henschel
patent: 5885471 (1999-03-01), Ruben
Ruzin Donald
Sheldon Todd J.
Drosech Kristen
Girma Wolde-Michael
Medtronic Inc.
Schaetzle Kennedy
LandOfFree
Accelerometer count calculation for activity signal for an... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Accelerometer count calculation for activity signal for an..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Accelerometer count calculation for activity signal for an... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2858854