RISK MODELING FOR PRESSURE ULCER FORMATION

• US 20130006151A1
• Filed: 01/27/2011
• Published: 01/03/2013
• Est. Priority Date: 01/27/2010
• Status: Active Grant

• Current Assignee: Xsensor Technology Corp
• Original Assignee: Xsensor Technology Corp
• Inventors: Main, Ian, Miller, Robert, Russell, Terry, Ousdahl, Mitch
• Granted Patent: US 9,320,665 B2
• Time in Patent Office: Days
• US Class Current: 600/587
• CPC Class Codes: A61B 2562/0247 Pressure sensors
• CPC Class Codes: A61B 2562/046 in a matrix array
• CPC Class Codes: A61B 5/103 Detecting, measuring or recording devices for testing the shape, pattern, colour, size or movement of the body or parts thereof, for diagnostic purposes A61B5/08 takes precedence; measuring aids for tailors A41H1/00; measuring instruments specially adapted for dentistry A61C19/04
• CPC Class Codes: A61B 5/447 specially adapted for aiding the prevention of ulcer or pressure sore development, i.e. before the ulcer or sore has developed
• CPC Class Codes: A61B 5/6891 Furniture
• CPC Class Codes: A61G 2203/34 for pressure
• CPC Class Codes: A61G 2203/46 for temperature
• CPC Class Codes: A61G 7/057 Arrangements for preventing bed-sores or for supporting patients with burns, e.g. mattresses specially adapted therefor ventilation openings in mattresses A47C21/042; pneumatic or hydraulic mattresses A47C27/08

Abstract

A method for modelling pressure exposure and/or the risk of pressure ulcer formation includes steps of using pressure sensors to derive pressure exposure or risk values and displaying the pressure exposure or risk values in a graphical manner to a user. Computer-implemented systems includes a pressure-sensing interface mat and components for implementing the steps of the methods.

Claims

1. A method of assessing a patient'"'"'s exposure to interface pressure, wherein the patient is supported on a support surface and a pressure sensing interface having a plurality of sensels is placed between the patient and the support surface, the method comprising the steps of:

(a) determining a desired turning interval;

(b) calculating a pressure exposure delta, EΔ

, for each of a plurality of sensels, based on the measured pressure value, P, multiplied by an interval of time (EΔ

=P×

Δ

t);

(c) determining a pressure exposure value, E(t), for each of a plurality of sensels, by accumulating pressure exposure deltas over a pre-determined period of time (E(t)=Σ

EΔ

(t));

(d) deriving a normalized pressure exposure, E_norm, from E(t), the selected turning interval and the maximum pressure range of the sensor;

(e) displaying the normalized pressure exposure value for each sensel to a user; and

(f) periodically repeating steps (b) to (e).

2. The method of claim 1 wherein the desired turning interval is determined using at least one predetermined interval modifier which comprises at least one data input representative of a risk assessment score, shear, moisture, temperature, tissue health, tissue deflection, or a clinical observation, or combinations thereof.

3. The method of claim 1 wherein the pressure exposure delta is negative and the normalized pressure exposure value is reduced if the measure pressure value is lower than a minimum pressure threshold.

4. The method of claim 3 further comprising the step of reducing the normalized pressure exposure value for at least a portion of the plurality of sensels in response to a user reset input or an automatic identification of a patient repositioning.

5. The method of claim 1 wherein the pressure exposure value or normalized pressure exposure value for each of the plurality of sensels is graphically displayed to a user as a pressure exposure map.

6. The method of claim 5 wherein the normalized pressure exposure map is either 2 dimensional or 3 dimensional.

7. The method of claim 5 wherein the normalized pressure exposure map comprises a graphical indicator, or multiple indicators, overlaid on an interface pressure map that draws attention only to the areas of highest pressure exposure.

8. The method of claim 4 comprising the further step of initiating a patient turn or repositioning in response to a normalized pressure exposure value or group of values exceeding a pre-determined threshold.

9. A system for determining and displaying pressure exposure values for a patient supported on a support surface, comprising:

(a) a pressure sensing interface having a plurality of sensels placed between the patient and the support surface;

(b) computer-implemented processing means comprising a component for calculating a pressure exposure delta, EΔ

, for each of a plurality of sensels based on the measured pressure value, P, multiplied by an interval of time (EΔ

=P×

Δ

t);

a component for determining a pressure exposure, E(t), for each of a plurality of sensels by accumulating pressure exposure deltas over a chosen period of time (E(t)=Σ

EΔ

(t));

a component for deriving a normalized pressure exposure E_norm based on a selected turning interval and a maximum pressure range of the sensor for each of the plurality of sensels;

wherein the processing means is operatively connected to the pressure sensing interface; and

(c) a display connected to the processing means for showing the E_norm values to a user.

10. The system of claim 9 wherein the processing means further comprises a component for producing a pressure exposure map from the plurality of E_norm values, which pressure exposure map is shown on the display.

11. The system of claim 9 wherein the processing means further comprises a machine vision component for detection of patient turns.

12. The system of claim 11 wherein the machine vision component detects a patient body position.

13. A method of assessing the risk of a patient developing a pressure ulcer, wherein the patient is supported on a support surface, and a pressure sensing interface having a plurality of sensels is placed between the patient and the support surface, the method comprising the steps of:

(a) obtaining a pressure value from each of a plurality of sensels and deriving a time-to-high risk (T_HR) value for each sensel from the pressure value;

(b) adjusting the T_HR value by considering at least one risk modifier;

(c) converting the risk-adjusted T_HR value into a risk delta comprising a change in risk over a unit of time;

(d) adjusting a risk value by the risk delta;

(e) displaying the adjusted risk value to a user; and

(f) periodically repeating steps (a) to (e).

14. The method of claim 13, wherein the T_HR value is determined by comparing the pressure value to stored pressure vs. time data which comprises a T_HR value for a given pressure value, or by applying a pre-determined mathematical formula to the pressure value.

15. The method of claim 13 wherein the at least one risk modifier comprises at least one data input representative of a risk assessment model, shear, moisture, temperature, tissue health, tissue deflection, or a clinical observation or combinations thereof.

16. The method of claim 13 wherein the risk delta is determined by converting the T_HR value into a risk coefficient.

17. The method of claim 13 wherein the adjusted risk value for each of the plurality of sensels is graphically displayed to a user as a risk map image, comprising a representation of risk correlated to the interface pressure map.

18. The method of claim 17 wherein the risk map is either a 2 dimensional or 3 dimensional image.

19. The method of claim 17 wherein the interface pressure map is divided into a plurality of body zones which correspond to the patient'"'"'s anatomical features.

20. The method of claim 19 wherein a risk modifier level is independently determined for each of the body zones.

21. The method of claim 19 wherein the size and location of each body zone is automatically derived from the interface pressure map by automatic identification of anatomical features from the interface pressure map.

22. A risk assessment system for assessing the risk of a patient developing a pressure ulcer, wherein the patient is supported on a support surface, the system comprising:

(a) a pressure sensing interface having a plurality of sensels placed between the patient and the support surface;

(b) an input device for accepting a risk modifier level by considering at least one risk modifier;

(c) computer-implemented processing means comprising a component for determining a pressure value for each of the plurality of sensels and deriving a T_HR value for each pressure value, a component for adjusting the T_HR value for the risk modifier level, a component for converting the risk-adjusted T_HR value into a risk delta comprising the change in risk over a unit of time, and adjusting a risk value by the risk delta, wherein the processing means is operatively connected to the pressure sensing interface and the input device; and

(d) a display connected to the processing means for displaying the adjusted risk value to a user.

23. The system of claim 22 wherein the component for determining a T_HR value for each of the plurality of sensels may do so by obtaining a pressure value from the sensel and comparing it to stored pressure vs. time data which comprises a T_HR value for a given pressure value, or by applying a mathematical formula to the pressure value.

24. The system of claim 22 wherein the processing means further comprises a component for creating a risk map from the risk values for each of the plurality of sensels, which risk map is shown on the display.

25. The system of claim 24 wherein the risk map comprises a graphical 2-dimensional or 3-dimensional image.

26. The system of claim 22 wherein the processing means further comprising a machine vision component for dividing the pressure interface map into a plurality of body zones or detecting the patient'"'"'s position, or detecting a patient turn or repositioning, or combinations thereof.

27. A patient turn management system comprising:

(a) a pressure sensing interface having a plurality of sensels placed between the patient and the support surface and means for producing a pressure interface map;

(b) an input device for indicating when a caregiver has initiated a patient turn or repositioning;

(c) a timer for tracking elapsed time since the last caregiver initiated turn or repositioning;

or the remaining time until the next scheduled turn is due;

(d) computer-implemented processing means comprising;

(i) a component for determining a pressure value for each of the plurality of sensels and deriving a pressure exposure value based on the determined pressure value;

wherein the processing means is operatively connected to the pressure sensing interface;

or

(ii) a component for determining a pressure value for each of the plurality of sensels and deriving a T_HR value for each pressure value, a component for adjusting the T_HR value for the risk modifier level, a component for converting the risk-adjusted T_HR value into a risk delta comprising the change in risk over a unit of time, and adjusting a risk value by the risk delta;

wherein the processing means is operatively connected to the pressure sensing interface and the input device; and

(e) a display connected to the processing means for displaying the pressure exposure values or risk values, the pressure interface map, and the elapsed time since the last caregiver turn or repositioning.