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EP-4734827-A1 - A METHOD FOR MONITORING BED MOBILITY

EP4734827A1EP 4734827 A1EP4734827 A1EP 4734827A1EP-4734827-A1

Abstract

The invention involves a method for monitoring bed mobility, - the method comprising detecting a postural change of a target person lying on a target mattress (11TA), which detection is made by use of at least one pressure sensor (231-233) arranged to sense the pressure in at least one air chamber configuration (1101-1103) of the target mattress (11TA), and - determining whether or not the detected postural change of the target person is a tissue offloading postural change which substantially offloads tissue of the target person.

Inventors

  • Malmström, Kenneth
  • MBITHI, Florence
  • CAGGIARI, Silvia
  • WORSLEY, Peter R.

Assignees

  • Care of Sweden AB

Dates

Publication Date
20260506
Application Date
20240628

Claims (20)

  1. 1. A method for monitoring bed mobility, - the method comprising detecting a postural change of a target person lying on a target mattress (11TA), which detection is made by use of at least one pressure sensor (231-233) arranged to sense the pressure in at least one air chamber configuration (1101-1103) of the target mattress (11TA), characterised by determining whether or not the detected postural change of the target person is a tissue offloading postural change, which substantially offloads tissue of the target person and comprising, while the detected postural change of the target person takes place, making a plurality of measurements of the pressure in the at least one air chamber configuration of the target mattress (11TA), and determining a time derivative of the pressure measurements, wherein the determination whether or not the detected postural change of the target person is a tissue offloading postural change is made in dependence on the time derivative.
  2. 2. A method according to claim 1 wherein one or more of the following postural changes are categorised as tissue offloading postural changes: lateral turn, pelvic shift and moving up or down in bed, transfer from lying to sitting.
  3. 3. A method according to claim 1 or claim 2 wherein one or more of the following postural changes are categorised as tissue non-offloading postural changes: head of bed raise, head of bed drop, arm and/or leg elevation.
  4. 4. A method according to any of the previous claims wherein the determination of whether or not the detected postural change of the target person is a tissue offloading postural change comprises comparing the time derivative of the pressure measurements at the postural change to a predetermined threshold time derivative.
  5. 5. A method according to claim 4 wherein the predetermined threshold time derivative is based on a test set of sensing data obtained from the target person.
  6. 6. A method according to claim 4 or 5 wherein if the determined time derivative of the measurements of the pressure in the at least one air chamber configuration of the target mattress is above the predetermined threshold value, it is determined that the detected postural change of the target person is a tissue offloading postural change.
  7. 7. A method according to any of claims 4 to 6 wherein if the determined time derivative of the pressure measurements is below the predetermined threshold value, it is determined that the detected postural change of the target person is a tissue non-offloading postural change.
  8. 8. A method according to any one of the preceding claims, comprising taking a clinical action in relation to the target person lying on the target mattress (11TA) in dependence on the determination whether or not the detected postural change is a tissue offloading postural change.
  9. 9. A method according to any one of the preceding claims, comprising collecting a test set of sensing data, comprising, for each of one or more test mattresses (11TE), collecting sensing data from at least one pressure sensor (231-233) arranged to sense the pressure in at least one air chamber configuration (1101-1103) of the test mattress (11TE), wherein the sensing data is collected while a test person undergoes a plurality of postural changes on the test mattress (11TE), which postural changes preferably are predetermined, wherein the determination whether or not the detected postural change of the target person is a tissue offloading postural change is done in dependence on the test set of sensing data.
  10. 10. A method according to claim 9, wherein the test set of sensing data is collected on two or more test mattresses (11TE), wherein one or more air chamber configurations (1101-1103) of one of the two or more test mattresses (11TE) are identical to one or more air chamber configurations (1101-1103) of the remaining of the two or more test mattresses (11TE).
  11. 11. A method according to any one of claims 9 or 10, wherein one or more air chamber configurations (1101-1103) of the target mattress (11TA) are identical to one or more air chamber configurations (1101-1103) of the one or more test mattresses (11TE).
  12. 12. A method according to any one of claims 9-11, comprising categorising one or more of the postural changes, which the test person undergoes, as tissue offloading postural changes which substantially offloads tissue of the target person, and categorising one or more of the postural changes, which the test person undergoes, as tissue non-offloading postural changes which do not substantially offload tissue of the target person, wherein the determination whether or not the detected postural change of the target person is a tissue offloading postural change is done in dependence on the categorisation of the postural changes which the test person underwent.
  13. 13. A method according to any one of claims 9-12, comprising processing the test set of data to create an algorithm, wherein the determination whether or not the detected postural change is a tissue offloading postural change is done using the algorithm.
  14. 14. A method according to claim 13, wherein processing the test set of data to create an algorithm comprises determining for the postural changes that the test person undergoes time derivatives of the pressure sensed in the at least one air chamber configuration (1101-1103) of the test mattress (11TE), wherein the determination whether or not the detected postural change of the target person is a tissue offloading postural change is made in dependence on the determined time derivatives.
  15. 15. A method according to any one of claims 13-14, wherein processing the test set of data to create an algorithm comprises using a Receiver Operating Characteristic (ROC) analysis on the test set of sensing data, to characterize the sensitivity and specificity of the detection threshold.
  16. 16. A method according to any one of the preceding claims, comprising providing a pump (2), wherein the pump comprises a compressor (201), a valve assembly (211- 213), and one or more mattress interfaces (221-223), wherein the valve assembly is arranged to communicate with the compressor and with the one or more mattress interfaces, wherein a mattress assembly (1), comprising the target mattress (11TA), comprises one or more pump interfaces (1121-1123) each connected to a respective of the mattress interfaces (221-223) of the pump, wherein each pump interface communicates with a respective of the at least one air chamber configurations (1101-1103) of the target mattress (11TA).
  17. 17. A method according to claim 16, wherein the pump comprises the pressure sensor (231-233) by use of which the postural change of the target person is detected, wherein the pump forms a space (221-223) arranged to communicate with one of the at least one air chamber configuration (1101-1103) of the target mattress (11TA), wherein the sensor is located in said space (221-223).
  18. 18. A method according to any one of claims 16-17, comprising taking a clinical action in relation to the target person lying on the target mattress (11TA) in dependence on the determination whether or not the detected postural change is a tissue offloading postural change, wherein the clinical action comprises controlling the valve assembly (211-213) of the pump (2).
  19. 19. A method according to any of claim 9-18 wherein the test person is the target person.
  20. 20. A computer program comprising program code means for performing the steps of any one of claims 1-19 when said program is run on a computer.

Description

A METHOD FOR MONITORING BED MOBILITY TECHNICAL FIELD The invention relates to a method for monitoring bed mobility, and to a computer program, a computer readable medium, and a control unit for carrying out steps of the method. The method may be used to prevent and/or treat pressure ulcers. BACKGROUND Pressure ulcers, also known as pressure sores, bedsores and pressure injuries, are localized damage to the skin and/or underlying tissue that usually occur over a bony prominence of a person as a result of pressure or pressure in combination with shear. Pressure ulcers commonly occur among individuals with low mobility, i.e. individuals who are unable to change position when for instance lying in a bed. Pressure ulcer prevention guidelines promote the use of pressure redistribution through support surfaces such as bed mattresses and wheelchair cushions, in addition to frequent repositioning to offload vulnerable skin sites. Nursing homes and hospitals usually set care processes to assess the risk of their individuals in care and provide interventions to those that need it. This may include using a routine time frame for turning and repositioning a patient to support skin health. However, such programs will increase the workload of the staff working in the care setting and are often not personalized to the individual. This can result in both under and over treatment burden for a given individual. In many cases, the use of pressure redistribution mattresses provides a high level of protection from skin damage. Such mattresses, which are becoming more popular, can be connected to a pump that is capable of supplying and evacuating air to or from the mattress to periodically change pressures under the individual. Pressure redistribution mattresses may contain multiple air chambers that are alternately pumped. The pump may follow a particular control strategy for increasing and reducing the air in the chambers. In such a way, the pressure may be varied and thus it provides time for the skin to recover between periods of loading. Typically, these mattresses controlled by pumps are implemented through settings, operated by a care worker or healthcare professional. The digital information gathered by the pump is primarily used to control internal pressures within the mattress. However, there is a need for a cost effective way to determine the mobility status of individuals deemed at risk of developing pressure ulcers. Existing sensing technologies, such as wearable sensors, or mattress covers with pressure measuring sensor cells, are relatively costly, and may also complicate the care of the individuals. US9295600B2 describes monitoring the activity level of an individual whilst positioned on a support apparatus which includes a plurality of separately or independently controllable inflatable zones. At least one pressure sensor is operably coupled to the interior region of each of the zones and/or the fluid conduit connected thereto. A mobility score is determined based on the person's activity level. It is suggested that “major” movements, “minor” movements, or combinations thereof may be detected and monitored. The documents describes minor changes in the position of a person's body or an extremity that are indicative of person’s mobility, while the person is positioned on the person support apparatus, where the minor changes in position are more significant in degree than physiological functions of the person such as breathing or heart rate. A major position change is exemplified as bed exit or sitting up. Further, according to US9295600B2 threshold values for determining when the person's activity constitutes a major or minor movement are calculated or obtained from a lookup table. It is suggested that the activity threshold values are adjusted based on the person's weight, and/or the position of the person support apparatus. The document also suggests deriving an activity score by mapping results of an analysis of sensor inputs to threshold values that are indicative of different activity levels, which threshold values are determined through laboratory testing. For example, in the load cell embodiment, sensor inputs that indicate that each load cell is at about 50% of its dynamic range may indicate that a person is on the person support apparatus and is not moving. There is nevertheless a desire to provide a more accurate method for assessing or monitoring the bed mobility status of a person. SUMMARY An object of the invention is to provide a more accurate method for assessing or monitoring the bed mobility status of a person. The object is reached with a method according to claim 1. Thus, the invention involves a method for monitoring bed mobility, - the method comprising detecting a postural change of a target person lying on a target mattress, which detection is made by use of a pressure sensor arranged to sense the pressure in an air chamber configuration of the target mattress, and determining whether or