Patent Application
20130074262
A number of commercially available person-support apparatus include an air filled person support surface. Normally, the air within the person support surface can be regulated depending on the patient's requirement. It is preferable that the air pressure inside the person support surface be maintained such that the contact area between the patient and the person support surface is therapeutically optimal to minimize peak interface pressures. Air pressure should also be sufficient so that the weight of patient preferably does not cause the patient to touch the firm, structural bottom of the person support surface. An optimum value of pressure within the person support surface is called as the pressure relief set point. Pressure relief set point values can vary from patient to patient depending, for instance, on their weight as well as potentially other variables. While various systems and methods have been developed to accommodate patients of various weights on a person support surface in an optimal manner, there is still room for improvement. Thus a need persists for further contributions in this area of technology.
The present disclosure includes one or more of the features recited in the appended claims and/or the following features which, alone or in any combination, may comprise patentable subject matter.
One illustrative embodiment of the present disclosure includes a method and a system to determine the weight of a person supported on a person-support apparatus. The method includes the step of maintaining a predetermined pressure in at least one zone of the person support surface in a vacant mode. The next step includes measuring the pressure in at least one zone in a patient occupied mode. The next step includes calculating the volume of the medium in patient occupied mode based on pressure and volume in vacant mode and pressure in patient occupied mode in at least one zone. The next step includes determining the volume difference in a vacant mode and a patient occupied mode in at least one zone of the person support surface. The next step includes determining the air density in at least one zone using the pressure determined in patient occupied mode calculated for at least one zone. A further step includes determining the weight of the person using the density of the medium in the patient occupied mode and the volume difference from the at least one zone. A further step includes determining the pressure relief set point as a function of the weight of the person.
Additional features alone or in combination with any other feature(s), including those listed above and those listed in the claims and those described in detail below, can comprise patentable subject matter. Others will become apparent to those skilled in the art upon consideration of the following detailed description of illustrative embodiments exemplifying the best mode of carrying out the invention as presently perceived.
Referring now to the illustrative examples in the drawings, wherein like numerals represent the same or similar elements throughout:
While the present disclosure can take many different forms, for the purpose of promoting an understanding of the principles of the disclosure, reference will now be made to the embodiments illustrated in the drawings, and specific language will be used to describe the same. No limitation of the scope of the disclosure is thereby intended. Various alterations, further modifications of the described embodiments, and any further applications of the principles of the disclosure, as described herein, are contemplated.
One illustrative embodiment of the present disclosure can include a method and a system to determine the weight of a person supported on a person-support apparatus.
A person-support apparatus 10 according to one illustrative embodiment of the disclosure is shown in
The person-support apparatus 10 supports a person support surface 18 on the upper frame 16. The person-support surface 18 is configured to support a person P1 in multiple articulated positions. The person-support surface 18 includes at least one zone 20 capable of containing a medium such as air. In one embodiment the at least one zone 20 also include foam. In another embodiment, the at least one zone delivers therapy to the person through expansion/or contraction and changes in pressure of the medium contained in the at least one zone. In one embodiment, one or more zones of person support surface 18 provide alternating pressure therapy, continuous lateral rotation therapy, low air loss therapy, boost assistance, percussion/vibration therapy, or turn assistance. According to an illustrative embodiment of the disclosure shown in
The person-support apparatus 10 includes a system configured to measure the weight of the person P1 supported on the person-support apparatus 10. The measured weight in turn can be used to calculate pressure relief set points for the at least one zone 20 for the particular person. Pressure relief set points are an optimum pressure which the caregiver needs to maintain within the at least one zone 20. The pressure relief set points can be set inside the at least one zone 20 in such a way that the contact area between the person P1 and the person support surface 18 is optimum.
The system includes at least one pressure sensor 28 and a controller 30 coupled with the at least one pressure sensor 28 as shown in
In one embodiment, the system to determine weight of the patient includes at least two modes, with an additional mode to set pressure in the at least one zone in accordance to a pressure relief set point based on the calculated weight of the person obtained from the first two modes. In the first mode as shown in
In the second mode, the person P1 has just entered the person-support apparatus 10 as shown in
In a third optional mode, pressure within the at least one zone 20 is adjusted so as to maintain a pressure relief set point in the person support surface 18, accordingly the third optional mode is referred to as pressure relief mode. In one embodiment, the optimal value of pressure is a discrete value. In another embodiment, the optimal value of pressure, pressure relief set point, may be specified as a range of acceptable pressure values. In the third mode, the controller 30 is configured to control the operation of the fluid supply unit 32 to maintain the pressure within the head zone 22, the foot zone 24 and the seat zone 26 at pressure relief set points in one embodiment. In another embodiment, there may be one or a multitude of zones, and the controller 30 is configured to control the operation of the fluid supply unit 32 to maintain the pressures within each zone at pressure relief set points. In yet another embodiment, the pressure relief set point is specified as a range of pressure, and the controller 30 is configured to control the operation of the fluid supply unit 32 to maintain the pressure within at least one zone 20 within the specified range of pressure.
In operation, the system is configured to determine the weight of the person P1 supported by the person-support apparatus 10 as shown in flowchart 100 of
ΔPH=PH
ΔPF=PF
ΔPS=PS
In step 106, the controller 30 determines the volume of the medium, in the at least one zone 20 in the person occupied mode as follows:
V
occupied=(Pvacant/Poccupied)·Vvacant (4)
In equation (4) pressure Pvacant and volume Vvacant are known for the at least one zone 20. Therefore the controller 30 can calculate volume Voccupied for the at least one zone 20. In equation (4), isothermal condition may be assumed and pressure Pvacant and volume Vvacant are not expected to change from the time the medium was inserted in the at least one zone. In another embodiment, pressure at the time of insertion of the fluid Pinitial, along with the volume Vinitial of medium inserted at a particular temperature Tinitial is recorded. Volume Vvacant in the vacant mode can be found as:
V
vacant=(Pinitial·Vinitial/Tinitial)·(Tvacant/Pvacant)
Where, Tvacant is the temperature of the medium in the vacant mode which may be obtained using a temperature sensor.
At step 108, difference in volume is calculated between volume Vvacant in the vacant mode and volume Voccupied in the person occupied mode in the at least one zone 20. In one embodiment, the difference in volume is calculated for the head zone 22, the foot zone 24 and the seat zone 26 as ΔVH, ΔVF and ΔVS respectively.
At step 110, the controller 30 calculates an air density ρzone inside the at least one zone 20 for the person occupied mode using following equation:
ρzone=(Mmed/R·Toccupied)*Poccupied (5)
At step 112, the controller calculates the weight of the person P1 being supported by individual zones using equation (6) below. Equation (7) alternatively provides the total weight of the person P1 supported by all the zones, found by summing the weight of the person supported by each zone.
W
ZONE
=B
ZONE=ρzone*ΔVZONE (6)
W
Person=Σ(ρzone*ΔVZONE) (7)
Where, ΔVZONE can be ΔVH, ΔVF or ΔVS for the head zone 22, the foot zone 24 and the seat zone 26 respectively in one embodiment.
As the person P1 settles on the person support surface 18, the buoyant forces BZONE between the air in the person support surface 18 and the person's weight WZONE balance to attain equilibrium as shown in
In an optional step 114 the controller 30 determines the pressure relief set points for the at least one zone 20 for a particular person P1. The pressure relief set points can be changed from person to person depending upon the weight of the person supported on the person-support apparatus 10. The pressure relief set point may be defined as a function of the weight of the person. In one embodiment, the buoyant forces or weight borne by each zone are compared to values from a pre-determined look-up table for optimal pressure relief set point and each zone is set to corresponding pressure relief set points. In yet another embodiment, a pressure relief set point is defined as a function of the total weight of the person, or summation of weight borne by all the individual zones determined in the first two modes and all the zones are set to this singular pressure relief set point value. In another embodiment medical records obtained from electronic medical records (EMR) may be used to obtain optimal relationship between patient weight and pressure relief set point or for verifying calculated patient weight. Several factors may be taken into account when determining the relationship between weight borne by each zone and the ideal pressure relief set point, including but not limited to body type, whether or not patient is an amputee, medical conditions such as elephantiasis, hydrocephalous or any other medical condition.
Any theory, mechanism of operation, proof, or finding stated herein is meant to further enhance understanding of principles of the present disclosure and is not intended to make the present disclosure in any way dependent upon such theory, mechanism of operation, illustrative embodiment, proof, or finding. It should be understood that while the use of the word preferable, preferably or preferred in the description above indicates that the feature so described can be more desirable, it nonetheless can not be necessary and embodiments lacking the same can be contemplated as within the scope of the disclosure, that scope being defined by the claims that follow.
In reading the claims it is intended that when words such as “a,” “an,” “at least one,” “at least a portion” are used there is no intention to limit the claim to only one item unless specifically stated to the contrary in the claim. When the language “at least a portion” and/or “a portion” is used the item can include a portion and/or the entire item unless specifically stated to the contrary.
It should be understood that only selected embodiments have been shown and described and that all possible alternatives, modifications, aspects, combinations, principles, variations, and equivalents that come within the spirit of the disclosure as defined herein or by any of the following claims are desired to be protected. While embodiments of the disclosure have been illustrated and described in detail in the drawings and foregoing description, the same are to be considered as illustrative and not intended to be exhaustive or to limit the disclosure to the precise forms disclosed. Additional alternatives, modifications and variations can be apparent to those skilled in the art. Also, while multiple inventive aspects and principles can have been presented, they need not be utilized in combination, and various combinations of inventive aspects and principles are possible in light of the various embodiments provided above.
