Source: http://www.freepatentsonline.com/6220088.html
Timestamp: 2019-11-14 05:48:01
Document Index: 193056427

Matched Legal Cases: ['art 90', 'arts 92', 'art 90', 'art 91', 'arts 93', 'arts 91', 'arts 91', 'art 96', 'art 90', 'art 96', 'arts 78']

Assessment of patient support systems - RAFT Trustees Limited
Assessment of patient support systems
United States Patent 6220088
Scales, John Tracey (Pangbourne, GB)
Bain, Duncan Shirreffs (Middlesex, GB)
08/624522
RAFT Trustees Limited (Middlesex, GB)
73/774, 73/781, 73/866.4
A47C31/12; G01M99/00; G01N3/40; G09B23/32; G01N3/02; (IPC1-7): G01N1/00; G01N19/00
73/172, 73/866.4, 73/379.01, 128/774, 128/781, 128/779
Download PDF 6220088 PDF help
5253656 Apparatus and method for monitoring contact pressure between body parts and contact surfaces 1993-10-19 Rincoe et al. 128/782
4140008 System for testing firmness 1979-02-20 Golembeck et al. 364/468
3822588 APPARATUS FOR MEASURING THE HARDNESS OF MATERIAL 1974-07-09 Knight et al. 73/81
3818756 LOAD PROFILE ANALYZER IN THE ATTACHED SPECIFICATION 1974-06-25 Barron et al. 73/172
WO1995010762A1 1995-04-20 ASSESSMENT OF PATIENT SUPPORT SYSTEMS
WO1995020279A1 1995-07-27 APPARATUS AND METHOD FOR CONTROLLING ACCESS TO AND INTERCONNECTION OF COMPUTER SYSTEM RESOURCES
In one recent study (see A. B. Ward, Prescriber's Journal, 30(6) 1990), it was stated that between 3 and 11% of all patients admitted to hospital develop a pressure sore, and the average duration of treatment for those with significant lesions is 51 days at an estimated cost of .English Pound.26,000. It has been estimated (see Turner, Wound Management, 1(1), April 1991) that the care of patients suffering from pressure sores is costing the National Health Service as much as .English Pound.200,000,000 per annum.
Alternatively some or all of the transducers can be located between the "skeleton" of the phantom and the deformable parts. This technique enables the contact point at which pressure is to be measured to be accurately predetermined and it avoids distortions caused by tension or slipping between the surface of the phantom and the material of the support surface. In this embodiment the pressure transducers may be attached to the part of the "skeleton" representing the main bony prominences beneath the deformable part or incorporated or encapsulated within the deformable part. It has been found by the inventors that it is only necessary to measure the contact pressures in a small number of areas on the phantom to give a substantially complete representation of the performance of a support surface in reducing the likely occurance of pressure sores. The primary areas are the heel, sacrum, and ischial tuberosities and it is in one or more of the deformable portions representing these parts of the human body where the major incidence of pressure sores occurs.
FIG. 7 shows a schematic side elevation of the phantom shown in FIG. 6. instrumentation, connection to heating and/or artificial `sweating` means so that different parts of the phantom can be loaded to various levels.
As can be seen in FIG. 1, the indenter 1 in the form of a 7 inch diameter rigid plastic dome is supported from a gantry 2 on a spindle 3, which can be moved along an axis towards and away from a support surface to be tested (not shown), placed beneath the gantry. Spindle 3 is attached to a threaded rod 4 which is driven by an electric motor 5. The end of the spindle is connected to a load cell 7 and means for applying varying load to the spindle and hence to the support surface to be tested. Attached to the outer surface of the indenter, (e.g. with adhesive) in selected positions are one or more pressure transducers which are connected to the pressure monitor 6. The pressure transducers are of the kind comprising a pouch of plastic material which can be inflated to a series of known pressures. By measuring the back pressures generated when the pouch is pressed between two surfaces the interfacial pressures may be calculated using the monitor 6. Suitable equipment is manufactured by Oxford Instruments Ltd under the trade name `Oxford Pressure Monitor`.
In a further series of tests on the same three mattresses, the test rig shown in FIG. 1 was used. However, the 7" dome shown in FIG. 1 was replaced with a rigid, polyacrylic breast-like shape 41 and subsequently with a deformable indenter having the same profile but manufactured using a viscoelastic silicon polymer as depicted in FIG. 3. Measurements were repeated using the test rig in FIG. 1 of interfacial pressures at corresponding points with the soft and hard indenters for the three mattresses at a number of different loadings, and the results are shown in FIG. 5. FIG. 4 shows the application of the indenter 41 to a mattress support surface 42 under test. As can be seen the indenter 41 is supported on the spindle 3 and varying loads are applied through the load cell 7. As can be seen from the code at the foot of the graph in FIG. 5, the thin lines represent measurements taken with each of the mattresses using the deformable indenter, while the thick lines represent measurements taken with the rigid indenter.
As best seen in FIG. 7, the phantom is placed on a support surface to be tested, e.g. a mattress 77, the attitude frame 100 enabling the phantom to be placed in a precisely, predetermined and repeatable position and attitude on the support surface. Some or all of the members 71.about.75 can be replaceable partly or wholly with members of the same shape but manufactured from viscoelastic materials or partially therefrom. For example, it may be preferable to replace the members with composite members of the same shape having portions 78, 79, 80 and/or 81 which are made from viscoelastic material, the remainder of the member being manufactured from a stiff, substantially rigid material, such as g.r.p. or metal. It will be appreciated that the portions 78, 79, 80 and 81 represent those parts of the human body which are most prone to the development of pressure sores. In order to represent more faithfully the physical/mechanical characteristics of the human body, the viscoelastic parts may incorporate internal rigid parts representing bones. This is illustrated in FIG. 6, in which it can be seen that the `skeletal` frame includes a pelvic/femoral part 90 and heel parts 92.
The `skeletal` frame of the phantom and the attitude frame is shown in FIG. 6. The skeletal frame includes the pelvic/femoral part 90 which is connected to a thigh part 91 and to leg parts 93. Preferably, the parts 91 and 93 are connected by pivotable links 94 which can be locked in a fixed position, e.g. by magnetically operated locks. Parts 91 and 93 are provided with studs on which weights 95 can be threaded so that different parts of the skeletal frame can loaded with known loads. A torso part 96 is connected to the pelvic part 90, also by a pivotable link, which again may be lockable at a number of desired angles with respect to the pelvic part. Torso part 96 is connected to the head 97 by a pivotable and lockable link and is also provided with means for applying known loads 95 to the head part.
At the same time, the attitude of the skeletal frame can be adjusted by lengthening or shortening the struts 101,102 and/or by pivoting the plate 107 with respect to the gimbels 108, e.g. using a linear actuator. In this way, a support structure can be placed beneath the phantom in a predetermined position and the interfacial pressures developed between the phantom and the support surface measured under a variety of known loads and at a number of preselected angular attitudes of the phantom. The pressures may be measured using pressure transducers attached to the outside of the body members 71.about.75, particular to the parts 78, 79, 80 and 81. The pressure transducers may be of the kind described above in relation to FIG. 1. It will be appreciated that once the attitude of the phantom has been selected and established, the cable or actuator holding the carriage 103 on the tracks 106 will be allowed to go free so that the whole mass of the phantom will rest on the support surface.
<- Previous Patent (Method for determini...) | Next Patent (Vibration dummy appa...) ->