Patent Publication Number: US-2002005300-A1

Title: Patient transporting apparatus

Description:
[0001] The present invention relates to monitoring patient support apparatus and a method of monitoring patient support apparatus.  
       [0002] With stretcher trolleys, attendants often have to lift the stretcher, either from a lower position to a higher position or into and out of ambulances. The attendants are thus required to exert a significant physical effort. Similarly, with patient transport chairs the attendants often have to lift the chairs upstairs and downstairs. If a patient is excessively heavy this can result in back injuries to the attendants. Furthermore, it is possible that the trolleys themselves may not be designed to be sufficiently strong to support excessively heavy patients and whilst the trolleys and chairs may satisfactorily support the patients when they are stationery, it may be that excessive strains that could cause failure of the stretchers or chairs and damage to the patient may result during movement.  
       [0003] It is an object of the present invention to attempt to overcome at least some of the above described or other disadvantages.  
       [0004] According to a first aspect of the present invention patient support apparatus comprises patient support means arranged, in use, to support a patient and a plurality of monitoring means arranged, in use, to provide an indication of the weight of a patient on the support means.  
       [0005] The apparatus may include control means arranged to receive a signal from the monitoring means and to give an indication of the weight of a patient on the support means. Such means may be selectively operable to activate the control means. When the switch is in one position, an indication may be given of the weight of a patient on the stretcher. When the switch is in another position, no indication may be given. The switch may be biased to said another position. The control means may be battery powered.  
       [0006] The indication of the weight of a patient may comprise a sound or, alternatively or additionally, a visual warning if the patient exceeds a predetermined weight or, alternatively or additionally, a visual indication of the weight of the patient, for instance by an LED. The predetermined weight may be arranged to be set at one of a plurality of values, for instance in dependence upon the apparatus or load carrying abilities of the operator.  
       [0007] The control means may be arranged to compensate for a signal given by the monitoring means before a patient is located on the stretcher.  
       [0008] Each of the monitoring means may be spaced from each other, and may be evenly spaced from each other.  
       [0009] A signal from each monitoring means may be added together.  
       [0010] The monitoring means may comprise fluid monitoring means such as hydraulic monitoring means.  
       [0011] The apparatus may comprise a first support arranged to receive the weight of a patient on the support means. The first support may be mounted on monitoring means and may be solely supported by monitoring means. The first support and the monitoring means may comprise a unit which may be enclosed and alternatively or additionally, may be upholstered.  
       [0012] When the monitoring means comprises fluid monitoring means, each monitoring means may include a portion that is movable downwardly to increase pressure on a fluid when a patient is supported on the support means. Each fluid monitoring means may comprise a flexible container of fluid. A flexible wall of the container may be arranged to be moved downwardly by said portion that is movable downwardly.  
       [0013] Each monitoring means may comprise a strain gauge such as an electronic strain gauge.  
       [0014] The apparatus may include projections that are arranged to be supported on further portions of the apparatus with means for monitoring the strain on the projections to provide an indication of the weight of a patient on the support means.  
       [0015] The projections may be movable from a position in which they are spaced from the supports to a position in which they are located on the supports. The projections and the supports may include cooperating portions arranged to assist in retaining or, alternatively or additionally, to assist in aligning the projections and the supports.  
       [0016] The projections may be secured to an upper frame of a stretcher trolley which upper frame is movable from a raised to a lowered position in which, in the lowered position, the projections are located on the supports.  
       [0017] The transport means may comprise a chair or a stretcher trolley and may comprise patient transport means.  
       [0018] According to a further aspect of the present invention a method of monitoring patient support apparatus comprises locating a patient on a support of the apparatus and monitoring the weight of the patient with a plurality of monitoring means to provide an indication of the weight of the patient on the support.  
       [0019] The method may comprise using control means to receive a signal from the monitoring means and giving an indication of the weight of the patient on the support. The method may comprise selectively operating the control means.  
       [0020] The method may comprise giving an audible or, alternatively or additionally, a visual warning when the weight of the patient exceeds a predetermined weight. Alternatively or additionally, the indication may comprise a visual indication of the weight of the patient, for instance by an LED. The method may comprise varying the value of the predetermined weight.  
       [0021] The method may comprise taking the weight of the apparatus exerted on the monitoring means into account such that the weight of the patient only is monitored.  
       [0022] The method may comprise receiving different signals from different monitoring means, in dependence upon where the patient is located on the support in order to give an indication of the weight of the patient on the support regardless of where on the support the patient is located. The method may comprise adding the signals from each of the monitoring means together.  
       [0023] The method may comprise supporting the support with each of the monitoring means and causing fluid in each of the monitoring means to have their pressure increased when the weight of the support above a particular monitoring means is increased.  
       [0024] The method may comprise monitoring the weight of the patient with strain gauges that comprise the monitoring means.  
       [0025] The method may comprise mounting the support on portions that each include a strain gauge or alternatively or additionally a load cell whereby those portions are subject to the weight of a patient located on the support with the signals from the strain gauges being used to give an indication of the weight of the patient. The method may comprise moving those portions downwardly into a position in which they are able to support the weight of a patient located on the support.  
       [0026] The present invention also includes a method of monitoring patient support apparatus when the apparatus is as herein referred to.  
       [0027] The present invention includes any combination of the herein referred to features or limitations. 
     
    
    
     [0028] The present invention can be carried into practice in various ways but several embodiments will now be described, by way of example, and with reference to the accompanying drawings, in which:  
     [0029]FIG. 1 is a schematic perspective view of a stretcher platform incorporating a load monitoring arrangement;  
     [0030]FIG. 2 is a detailed cross-sectional view of one of the load measuring portions used on the platform of FIG. 1;  
     [0031]FIG. 3 is a schematic perspective view of a load monitoring arrangement used in relation to a chair;  
     [0032]FIG. 4 is a perspective view of a stretcher in a raised position;  
     [0033]FIG. 5 is a side view of the stretcher of FIG. 4 shown in a collapsed position, and  
     [0034]FIG. 6 is a detail of a load measuring device used on the stretcher shown in FIGS. 4 and 5. 
    
    
     [0035] As shown in FIG. 1, an upper board  10  is supported on eight evenly distributed load cell or strain monitoring devices  12  that are mounted on a lower board  14 . In use, the lower board could be supported by or attached to a bed or a stretcher. The upper board  10  could have a mattress comprising part of that board or a patient support mattress mounted on top of the board.  
     [0036] Each of the load cells  12  comprises a flexible liquid container  16  that is secured to the lower board  14  with an upper plate  18  being located over the liquid container  16 . The plate  18  includes a centrally located opening through which a piston  20  extends such that the lower portion of the piston  20  abuts against the liquid container  16  with the upper board  10  resting on the upwardly facing surface of the piston  20 . A connecting tube  22  extends from each load cell  12  towards a control and display device  24 . As the connecting tubes  22  from the furthermost load cells  12  go past connecting devices on the same side of the board that are nearer to the control and display device  24 , the tubes meet up until finally all of the tubes are in connection with a tube  26  that projects from the rear of the control and display device  24 .  
     [0037] The load cells  12 , shown in FIG. 3, are also evenly distributed about the lower board  14  and the upper board  10  is supported on the pistons  20  from the load devices. The lower board can comprise part of or be connected to or rest on a chair. The upper board  110  can be upholstered or it can have a cushion located or attached to it.  
     [0038] When a person sits directly or indirectly on the stretcher or chair such that their weight is taken by the board  10 , that weight is transferred to the pistons  20  to urge the pistons  20  down into the liquid containers  16  to increase the pressure in the system. That increased pressure is passed through to the control and display device  24 . In the case of the stretcher this device is mounted at one end. In the case of the seat, this device is mounted at the side.  
     [0039] The control and display device would be aware of the weight that is on the board  10  comprising not only the weight of the board but also any upholstery before a person gets onto the stretcher. With a person supported on the stretcher, and when a button is pressed, the control and display device will give either a direct reading in kilograms for example of the weight of the person or, alternatively or additionally, it can indicate that an excess weight is located on the stretcher such that it would not be safe either to lift the stretcher or to move the stretcher or to have the person located on the stretcher. The indication may, for instance, be simply a safe indication or an unsafe indication such as a green or red light respectively. Similar indications may be given in relation to the chair control and display device. Alternatively or additionally an audible or visual alarm or both may be given when a predetermined load is exceeded. The control and display device may have an LED output. The control and display device may be battery operated which battery may be rechargeable or replaceable.  
     [0040] Both the upper and lower boards  10  and  14  in either embodiment can be encased in fabric to provide what appears to be a unitary item.  
     [0041] If a person were to sit at one end of the stretcher or chair then obviously the pistons  20  at that end would be further depressed than the pistons  20  at the other end. Nevertheless, the overall pressure increase in the system that eventually passes through the tube  26  still gives a reasonably accurate indication of the weight of the person.  
     [0042] Although the liquid container  16  has been described as being a flexible container, it will be appreciated that the base, sides and perhaps the majority of the top of the container could be rigid. This can be achieved by locating a sack of liquid therein with only the top of the container having access for the piston  20  to bear directly against the flexible portion.  
     [0043] The liquid may comprise a relatively incompressible fluid such that a person sitting on the stretcher or chair does not notice any movement between the boards  10  and  14  and such that the system operates in much the same way as a conventional stretcher or chair that is used in relation to patient handling.  
     [0044] The embodiment described in relation to FIGS.  4  to  6  may have any of the modifications or features of the earlier described embodiments.  
     [0045] As shown in FIG. 4, a stretcher trolley  30  includes patient support sections comprising a head end  32 , a mid section  34  and a foot end section  36 . Each of these sections can be folded flat and have the load measuring arrangement shown in FIG. 1 mounted on top of all of the sections or only on the sections  34  and  36 , if desired.  
     [0046] A stretcher trolley  30  includes an upper frame  38 , to which the sections  32 ,  34  and  36  are connected, and a lower frame  40 . The frames are connected together by a pair of struts  42  and  44  at each side which are pivotally connected about a rod  46 . In a well known manner, the upper frame can be moved relative to the lower frame by pivotal movement occurring about the struts  42  and  44  to cause the upper frame  38  to rest on the lower frame. As shown in FIG. 2, the upper frame includes four downwardly extending sockets  48  that rest on spigots  50  mounted on the top of arms  52 . The lower ends of the arms  52  are connected to wheels  54  that support the stretcher trolley. Accordingly, in this position, all of the weight of the patient is taken by the four lower wheels  54  and thus all of the weight of the upper frame and any patient located thereon is transmitted through the sockets  48  to the spigots  50 .  
     [0047] In FIGS. 4 and 5, the sockets  48  are shown as being directly connected to the upper frame. FIG. 6 shows a modification that is effected at each socket. In this modification, a socket  56  comprising an opening is located on the end of a horizontally extending arm  58  with the arm then being connected to the upper frame  38  at a location spaced laterally from the socket  56 . Accordingly, when the upper frame is supported directly on the lower frame, the spigot  50  extends partially through the opening  56  and the arm  58  is caused to undergo stress and a slight deflection. Load cells or strain gauges  60  are provided on each arm  58  such that the stress induced on each arm is able to be measured.  
     [0048] A wire connection extends through the arm, into the hollow tubular construction of the upper frame to a common control and display device  62 . The device  62  includes an operating button  64  which, when actuated causes a readout, as in any of the modifications referred to above, to be given on the screen  66 . The control and display device  62  is connected to the upper frame and depends downwardly therefrom.  
     [0049] The control and display device  62  is able to pick up the stresses induced in each arm  58  and give an indication, for instance comprising the exact weight of a person on the trolley, after the control in the device  62  has taken into account the inherent weight present in the upper frame that will in any event produce a small strain on each arm  58 .  
     [0050] In any of the above described devices, an audible or a visual warning may be given when a patient is over the designated weight.  
     [0051] In any of the above referred to embodiments, the safe working load where for instance a warning is given may be variable. For instance it may be set at 150 Kg for one stretcher and 180 Kg for another stretcher. Thus the safer working load can be varied in dependence upon the apparatus on which it is used or in dependence upon the load carrying abilities of the operators or both.  
     [0052] Any parts of the apparatus may be powered by battery means such as rechargeable or replaceable batteries.  
     [0053] The reader&#39;s attention is directed to all papers and documents which are filed concurrently with or previous to this specification in connection with this application and which are open to public inspection with this specification, and the contents of all such papers and documents are incorporated herein by reference.  
     [0054] All of the features disclosed in this specification (including any accompanying claims, abstract and drawings), and/or all of the steps of any method or process so disclosed, may be combined in any combination, except combinations where at least some of such features and/or steps are mutually exclusive.  
     [0055] Each feature disclosed in this specification (including any accompanying claims, abstract and drawings), may be replaced by alternative features serving the same, equivalent or similar purpose, unless expressly stated otherwise. Thus, unless expressly stated otherwise, each feature disclosed is one example only of a generic series of equivalent or similar features.  
     [0056] The invention is not restricted to the details of the foregoing embodiment(s). The invention extend to any novel one, or any novel combination, of the features disclosed in this specification (including any accompanying claims, abstract and drawings), or to any novel one, or any novel combination, of the steps of any method or process so disclosed.