Patent Publication Number: US-6654973-B2

Title: Mobile lift-assisted patient transport device

Description:
FIELD OF THE INVENTION 
     The present invention relates generally to mobile lift-assisted transport devices. More specifically, the present invention relates to a mobile lift-assisted transport device which is able to easily be elevated and lowered through the use of pneumatic powering means. 
     BACKGROUND OF THE INVENTION 
     A busy Emergency Medical Services (EMS) crew may handle as many as 20 calls during the work shift. Typically one or more such calls involve moving a patient from a field location, such as his home or the scene of an accident, to a health care facility such as an emergency room at a hospital. 
     Providing transport for the patient involves various procedures for appropriately securing the patient in different transport vehicles for transport to the hospital or other appropriate destination. Such transport involves a constant risk to the EMS crew and to the patient. The risk arises from the activity involving the EMS crew, usually two persons, lifting and moving the patients. There is also the danger that the patient may be dropped or roughly handled while being moved. As for the EMS crew, they are routinely faced with lifting situations which can and often do result in significant and even crippling back injuries. This can occur either because of the repetitive lifting of average size patients or occasional lifting of large patients. 
     The dangers of lifting-related injury is compounded because an EMS crew must lift a patient approximately 7 times during the course of a call. For example, for lifting purposes only, in an emergency involving a 200 lb. man the crew must: 1) lift the patient to a mobile, wheeled device placed at its lowest height adjustment; 2) lift the device and patient to the maximum height adjustment, and then move the device and patient to an ambulance; 3) lower the device and patient back to the lowest height adjustment; 4) lift the device and patient into the ambulance; 5) upon arrival at the medical facility, remove the device and patient from the ambulance and lower them to the ground; 6) again, lift the device and patient to the maximum height adjustment, and then move the device and patient into the facility; and 7) lift to transfer the patient from the device to a bed at the facility. During this very typical call the crew has lifted or lowered the patient seven times, thereby doing an amount of work equivalent to lifting more than 1400 pounds when the weight of the device is included. 
     A particularly difficult part of this process results from the fact that the typical device that is used in the field, e.g., a stretcher for transfer of patients via ambulances, is not well-designed for lifting and lowering. Because of the location of the undercarriage and supporting structure, the members of the EMS crew cannot simply stand on each side of the device and lift or lower it using proper lifting techniques with their legs. Rather, to avoid hitting the undercarriage with their knees, they must turn their bodies sideways, imposing a torquing motion on their backs as they lift and lower. This consequence results in a significant number of disabling back injuries to EMS personnel each year. In addition, because of the strength that is required to lift and lower a device with this type of motion, smaller people, particularly women, are effectively precluded from working as emergency medical technicians. 
     The foregoing illustrates that it would be advantageous to provide a patient transport device having a lift assisting mechanism, to overcome the need for an EMS crew to exert a great amount of lifting force during a routine emergency call. 
     Although several such transport devices have been proposed, all are too cumbersome to be practically implemented. One example of such a device is found in U.S. Pat. No. 2,833,587 to Saunders which discloses an adjustable height gurney which includes power cylinders provided in the legs of the upper frame and connected to two of the intersecting lever arms (one on each side of the gurney). To operate the cylinders, the EMS technician repeatedly works the handle of a grip up and down to actuate the hydraulic pump. As an alternative, a valve connects the power cylinders to the fluid reservoir, which valve may be opened by a hand lever connected thereto. Both mechanisms for actuating the hydraulic pump cause problems in operation. Use of the handle, which requires repeatedly working the handle up and down is time consuming and be quite difficult when a patient is on a gurney. Further, in order to remove the gurney from the ambulance, or to place it in the ambulance, the EMS technicians must lift the stretcher, and the patient, from the ambulance to the ground, and visa versa. Then the technicians can use the grip or hand lever to raise the upper carriage. the gurney in the Saunders patent does not provide a means for raising and lowering the lower carriage, in addition to raising and lowering the upper carriage. 
     SUMMARY OF THE INVENTION 
     The present invention provides a novel lift-assisted device for transporting objects or patients from one location to another. The present invention allows the lift-assisted apparatus to easily be raised and lowered through pneumatic powering means so that the user has to use little force or energy. 
     The present invention provides a novel lift-assisted device which is able to lift and lower heavy loads while enduring the stress and strains caused by the heavy loads. 
     The present invention provides a novel lift-assisted device wherein the powering means is easily accessible, reasonably priced and may easily be replaced. 
     The present invention provides the above advantages, amongst others, by providing a lift-assisted device having a seat portion, a seat support portion which supports the seat portion, a base portion, an undercarriage portion which comprises of at least one scissor linkage member, each scissor linkage member including a first member pivotable connected to a second member near a center portion of the first and second member, a pneumatic bag located between the seat portion and the base portion, a pneumatic cylinder located between the seat portion and the base portion, a pneumatic powering means for powering the pneumatic bag and/or pneumatic cylinder, and wherein the first member and second member are slidably connected to the seat portion on one end and fixedly connected to the base portion on an opposite end. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Preferred embodiment/s of the invention is/are disclosed in the following description and illustrated in the accompanying drawings, in which: 
     FIG. 1 is a perspective view of an exemplary embodiment of a lift-assisted device according to the present invention; 
     FIG. 2 is side view of the lift-assisted device; 
     FIG. 3 is a perspective view of the seat support portion of the lift-assisted device; 
     FIG. 4 is a perspective view of the base portion of the lift-assisted device; 
     FIG. 5 is a side view of another exemplary embodiment of a lift-assisted device; 
     FIG. 6 is a top view of the lift-assisted device as shown in FIG. 5; 
     FIG. 7 is a top view of the scissor linkage; and 
     FIG. 8 is a side view of the lift-assisted device as shown in FIG. 5 in a lowered position. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     FIG. 1 illustrates a perspective view of an exemplary embodiment of a mobile lift-assisted device  10 . The mobile lift-assisted device  10  is generally used to transport patients from one location to another, while allowing a patient to be placed in a desired position. Furthermore, the mobile lift-assisted device  10  is able to elevate and lower an object or person to a desired height. 
     As shown in the exemplary embodiment in FIG. 1, the lift-assisted device  10  generally includes four main structural portions which include: a seat portion  20 , a seat support portion  40 , an under carriage portion  60  and a base portion  80 . Additionally, to aid the lift-assisted device  10  in being raised and lowered, as desired, an pneumatic bag  90 , a pneumatic cylinder  92  and a pneumatic powering means  99  are provided. 
     As shown in FIG. 1, the seat portion  20  has a rectangular shape, when the seat portion  20  is in a flat position. The seat portion  20  includes a first end portion  22 , a middle portion  24  and a second end portion  26 . In the exemplary embodiment, the first end portion  22  and the second end portion  26  are able to be elevated or lowered to either allow the patient to be positioned so that his upper body is in an upright position and/or to have his legs in an upright or downward position. The seat portion  20  includes a cushioning means (not shown) which would be located above the seat portion  20  SO that a user is able to be comfortably positioned on the cushioning means while being transported on the lift-assisted device  10 . 
     The under carriage portion  60  comprises a pair of scissor linkages  62  and  64 . Each scissor linkage has a fixed end  66  and a movable end  68 . When the lift-assisted device  10  is in an upright position as shown in FIG. 1 the scissor linkages  62  and  64  appear to have an “x” configuration. However, when the lift-assisted device  10  is in a lowered position, each link of the scissor linkages  62  and  64  are essentially parallel to one another. 
     FIG. 2 illustrates a side view of the exemplary embodiment shown in FIG.  1 . As shown in FIG. 2, the lift-assisted device  10  includes at least one air bag  90  and at least one pneumatic means  92  located between the seat support portion  40  and the base portion  80 . As shown in FIGS. 1 and 2, in an exemplary embodiment the pneumatic means  92  has a first end attached to the base portion  80  and the opposite end attached to the seat support portion  40 . The pneumatic means includes a pneumatic air cylinder  92  and is powered by compressed gas which is readily available in most EMS environments. 
     The pneumatic cylinder  92  is provided with compressed air by any device known to one skilled in the art to supply compressed air. In the exemplary embodiment, a tank  99  of oxygen is positioned underneath the seat portion  20  and attached to the seat support portion  40 . In a preferred embodiment, the tank is a S.C.U.B.A. cylinder. The advantage of using such a tank is that this type of tank is non-corrosive, is readily available and is non-flammable. Another advantage is that emergency medical technicians generally have compressed oxygen with them on emergency calls. One advantage, amongst others, of positioning the tank  99  under the seat portion  20  is to protect the tank from various types of fluids or other substances from coming into contact with the tank, e.g. rain, blood, etc. The tank  99  of the compressed gas can be easily connected to the pneumatic cylinder  92 , and a suitable valve on the tank  99  may be opened and closed to assist in raising and lowering the patient transport device during use. 
     As shown in FIGS. 1 and 2, the exemplary embodiment also includes an inflatable device which is a pneumatic bag  90 . Similar to the pneumatic cylinder  92 , the pneumatic bag is powered by compressed gas which is supplied by the tank  99 . The pneumatic bag  90  is also positioned below the seat support portion  40  so as to be protected from various types of fluids or other objects which could damage the pneumatic bag during use of the lift-assisted device  10 . 
     In the exemplary embodiment, a closed circuit is provided between the pneumatic bag  90 , pneumatic cylinder  92  and the tank  99 . However, it should be appreciated that the pneumatic cylinder and the pneumatic bag may be powered by individual tanks. 
     FIG. 3 illustrates a perspective view of the seat support portion  40 . As shown in FIGS. 1 and 3, the seat support portion  40  also has a rectangular shape. The seat support portion  40  includes two side frames  48  and two end frames  49 . The seat support portion  40  includes a front portion  42  and a rear portion  44 . Located near the front portion  42  is a slidable connection means  43 . The slidable connection means  43  comprises of two track members  44  which are slidably connected to two brackets  45 , respectively. In the exemplary embodiment, the track members  44  include a plurality of bearings which allow the track members  44  to smoothly slide along the respective bracket  45 . The movable end  68  of the linkages  62  and  64  is connected to the respective track member  44  and the fixed end  66  of the linkages is fixed to fixed connected means  46 . 
     As shown in FIG. 3, located between the front portion  42  and the rear portion  44  is a connection means  47 . The purpose of the connection means  47  is to hold and support the pneumatic bag  90  shown in FIG.  1 . The pneumatic bag  90  is connected to the attachment member  51 . 
     FIG.  4 . illustrates a perspective view of the base portion  80 . The base portion  80  has a plurality of wheels  89  located at the corners of the base portion  80 . The wheels are pivotable connected to the base portion  80 . The base portion  80  also includes two end frame members  82  and two side members  84 . On one end of the base portion are two railings  86  which are positioned essentially parallel to each other. Guide members  87  are located on each railing  86  and are able to slide back and forth along its respective railing  86 . On the opposite end of the base portion  80  is connection means  88 . The movable end  68  of the links  62  and  64  is connected to the respective guide member  87  and the fixed end  66  of the linkages is fixed to the connection means  88 . 
     FIG. 5 illustrates another exemplary embodiment of a lift-assisted device  210 . The lift-assisted device shown in FIG. 5 is in an upright or raised position. Similar to the lift-assisted device shown in FIG. 1, the lift-assisted device  210  also includes a pneumatic bag  290  and a pneumatic cylinder  292  which are powered by an air supply device  299 . The lift-assisted device  210  includes a seat portion  220 , a seat support portion  240 , an undercarriage portion  260  and a base portion  280 . The undercarriage portion  260  is located between the seat support portion  240  and the base portion  280 . 
     The lift-assisted device  210  includes a holding device  298  which the air supply device  299  may be secured into and easily removed from. Also the seat portion  220  includes end portions  221  and  222  which are able to extend upwards and downwards. It should be appreciated that the seat support portion  40  may comprise one unitary frame which is detachable from the lift-assisted device  220 . A wheel  225  is provided on the seat support portion  240  which is able to extend outwards and inwards as indicated by arrows B and A, respectively. A hand rail  223  is attached to either the seat portion  220  and/or seat support portion  240 . As shown in FIG. 5, a control means  270  is provided on one end of the lift-assisted device  210 . It should be appreciated that the lift-assisted device  210  could have more than one control means  270  located at any desired location on the lift-assisted device. However, in a preferred embodiment the control means  270  is located at at least one end of the lift-assisted device so that a person, e.g. EMS crew member, may easily have access to the control means  270  to either raise or lower the seat portion to the desired height. 
     The control means  270  comprises a handle bar member  272  and a lever  274 . In an exemplary embodiment, the lift-assisted device  210  includes at least two handle bar members  272  each having a lever. In an exemplary embodiment, one of the handle bar member/lever combinations would allow the user to squeeze the lever to allow air to flow into the pneumatic bag  290  and the pneumatic cylinder  292  from the tank  299 , so that the pneumatic cylinder and pneumatic bag are expanded and raise the height of the lift-assisted device  210 . Whereas, the other handle bar/lever combination would allow the user to squeeze the lever to allow the air to be exited from the pneumatic bag  290  and the pneumatic cylinder  292  so that the lift-assisted device is lowered to the desired height. 
     The pneumatic bag  290 , pneumatic cylinder  292  and tank  299  are connected in a closed system. Within the closed system is a plurality of devices which assist in monitoring and controlling the air pressure within the system. For example, as shown in FIG. 6, in the exemplary embodiment the lift-assisted device includes a control valve  294  and a regulator  291  which assist in controlling the various pressure changes occurring within the closed system. Furthermore, emergency release valves  295  may be located at various locations on the lift-assisted device  210 . 
     In an exemplary embodiment, the control valve is a high flow valve which allows the pneumatic bag  290  to release the compressed air which has filled up the pneumatic bag  290 . 
     The undercarriage portion  260  comprises of at least one scissor linkage which includes a first member  260   a  and a second member  260   b . As shown in FIGS. 5 and 7, the first member  260   a  and the second member  260   b  are rotatably connected to a shaft  263 . When the seat portion  220  is being raised and lowered the first member  260   a  and the second member  260   b  are rotating in the opposite direction, i.e. when the first member  260   a  is rotating clockwise, the second member  260   b  is rotating counter-clockwise and vise-versa. Furthermore, the first member  260   a  and the second member  260   b  are separated by a predetermined distance x. Preferably, the distance x between the first member  260   a  and the second member  260   b  is in the range of about 1 to 2 inches, but in a preferred embodiment about 1⅝ inches. 
     In the exemplary embodiment shown in FIG. 5, one end of the pneumatic cylinder  292  is pivotally connected  301  to a connecting member  228 , e.g. bracket, located on either the seat portion  220  or the seat support portion  240 . The opposite end of the pneumatic cylinder  292  is pivotally connected  302  to a shaft  303  which is connected to the under carriage portion  260 . As compressed air is supplied to the pneumatic cylinder  292  the shaft portion  293  is extended outwards from the body  294 . 
     The pneumatic bag  290  is connected to either the seat portion  220  or the seat support portion  240 , but preferably to the seat support portion  240 . It should be appreciated that the pneumatic bag and pneumatic cylinder may be located anywhere between the seat portion and base portion. Furthermore, it is preferable to position the pneumatic bag  290  to be positioned between the first and second members of the scissor linkage and attached to either the seat support portion or the base portion. Thus, as compressed air is supplied to the pneumatic bag  290  and the pneumatic bag  290  begins to expand, the pneumatic bag  290  will exert a force onto the first and second member forcing the members to separate and raise the lift-assisted device to the desired height. 
     FIG. 8 illustrates a side view of the lift-assisted device  210  in a lowered position when the pneumatic bag  290  is fully deflated and the shaft  293  of the hydraulic cylinder  292  is fully retracted. As compressed air is supplied from the tank  299  to the pneumatic bag  290  and the pneumatic cylinder  292 , this causes each of the devices to expand outwards causing the scissor linkage to raise the height of the seat portion  220 . 
     One of the advantages the present invention provides is that it allows the lift-assisted device  210  to be lowered as close as possible to the ground because of its compact configuration. Furthermore, because of the force provided by the pneumatic bag  290  when the lift-assisted device  210  is in the lowered position shown in FIG. 8, the pneumatic cylinder  292  is able to be positioned essentially parallel with the base portion and the seat portion.