Abstract:
A wheeled dolly assembly for a patient carrier device has a box frame with a foldable footrest. Interchangeable wheels are mounted to an axle to facilitate rapid and easy movement of the dolly when a patient is strapped onto the patient carrier. The patient carrier device, such as a backboard, is retained in the box frame with adjustable pressure plates. Optional handles are mounted to the backboard through slots pre-formed in the backboard.

Description:
FIELD OF THE INVENTION 
     This invention relates to patient carrier devices, and more specifically to a wheeled dolly for use with patient carrier devices such as backboards that are used in the evacuation of patients needing medical attention. 
     BACKKGROUND AND SUMMARY OF THE INVENTION 
     Paramedics and other emergency medical personnel routinely use patient carrier devices to evacuate injured patients. There are many different kinds of patient carriers, including numerous styles of backboards and extrication cots, and they are available from many commercial sources, in many different shapes and styles. Almost all such devices include a variety of straps that are used to secure the patient in place on a patient-carrying platform. With reference to a typical “backboard,” in a typical emergency patient evacuation the injured patient is strapped to the platform defined by the backboard in a manner appropriate for the patient&#39;s particular medical condition. Often the patient is either not ambulatory or the patient&#39;s medical condition necessitates careful movement of the patient—hence the backboard serves as a platform on which the patient is immobilized while being transported to a remote location, for instance an ambulance or a triage location. 
     As a first step in patient evacuation, when a patient is ready to be moved the patient must be adequately immobilized on the backboard. This is typically accomplished with the patient in a supine position. In most cases at least four medical personnel are required to transport an injured patient secured to a backboard. In some cases more than four personnel are needed. One of the team is positioned at each of the four corners of the backboard. Each of the four personnel carefully lifts the backboard to raise the patient. The fully loaded backboard must then be carefully transported to a safe location. Transporting the patient often requires careful maneuvering. For instance, moving an injured patient through a typical house often presents difficult situations, such as maneuvering around tight corners, and going up or down stairs. This kind of maneuvering is difficult enough when transporting inanimate objects such as furniture. But when it is an injured patient that is being transported, the difficulties encountered in transporting the patient become far greater. 
     Other evacuation scenarios present even more difficult problems. To identify just a few of the difficult situations faced everyday by paramedics, consider the example of a victim who, because of his or her location in a dangerous or potentially dangerous situation, must be transported quite rapidly—the victim of a fire who is unable to move on their own is a good example. The need to move the victim quickly out of harm&#39;s way greatly compounds the difficulties faced by the paramedics. As another example, many automobile accidents involve “over the side” situations where in an accident the automobile has gone over an embankment. Often this occurs in difficult terrain. Getting an injured victim out of this kind of a precarious situation often mandates that a team of more than four personnel are needed to move the patient on the backboard. An over the side accident even often necessitates a system of ropes, pulleys and winches to pull the backboard up the embankment slope. When several paramedics are carrying the backboard it is easy to understand the difficulties the paramedics face in attempting to minimize patient disruption during even relatively simple evacuations. 
     Another graphic example is the situation where a victim is located in a bedroom having a narrow doorway, and/or a house having narrow hallways. Many structures existing today have narrow doorways and corridors. Transporting a patient through such restricted passages can be very difficult, especially where the patient&#39;s medical condition mandates extremely careful patient handling. When a backboard requires a team of four paramedics to carry the patient, maneuvering the backboard and the patient is very difficult. 
     As a final example of the difficulties emergency medical personnel encounter when transporting injured patients, it is of course obvious that extreme care must be taken to transport a patient having a potential spinal injury. Even in a relatively straightforward evacuation where no great obstacles are encountered, paramedics must exercise the utmost caution when transporting the patient. This can make the paramedic&#39;s job very difficult in even the most routine transportation of victims of spinal injuries. When the evacuation scenario is more difficult, as is often the case, the difficulties of the paramedics&#39; job is compounded. 
     Patient transport is not the only function of patient carrier devices such as backboards. Often a victim is located remotely from the nearest vehicular access. This occurs, for instance, where a hiker or climber has been injured in a remote location that is not accessible to emergency vehicles. In that case, paramedics may need to carry emergency medical equipment such as jump bags, oxygen canisters and even cardiac monitoring equipment a long distance to the victim. Many paramedics use backboards as a platform onto which such equipment may be loaded and secured. Of course, more than one person is needed to carry a heavy load. But the backboard nonetheless provides a convenient method of transporting the equipment. 
     As may be derived from the discussion above, patient transport on patient carrier devices is often a difficult and dangerous operation. The difficulties encountered with even the most routine patient moves are compounded when the victim is located in a dangerous or restricted area, or where the patient&#39;s medical condition presents special concerns, for instance where the patient is unconscious and unable to assist in the move, or where the injury mandates special patient treatment. Nonetheless, patient carrier devices are used ubiquitously in the emergency medical field. Such devices are used everywhere from civilian medical evacuations to military evacuations—they are used wherever there is a need to transport the injured, and they make the paramedics&#39; job much easier and the offer significant improvements in patient care. 
     But despite their everyday usefulness in securing injured patients and their role in transporting the patient, patient carrier devices ironically cause many problems, including injuries to both the patient and to the team of emergency personnel transporting the patient. For example, many, many emergency medical personnel are injured every year while patients are being transported on carrier devices. Back, shoulder and other injuries are common among paramedics caused by lifting patients who are secured to backboards. Sometimes the patients are simply so heavy that even a team of four paramedics has trouble lifting the patient, creating great lifting strain on the team members. These problems are compounded where the patient is in a difficult environment that necessitates lifting in other than ideal lifting positions, and when the patient must be moved in a low-angle evacuation. 
     Thus, there is a need for a patient carrier device system that is ergonomically designed to consider both the needs of the patients and the paramedics who transport them. As noted, in some situations the patient must be evacuated with haste. This is the case, for instance, in a tactical response type of emergency where it is necessary to get victims out of a dangerous situation very quickly. Standard carrier devices such as backboards make this job difficult, since at least four people are needed to carry the device when a patient is strapped to it. This also puts four medical personnel in a dangerous situation while the victim is being loaded onto the backboard and during transportation to a safe location. 
     Thus, there is a very real need for a patient carrier device that addresses the needs of both medical personnel and patients. The present invention addresses these needs by providing a wheeled dolly that is adapted for use with almost every patient carrier device available on the market today, from all types of backboards to extrication cot devices. The invention converts a standard carrier device such as a backboard into a rapid deployment and evacuation system for injury victims. The wheeled dolly has a box frame that accepts the carrier device and secures it into place in the box frame to thereby provide a two-wheeled platform on which to transport the victim. Handles are optionally provided with universal attachments for rapid connection with any backboard or carrier device. With the combination of the dolly and the optional handles, the patient carrier may be transported through even the most difficult locations and terrain. Moreover, the use of a wheeled dolly allows even heavy and/or severely injured patients to be reliably transported by fewer personnel than is required when the present invention is not employed. Various types of wheels may be mounted onto an axle to meet the needs of the varying conditions where victims may be located. With the appropriate wheels in place, the injured patient may be moved around corners and through doorways that would be all but impassible with the carrier device alone. Even heavy equipment may be strapped to the wheeled system and moved by a single paramedic. The risk of injuries to the paramedics—especially back and shoulder injuries—is greatly reduced since the dolly reduces the effective load weight that the paramedic must heft. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view of a preferred embodiment of the present invention, showing the wheeled dolly box frame, a backboard and one of the optional handles. 
     FIG. 2 is a side elevational view of the embodiment of FIG. 1 with a portion of the box frame partially cut away to show the pressure pads. 
     FIG. 3 is a side view of an alternative embodiment of the present invention with an alternate, off-road wheel. 
     FIG. 4 is a rear elevational view of the box frame of the present invention, showing the pressure pads in phantom lines. 
     FIG. 5 is a cross sectional view of the box frame taken along the line  5 — 5  of FIG.  4 . 
     FIG. 6 is a partial cross sectional view taken along the line  6 — 6  of FIG. 1, showing a detail of the handle assembly. 
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     With reference to the figures, a preferred embodiment of a patient carrier dolly assembly  10  is shown in FIG.  1 . Dolly assembly  10  includes three primary components, box frame  12 , handles  14   a,    14   b  (FIGS.  1  and  2 ), and patient carrier device  16 . The box frame  12  and the handles  14  are designed to adapt to most every style of patient carrier device found on the market today, from standard backboards to extrication cots. The particular patient carrier device shown in the drawings is in the form of a typical “backboard.” These products are commercially available from many different sources and are available in many different styles. The backboard  16  shown in the figures is a generic representation of a backboard that could be obtained from any number of sources. Most of these devices have certain structural attributes in common. For instance, since they are designed to support a human patient, and often one that is unconscious, the devices are typically planar elongate structures that are sufficiently stiff to support the patient without excessive flexing of the carrier. Patient carriers have a plurality of slots and holes for attaching straps, which are used, for example, to strap the patient to the device, thereby immobilizing the patient to the degree necessary under the conditions. The word “backboard” as used herein should be understood as a generic reference to all such patient carrier devices. 
     Backboard  16  shown in FIG. 1 includes three patient straps  18   a,    18   b  and  18   c.  These straps are used to strap the patient on the backboard to thereby immobilize the patient, and they generally are provided with appropriate clasps to secure the free end or ends, as illustrated with the interconnected straps  18  shown in FIG.  1 . The lowermost of the three patient straps ( 18   c ) is positioned near the patient&#39;s knees. This type of a strap is referred to as a “lock-out” strap. If the patient is unconscious, this strap helps prevent the patient&#39;s knees from buckling if the patient&#39;s head is elevated higher than his or her feet during transport. With the present invention the patient likely will be transported with the backboard at an incline or an oblique angle relative to the ground plane. That is, the patient is transported with the dolly wheels on the ground, and the “upper” end of the backboard being held by the paramedic—much in the fashion of a traditional hand truck. At such an incline the patient&#39;s knees naturally might have a tendency to bend or buckle, particularly if the patient is not conscious. The lockout strap  18   c  thus may be wider than the other straps used with the backboard to provide a secure method of preventing the patient&#39;s knees from buckling when at such an incline. 
     Most all backboards also typically include numerous handhold slots positioned around the periphery of the backboard. Paramedics use these as handholds to grasp the backboard when picking it up. 
     Referring now to box frame  12 , the frame is formed of lateral upright frame members  20   a  and  20   b,  which are interconnected on the front side by a top front plate  22  and a bottom front plate  24 , and at the back side by a rear plate  26  (FIG.  4 ). A bottom plate  28  interconnects lateral upright frame members  20   a,    20   b  and rear plate  26  at the lower edges thereof and extends in the forward direction beyond the forward edges of the upright frame members  20   a  and  20   b,  as shown in FIGS. 1 and 5. Together the lateral frame members  20   a  and  20   b,  rear plate  26 , top and bottom front plates and the bottom plate define a box frame having an interior compartment that has an opening into it through the top or upper side of the box frame. As detailed below and as illustrated in the drawings, in use the backboard is inserted into the interior compartment of the box frame through the opening and is secured therein. 
     The box frame is made of any sufficiently strong material, and is preferably fabricated from heavy gauge aluminum. 
     The bottom plate  28  defines a platform that provides support for a fold-down footrest  30 . Footrest  30  is pivotally connected to frame members  20   a  and  20   b  with, for example, threaded bolts/nuts  32  (one of which is shown in FIG.  1 ). Footrest  30  comprises a pair of outer arms  34   a  and  34   b,  which are interconnected with a foot plate  36 . Footrest  30  may be pivoted about threaded bolts/nuts  32  to move the foot rest between a lowered position (shown in the drawings) in which a patient&#39;s feet are able to rest on foot plate  36 , and a folded position (not shown) in which foot plate  36  lies adjacent and abuts bottom front plate  24 . Foot rest  30  is pivoted into the folded position in the direction of arrow A in FIG.  1 . When the foot rest is in the lowered position, bottom plate  28  underlies foot plate  36  to provide support and strength for the foot plate. The dolly assembly may be stored more efficiently with the foot rest in the folded position, although in some patient-carrying situations it may be advantageous to strap the patient to the device with the foot rest in the folded position. 
     A pair of stair glides  38   a  and  38   b  is affixed to rear plate  26 . The stair glides are of the usual construction and function in a known manner to ease moving the dolly assembly up or down a flight of stairs. 
     Referring to FIG. 4, a pair of wheels  40   a  and  40   b  are mounted on axle  42  that extends through axle bushings  44   a  and  44   b,  which are mounted on stair glides  38   a  and  38   b,  respectively. Various types of wheels may be used with the dolly assembly of the present invention, and, as detailed below, the wheels may be quickly removed to allow different types of wheels to be mounted to axle  42 , or as detailed below, an alternate axle for use with the alternate wheel. The wheels shown in FIG. 1 are standard heavy-duty wheels. To facilitate quick interchangeability of the different wheels, the outer or distal ends of axle  42  are threaded, and the wheels are mounted on axle  42  with threaded lugs  46   a  and  46   b,  which thread onto the axle. 
     Adjustable pressure plates are provided with box frame  12  to make a secure connection between backboard  16  and the box frame. Specifically, as best illustrated in FIGS. 4 and 5, there is provided a top pressure plate assembly  48  and a bottom pressure plate assembly  50 . Top pressure plate assembly  48  includes an internally threaded bushing  52  attached to rear plate  26 . A bore through rear plate  26  communicates with the internally threaded bushing to define a passageway through the rear plate and the bushing. A threaded shaft  54  is threaded through bushing  52  such that the shaft extends into the interior compartment defined by the box frame. A knurled knob  56  is attached to the outer end of shaft  54  rearward of rear plate  26  and a pressure plate  58  is attached to the opposite end of shaft  54  in the interior compartment of the box frame. More specifically, the interior distal end of shaft  54  comprises a ball joint  55 . Pressure plate  58 , which in the preferred embodiment is a circular plate (phantom lines in FIG.  4 ), includes a socket  57  configured for receiving ball joint  55 . The ball and socket connection between shaft  54  and pressure plate  58  allows the pressure plate to “float” on shaft  54 . An optional shaft retaining collar  61  may be fixed to shaft  54  adjacent the interior distal end of the shaft as shown in FIG.  5 . The retaining collar functions as a keeper that prevents the shaft from being threaded out of bushing  52 . The inner surface of pressure plate  58  (that is, the surface of pressure plate  54  that abuts backboard  16  when a backboard is installed in the dolly, FIG. 2) is preferably covered with a non-slip surface  59  such as an adhesive-backed non-slip material. 
     A second pressure plate  60  is used in bottom pressure plate assembly  50 . As shown in the phantom lines in FIG. 4, bottom pressure plate  60  is an elongate plate member that is operated by a pair of independently operable lower pressure plate knobs  62   a  and  62   b,  each of which is connected to the pressure plate in a manner identical to that described above with reference to top pressure plate assembly  48 . An identical ball  55  and socket  57  assembly is used to connect the pressure plate  60  to the two shafts  54  used in bottom pressure plate  60 , allowing the pressure plate to float on the shafts. 
     The handles are shown in detail in FIG.  6 . In most instances, two handles are used with the dolly assembly, although the handles may be omitted, or more or less than two may be used in a particular situation. Regardless of whether or how many handles are used, handles  14   a  and  14   b  shown in the figures are identical in structure. Each handle  14  includes an elongate toggle bar  64  (FIG. 1) that is pivotally connected to a threaded shaft  66 . As shown in FIG. 6, toggle bar  64  includes a bracket  67  on one side of the bar. A hole is bored through the distal end of shaft  66 . A pin or bolt extends through holes in bracket  67  (not shown) and through the hole through shaft  66  to connect the shaft to the bracket. The toggle bar pivots on the pin. The opposite end of threaded shaft  66  is threaded into a threaded bore in the handle body  68 . A handle pressure plate  69  is positioned at the base of the handle body. 
     Assembly and Operation 
     As noted above, the patient carrier dolly assembly of the present invention may be used with most patient carriers on the market. The patient carrier is assembled by first adjusting the pressure plates to define an opening into the space between the inner-facing surfaces of the pressure plates (i.e., the surfaces defined by non-slip coating  59 ) and the rear-facing walls of top front plate  22  and bottom front plate  24 . This is accomplished by rotating knobs  56  and  62   a  and  62   b  so that the pressure plates are moved in a rearward direction. Since the dimensions of backboards and other patient carrier devices are not standardized, and in particular because the thickness of such devices may vary from one manufacturer to the next, the ability to adjust the width of the space into which the backboard is inserted is beneficial. This lends to the ability of the present invention to be used with almost any patient carrier. 
     When the space so-defined by adjustment of knobs  56 ,  62   a  and  62   b  is sufficiently wide that the selected backboard may be inserted into the space, the backboard is inserted into the space through the opening at the top of the box frame until the lowermost edge of the backboard abuts bottom plate  28  (FIG.  1 ). Each of the knobs  56  and  62   a,    62   b  is then rotated such that the associated pressure plates  58  and  60  are moved inwardly in the “forward” direction, toward the backboard. The knobs are rotated until the pressure plates make contact with the backboard, thereby exerting pressure between the pressure plates and the backboard. The backboard is thus trapped between the pressure plates on the rearward side, and the inner walls of top front plate  22  and bottom front plate  24 . The knobs are tightened to trap the backboard securely in the box frame. As noted, a non-slip surface material may be applied to the inner-facing surfaces of the pressure plates. The same material may also be optionally added to the inner-facing walls of the top and bottom front plates. Since each of the pressure plates is connected to the associated knobs with a ball and socket joint, the pressure plates “float” and therefore are suited for use with backboards that may have an uneven surface where the pressure plates abut the backboard. When the backboard is thus assembled, the backboard defines a longitudinal axis along its length dimension. That axis is preferably substantially transverse to the axis defined by axle  42 . 
     As a safety measure to ensure a secure connection between the box frame and the backboard, a strap connected to the backboard may be clipped or otherwise attached to the box frame. For instance, as illustrated in FIG. 1, straps  70   a,    70   b  may be clipped to or threaded through retainer loops  72   a,    72   b  located on outer upright frame members  20   a  and  20   b,  respectively. These safety straps are optional. 
     With the backboard thus assembled with the box frame the footrest  30  may then be moved into the lowered position, as dictated by the particular situation. 
     If the optional handles are to be used, the handle toggle bars are inserted through appropriately sized elongated slots formed in the backboard, such as slots  76   a  and  76   b  shown in FIG.  1 . The handles are usually positioned near the upper end (or the patient&#39;s head end) of the backboard. However, a handle may be inserted into any slot of an appropriate size and shape to receive the toggle bar. The toggle bar is then rotated approximately 90° relative to the longitudinal axis of the elongate slot such that the longitudinal axis of the toggle bar is transverse to the longitudinal axis of the slot, and such that the outer distal ends of the toggle bar spans the elongate slot and overlap the edges of the slot, as shown in FIG.  1 . The handle body may then be rotated on threaded shaft  66  to move handle pressure plate  69  toward backboard  16  until pressure plate  69  bears against one surface of the backboard and the toggle bar bears against the opposite surface of the backboard. Rotation of the handle body is continued until the handle is locked into place by the “pinching” action exerted on the backboard between the toggle bar and the handle pressure plate. 
     At this point a patient may be secured to the backboard in the usual fashion, except the patient&#39;s feet will in most cases be resting upon the platform defined by footrest  30 . In most cases the patient will be in a supine position when first strapped to backboard  16 . When handles  14   a  and  14   b  are used, and when the wheels  40   a  and  40   b  shown in FIG. 1 are used, the dolly assembly may be laid down such that the backboard forms a horizontal platform that rests on the two wheels, and the two handles such that the platform is substantially parallel to the ground plane. The patient may then be lifted by raising the “upper” or “head” end of the backboard, either by grasping the handles or by using other slots in the backboard as handholds. 
     Since the dolly assembly utilizes wheels, the patient may be maneuvered out of difficult locations quickly and easily, and with fewer paramedics than would otherwise be required. This is true even for very heavy patients that otherwise might present severe difficulties for the paramedics. 
     In some instances it is preferable to use an off-road type of wheel. This is accomplished by removing wheels  40   a  and  40   b  by removing lugs  46   a  and  46   b,  respectively. With an off-road type of wheel a new axle must be inserted through the axle bushings. Thus, axle  42  is removed and the new, longer axle is inserted through the bushings. As illustrated in FIG. 3, an off-road a wheel may be quickly mounted to the axle. The bicycle-type off road wheel  74  shown in FIG. 3 is typically used in an “over the side” situation where a patient is located, for instance, over a cliff or an embankment. The use of a larger diameter wheel, like wheel  74 , allows the patient to be extricated from such a situation with fewer paramedics since a pulley and sling system can easily be rigged to pull the dolly assembly up an embankment with as few as two paramedics supporting the head end of the apparatus. Off-road wheel  74  is sufficiently strong to meet the demands placed on it, and preferably includes a pneumatic tire. 
     The backboard is quickly disassembled from the box frame. This may be done when the patient is loaded into a transport vehicle, or at any other appropriate time. The backboard is released by turning the knobs of pressure plate assemblies  58  and  60  to release the pressure between the pressure plates and the backboard. The handles may also be quickly removed in a like manner. 
     Those skilled in the art will appreciate that various alternate equivalent structures may be used in place of some of the structural features described above. For instance, the threaded shafts of the pressure plate assemblies may be replaced with cams, which perform the equivalent function—that is, to exert pressure between the pressure plate and the backboard to lock backboard in place in the box frame. A similar cam mechanism may be used with the optional handles. As a further example of an equivalent mechanism for making a secure connection between the backboard and the box frame, a spring-loaded detent may be positioned to engage a slot formed in the backboard. Further, while the preferred embodiment of the box frame is an enclosed structure defining an interior compartment (for receiving and holding the backboard) and having an opening thereto through the upper side, the front and rear plates may be manufactured such that the frame assembly is not fully enclosed. For example, the top and bottom front plates ( 22 ,  24 ) could be manufactured such that they do not extend all of the way between the upright frame members  20   a  and  20   b.    
     Use of the present invention greatly simplifies patient transport from difficult locations and greatly reduces the risk of injury to emergency medical personnel. While the invention has been described in terms of a preferred embodiment and certain alternatives, it will be appreciated by one of ordinary skill that the spirit and scope of the invention is not limited to those embodiments, but extend to the various modifications and equivalents as defined in the appended claims.