Patent Publication Number: US-7716759-B2

Title: Patient transport apparatus

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
   Not Applicable. 
   STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
   Not Applicable. 
   BACKGROUND OF THE INVENTION 
   1. Field of Invention 
   The invention relates to a patient transport apparatus. 
   2. Description of the Related Art 
   Over the last thirteen years, healthcare providers have witnessed marked change in patient numbers as well as patient needs. Thirteen years ago, a patient weighing 400 pounds or more was a rarity. These patients were extraordinary cases and not an everyday assignment. Today, dealing with patients weighing 400 pounds or more is a daily way of life. At any given time, any healthcare facility is likely to have admitted at least one patient who weighs 600 pounds or more. Although healthcare providers work to provide services to heavier patients by purchasing new equipment and educating staff members; however, the reality remains that it has become increasingly difficult to simply convey patients. 
   While healthcare providers and healthcare equipment vendors have attempted to address this growing challenge, the currently available solutions appear insufficient when looking at the growing number of staff injuries and lost work time that is associated with conveying patients. Moving heavier patients is one significant contributor to work related injuries. A staff member may be off the schedule for weeks and even months due to such injuries. In addition to the risk to the staff members, there are concerns on the patient side as well. 
   A patient expects a healthcare provider to meet the patient&#39;s healthcare needs. This expectation is independent of the patient&#39;s weight. When a patient weighing 150 pounds falls down, it is expected that the healthcare provider will help them up. That same expectation is held by a patient weighing 600 pounds or more. Like the staff member, the patient also runs a risk of injury during transport as a result of being lifted, pulled, pushed, slid from, or transferred into, out of, or between conveyances. While dealing with the very real, difficult, and unfortunate problem of transporting heavier patients, the patient&#39;s dignity is often compromised. It is difficult for patients to maintain dignity when ten men are called to move them. It is not uncommon for patients apologize for being so large and so much trouble. One&#39;s dignity should not be overlooked, regardless of the weight of the patient. 
   One of the most problematic areas in patient transport is the loading and unloading of a patient from a vehicle. Patients arriving at a healthcare facility are often transferred from an automobile to a wheelchair so that they may be conveyed to the Emergency Department. The staff member faced with assisting a patient who weighs many times more than the staff member, and who can offer little or no help in exiting the vehicle, gains a completely new appreciation for the many phases of patient conveyance. The confines of the automobile, the obstruction of the door, and the low seat height make patient assistance a difficult task. Conditions such as these are especially likely to result in embarrassment or injury. For example, it is not uncommon to inadvertently set the patient on the ground during this type of transfer, which at best only diminishes the dignity of the patient, and embarrasses the staff member. With luck, no one is injured during this process. 
   BRIEF SUMMARY OF THE INVENTION 
   A patient transport apparatus is shown and described. The patient transport apparatus of the present invention is articulated and sized to fit within the door opening of virtually all vehicles. Further, the patient transport apparatus uses a height-adjustable seat that is aligned with the vehicle seat to allow for simplified extraction of the patient from the vehicle. The height-adjustable seat lowers to just above ground height making the recovery of a fallen patient easier. A set of casters allows omni-directional travel of the patient transport apparatus for precise placement and a pair of primary motion wheels makes linear travel easier while providing a minimal turning radius. 
   The major components of the patient transport apparatus include a frame having a base and a chair support, and a chair having a seat and a back. The base provides stability and a framework for the wheel system. The chair support is substantially orthogonal to the base and carries the chair. The chair is moveable vertically along the substantial height of the chair support. The seat is sized to accommodate a patient of large girth. The backrest is narrower than the seat. The chair is reclined to provide greater comfort for the patient and to position the patient in a manner where gravity assists in holding the patient in the desired position. 
   The frame is fabricated from a rigid material rated to withstand the applied forces without bending or incurring other damage. The base includes a first side rail and a second side rail. The first side rail and the second side rail are connected by one or more cross-members that are substantially perpendicular to the side rails. One function of the cross-members is to maintain the position of the first side rail relative to the second side rail. The distance between the side rails is selected to provide lateral stability. In addition, the cross-members provide a mounting point for the chair support. 
   A plurality of free-moving wheels, such as orbital casters, provide the patient transport apparatus with omni-directional movement for precise positioning and control. In addition, a plurality of primary motion wheels are provided for efficiently moving the patient transport apparatus over longer linear distances and for making turns with a substantially zero-degree turn radius. 
   The chair also includes a pair of articulated armrests generally having three degrees-of-freedom allowing the armrests to surge, sway, and pitch. Once a patient is positioned in the chair, a safety restraint secures the patient in place. A footrest is located proximate to the forward end of the base. 
   The chair support is a substantially vertical pillar that serves as a guide and support for the vertically-moving chair. The chair support is designed to withstand the frontal torque and the load requirements of the patient transport apparatus. Positioned at the second end of the chair support and distal from the base is a control box. The control box encloses the drive control system. The drive control system actuates the vertical movement of the chair. A simple user interface allows the operator to control the up and down movement of the chair. 
   The foundation of the chair is the chair frame. The chair frame includes a pair of side brackets that are connected by a plurality of cross members. The side brackets define substantially vertical extensions and substantially horizontal extensions. The substantially horizontal extensions is connected to the carriage, which travels on the chair support, and supports the seat and the substantially vertical extensions carry the backrest. 

   
     BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
     The above-mentioned features of the invention will become more clearly understood from the following detailed description of the invention read together with the drawings in which: 
       FIG. 1  is a perspective view showing the front of one embodiment of the patient transport apparatus of the present invention having a small-diameter primary motion wheel system and a manual lift system; 
       FIG. 2  is a perspective view showing the rear of the patient transport apparatus of  FIG. 1 ; 
       FIG. 3  is a perspective view showing the rear and bottom of one embodiment of the chair; 
       FIG. 4  is a perspective view showing the side and rear of one embodiment of the chair; 
       FIG. 5  is a perspective view showing the front of one embodiment of the chair; 
       FIG. 6  is a perspective view showing the front of an alternate embodiment of the patient transport apparatus having a center-mounted primary motion wheel system and electronic lift system; 
       FIG. 7  is a sectional side elevation view of the center-mounted primary motion wheel system in a retracted position; 
       FIG. 8  is a sectional side elevation view of the center-mounted primary motion wheel system in an extended position; 
       FIG. 9  is a perspective view showing the rear of an alternate embodiment of the patient transport apparatus of  FIG. 6 ; 
       FIG. 10  is a sectional side elevation view of the electronic lift system; 
       FIG. 11  is a top plan view of one embodiment of the patient transport apparatus; 
       FIG. 12  is a side elevation view of one embodiment of the patient transport apparatus showing the chair in a fully raised position; 
       FIG. 13  is a side elevation view of one embodiment of the patient transport apparatus showing the chair in a fully raised position; and 
       FIG. 14  illustrates the patient transport apparatus of the present invention positioned at the passenger side of a vehicle for patient extraction. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   A patient transport apparatus is described and shown at  100  in the figures. The patient transport apparatus  100  of the present invention is articulated and sized to fit between the body and the open door of virtually all vehicles. Further, the patient transport apparatus  100  uses a height-adjustable seat that is aligned with the vehicle seat to allow for simplified extraction of the patient from the vehicle. The height-adjustable seat lowers to just above ground height making the recovery of a fallen patient easier. A set of casters allows omni-directional travel of the patient transport apparatus  100  for precise placement and a pair of primary motion wheels makes linear travel easier while providing a minimal turning radius. 
     FIG. 1  is a front perspective view of the patient transport apparatus  100 . The major components of the patient transport apparatus  100  include a frame  102  having a base  104  and a chair support  106 , and a chair  108  having a seat  110  and a back  112 . The base  104  provides stability and a framework for the wheel system. The chair support  106  is substantially orthogonal to the base  104  and carries the chair  108 . The chair  108  is moveable vertically along the substantial height of the chair support  106 . The seat  110  is sized to accommodate a patient of large girth. The backrest  112  is narrower than the seat  110 . 
   The frame  102  is fabricated from a rigid material rated to withstand the applied forces without bending or incurring other damage. The base  104  includes a first side rail  114  and a second side rail  116 . The first side rail  114  and the second side rail  116  are connected by one or more cross-members  122 . In the illustrated embodiment, the base  104  includes a pair of cross-members  122 . Each of the cross-members  122  is substantially perpendicular to the side rails  114 ,  116 . One function of the cross-members  122  is to maintain the position of the first side rail  114  relative to the second side rail  116 . The distance between the side rails  114 ,  116  is selected to provide lateral stability. The chair support  106  is positioned substantially midway between the side rails  114 ,  116  further contributing to the lateral stability of the patient transport apparatus  100 . In order to locate the chair support  106  between the side rails  114 ,  116 , the chair support  106  is connected to one or more of the cross-members  122 . In the illustrated embodiment, the cross members  122  are located rearward of the midpoints of the side rails  114 ,  116 . 
   Connected to the base  104 , at each end of the side rails  114 ,  116 , are a plurality of wheel support members  118   a ,  118   b . The wheel support members  118   a ,  118   b  serve as carriers for a plurality of wheels  120   a ,  120   b  that impart mobility to the patient transport apparatus  100 . In one embodiment, the wheel support members  118   a ,  118   b  are integrally formed with the side rails. In another embodiment, the wheel support members  118   a ,  118   b  are permanently attached to the side rails  114 ,  116  through a process such as welding. In yet another embodiment, the wheel support members  118   a ,  118   b  are temporarily attached through releasable fasteners such as bolts. 
   The patient transport apparatus  100  of the present invention is designed to allow an operator to precisely control the movement of the patient transport apparatus  100  with a wide range of motion. Accordingly, the plurality of wheels  120   a ,  120   b  is selected to allow freedom of movement in substantially all directions. In one basic embodiment, non-locking orbital casters are used. In another embodiment, non-locking orbital casters are attached to the front pair of wheel support members  118   a  and locking orbital casters are used with the rear pair of wheel support members  118   b . In other embodiments, the wheels used can vary without departing from the scope and spirit of the present invention. 
   In addition to the aforementioned plurality of wheels  120   a ,  120   b , the patient transport apparatus  100  includes a pair of side-mounted primary motion wheels  126 . The distance between the side-mounted primary motion wheels  126  is sufficient to allow the seat to pass between them and lower all the way to the ground. In the illustrated embodiment, the primary motion wheels  126  are free-rolling. In another embodiment, the primary motion wheels  126  are motorized to provide forward motion assistance. 
   In one embodiment, the seat  110  is a platform supported by a fixed-end cantilever. The seat  110  includes a major portion that is substantially planar and defines the seating area. In the illustrated embodiment, the seat  110  includes a substantially orthogonal extension that provides a rear stop to prevent the patient from sliding past the rear edge of the seat. The forward edge and rearward edge of the seat are rolled edges for the comfort of the patient and present a substantially snagless surface. In another embodiment, the side edges of the seat are rolled edges. 
   The seat  110  and the backrest  112  are fabricated from a substantially rigid material with a low coefficient of friction. The rigidity that is selected to support the target load capacity of the chair. The material used in the fabrication of the seat  110  and the backrest  112  is selected to have a substantially low coefficient of friction intended to allow a patient to easily slide along the surface. In one embodiment, the seat and backrest are fabricated from a metal such as stainless steel and finished with a smooth surface. 
   The chair  108  also includes a pair of articulated armrests  128 . In one embodiment, the articulated armrests  128  are constructed with three degrees-of-freedom allowing the armrests to surge, sway, and pitch. First, the articulated armrests  128  are capable of longitudinal translation (surging) allowing forward and backward motion for patient comfort. Second, the articulated armrests  128  are capable of lateral translation (swaying) allowing the armrests to slide left and right to accommodate patients of varying girth. Finally, the articulated armrests  128  are pivotally mounted to the chair  108  allowing them to be rotated from a substantially horizontal position to a substantially vertical position (pitch). When in the substantially vertical position, the articulated armrests  128  are even with or behind the plane defined by the chair back  112  allowing a patient to slide laterally onto the seat  110  unhindered. When in the substantially horizontal position, the articulated armrests provide the patient with positional security. As with other components of the patient transport apparatus, the articulated armrests are fabricated from a material that is substantially rigid and exhibits sufficient structural strength to withstand the anticipated load conditions. 
   Once a patient is positioned in the chair  108 , a safety restraint  130  secures the patient in place. The safety restraint  130  is attached to the rear of the chair back  112  and has a front latch mechanism that is actuated by the patient or an operator. Further the safety restraint  130  is length adjustable to accommodate patients of varying girth. 
   A footrest  132  is located proximate to the forward end of the base  102 . In one embodiment, the rear edge of footrest  132  is pivotally secured to the side rails  114 ,  116  of the base  104 . When not needed, the footrest  132  is moved out of the way by catching underneath the front of the footrest  132  and rotating it up, back, and out of the way. The footrest offers comfort and stability by helping the patient to maintain a seated position while being transported. In another embodiment, the footrest  132  is removably secured to the side rails  114 ,  116  and can be removed when necessary. 
     FIG. 2  illustrates a rear perspective view of the patient transport apparatus  100 . From this perspective, the details of the chair support  106  are visible. The chair support  106  is a substantially vertical pillar that serves as a guide and support for the vertically-moving chair  108 . The chair support  106  is designed to withstand the frontal torque and the load requirements of the patient transport apparatus  100 . In the illustrated embodiment, the chair support  106  includes a housing  200 . Within the housing  200  is the lift mechanism that raises and lowers the chair  108 . In one embodiment, the lift system uses hydraulic pressure to raise and lower the chair. In a manual embodiment, a foot pedal  202  increases the hydraulic pressure to raise the chair  108  and a relief knob releases the hydraulic pressure lowering the chair  108 . 
   Attached to the chair support  106  are one or more folding control handles  206 . The folding control handles  206  are pivotally connected to the chair support  106  allowing the folding control handles  206  to be folded up and out of the way when the patient transport apparatus  100  needs to be brought into close proximity with an object such as an automobile. A substantially rigid material having sufficient strength to allow the patient transport apparatus  100  to be pushed or pulled using the folding control handles  206  without deformation of the folding control handles  206  is used. The opposing side placement of the folding control handles  206 , in combination with the plurality of wheels  120   a ,  120   b , allows an operator to precisely control the movement of the patient transport apparatus  100 . The folding control handles  206  are positioned for a person of average height pushing a patient of average height positioned at a comfortable seat to footrest ratio. 
     FIGS. 3 ,  4 , and  5  are perspective views of one embodiment of the chair  108  of the patient transport apparatus  100  from differing vantage points.  FIG. 3  shows the rear and bottom of the chair  108 . The foundation of the chair  108  is the chair frame  300 . The chair frame  300  includes a pair of side rails  302  that are connected by a plurality of cross members  304 . The side rails  302  define substantially vertical extensions  306  and substantially horizontal extensions  308 . The substantially horizontal extensions  308  are connected to  218  a bracket used to attach the chair  108  to the lift mechanism and support the seat  110  and the substantially vertical extensions  306  carry the backrest  112 . 
   The chair frame  300  also includes a telescopic carrier  310  for the supporting the articulated armrests  128 . The telescopic carrier  310  is securely affixed to the chair frame  300 . The telescopic carrier  310  extends axially allowing the lateral position of the articulated armrests  128  to be adjusted as desired. Each end of the telescopic carrier  310 . An articulated armrest is pivotally attached to the each end of the telescopic carrier  310 . In one embodiment, the end sections of the telescopic carrier  310  are hollow cylindrical members that receive a rotating shaft connected to the armrest. In another embodiment, the articulating armrests are rotatably secured to the outside diameter of the telescopic carrier  310 . In one embodiment, the telescopic sections are free sliding and are secured in a locked relationship using a clamp. In another embodiment, notches provide periodic stops that hold the telescopic sections in a locked relationship. In still another embodiment, the telescopic sections are locked in a fixed position by a releasable pin. In yet another embodiment, the outer section of the telescopic carrier  310  includes a longitudinal groove and a series of spaced apart lateral grooves that intersect the longitudinal groove. The inner section of the telescopic carrier  310  has an external key that engages the grooves. When aligned with the longitudinal grove, the inner section slides laterally. When the key engages one of the lateral grooves, the inner section becomes locked in a fixed position. 
     FIG. 4  shows the rear of the chair  108  from a different perspective. Whereas the seat  110  is secured in a fixed position, the backrest  112  moves laterally. A pair of horizontal linear slide rods  400  passes through openings defined by each of sets of linear bearings  402  connected to the side rails  302 . A pair of stop brackets  404  for each of the linear slide rods  400  is located on the backrest  112  proximate to the side edges. The stop brackets  404  are attached proximate to ends of the linear slide rods  400 . The backrest  112  moves laterally as the slide rods  400  pass through the linear bearings  402 . The stop brackets  404  limit the travel of the backrest  112 . The lateral movement of the backrest  112  allows the patient transport apparatus  100  to be brought into close proximity of a vehicle. More specifically, the lateral movement allows the seat  110  to be moved unobstructed beyond the door post of a vehicle to position the patient transport apparatus  100  for patient extraction. In addition providing lateral movement, the stop brackets  404  and the linear bearings  402  support the backrest  112  at a distance from the substantially vertical extensions  306  allowing the articulated armrests  128  to be positioned behind the plane of the backrest  112  when the articulated armrests  128  are moved to a substantially vertical position. 
   The side rails  302  carry at least one tram axle  408  that supports a pair of tram rollers  410 . In the illustrated embodiment, two tram axles  408  are shown with one located proximate the midpoint and the other proximate to the lower end of the substantially vertical extensions  306 . The tram rollers  410  are secured on the tram axle  408  in a spaced-apart relationship and each tram roller  410  is aligned with one of the vertical tram rails  200 ,  202 . As the chair  108  is moved up and down the chair support  106 , the tram rollers  410  provide additional support for the chair  108 . In one embodiment, the tram rollers  410  utilize roller or needle bearings for smooth operation and long life. A pivot axle  412  connects the chair frame  300  to a carriage that moves vertically in response to the lift system. The pivot axle  412  is designed to allow the chair to pivot relative to the chair support  106 . This subtle pivotal action is necessary in that the seat while remaining on a recline position on the vertical tram rails will rest flat on the floor when at the bottom of the vertical tram rails the tram guide rollers pass over the 90° angle of the tram. This allows the seat to rest flat on the floor for recovering fallen patients. 
     FIG. 5  shows the chair  108  from the front providing an alternate view of the features described in relation to  FIGS. 3 and 4 . The patient transport apparatus  100  has a reclined chair  108  in contrast to the traditional right angle seat found in the prior art. The reclined chair  108  provides greater comfort for the patient and positions the patient in a manner where gravity assists in holding the patient in the desired position. With traditional wheelchairs, it is not uncommon for an unconscious or a semi-conscious patient to slide down and out of the wheelchair and onto the floor. By reclining the chair  108  and raising the patient&#39;s knees equal to or above their beltline, it is possible for a totally relaxed person not to slide down and out of a seated position. The position of the patient&#39;s knees is adjusted by raising or lowering the chair  108  to achieve the desired seat-to-footrest height ratio. Further, the reclined chair does not interfere with the ability of an ambulatory patient to stand up and exit from the patient transport apparatus  100  unassisted. 
     FIG. 6  illustrates an alternate embodiment of the patient transport apparatus  600  that replaces the side-mounted primary motion wheels with a center-mounted primary motion wheel system  602 . In this instance, large diameter generally refers to a diameter that is larger than the diameter of the casters used. Actuating a foot peddle  604  deploys the center-mounted primary motion wheel system  602  and transfers a percentage of the load borne by the patient transport apparatus  600  off of the plurality of corner wheels  120   a ,  120   b . Use of the center-mounted primary motion wheel system  602  makes the patient transport apparatus  600  easier to roll while retaining steering and control. 
     FIG. 7  is a side elevation of the patient transport apparatus  600  showing the center-mounted primary motion wheel system  602  in a retracted position. Through the use of foot pedal controlled levers, the engagement of the center-mounted wheels is controlled. In the illustrated embodiment, the foot pedal  604  is substantially L-shaped with the corner of the foot pedal  604  pivotally connected to the frame  102  and, more specifically, pivotally connected to one of the cross members  122 ,  124 . Pivotally connected to one end of the foot pedal  604  is a lever arm  702 . The lever arm  702  engages a hinged member  704  proximate to the midpoint of the hinged member  704 . The lever arm  702  is sized such that when the foot pedal  604  is in the raised position, the hinged member  704  is bent. A first end  706  of the hinged member  702  is pivotally supported by a fixed-position support arm  710  attached to the frame  102 . A second end  708  of the hinged member  704  is connected to a movable support arm  712  pivotally connected to the end of the fixed-position support arm  710  proximate to the frame  102 . The distal end of the movable support arm  712  is carries the axle of the center-mounted wheel  700 . The bending of the hinged member  704  raises the center of the wheel  700  and disengages the wheel from the ground  714 . 
     FIG. 8  shows the center-mounted wheel  700  in an extended position engaging the ground  714 . By depressing the foot pedal  604 , the lever arm  702  exerts a force on the hinged member  704  that straightens and extends the hinged member  704 . In turn, the extension of the hinged member  704  forces the movable support arm and the associated center-mounted wheel  700  to move downward and engage the ground  714 . While one implementation of the retractable center-mounted wheel system  600  is shown, those skilled in the art will recognize that other retraction/engagement mechanisms can be used without departing from the scope and spirit of the present invention. Further, such retraction/engagement systems are suitable for use with both large and small diameter wheels. 
     FIG. 9  is a rear perspective view of the patient transport apparatus shown in  FIG. 6 . The chair support  606  of the alternate embodiment incorporates an electronically controlled lift system instead of the manually controlled lift system of  FIGS. 1 and 2 . In the alternate embodiment, the chair support  606  includes a first vertical tram rail  900  and a second vertical tram rail  902 . The first ends of the vertical tram rails are connected to one or more of the cross members  122 ,  124 . In one embodiment, the vertical tram rails  900 ,  902  are connected to the base  104  using a permanent attachment method, such as welding. In another embodiment, the vertical tram rails  900 ,  902  are connected to the base  104  using a removable attachment method, such as nuts and bolts. One or more tram rail supports  904  are connected between the vertical tram rails  900 ,  902 . In the illustrated embodiment, a plurality of tram rail supports  904  is arranged in a spaced-apart relationship leaving the rear of the chair support  606  partial open. In another embodiment, a single tram rail support panel substantially encloses the rear of the chair support  606 . The tram rail supports  904  provide structural support and maintain the position of the first vertical tram rail  900  relative to the second vertical tram rail  902 . 
   Positioned at the second end of the chair support  606  and distal from the base is a control box  906 . The control box  906  encloses the drive control system, which actuates the vertical movement of the chair  108 . Externally visible on the control box  906  is the user interface  908  for the drive control system. In one embodiment, the user interface  908  includes a first switch  910  and a second switch  912  that control the up and down movement of the chair  108 . The embodiment of the patient transport apparatus illustrated in  FIGS. 6 and 9  is designed using an electric motor located in the control box  906 . A drive shaft  914  is located within the enclosure defined by the vertical tram rails  900 ,  902 . A first end of the drive shaft  914  is operatively connected to electric motor within the control box  906 . The opposing second end of the drive shaft  914  is rotatably carried by an end support  916 . The end support  916  is connected to the vertical tram rails  900 ,  902  proximate to the lower end of the chair support  606  on either of the cross members  122 ,  124  or the chair support  606  itself. 
   The vertical tram rails  900 ,  902  carry a carriage  918 . In the illustrated embodiment, the carriage  918  is a sleeve that overlies the exterior of the vertical tram rails  900 ,  902 . The carriage  918  is designed to move vertically along the substantial length of the vertical tram rails  900 ,  902 , which serve as a guide for the carriage  918 . The carriage  918  engages the drive shaft  914 , which imparts movement to the carriage  918 . In one embodiment, the drive shaft  914  is a threaded rod that engages a threaded receptor on the carriage  918 . The carriage  918  is raised or lowered depending upon the direction of rotation of the drive shaft  914 . In order to facilitate the smooth movement, the carriage  918  has a low friction liner about the inner surface that contacts the chair support  606 . In another embodiment, the low friction liner is replaced with bearings, rollers, or wheels. 
   Attached to the carriage  918  are one or more folding control handles  920 . The folding control handles  920  are pivotally connected to the carriage  918  allowing the folding control handles  920  to be folded up and out of the way when the patient transport apparatus  600  needs to be brought into close proximity with an object such as an automobile. A substantially rigid material having sufficient strength to allow the patient transport apparatus  600  to be pushed or pulled using the folding control handles  920  without deformation of the folding control handles  920  is used. The opposing side placement of the folding control handles  920 , in combination with the plurality of wheels  120   a ,  120   b , allows an operator to precisely control the movement of the patient transport apparatus. The folding control handles  920  are positioned for a person of average height pushing a patient of average height positioned at a comfortable seat to footrest ratio. 
   In one embodiment, the patient transport apparatus  600  also includes a fixed accessory handle  922  connected to the carriage  918 . The fixed accessory handle  922  provides the operator an alternate handle to use when the seat is in the upper position. Generally, the fixed accessory handle  922  is intended for extraction of the patient transport apparatus  600  from a stationary position with limited movement area. Typically, the fixed accessory handle  922  is useful to pull the patient transport apparatus  600  from a restricted space, for example when removing a patient from the passenger compartment of an automobile. Because of the more precise control, it is contemplated that the folding control handles  920  should be used to transport patient. 
     FIG. 10  is a side elevation view, in section, of the patient transport apparatus  600  shown in  FIGS. 6 and 9 . The illustrated embodiment shows the drive motor  1000  of the lift system. The drive motor  1000  is housed in the control box  906 . The drive motor engages a first end of the drive shaft  914 . The opposing end of the drive shaft  914  is secured in a rod support base  1002  via a rotatable linkage. In the illustrated embodiment, the drive shaft  914  is a threaded rod or lead screw. The spacing of the threads on the lead screw  914  depends is selected based upon load bearing capacity and desire rate of travel. The lead screw  914  is received by a linear drive or lead nut  1004  that converts the rotary motion into linear motion. The lead nut  1004  is connected to the chair frame  300  by a mounting bracket  1006 . A thrust bearing  1008  is mounted to a supporting member at the top of the chair support  606 . The thrust bearing  1008  supports the load of the lead screw  914  while allowing rotational motion. A bearing nut  1010  attached to the lead screw  914  rests on the thrust bearing  1008  and transfers the load from lead screw  914  to the thrust bearing  1008  thereby not requiring the drive motor  1000  to support the load. 
   Thus far, two lift systems have been described. One is a hydraulic lift system and the other is a linear drive motor system. Those skilled in the art will appreciate that other lift systems can be used without departing from the scope and spirit of the present invention, including pneumatic systems, winch systems and other types of linear actuator systems. 
   The primary function of the patient transport apparatus is patient extraction and delivery. When an operator is called upon to help remove a patient from a vehicle, the patient transport apparatus is positioned between the open door and the body of the vehicle. In order to place the patient transport apparatus in seat-to-seat alignment, the first step is to raise the articulated armrest closest to the vehicle into the substantially vertical position and to slide the articulated armrest laterally toward the chair support. Next, the seat back is slid laterally away from the body of the vehicle. Then, the folding control handle closest to the vehicle is moved out of the way. It should be noted that these changes can be accomplished with one hand while in motion, without releasing any latches, within approximately five seconds. 
   By way of example, suggested materials and/or dimensions for various parts of the patient transport apparatus are provided. The identification of dimensions and materials is not intended to limit the disclosure but merely show one embodiment of a patient transport apparatus falling within the scope and spirit of the present invention. Those skilled in the art will recognize that the suggested materials and/or dimensions can be varied without departing from the scope and spirit of the present invention. 
     FIG. 11  is a top plan view and  FIGS. 12 and 13  are side views of the patient transport apparatus  100  depicted in  FIG. 1 . The maximum height of the base  104 , including the caster height, is selected so that the base  104  is easily maneuvered under most automobiles. One acceptable value for the maximum height that accommodates the ground clearance of most current commercially available passenger vehicles is approximately six inches. The maximum height can vary without departing from the scope and spirit of the present invention based upon the intended usage and especially in response to design changes from the automotive industry that affect the typical ground clearance values. 
   In one exemplary embodiment, the base is fabricated from three-inch square steel members that are welded together. The chair support is fabricated from two-inch by four-inch steel members that are welded to the base. The base has overall dimensions of approximately 36 inches in width by approximately 42 inches in length. The width is selected for stability and to allow the patient transport apparatus to pass through doorways and portals found in a healthcare facility. The length of the base is selected to provide stability. The load-bearing capacity of the patient transport apparatus is nominally 1,000 pounds. The width of the chair support is approximately 13 inches. The width of the seat is approximately 24 inches and the width of the chair back is approximately 18 inches. The side brackets and the cross members of the chair frame are fabricated from 1.5 inch square steel members to allow the seat to move as close to the floor as possible for patient recovery. 
   With the chair raised, as shown in  FIG. 12 , the maximum height of the patient transport apparatus is approximately 68 inches. With the chair lowered, as shown in  FIG. 13 , the minimum height of the patient transport apparatus is approximately 61 inches. The vertical movement of the chair allows the seat height be varied between a minimum of approximately 1.5 inches above the ground and a maximum height of approximately 46 inches. With the footrest removed and the chair at the minimum height, a patient can slide onto the seat from a seated position on the ground, potentially with little or no assistance. 
   Those skilled in the art will recognize that the connections between the various components of the patient transport apparatus can be accomplished in either permanent or temporary fashion, unless otherwise noted. As an example, one suitable permanent attachment method includes welding for metallic components. An example of a suitable removable attachment method includes the use of temporary fasteners such as nuts and bolts. 
     FIG. 14  illustrates the patient transport apparatus  100  of  FIG. 1  positioned at the passenger side of a vehicle  1400  for patient extraction. These initial steps result in the patient transport apparatus having only two components that extend substantially beyond the chair support. The first component extending beyond the chair support is the base. As previously discussed, the base is sized to slide under the body of the vehicle and allow the patient transport apparatus to be moved very close to the vehicle. Specifically, the chair support of the patient transport apparatus is placed in a position immediately next to the body of the vehicle. The second component extending beyond the chair support is the seat. The width generally allows the seat of the patient transport apparatus to be positioned proximate to the seat of the vehicle. The height of the patient transport apparatus seat is adjusted to match the height of the vehicle seat. When properly positioned, the vehicle seat and patient transport apparatus seat lie in the same plane and any gap between the two is negligible with respect to the size of the human body. The patient transport apparatus is held in the desired position to limit movement of the patient transport apparatus while the patient is being transferred from the automobile. Examples of suitable mechanism for holding the patient transport apparatus in place include wheel chocks or wheel locks. Once properly positioned, the patient slides, with or without assistance from the operator, from the vehicle onto the patient transport apparatus. Such a transfer is not possible with presently available patient conveyances including wheelchairs, gurneys, and the cranes/lifts identified in the prior art. 
   While the present invention has been illustrated by description of several embodiments and while the illustrative embodiments have been described in detail, it is not the intention of the applicant to restrict or in any way limit the scope of the appended claims to such detail. Additional modifications will readily appear to those skilled in the art. The invention in its broader aspects is therefore not limited to the specific details, representative apparatus and methods, and illustrative examples shown and described. Accordingly, departures may be made from such details without departing from the spirit or scope of applicant&#39;s general inventive concept.