Patent Publication Number: US-7716762-B2

Title: Bed with sacral and trochanter pressure relieve functions

Description:
RELATED APPLICATIONS 
     This application claims priority to, and incorporates herein by reference, our U.S. provisional patent application, application Ser. No. 60/979,837, filed on Oct. 14, 2007, entitled “Adjustable Bed With Sacral Pressure Relieve Function.” 
    
    
     FIELD OF THE INVENTION 
     This invention relates generally to specialized therapeutic beds and surfaces, and more particularly, to beds with mechanically adjustable therapeutic surfaces for the treatment and prevention of a patient immobility induced complications. 
     BACKGROUND OF THE INVENTION 
     A normal person, while sleeping, generally turns or moves frequently. This mobility restores blood circulation to the compressed areas of the subcutaneous tissues. When a patient is partially or permanently immobilized, the blood supply in the area under pressure is restricted or blocked. If the blood supply is not restored it will be predisposed to induce local injury, which might lead to decubitus or pressure ulcers (bedsores). Pressure sores occur most commonly in the buttocks, sacrum, hips and heels. When infected, these sores can become life threatening. Besides pressure ulcers, immobility can cause other pathologies including pneumonia, atelectasis, thrombosis, urinary tract infections, muscle wasting, bone demineralization and other undesired events. 
     To prevent such complications, many medical care facilities buy or rent extraordinarily expensive beds and therapeutic support surfaces, costing upwards of seventy-five thousand dollars each or more than $100/day in rent. Other medical and nursing care facilities rely on nurses and aides to turn bedridden patients manually, preferably at least every 2 hours—day and night—to relieve tissue compression and reestablish blood flow. Both alternatives put a significant strain on limited medical care resources. 
     The manual procedure, in particular, has many drawbacks. The need to frequently turn and move patients is costly, and requires an increased ratio of personnel to patient. The immobilized patient is also awakened every time he is mobilized. If family members are the caregivers, they need to be in attendance 24 hours a day, which might lead to fatigue and distress. 
     Many attempts have been made to solve the above-mentioned problems utilizing mattresses filled with air, water or gel. These solutions generally fall into one or both of two categories—very expensive solutions, and inadequate or unreliable solutions. Today, the medical bed industry has largely abandoned strictly or predominantly mechanical approaches in favor of costly therapeutic support surfaces that use managed multi-compartment air mattresses to distribute pressure and laterally rotate the patient. Thus, there is still a very great need for fresh, less costly solutions to problems of patient immobility. There is also a great need for improved ways of both preventing ulcers and treating patients with existing ulcers. 
     SUMMARY OF THE INVENTION 
     An adjustable bed is provided with lifting mechanisms operable to modulate the patient support surface to relieve pressure on the sacral area of a patient resting on the patient support surface. 
     In one embodiment, the patient support structure comprises a torso support structure, a pelvic support structure, an upper-leg support structure, and a lower-leg support structure. Lifting mechanisms are operable to elevate the torso and upper-leg support structures relative to the pelvic support section sufficiently to substantially reduce pressure on the sacral area of a patient resting on the patient support surface. These lifting mechanisms are also operable to modulate the patient support surface to create a trough that relieves pressure on the sacral area of the patient or on the heads of the patient&#39;s trochanters if the patient is tilted to one side. 
     The torso support, upper-leg support and lower-leg support structures are each operable to articulate about separate transverse axes of articulation. The torso support structure comprises a patient support litter mounted on a torso support base structure. Likewise, the upper-leg support structure comprises another patient support litter mounted on an upper-leg support base structure. Each patient support litter comprises a mattress-supporting foundation or hammock mounted on two bars on the right and left sides of the corresponding (torso support or upper-leg support) base structure. The patient support litter mounted on the torso support base structure is mounted on telescoping bars that are mounted on four independently controllable vertices (right and left lower thorax support vertices and right and left shoulder support vertices) situated near the four corners of the torso support base structure. The patient support litter mounted on the upper-leg support base structure is mounted between non-telescoping right and left side support bars which are pivotally joined to two independently controllable hip support vertices mounted on an articulating hip support base structure. 
     In a sacral-pressure-relief mode, several mechanisms are coordinated to create a trough that relieves pressure on the sacral area of the patient. Both the articulating torso support base structure and the articulating upper-leg support base structure are rotated moderately upward. Also, the right and left lower thorax support vertices of the torso support structure move along upward and inward trajectories—and independently of the right and left shoulder support vertices—to cradle and elevate the patient&#39;s lower thorax. Furthermore, the upper-leg support bars are elevated by—while pivoting with respect to—the corresponding vertices to lift the patient&#39;s hips and upper legs. The elevation of the lower thorax and upper leg support vertices, relative to the pelvic support structure, reduces pressure on the sacral area of the patient. 
     In a trochanter-pressure-relief mode, several mechanisms are coordinated to both create a trough in the patient support surface and tilt the patient to one side. As with the sacral-pressure-relief mode, both the articulating torso support base structure and the articulating upper-leg support base structure are rotated moderately upward. The right and left lower thorax support vertices of the torso support structure move along upward and inward trajectories—and independently of the right and left shoulder support vertices—to help create a trough. The upper-leg support vertices also move along upward and inward trajectories to help create the trough. Once a suitable trough has been created to cradle the patient&#39;s midsection, the lower thorax and upper-leg support vertices on one side of the bed are selectively further elevated (with respect to the lower thorax and upper-leg support vertices on the other side of the bed), causing the patient to tilt toward her left or right side. 
     Each of the vertices is driven by an independently operable actuator. Many different preferred embodiments of independently operable actuators are shown. One embodiment of an independently operable actuator, illustrated in  FIG. 11 , comprises screw-type linear actuator driving a sliding element, a sliding guide that confines the movement of the sliding element to a horizontal linear segment within the transverse plane perpendicular to the longitudinal axis of the torso-supporting or hip-supporting base structure, and a principal arm having superior and inferior ends, the inferior end of which is hingedly linked to the sliding element, and the superior end of which is joined to a side support bar corresponding to the independently operable actuator of which the principal arm is a part. This embodiment also includes a secondary arm having superior and inferior ends, the inferior end of which is hingedly linked to the torso-supporting or hip-supporting base structure and the superior end of which is hingedly joined to a midsection of the principal arm. 
     Another embodiment of an independently operable actuator, illustrated in  FIG. 12 , includes many of the elements of the embodiment of  FIG. 11 , and further includes a principal arm that comprises an inner rod that telescopes within an outer rod. A second linear actuator is operable to drive the telescoping inner rod of the principal arm. 
     Another embodiment of an independently operable actuator, illustrated in  FIGS. 13-14 , has a principal arm—like that of FIG.  12 —that comprises an inner rod that telescopes within an outer rod. But the embodiment of  FIGS. 13-14  uses one linear actuator, whereas the embodiment of  FIG. 12  uses two. Rather than having a linear actuator at the base of the principal arm operable to drive the telescoping inner rod of the principal arm, the embodiment of  FIGS. 13-14  uses a cord connected on one end to the telescoping inner rod and on an opposite end to a spring, the cord being mounted, at one or more intermediate points along the cord, on a one or more pulleys, the cord being operable to cause the telescoping inner rod of the principal arm to extend. In this embodiment, activation of the same actuator that moves the position of the sliding element also causes the telescoping inner rod of the principal arm to extend or retract. 
     Another embodiment of an independently operable actuator, illustrated in  FIG. 15 , includes a telescoping principal arm having superior and inferior ends, the inferior end of which is hingedly linked to the hip-supporting base structure, and the superior end of which is joined to the support arm corresponding to the independently operable actuator of which the telescoping principal arm is a part. This embodiment also includes a telescoping secondary arm having superior and inferior ends, the inferior end of which is hingedly linked to the hip-supporting base section and the superior end of which is hingedly joined to a midsection of the principal telescoping arm. In this embodiment, each of the principal and secondary telescoping arms comprises an inner rod, driven by a linear actuator, that telescopes within an outer rod. This embodiment eliminates the sliding element of the previous three embodiments. 
     A further embodiment of an independently operable actuator, illustrated in  FIGS. 16-17 , comprises a curved arm sliding within a curved guide and a linear actuator hingedly mounted on one end to the hip-supporting base structure and on an opposite end to the curved arm that is operable to move the curved arm between retracted and extended positions. 
     Yet another embodiment of an independently operable actuator, illustrated in  FIG. 18 , comprises a curved arm sliding within a curved guide, gear teeth disposed along a concave surface of the curved arm, and a rotary actuator with gear teeth adapted to mesh with the gear teeth of the curved arm, the rotary actuator being operable to drive the curved arm between retracted and extended positions. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  illustrates a perspective view of one embodiment of the adjustable bed, adapted especially for a hospital environment. 
         FIG. 2  illustrates a perspective view of the adjustable bed of  FIG. 1  with the overlying patient support surface removed. 
         FIG. 3  illustrates a side view of the patient support structure and upper and lower chasses of the adjustable bed of  FIG. 1 . 
         FIG. 4  illustrates a partial top plan view of linear actuators for torso elevation and leg elevation. 
         FIG. 5  is an exploded-view schematic diagram illustrating the relationship between the articulating multisectioned base platform of the patient support platform, the adjustable patient support framework of the patient support platform, and the patient support surface, which is modulated by movement of points and segments oriented at or near its periphery. 
         FIG. 6  illustrates a perspective view of the torso support structure of the adjustable bed. 
         FIG. 7  illustrates a perspective view of the hip support structure and the central support structure of the adjustable bed. 
         FIG. 8  illustrates the adjustable torso support litter of  FIG. 6 . 
         FIG. 9  further illustrates the adjustable torso support litter of  FIG. 8 , in a different orientation. 
         FIG. 10  illustrates the adjustable hip support litter of  FIG. 7 . 
         FIG. 11  illustrates a preferred embodiment of a mechanical actuator assembly to manipulate one of the vertices of the torso support structure. 
         FIG. 12  illustrates a sectional rear plan view of another embodiment of a mechanical actuator assembly, incorporating a telescopic arm, to manipulate one of the vertices of the torso support structure. 
         FIG. 13  illustrates yet another embodiment of a mechanical actuator assembly, incorporating a telescopic arm operated by a spring and steel cord, to manipulate one of the vertices of the torso support structure. 
         FIG. 14  illustrates the embodiment of  FIG. 13  in the upper position. 
         FIG. 15  illustrates a sectional rear plan view of yet another embodiment of a mechanical actuator assembly, utilizing two linear actuators driving telescoping principal and secondary arms, to manipulate one of the vertices of the torso support structure. 
         FIG. 16  illustrates a perspective view of a torso support structure using a curved telescoping arm and actuator assembly to manipulate the vertices of the torso support structure. 
         FIG. 17  illustrates a partial rear plan view of curved telescoping arm and actuator assembly of  FIG. 16 . 
         FIG. 18  illustrates a partial rear plan view of an alternative embodiment of the curved telescoping arm and actuator assembly of  FIGS. 16 and 17 , employing sliding arms with gears. 
         FIG. 19  illustrates a perspective view of another embodiment of a torso support structure that includes additional independently movable points or vertices of actuation. 
         FIG. 20  illustrates  FIG. 19  with the sheets removed for clarity. 
         FIG. 21  illustrates a perspective view of a simplified adjustable bed  100  that is especially adapted to a home embodiment. 
         FIG. 22  illustrates the adjustable bed of  FIG. 21  in a patient-tilting mode. 
         FIG. 23  illustrates a patient support surface being modulated to relieve pressure on a patient&#39;s sacral area as well as an alternative embodiment of the lower-leg supporting structure to relieve pressure on the heel area. 
         FIG. 24  illustrates a magnified view of a portion of  FIG. 23  to illustrate the pressure relief to the sacral area. 
         FIG. 25  illustrates a perspective view of an embodiment of the adjustable bed adapted to an airplane seat embodiment. 
         FIG. 26  illustrates a perspective view of an embodiment of the adjustable bed in an incubator embodiment. 
         FIG. 27  illustrates a perspective view of the patient support surface being modulated to rotate the patient towards his right side while relieving pressure on the head of right trochanter. 
         FIG. 28  illustrates a perspective view of the adjustable bed with the patient support surface being modulated to maintain a patient in a prone and rotated position. 
         FIG. 29  illustrates a perspective view of the adjustable bed with the patient support surface in a patient-twisting mode to cause counter-rotation of the patient&#39;s torso and legs. 
         FIG. 30  illustrates the embodiment of  FIG. 30  from an alternative perspective view for clarity. 
         FIG. 31  illustrates a perspective frontal view of the patient support surface being modulated to selectively squeeze the patient support surface on either side of a patient&#39;s waist. 
         FIG. 32  illustrates the adjustable bed the patient support surface being modulated to selectively squeeze the patient support surface on either side of a patient&#39;s waist. 
         FIG. 33  illustrates a perspective view of the adjustable bed with the patient support surface modulated to facilitate patient ingress or egress on or off the adjustable bed. 
         FIG. 34  illustrates the embodiment of  FIG. 33  from an alternative perspective view. 
         FIG. 35  illustrates a partial top plan view of electrical connections between parts of the adjustable bed. 
     
    
    
     DETAILED DESCRIPTION 
     In describing preferred and alternate embodiments of the technology described herein, as illustrated in  FIGS. 1-35 , specific terminology is employed for the sake of clarity. The technology described herein, however, is not intended to be limited to the specific terminology so selected, and it is to be understood that each specific element includes all technical equivalents that operate in a similar manner to accomplish similar functions. 
     I. Mechanical Overview 
     A. Main Structures of the Adjustable Bed 
       FIG. 1  illustrates a perspective view of a preferred embodiment of an adjustable bed  100  embodied as a hospital bed and that offers support to a patient weighing as much as 1000 pounds. The adjustable bed  100  comprises a patient support surface  36  that extends from the edge of the headboard  9  to the edge of the footboard  10 . The patient support surface  36  overlays a versatile patient support structure  60  (FIG.  3 )—discussed in much greater detail in the following sections—that supports and modulates the patient support surface  36 . This patient support structure  60  is mounted on an upper chassis  7 , which is in turn mounted on a lower chassis  8 . The lower chassis  8  is mounted on wheels  114 . The headboard  9  and footboard  10  are attached to opposite ends of the upper chassis  7 . 
     A prototype version of the adjustable bed  100  has a length of about 248 cm. and a width of about 107 cm. The patient support surface  36  is 91 cm. wide. It is anticipated that bariatric versions of the adjustable bed  100  would have a width of about 137 to 153 cm. 
     Mechanical linear actuators  104  ( FIGS. 1 ,  3 ) positioned between the upper chassis  7  and a lower chassis  8  allow the head and foot ends of the upper chassis to be independently raised or lowered with respect to the lower chassis  8 . To adjust the elevation of the patient support surface  36 , all of the linear actuators  104  are synchronously activated to uniformly raise or lower both the headboard  9  end and the footboard  10  end of the upper chassis  7  with respect to the lower chassis  8 . To incline the bed  100  into a Trendelenburg position, with the feet higher than the head, the footboard linear actuators  104  are activated to raise the footboard  10  end of the upper chassis  7 . To incline the bed  100  into a reverse-Trendelenburg position, with the head higher than the feet, the headboard linear actuators  104  are activated to raise the headboard  8  end of the upper chassis  7 . Accordingly, the upper chassis can be moved between raised, lowered, Trendelenburg, and reverse-Trendelenburg positions. 
     In other embodiments, not shown here, side guard rails may be added to the upper chassis  7 , and specially designed attachments may be provided to increase the width of the patient support structure  60  to accommodate bariatric patients. For example, side guards of the type shown and described in our U.S. patent application Ser. No. 12/176,338, filed on Jul. 19, 2008 and entitled “Side Guard for Bed” may be included on the adjustable bed  100 . 
     The patient support surface  36  is highly flexible in order to conform to several different configurations of the bed  100 . The patient support surface  36  may comprise a polyurethane foam mattress or, optionally, a mattress filled with air, water or gel. The density and thickness of the patient support surface  36  may be selected based on the weight and condition of the patient. The patient support surface  36  is characterized by a head end  36   a , a foot end  36   b , a right side  36   c , a left side  36   d  ( FIG. 1 ), and an upper-body supporting section  82 , a midsection  83 , and a lower-body supporting section  84  ( FIG. 5 ). 
     The patient support surface  36  is operable to be modulated into numerous configurations through manipulation of points and segments along the periphery  81  ( FIG. 5 ) of the patient support surface  36 . The periphery  81  of the patient support surface  36  consists of a head-side peripheral portion  120  adjoining a right-torso-adjacent peripheral portion  121  adjoining an intermediate right-side peripheral portion  122  adjoining a right-hip-adjacent peripheral portion  123  adjoining a right-calf-adjacent peripheral portion  124  adjoining a foot-side peripheral portion  125  adjoining a left-calf-adjacent peripheral portion  126  adjoining a left-hip-adjacent peripheral portion  127  adjoining an intermediate left-side peripheral portion  128  adjoining a left-torso-adjacent peripheral portion  129  adjoining the head-side peripheral portion  120 . The patient support surface  36  has sufficient flexibility so that desired modulations of the patient support surface  36  can be effected through movements of the patient support structure  60  that reposition multiple points and segments along the periphery  81  of the patient support surface  36 . 
     B. Basic Components of the Patient Support Structure Used to Modulate the Patient Support Surface. 
     This specification characterizes the patient support structure  60  ( FIG. 5 ) used to modulate the patient support surface  36  in two different ways. From a top-down perspective, this specification characterizes the patient support structure  60  as an adjustable patient support framework  95  mounted on an articulatable, multi-sectioned base platform  90 . From a headboard-to-footboard perspective, this specification characterizes the patient support structure  60  as a combination of a plurality of adjacent lateral patient support structures. 
     The top-down perspective best illustrates two conceptually independent mechanisms by which the patient support structure  60  modulates the patient support surface  36 . First, the patient support structure  60  comprises an articulatable, multi-sectioned base platform  90  having several sections that are operable to articulate relative to each other. Second, the patient support structure  60  comprises an adjustable patient support framework  95  mounted on the base platform  90 . The adjustable patient support framework  95  comprises a plurality of independently movable points, vertices, or nodes oriented at or near the periphery  81  of the patient support surface  36 . The adjustable patient support framework  95  also comprises several fixed-length or variable-length telescoping side support segments, oriented longitudinally along the periphery of the patient support surface  36 , that are pivotally connected to these points or nodes. A combination of articulation of the base platform  90  and adjustment of the patient support framework  95  modulates the patient support surface  36 . 
     The headboard-to-footboard perspective best illustrates the mechanical interrelationships of the components of the patient support structure  60 . From this perspective, best illustrated in  FIG. 3 , the patient support structure  60  comprises an articulatable torso support structure  62  hingedly adjoining a preferably non-articulatable central or pelvic support structure  1  hingedly adjoining an articulatable hip and upper-leg support structure  63  hingedly adjoining an articulatable lower-leg support structure  4 . 
     Continuing with the headboard-to-footboard perspective, each of the substructures of the patient support structure  60  supports a different part of a patient lying on the patient support surface  36 . The articulatable torso support structure  62 , shown by itself in  FIG. 6 , is positioned to support the patient&#39;s torso and head. The articulatable hip and upper-leg support structure  63 , shown in  FIG. 7 , is positioned to support the patient&#39;s hip and upper legs. The articulatable lower-leg support structure  4  ( FIG. 1 ) is positioned to support the patient&#39;s lower legs. The central or pelvic support structure  1  ( FIGS. 1 ,  3 ,  7 ), which is preferably rigidly attached to the upper chassis  7  between the hingedly adjoining torso support structure  62  and the hingedly adjoining hip and upper-leg support structure  63 , is positioned to support—or relieve pressure upon, as explained in connection with FIGS.  23 - 24 —the pelvic area of the patient. 
     As shown in  FIGS. 3 and 4 , a hinge  106  connects the inferior side of the torso support structure  62  to the central support structure  1  and allows the torso support structure  62  to be rotated about transverse axis  66  ( FIG. 5 ) for torso elevation. Another hinge  106  connects the superior side of the hip support structure  63  to the central support structure  1  and allows the hip support structure  63  to be rotated about transverse axis  86  for elevation of the patient&#39;s upper legs. Yet another hinge  106  connects the superior side of the lower-leg support structure  4  to the hip support structure  63  and allows the lower-leg support structure  4  to be rotated about transverse axis  87  for flexing of the legs and/or elevation of the lower legs. 
     Linear actuators  105  mounted between the central support structure  1  and the torso support structure  62  drive and rotate the torso support structure  62  about an axis  66  ( FIG. 5 ) defined by hinge  106  (coinciding with a transversal axis of the bed  100 ). Another linear actuator  113  mounted between the central support structure  1  and the hip support structure  63  drives and rotates the hip support structure  63  about an axis  86  ( FIG. 5 ) defined by hinge  106  (also coinciding with a transversal axis of the bed  100 ). Electric motors  29 , each activated by a peripheral control unit  13 , drive each of the linear actuators  105  and  113 . Alternatively, various types of actuators, including hydraulic and pneumatic actuators, replace the electric motors  29 . 
     Returning to the top-down perspective, the torso support structure  62  and the hip and upper-leg support structure  63  each comprise versatile support litters mounted upon articulating base structures. In particular, and as shown in  FIG. 6 , the torso support structure  62  comprises an adjustable torso support litter  68  mounted on an articulatable torso support base structure  2 . As shown in  FIG. 7 , the hip and upper-leg support structure  63  comprises an adjustable hip and upper leg support litter  69  mounted on an articulatable hip support base structure  3 . 
     The adjustable torso support litter  68  and the adjustable hip and upper leg support litter  69  together make up the adjustable patient support framework  95 . The combination of the torso support base structure  2  (which articulates about transverse axis  66  (FIG.  5 )), the preferably non-articulating central or pelvic support structure  1 , the hip support base structure  3  (which articulates about transverse axis  86 ), and the lower-leg support structure  4  (which articulates about transverse axis  87 ) make up the articulatable, multi-sectioned base platform  90 . 
     Focusing specifically on the torso support structure  62  ( FIG. 6 ), four movable arms  30  are attached to the ends of two side support bars  103   a  and  103   b . Independently controllable actuator assemblies  11  mounted on the torso support base structure  2  are drivingly connected to the moveable arms  30  and provide means to move the side support bars or segments  103  in both vertical and lateral directions to modulate the patient support surface  36  in various ways. For example, the independently controllable actuator assemblies  11  are operable to induce rotational movement of the patient about a longitudinal axis  65  of the torso support structure  62 . 
       FIGS. 8 and 9  illustrate the adjustable torso support litter  68  of the torso support structure  62  in further detail. The adjustable torso support litter  68  comprises four independently movable points or vertices: a right side shoulder support vertex  70 , a left side shoulder support vertex  71 , a right side lower thorax support vertex  72 , and a left side lower thorax support vertex  73 . The shoulder support vertices  70 ,  71  are located on the superior or upper end  54  of the torso support structure  62 , close to the head end  36   a  of the patient support surface  36 . Movement of each of these vertices  70 - 73  is accomplished by operation of an independently controllable actuator assembly  11  ( FIG. 6 ), which is coupled by a movable arm  30  to, and operable to independently raise, its respective vertex  70 ,  71 ,  72 , or  73 . Each actuator assembly  11  is operable to independently raise its respective vertex  70 ,  71 ,  72 , or  73  relative to the other vertices. 
     Each of the vertices  70 - 73  comprises a pivotal joint  20  that connects its respective movable arm  30  ( FIG. 6 ) to one end of a side support bar  103   a  or  103   b . More particularly, a right side support bar  103   a  connects the right side shoulder support vertex  70  to the right side lower thorax support vertex  72 , and a left side support bar  103   b  connects the left side should support vertex  71  to the left side lower thorax support vertex  73 . A flexible mattress-supporting foundation  14 —which provides support to the corresponding portion (i.e., torso area) of the patient support surface  36 —is mounted to the side support bars  103   a  and  103   b . As illustrated in the sectional diagram of  FIG. 5 , the right and left side lower thorax support vertices  72  and  73  are oriented near the lower or inferior end  53  of the torso support structure  62 , near the intersection between the upper-body supporting section  82  and the midsection  83  of the patient support surface  36 . 
     To increase the range of motion of each of the vertices  70 - 73 , and to reduce bending forces and torsional loads on the movable arms  30 , the right and left side support bars  103   a  and  103   b  preferably have adjustable lengths. In a preferred embodiment, this is accomplished by providing that each right and left side support bar  103   a  and  103   b  comprise an inner rod  16  that telescopes or slides within an outer rod  15  ( FIG. 8 ). 
       FIG. 3  illustrates the relative location of the torso support section actuator assemblies  11  that control the position of each of the vertices  70 - 73 . As shown in  FIG. 3 , the actuator assemblies are positioned on the inferior and superior ends  53  and  54  of the torso support structure  62 . This provides a radiolucent area, between the inferior and superior ends  53  and  54 , free of metallic parts and mechanical obstructions for taking X-rays of the thorax of a patient resting on the patient support surface  36 . 
       FIGS. 8 and 9  also illustrate a flexible mattress-supporting foundation or hammock  14  that consists essentially of a sheet mounted on the right and left side support bars  103   a  and  103   b  and stretched between the four vertices  70 ,  71 ,  72 , and  73 . Alternatively, the flexible mattress-supporting foundation  14  may comprise a plurality of straps, bands or belts (preferably slightly elastic) (not shown) affixed to and bridging the side support bars  103   a  and  103   b . Also alternatively, the flexible mattress-supporting foundation  14  may be incorporated within the wrapping of the patient support surface  36 , and secured to the side support bars  103   a  and  103   b  through straps or clamps (not shown). The flexible mattress-supporting foundation  14  may alternatively comprise a net or any other suitable material. 
       FIG. 7  illustrates the hip support structure  63  and also the central support structure  1  to which it is connected. Two independently controllable actuator assemblies  11  are mounted on the hip support base structure  3 , and drivingly connected to the moveable arms  30  of the adjustable hip and upper-leg support litter  69 . 
       FIG. 10  further illustrates the adjustable hip and upper-leg support litter  69  of the hip support structure  63 . The adjustable hip and upper-leg support litter  69  comprises two independently movable vertices  76  and  77  that are respectively pivotally joined to a right side support bar  78  and a left side support bar  79 . Each vertex  76  and  77  is pivotally coupled to a movable arm  30 . Selective operation of the independently controllable actuator assemblies  11  ( FIG. 7 ), which are coupled to respective movable arms  30 , selectively raises a respective side support bar  78  or  79 . This provides a means to move side support bars  78  and  79  in both vertical and lateral directions in such a way as to tilt, hug, or induce rotational movement of the a patient&#39;s hip and upper legs about a longitudinal axis  85  ( FIG. 5 ). 
     A flexible mattress-supporting foundation or hammock  17  is mounted on and between side support bars  78  and  79 . Like the flexible mattress-supporting foundation or hammock  14 , the flexible mattress-supporting foundation or hammock  17  comprises a sheet, straps, netting, or any other suitable material. 
     The ability of the side support bars  78  and  79  to pivot with respect to vertices  76  and  77  maximizes the distribution of the patient&#39;s weight on the patient support surface  36  and also reduces shearing forces between the patient&#39;s body and the mattress in this zone. This is because the adopted position of the hips and upper legs of the patient define the angular orientation of the side support bars  78  and  79 . 
     C. Independently Controllable Actuator Assemblies for the Torso and Hip Support Litters. 
       FIGS. 11-18  illustrate various embodiments of independently controllable actuator assemblies  11  mounted on the torso support base structure  2  or the hip support base structure  3  and operable to move the vertices  70 - 73  of the torso support litter  68  or the vertices  76  and  77  of the hip and upper-leg support litter  69 . 
       FIG. 11  illustrates a mechanical lateral actuator  31  drivingly connected to a principal arm  21 . The mechanical lateral actuator  31  comprises a sliding element  25  movable within a sliding guide  24 . The inferior (i.e., lower) end  21   b  of the principal arm  21  is connected to the sliding element  25  via a hinge  26 . The superior (i.e., upper) end  21   a  of the principal arm  21  is connected to the pivotal joint  20  that forms one of the torso support section vertices  70 - 73 . 
     A secondary arm  22 , having superior and inferior ends  22   a  and  22   b , respectively, provides support to the principal arm  21 . The superior end  22   a  of the secondary arm  22  is connected a midsection  21   c  of the principal arm  21  via a hinge  26 . The inferior end  22   b  of the secondary arm  22  is attached to the torso support base structure  2  via another hinge  26 . A screw  23  driven by an electric motor  29  and a mechanical reducer  28  advances or retreats the sliding element  25  within the sliding guide  24 . A peripheral control unit  13  connected to motor  29  via cable  12  operates the motor  29 . 
     Operation of the mechanical lateral actuator  11  causes the respective vertex  70 ,  71 ,  72 , or  73  to travel along a characteristic path or trajectory  101 . This characteristic path or trajectory  101 —which more closely approximates a semi-parabolic arc than a semi-circular arc—is defined, in part, by the position of hinge  26  joining the secondary arm  22  to the principal arm  21 . The approximately semi-parabolic trajectory yields more vertical than lateral displacement, and is better suited to rotating the patient than a semi-circular trajectory would be. 
     One embodiment of the lateral actuator  11  of  FIG. 11 , designed for a 91-cm-wide patient support surface  36 , has a 91-cm-long principal arm  21  and a 50-cm-long secondary arm  22 . Hinge  26  connecting the secondary arm  22  to the principal arm  21  is located 34 cm. from the inferior end  21   b  of the principal arm  21 . The vertices driven by the mechanical lateral actuators  11  of  FIG. 11  have 62 centimeters of vertical travel and 30 centimeters of lateral travel. They are also capable of tilting the patient support surface  36  to an angle of 40 degrees, measured between the horizontal and a line connecting two opposing vertices. 
       FIG. 12  illustrates an alternative independently controllable actuator assembly, similar to the assembly depicted in  FIG. 11  but having a telescoping principal arm  21  driven by an additional linear mechanical actuator  39 . The additional linear mechanical actuator  39  causes an inner rod  46  of the principal arm  21  to telescope within a coaxial outer rod  45  of the principal arm  21 . This gives the independently controllable actuator assembly of  FIG. 12  two degrees of freedom with respect to the section  1 ,  2 ,  3 ,  4  of the base platform  90  to which the actuator assembly is mounted, facilitating extra displacement of joint  20  and increasing the range of motion of the assembly. In this embodiment, operation of the mechanical lateral actuator  31  together with linear mechanical actuator  39  causes the respective vertex  70 ,  71 ,  72 , or  73  to travel along a selected and adjustable one of multiple characteristic paths or trajectories  101 ,  102 , etc. 
       FIGS. 13 and 14  illustrate another independently controllable actuator assembly. Like  FIG. 12 , this alternative assembly has a telescoping principal arm  21 . But in  FIGS. 13 and 14 , a steel cord  48  mounted on several pulleys  47 , and tensioned by a spring  49 , drives the sliding action of the telescoping inner rod  46 . One end  48   a  of the steel cord  48  is connected to the telescoping inner rod  46 . The opposite end  48   b  of the steel cord  48  is connected to the spring  49 . Operation of the mechanical lateral actuator  31  to raise the principal arm  21  increases the tension on the steel cord  48 . This causes the spring  49  to stretch and the telescoping inner rod  46  to extend. 
     To further regulate the characteristic path or trajectory  101  about which the respective vertex  70 ,  71 ,  72 , or  73  moves, a register  50  is secured to the steel cord  48 , and the steel cord is threaded through a mechanical limit  51 . When the register  50  meets the mechanical limit, further operation of the mechanical lateral actuator  31  to raise the principal arm  21  causes the steel cord  48  to exert traction action on the telescoping inner rod  46 , thereby raising it. As the principal arm  21  is lowered, tension on the spring  49  is relieved, and the telescoping inner rod  46  retracts back into the coaxial outer rod  45 . The position of the register  50  can be changed to adjust the desired characteristic path or trajectory  101 . 
     In  FIG. 13  shows the mechanism in a position in which the register  50  did not reach the mechanical limit  51 . Accordingly, the telescoping inner arm  46  is fully retracted within the telescopic principal arm  45 .  FIG. 14  shows the mechanism in a position after the register  50  has reached the mechanical limit  51 . Here, the telescoping inner rod  46  is in an extended position. As result of this action, the joint  20  is moved higher than it would otherwise be. This alternative assembly increases the range of motion of joint  20  in a more economical manner than shown in  FIG. 12 , using only one actuator. 
       FIG. 15  illustrates yet another alternative independently controllable actuator assembly. This embodiment comprises a telescoping principal arm  21  and a telescoping secondary arm  40 , each driven by a linear mechanical actuator  39 . Moreover, the two linear mechanical actuators  39  in this embodiment substitute for the mechanical lateral actuator  31  shown in  FIG. 11 . The telescoping principal arm  21  comprises an inner rod  46 , driven by a linear actuator  39 , the telescopes within a coaxial outer rod  45 . Likewise, the telescoping secondary arm  40  comprises an inner rod  56 , also driven by a linear actuator  39 , that telescopes within an outer rod  55 . The inferior (i.e., lower) end  21   b  of the principal arm  21  is hingedly linked to the torso support base structure  2 , while the superior (i.e., upper) end  21   a  of the principal arm  21  is joined to one of the torso support section vertices  70 - 73 . The inferior end  40   b  of the telescoping secondary arm  40  is hingedly linked to the torso support base structure  2 , while the superior end  40   a  of the telescoping secondary arm  40  is hingedly joined to a midsection  21   c  of the principal telescoping arm  21 . Like the actuator assembly of  FIG. 12 , FIG.  15 &#39;s actuator assembly provides two degrees of freedom with respect to the section  1 ,  2 ,  3 ,  4  of the base platform  90  to which the actuator assembly is mounted. FIG.  15 &#39;s actuator assembly also enables a different set of adjustable characteristic paths or trajectories than those obtained by the mechanism shown in  FIG. 12 . 
       FIGS. 16 and 17  illustrate yet another independently controllable actuator assembly. Here, each independently controllable actuator assembly comprises a curved arm  42 , sliding within a curved guide  41 , driven by a linear actuator  80  mounted on one end  80   b  by a hinge  26  to the torso support base structure  2  and on an opposite end  80   a  by another hinge  26  to the curved arm  42 . The linear actuator  80  is operable to move the curved arm  42  between retracted and extended positions, thereby displacing the associated joint  20 . The curvature of the curved arm  42  and curved guide  41  define the characteristic path or trajectory  101  over which the joint  20  travels. 
       FIG. 18  illustrates a modification of the independently controllable actuator assembly depicted in  FIGS. 16 and 17 . In  FIG. 18 , a curved arm  43  with gear teeth disposed along its concave surface replaces the curved arm  22  of  FIGS. 16 and 17 . Moreover, a rotary actuator  59  with gear teeth adapted to mesh with the gear teeth of the curved arm  43  replaces the linear actuator  80  of  FIGS. 16 and 17 . The rotary actuator  59 , which is affixed to the outside of the curved guide  41 , is operable to drive the curved arm  43  between retracted and extended positions. This alternative has the advantage of a reduced number of parts. 
     Any of the independently controllable actuator assemblies depicted in  FIGS. 11-18  for the torso support structure  62  can also be used for the hip support structure  63 . Because these assemblies are sufficiently illustrated in  FIGS. 11-18  with respect to the torso support structure  62 , they are not separately depicted with equal detail with respect to the hip support structure  63 . 
     Because the independently controllable actuator assemblies of  FIGS. 11-18  are mounted on a common bed frame section, namely either the articulatable torso support base structure  2  or the articulatable hip support base structure  3 , it will be observed that in the preferred embodiment, each of the actuator assemblies depicted therein comprises a plurality of moving parts whose movements, relative to the torso support base structure  2  or the hip support base structure  3 , are confined to a transverse plane perpendicular to the longitudinal axis  65  or  85  ( FIGS. 6 ,  7 ) of the torso support base structure  2  or hip support base structure  3 . Moreover, in  FIG. 11 , it will be observed that the sliding guide  24  confines the movement of the sliding element  25  to a horizontal linear segment within the transverse plane perpendicular to the longitudinal axis  65  or  85  ( FIGS. 6 ,  7 ) of the torso support base structure  2  or hip support base structure  3 . 
     Because of the independent versatility of the independently controllable actuator assemblies, the adjustable bed  100  is operable to configure the patient support surface  36  in ways never previously done by hospital beds.  FIG. 16  illustrates an example in which diagonally-opposed torso support section vertices  70 ,  73  are simultaneously raised while the other set of diagonally-opposed torso support section vertices  71 ,  72  are simultaneously lowered. The adjustable bed  100 &#39;s actuators facilitate significant side-to-side tilting. 
     D. Alternative Embodiments of  FIGS. 19-25   
       FIGS. 19 and 20  illustrate a perspective view of a torso support structure  62  that incorporates two more independently movable points or vertices. In particular, the torso support structure  62  further comprises an intermediate right-side vertex  74  between the right side shoulder and lower thorax support vertices  70  and  72  and an intermediate left side vertex  75  between the left side shoulder and lower thorax support vertices  71  and  73 . Each vertex  70 - 75  is defined by a joint  20 . And each joint  20  is independently actuated by its own corresponding controllable actuator assembly  11 . Two of these independently controllable actuator assemblies  11  are coupled to and operable to independently raise the intermediate right and left-side vertices  74  and  75  relative to the other vertices. In this embodiment, two flexible mattress-supporting foundations or hammocks  14  are incorporated for torso support. 
       FIGS. 21 and 22  illustrate a perspective view of two simplified embodiments of an adjustable bed  100  preferred for home use. Like the previously discussed embodiments, these embodiments comprise an adjustable patient support framework  95  mounted on a base platform  90 . But in these embodiments, the adjustable patient support framework  95  has only two independently movable vertices—the right side lower thorax support vertex  72  and the left side lower thorax support vertex  73  (FIG.  22 )—and corresponding independently controllable actuator assemblies. These two movable vertices  72  and  73 —which are made up of central joints  20 e and  20 c ( FIG. 21 ), respectively—allow for a degree of rotation of the torso, waist and leg area. The right and left side shoulder support vertices  70  and  71  ( FIG. 21 ), which are made up of superior joints  20   a  and  20   b  ( FIG. 22 ), respectively, are fixedly joined to the torso support base section  2 . Besides the side support bars  103  that join the central joints  20   e  and  20   c  to the superior joints  20   a  and  20   b , additional telescoping side support bars  103 —each comprising an inner telescoping rod  16  slidable within an outer rod  15 —link the central joints  20   e  and  20   c  to inferior joints  20   a  and  20   b  that are affixed to the lower-leg support structure  4 . The embodiments of  FIGS. 21 and 22  differ only in the location upon which the lower-leg support structure  4  the inferior joints  20   a  and  20   b  are affixed. 
       FIG. 23  illustrates an embodiment of the adjustable bed  100  with an alternative lower-leg supporting structure  116 . In  FIG. 34 , the upper surface of the lower-leg supporting structure  116  is curved into a concave shape to minimize pressure on the patient&#39;s heels, and even to enable the patient&#39;s heels to float. This assembly facilitates rapid healing in preexistent pressure ulcers. 
       FIG. 25  provides a perspective view of the adjustable bed  100  in the form of an airplane seat. All the mobility described in the bed embodiment is available for use here in a long distance travel. Here, the leg set may be flexed towards the floor. 
       FIG. 26  illustrates a perspective view of a miniaturized version of the adjustable bed  100  inside an incubator embodiment. All the mobility described in the bed embodiment is available for stimulation of a new born. It is known that this stimulatory process requires permanent random mobility, which can be obtained easily with this invention. 
     III. Therapeutic Modes of Operation 
     The patient support surface  36  of the adjustable bed  100  is modulated and configured through a combination of articulation of the base platform  90  and adjustment of the plurality of independently adjustable vertices (or points)  70 - 77  and pivotally-connected linking support segments  78 ,  79 ,  103   a , and  103   b  of the adjustable patient support framework  95 , all of which are oriented at or near the periphery or perimeter area  81  of the overlying patient support surface  36 . 
     The adjustable patient support framework  95  of the adjustable bed  100  facilitates a wide variety of modulations of the patient support surface  36 . FIGS.  23  and  27 - 34  illustrate several examples of configurations and modulations of the patient support surface  36 . In describing the means used to create these configurations, reference is made back to the components illustrated in earlier figures. 
     Importantly, the independent adjustability of the lower thorax support vertices  72  and  73  relative to the shoulder support vertices  70  and  71  gives the patient support surface  36  a unique ability to hug a patient&#39;s waist and elevate the sacral area to significantly reduce interface pressures without any tilting or lateral rotation of the patient. The patient support framework  95  can be modulated to selectively squeeze the periphery of the patient support surface  36  on either side of a patient&#39;s waist or hips or both to distribute pressure over a wider area and help maintain the patient in position during other bed movements. It can also be modulated to selectively elevate the torso and hip-supporting areas of the patient support surface  36  relative to a pelvic-supporting area of the patient support surface  36 , to thereby relieve pressure in that region. 
     The independent adjustability of the lower thorax support vertices  72  and  73  relative to the shoulder support vertices  70  and  71  also gives the patient support surface  36  a unique ability to support a patient in a more physiologically appropriate prone position. In the prone position, pressure sores often develop in the shoulder area.  FIG. 28  illustrates a configuration of the adjustable bed  100  that reduces interface pressures on the shoulders of a patient being laterally rotated while in the prone position. The lower thorax support vertices  72  and  73  are selectively and alternately raised far more than the shoulder support vertices  70  and  71 . 
     The patient support framework  95  can also be modulated to cause lateral rotation of the patient from side to side, as illustrated in  FIG. 27  for a patient in the supine position and in  FIG. 28  for a patient in the prone position. This can be accomplished by selectively raising either the left or the right independently movable vertices and segments of the patient support framework  95 . 
     Alternatively, the patient support framework  95  can be modulated to rotate the torso and legs in opposite directions, in a twisting mode, as illustrated in  FIGS. 29 and 30 . This can be accomplished by selectively raising the right side shoulder and lower thorax support vertices  70  and  72  (relative to the left side shoulder and lower thorax support vertices  71  and  73 ) while simultaneously selectively raising the left side hip support vertex  77  (relative to the right side hip support vertex  76 ). This can also be accomplished by selectively raising the left side shoulder and lower thorax support vertices  71  and  73  (relative to the right side shoulder and lower thorax support vertices  70  and  72 ) while simultaneously selectively raising the right side hip support vertex  76  (relative to the left side hip support vertex  77 ). A twisting mode may be indicated for patients with multi-fractures or other particular ailments that require the patient&#39;s torso and legs to be counter-rotated. The patient support framework  95  can also be modulated to facilitate ingress and egress of a patient onto or off of the patient support surface  36 . 
     These and other desired therapeutic effects can be achieved by acting on the preferably at least six independently movable points or segments of perimeter area, in conjunction with various movements of the articulating torso support base structure  2 , hip support base structure  3  and leg support base structure  4 . These six lateral points or segments of perimeter area are preferably positioned at or near areas of the patient support surface corresponding to the right shoulder, the left shoulder, the right waist or lower thorax, the left waist or lower thorax, the right hip, and the left hip of a patient resting on the patient support surface. The position of the lower-body supporting section  82  of the patient support surface  36  is indirectly affected by modulation of the other perimeter points or sections. In principle, the greater the number of independently movable vertices, the greater the number of possible configurations into which the patient support surface  36  can be modulated. 
     A. Selective Squeezing or Holding Mode 
       FIGS. 31 and 32  show perspective views of the patient support surface  36  being modulated to selectively squeeze the patient support surface  36  on either side of a patient&#39;s waist. In this configuration, the patient&#39;s right waist area  107  and left waist area  108  are hugged by the patient support surface  36 . This action results from the activity of two of the actuators  11  of the torso support structure  62  to raise and pull inward the right and left lower thorax support vertices  72  and  73 . The lower thorax support vertices  72  and  73  move along trajectories between a first relative position of maximum distance between the vertices  72  and  73  and a second relative position in which the vertices  72  and  73  approach the waist of a patient resting on the patient support surface  36 . Such action not only significantly reduces interface pressures when the patient is not being rotated, but also inhibits patient movements during lateral rotation and other adjustments of the adjustable bed  100 . 
     This “holding” action of the bed is further enhanced by causing the actuators  11  of the hip support structure  63  to raise and pull inward the right and left side support bars  78  and  79  to selectively squeeze the right-hip-adjacent peripheral portion  123  and the left-hip-adjacent peripheral portion  127  ( FIG. 5 ) of the patient support surface  36 . In this manner, the right and left side support bars  78  and  79  also move along trajectories between a first relative position of maximum distance between the left and right support rods  78  and  79  and a second relative position in which the left and right support rods  78  and  79  approach the hips of a patient resting on the patient support surface  36 . Such action inhibits a patient resting on the patient support surface  36  from rolling off of the patient support surface  36  during lateral rotation movements and minimizes patient movements during other adjustments of the adjustable bed  100 . 
     If the patient is rotated to any side or submitted to side-to-side rotation, the patient is maintained in that position, without sliding. This not only reduces the danger of shear lesions, but also facilitates a greater degree of rotation of the patient than would otherwise be possible. Moreover, these maneuvers help distribute the patient&#39;s load over a wider area. 
     It should be noted that a selective squeezing of opposite side portions of the patient support surface  36  can be effected through a single actuator operating on both opposite side portions of the patient support surface. Therefore it will be understood that one aspect of the invention covers adjustable beds that use a single actuator to accomplish a selective squeezing operation. 
       FIG. 27  illustrates a perspective view of a patient resting on a patient support surface  36  that has been modulated to create a trough  111  that prevents the patient from rolling off of the patient support surface  36 , and then further modulated to tilt the patient toward one side. When the patient is turned on her/his right side, the head of right trochanter  112  (opposite the patient&#39;s left trochanter  113 ) falls into the trough  111 . The trough  111  redistributes the weight of the hip section of the patient over a wider area, relieving pressure on the right trochanter  112 . The titled position of the patient relieves pressure on the left trochanter  113 . This position results from a combination of torso elevation, selective squeezing of the two inferior actuators  11  of the torso support structure  62 , and elevation of the actuators of the hip support structure  63 . Similarly, when the patient is turned on her/his left side, the converse happens. 
     To configure the patient support surface  36  as shown in  FIG. 27 , the patient is first positioned in the supine position, and facing the ceiling, on the patient support surface  36  while the surface  36  is flat. Next, the articulatable torso support base structure  2  and the articulatable upper-leg support base structure  3  are both rotated upward, moderately, and both of the lower thorax support vertices  72  and  73  and the hip support vertices  76  and  77  are elevated moderately, to create a trough  111 . The degree to which these elements are articulated and elevated may vary depending on the size and build of the patient. Once a suitable trough  111  has been created to hold the patient in place, the right side lower thorax support vertex  72  and the right side hip support vertex  76  are elevated significantly more, causing the patient to tilt toward her right side (i.e., toward the left side of the bed from the perspective of one facing the bed). 
     The patient can be held in this position, without alternating rotation, while still redistributing pressure over a wider surface area of the patient. Alternatively, the right side lower thorax support vertex  72  and the right side hip support vertex  76  may be lowered back to its moderately raised position, and the left side lower thorax support vertex  73  and the left side hip support vertex  77  raised to a significantly elevated position, in order to tilt the patient toward her left side. 
     The combination of creating a trough and tilting the patient not only improves the pressure relief capabilities of the bed  10 , but also significantly reduces the risk of the patient rolling or sliding toward the side of the bed  10 . 
     Preferably, a control and processing unit  5 , described further below in connection with  FIG. 35 , is programmed with a plurality of selective squeezing modes. 
     In a basic squeezing mode, the control and processing unit  5  is programmed to modulate the intermediate right-side peripheral portion  122 , the right-hip-adjacent peripheral portion  123 , the intermediate left-side peripheral portion  128 , and the left-hip-adjacent peripheral portion  127  of the patient support surface  36  to inhibit a patient resting on the patient support surface  36  from rolling off of the patient support surface  36 . 
     In a patient-tilting mode, the control and processing unit is programmed to simultaneously or sequentially (although not necessarily in the particular order shown below) effect the following modulations of the patient support surface  36 : 
     (a) raise the right-torso-adjacent peripheral portion  121  above the left-torso-adjacent peripheral portion  129  in order to tilt a patient&#39;s torso toward one side; 
     (b) raise the right-calf-adjacent peripheral portion  124  above the left-calf-adjacent peripheral portion  126  in order to tilt a patient&#39;s legs toward one side; and 
     (c) raise the left-hip-adjacent peripheral portion  127  to create a trough in the patient support surface for embracing a right hip of a patient resting on the patient support surface  36  and thereby inhibiting the patient from rolling off of the patient support surface  36 . 
     In a patient-twisting mode, the control and processing unit  5  is programmed to simultaneously or sequentially (although not necessarily in the particular order shown below) effect the following modulations of the patient support surface  36 : 
     (a) raise the right-torso-adjacent peripheral portion  121  above the left-torso-adjacent peripheral portion  129  in order to tilt a patient&#39;s torso to the left; 
     (b) raise the left-calf-adjacent peripheral portion  126  above the right-calf-adjacent peripheral portion  124  in order to tilt a patient&#39;s legs to the right; and 
     (c) raise both the left-hip-adjacent peripheral portion  127  and the right-hip-adjacent peripheral portion  123  to create a trough in the patient support surface  36  for embracing the hips of a patient resting on the patient support surface  36  and thereby inhibiting the patient from rolling off of the patient support surface  36 . 
     B. Pelvic-Pressure Relief Mode 
       FIGS. 23-24  illustrate modulations of the patient support surface  36  to selectively elevate the torso and hip-supporting areas of the patient support surface  36  relative to a pelvic-supporting area of the patient support surface  36 , to thereby relieve pressure in that region. This can be accomplished by elevating at least the left and right lower thorax support vertices  72  and  73  of the torso support litter  68  and the right and left side hip support vertices  76  and  77  of the hip support litter  69  sufficiently to substantially reduce pressure on the sacral area of a patient resting on the patient support surface  36 . 
     This action, in combination with the selective squeezing mode, significantly reduces interface pressures. So significant is the reduction in interface pressures that it should, for many patients, prevent pressures sores and eliminate the need for lateral rotation. 
     It should be noted that embodiments of the adjustable bed  100  could be provided wherein elevation of both left and right lower thorax support vertices  72  and  73  is effected through a single lifting mechanism mounted on the torso support base structure  2 . Likewise, embodiments of the adjustable bed  100  could be provided wherein elevation of both the right and left side hip support vertices  76  and  77  are effected through a single lifting mechanism mounted on the hip support base structure  3 . Therefore it will be understood that one aspect of the invention covers adjustable beds that just one or two lifting mechanisms to accomplish sacral pelvic-pressure relief mode. 
       FIG. 23  illustrates a side view of a position for sacral pressure relieve. Support of the patient is exerted mostly by the torso and upper leg area.  FIG. 24  is an enlargement view that shows a trough  110  or area of minimal contact between the sacrum  109  and patient support surface  36 . This position results from the combined action of torso elevation and operation of the actuators of the hip set to elevate and hug the patient&#39;s hips. 
     Preferably, the control and processing unit  5  has a pre-programmed mode operable to modulate the periphery  81  to raise the patient&#39;s sacrum above the patient support surface  36 , and thereby relieve pressure on the patient&#39;s sacrum. More particularly, this pre-programmed mode is operable to modulate the periphery  81  by raising the right-torso-adjacent peripheral portion  121  and right-hip-adjacent peripheral portion  123  above the intermediate right-side peripheral portion  122 , and by raising the left-torso-adjacent peripheral portion  129  and left-hip-adjacent peripheral portion  127  above the intermediate left-side peripheral portion  128 . 
     C. Ingress and Egress-Facilitating Mode 
       FIGS. 33 and 34  illustrate modulations of the patient support surface  36  to facilitate ingress and egress of a patient onto or off of the patient support surface  36 . Egress of a patient off of the patient support surface  36  is facilitated by actuation (preferably sequential but alternatively simultaneous) of the following movements: lowering the bed surface as close to the floor as it will go, by lowering the position of the upper chassis  7  relative to the lower chassis  8 ; articulating the torso support base structure  2  to a substantially upright or chair-like position (e.g., more than 45 degrees, and preferably 60-75 degrees); and tilting the torso support litter  68  toward the right or left, to facilitate patient entry or exit. Meanwhile, the upper-leg and lower-leg support base structures  3  and  4  are maintained in a flat, level position. The upper-leg support litter  69  may also (and preferably simultaneously) be tilted in the same direction as the torso support litter  62 , to further facilitate patient entry or exit. 
     In a prototype embodiment of the adjustable bed  100 , the patient support surface  36  may be lowered to within about 41 cm. (or 16 inches), plus the width of the mattress (which is preferably between 2 and 20 cm. thick), from the surface of the floor. This facilitates patient entry and exit much more readily than many prior art therapeutic beds. It is anticipated that future embodiments of the adjustable bed  100  will enable the patient support surface  36  to be lowered even further. The ability of the adjustable bed  100  to lower its patient support surface  36  this close to the ground is one of the benefits of using the innovative actuator  11  designs set forth in this specification. 
     The step of tilting the torso support base structure  2  entails selectively raising either the right or the left side support bar  103   a  or  103   b  of the torso support structure  62  to moderately tilt the upper-body supporting section  82  ( FIG. 5 ) of the patient support surface  36  to the left or right. Likewise, the step of tilting the hip support base structure  3  entails selectively raising either the right or left side hip support vertex  76  or  77  of the upper-leg and hip support structure  63  to moderately tilt the midsection  83  ( FIG. 5 ) of the patient support surface  36  to the left or right. The pivoting action of the right or left side support bar  78  or  79  on the corresponding right or left side hip support vertex  76  or  77  also helps to twist the patient into an existing position. Actuation of the same movements in reverse facilitates ingress of a patient onto the patient support surface  36 . In both cases, patient entry onto, or exit from, the adjustable bed  100  is accomplished with minimal caregiver aid. 
     The step of tilting the torso support litter  62  can be broken down into two smaller steps. In both steps, both one of the lower thorax support vertices  72  or  73  and one of the shoulder support vertices  70  or  71 , on the same right or left side of the bed, are gradually extended away from the torso support base structure  2 . In the first step, the lower thorax support vertex  72  or  73  extends more quickly, and farther, than the shoulder support vertex  70  or  71 . This maneuver helps twist the patient into an exiting position. During this time, a health care practitioner may take the patient&#39;s arm (on the same side being tilted) to help the patient twist into an exiting position. In the second step, the shoulder support vertex  70  or  71  extends more quickly, and ultimately as much as and then even farther, than the lower thorax support vertex  72  or  73 . This maneuver helps to push the patient off of the bed. During this time, a health care practitioner may pull on the patient&#39;s arm (on the same side being tilted) to help the patient out of the bed. These two steps are reversed to facilitate a patient entering the bed. 
     It should be noted that embodiments of the adjustable bed  100  could be provided wherein elevation of both right side vertices  70  and  72 , or both left side vertices  71  and  73 , is effected through a single lifting mechanism mounted on the torso support base structure  2 . Therefore it will be understood that one aspect of the invention covers adjustable beds that just one or two lifting mechanisms to accomplish the ingress- or egress-facilitating mode. 
     The control and processing unit  5  preferably has a pre-programmed mode operable to automatically articulate the torso-support base structure  2  and elevate the appropriate vertices  70 - 77 , in a timed and controlled sequence as set forth above, to facilitate bed ingress or egress. 
     Stated another way, the control and processing unit  5  preferably has a pre-programmed mode to modulate the right-torso-adjacent peripheral portion  121  and the right-hip-adjacent peripheral portion  123 , or alternatively to modulate the left-torso-adjacent peripheral portion  129  and the left-hip-adjacent peripheral portion  127 , of the patient support surface  36  to facilitate egress by a patient resting on the patient support surface  36  off of the patient support surface  36 . More particularly, this mode is programmed to raise the right-torso-adjacent peripheral portion  121  above the left-torso-adjacent peripheral portion  129 , or vice versa, in order to tilt a patient&#39;s torso toward one side; and raise the right-hip-adjacent peripheral portion  123  above the left-hip-adjacent peripheral portion  127 , or vice versa, in order to tilt a patient&#39;s legs toward one side. 
     IV. Programmable Control of the Bed 
       FIG. 35  is an abbreviated schematic diagram of electrical connections between various parts of the adjustable bed  100 . A control panel  6 , which preferably comprises an interactive user interface touch-screen monitor, provides a caregiver the capability to adjust the movable surfaces of the bed into desired positions, and to select pre-programmed routines, or program new routines, of successive movements of the adjustable bed  100 . The control panel  6  is connected to a control and processing unit  5 . This control and processing unit  5  contains a central processing unit (CPU)  32 , a memory  33 , a power source  34  and an interface  35  with several peripheral control units  13 . Each peripheral control unit  13  drives a defined movement. Moreover, each motor  29  or actuator has a security switch in both ends of the running means to preclude greater displacement than what is allowed. 
     The control and processing unit  5  also comprises one or more interfaces for connection with an external computer and other instruments and electronic devices. Various patient mobilization routines can be programmed into the control and processing unit  5  and can be administered continuously or episodically by the caregiver through the control panel  6 . 
     In one embodiment the control unit  13  receives from the central processing unit (CPU)  32  movement commands, e.g. positions, velocities and special action, and executes algorithms via an incorporated microcontroller, thus driving each actuator&#39;s mechanism to reach the pre-programmed position. The control panel  6  is used to select a routine to trigger a sequence of movements. The CPU  32  then sends to a corresponding control unit  13  the desired position and command information using bidirectional communication protocol. Next the control unit  13  analyzes the position information, determines the difference between the actual position and the desired position, and drives the actuators until the desired position is achieved. Velocity information may also be sent, as defined by the central processing unit  32 &#39;s algorithm plus the caregiver&#39;s input via the control panel  6 . In another embodiment, there is no microcontroller in the control unit  13 , and the CPU  32  triggers signals to the control unit to the actuators. 
     The storage memory for the algorithms and position data may be distributed among the CPU  32  and the control units  13 . The CPU  32  may have a high storage capacity while each control unit  13  has relatively less storage capacity. The means for CPU storage is capable of collecting a diverse final bed position, e.g. cardiac chair, etc., several sequences of patient movements, e.g. defined trajectories, algorithms for generation of the bed movement programs for prevention and/or treatment activities. The means for CPU storage may be capable of accumulating a clinical history database as well as accumulating clinical treatment results data. The means for CPU storage is capable of adding usage data for the technology described herein, e.g. a record of position information by time. 
     The control panel  6  also preferably presents intuitive selectable screen menus to the caregiver. The control panel  6  may be capable of having access levels controls, e.g., by password, biometrics, card key, etc. The control panel  6  may have a sector screen to manually direct the actuators, e.g. up, down. In close proximity to the manual mode controls may be a visual indication showing the actual position and the desired position. The control panel  6  may have a portion of the screen that shows a perspective view of the desired position of the bed  100  so that the caregiver has an initial impression of the patient movement desired for confirmation or correction. The control panel  6  may also have an interface screen for inputting individual patient data, e.g. status of consciousness, possible restrictions to movement, previous sites of occurrence of pressure ulcers or lesions, etc., in order to trigger a specific prevention/treatment routine. The control panel  6  may be capable of pausing the routine that is in progress, via access from the patient or caregiver. Algorithms may control the pause duration. 
     The interface for the control panel  6 , in a preferred form, is capable of multimedia output, including, but not limited to, offering audio advice to a caregiver, graphical advices and warnings as warranted. The control panel  6  may include pre-set memory position activators, e.g. buttons. Each button triggers a predetermined final position, e.g. cardiac chair, RX position, eating, resting, etc. The control panel  6  may include customizable memory position activators to save positions desired by a caretaker. The control panel  6  may include trajectory memory activators. A trajectory is defined as a series of predefined positions successively executed from an initial position to a final position. This allows for triggering specific movements of a patient by defined buttons, e.g. bed egress and bed ingress as an aid to a caregiver. The control panel  6  may include means to activate a diurnal mode, i.e. more accelerated, and a nocturnal mode, i.e. slower. This capability may be set automatically as a function of clock information, or may be set manually by a patient. 
     The control panel  6  may contain a special CPR button for use in an emergency. Activating this CPR button triggers signals for a rapid descending of all actuator mechanisms. The control panel  6  may contain a special button for pausing of a movement in progress. Activating this pause button freezes all movements of the technology described herein. Subsequent activation of the pause button results in returning to the movement in progress. If the pause button is not reactivated there may be a return to the movement in progress after a pre-established time for ulcer prevention has passed. The control panel  6  may contain a special stop button to stop the movement in progress. 
     The control panel  6  may have the capability of allowing connection of a remote control for use by a patient. The connection between the control panel  6  and the remote control may be wired or wireless. The remote control may have reduced functionality and may be configurable to address different needs. The control panel  6  may contain means to activate a remote operation of the bed  100 . This capacity may permit, e.g. via the Internet, total or partial control of the bed and total or partial access to the collected data. The control panel  6  may contain means for an audio-video connection, e.g. via the Internet, so that a visitor may have access in real time to audio and images of the patient. The control panel  6  may contain means to show the pressure value sensed via a special attachment for patient-to-mattress pressure determination. The control panel  6  may have the capability for the addition of specific controls to other accessories engaging the bed  100 , e.g. motorized rail, proning attachment, etc. 
     The technology described herein may include a black box recording unit that documents parameters of usage. This black box may be used for maintenance needs or technical service, thus reducing outside operation time. The black box may provide information to a caregiver about the intensity of recent use that is related to a prevention/treatment action. The black box may be capable of permitting a pay system based on use. The black box may collect data for future analysis and development, thus providing relationships between a patient&#39;s diagnosis and best preventive or treatment programs. 
     The technology described herein may include algorithms controlling sequences of movements and executed from the control panel by a caregiver or patient. Each algorithm may contain all the information needed to execute a defined flow of movements. In one embodiment of the technology described herein a caregiver may have the ability to create his own algorithmic sequences, adapted to the specific needs of an individual patient. The newly generated sequences may remain stored in memory for evaluation and future usage. The CPU  32 &#39;s algorithms may be directed to executing trajectories, generating movement flows, previewing movements, precluding mechanical interferences, establishing control units communication, modulating diurnal or nocturnal movement flows, determining index of use, documenting bed activity, etc. The control unit  6 &#39;s algorithms may be directed to establishing communication with the CPU  32 , driving actuators, sensing position, and synchronizing the advance of parallel actuators. 
     V. Conclusion 
     Having thus described exemplary embodiments of the present invention, it should be noted that the disclosures contained in  FIGS. 1-35  are exemplary only, and that various other alternatives, adaptations, and modifications may be made within the scope of the present invention. For example, the adjustable bed  100  may be further adapted as set forth in U.S. patent application Ser. No. 12/120,363, filed on May 14, 2008, and entitled “Adjustable Bed With Sliding Subframe for Torso Section,” and U.S. patent application Ser. No. 12/176,338, filed on Jul. 19, 2008 and entitled “Side Guard for Bed,” both of which are herein incorporated by reference. Accordingly, the present invention is not limited to the specific embodiments illustrated herein, but is limited only by the following claims. 
     This invention also relates to, and this application incorporates herein by reference, the following disclosures filed as part of the Patent and Trademark Office&#39;s Document Disclosure Program: the disclosure by Eduardo R. Benzo and Rodolfo W. Ferraresi entitled Levita-Bed System, received by the Patent and Trademark Office (“PTO”) on Dec. 27, 2005, and assigned document number 592241; the disclosure by Eduardo R. Benzo, Rodolfo W. Ferraresi, and Mario C. Eleonori entitled Dynamic Multipositional Hospital Bed, received by the PTO on Feb. 27 2006, and assigned document number 596795; the disclosure by Eduardo R. Benzo, Rodolfo W. Ferraresi, and Mario C. Eleonori entitled Dynamic Multipositional Hospital Bed, received by the PTO on Jul. 19, 2006, and assigned document number 603707; the disclosure by Eduardo R. Benzo, Rodolfo W. Ferraresi, and Mario C. Eleonori entitled Use and Control Methods for Multipositional Beds, received by the PTO on Dec. 13, 2006, and assigned document number 610034; and the disclosure by Eduardo R. Benzo, Rodolfo W. Ferraresi, and Mario C. Eleonori entitled System for Virtual Communication between Patient and the Rest, received by the PTO on Dec. 13, 2006, and assigned document number 610042.