Patient support guard structure

A guard structure of a patient support, such as a hospital bed, is electrically unlockable. An electromechanical actuator, such as a solenoid, may be used to electrically unlock the guard structure. The guard structure may also be mechanically unlockable. The guard structure may automatically unlock during a CPR emergency. A maximum allowable height of the patient support may be adjusted based on a sensed locked state or position of the guard structure. A release for the guard structure may be positioned to be accessible to an occupant of the patient support. The release may include an access port that may be opened. The release may include a button that electrically unlocks the guard structure.

FIELD OF THE INVENTION

This disclosure relates to patient supports, such as hospital beds, and more specifically, patient supports having a movable guard structure, such as a side rail.

BACKGROUND

Patient supports, such as hospital beds, are known to have guard structures, such as side rails, that are movable to permit patient entry and egress from the patient support; for example, they may be raised and lowered. Side rails are known to be mechanically lockable. When a typical side rail is locked, it cannot be moved.

Side rail locking mechanisms are limited in how they can be unlocked. This may lead to inconvenience when operating the patient support. For example, typical locking structures or locking mechanisms are operable only from outside the patient support or bed by a caregiver or attendant; this makes it difficult for patients to exit the bed once the rails have been raised without calling for help. This may be inconvenient in some situations, for example when a patient needs to quickly use a restroom or in maternity wards where an infant is present in the bed along with the patient. In addition, during a medical emergency, this may be dangerous if patient access is required quickly and the each rail needs to be manually unlocked by an attendant.

Side rails may also be lowered at times when they would better be left raised, such as when the patient support is adjusted to a high height or while the patient support is being lowered to a low height near the floor. This may be dangerous to the occupant of the patient support, due to the danger of falling out of the bed, or may damage side rails due to impact with the floor when the bed is lowered. Existing patient supports typically do not include patient support control mechanisms that determine the locking state and/or rail position in conjunction with other variables, such as bed height, or locking mechanisms that facilitate this determination.

There is therefore a need for improved patient supports, side rails and/or side rail unlocking mechanisms to mitigate some or all of these deficiencies.

SUMMARY OF THE INVENTION

A guard structure of a patient support includes a locking structure that is mechanically unlockable. A release for the locking structure may be positioned to be accessible to an occupant of the patient support. The release may include an access port that may be opened. The locking structure may additionally or alternatively be electrically unlockable. The release may include a button that electrically unlocks the guard structure. A solenoid may be used to electrically unlock the guard structure and may optionally be coupled with a locking structure that mechanically maintains the guard structure in an unlocked state. One or more guard structures may automatically unlock during a CPR emergency. A maximum or minimum allowable height of the patient support may be adjusted based on a sensed locked state and/or a sensed position of the guard structure. Other aspects of the guard structure are also disclosed.

DETAILED DESCRIPTION

As used herein, the term “patient support” refers to an apparatus for supporting a patient in an elevated position relative to a support surface for the apparatus, such as a floor. One embodiment of a patient support includes beds, for example hospital beds for use in supporting patients in a hospital environment. Other embodiments may be conceived by those skilled in the art. The exemplary term “hospital bed” or simply “bed” may be used interchangeably with “patient support” herein without limiting the generality of the disclosure.

As used herein, the term “guard structure” refers to an apparatus mountable to or integral with a patient support that prevents or interferes with egress of an occupant of the patient support from the patient support, particularly egress in an unintended manner. Guard structures are often movable to selectively permit egress of an occupant of the patient support and are usually located about the periphery of the bed, for example on a side of the bed. One embodiment of a guard structure includes rails, for example side rails, mountable to a side of a patient support, such as a hospital bed. Other embodiments may be conceived by those skilled in the art. The exemplary terms “guard rail”, “side rail”, “rail structure”, or simply “rail” may be used interchangeably with “guard structure” herein without limiting the generality of the disclosure.

As used herein, the term “control circuit” refers to an analog or digital electronic circuit with inputs corresponding to a patient support status or sensed condition and outputs effective to cause changes in the patient support status or a patient support condition. For example, a control circuit may comprise an input comprising an actuator position sensor and an output effective to change actuator position. One embodiment of a control circuit may comprise a programmable digital controller, optionally comprising or interfaced with an electronic memory module and an input/output (I/O) interface. Other embodiments may be conceived by those skilled in the art. The exemplary terms “controller”, “control system”, “control structure” and the like may be used interchangeably with “control circuit” herein without limiting the generality of the disclosure.

FIG. 1illustrates an embodiment of a height-adjustable patient support100. The patient support100includes a substantially horizontal frame102that supports an adjustable patient support deck104(or simply “deck”) positioned thereon to receive a patient support surface (or “mattress”) for supporting a patient thereon. For clarity, the mattress is not illustrated. The patient support deck104has an upper-body portion105capable of tilting up to form a backrest and tilting down to a prone position (tilt-up position shown). At the head end of the patient support100is a headboard106, while a foot-board108is attached to the frame102at the foot end of the patient support100. Guard structures comprising side rails110are positioned on each side of the patient support100. Such side rails110may be moveable so as to facilitate entry and exit of a person. In this embodiment, the patient support100is a bed. In other embodiments, the patient support100may be a chair, wheelchair, stretcher, or similar apparatus. The term “patient” is intended to refer to any person, such as a hospital patient, nursing-home resident, or any other occupant of the patient support100.

The patient support100includes two leg assemblies112,114, each having a pair of legs111. The head leg assembly112is connected at the head end of the patient support100and the foot leg assembly114is connected at the foot end of the patient support100. Upper portions of the legs111of the leg assemblies112,114are connected to one or more linear actuators that may move the upper portions of the legs111back and forth along the length of the patient support100. Leg braces116pivotably connected to the legs111and to the frame102constrain the actuator movement applied to the legs111to move the leg assemblies112,114in a manner that raises and lowers the frame102. In other words, the leg assemblies112,114act as linkages that collapse and expand to respectively lower and raise the frame102, whose height is indicated by H. The lower ends of the leg assemblies112,114are connected to caster assemblies118that allow the patient support100to be moved to different locations.

Articulation of the patient support deck104is controlled by actuators (not shown) that adjust the tilt of the upper-body portion105of the patient support deck104as well as the height of a knee-supporting portion of the patient support deck104.

A manual cardiopulmonary resuscitation (CPR) quick release handle124is provided on each side of the patient support100to rapidly lower the upper-body portion105of the patient support deck104and place the bed into an emergency state wherein the patient support deck104is flat and optionally the side rails are unlocked. This will be discussed in further detail below.

The patient support100further includes an attendant's control panel120located at the foot-board108. The attendant's control panel120may, among other things, control the height H of the frame102, as well as the articulation of the patient support deck104. To allow for similar adjustment, an occupant's control panel122may be provided, for example, on a side rail110.

The control panels120,122include user interfaces such as buttons. The buttons may be membrane style buttons that operate as momentary contact switches (also known as “hold-to-run” switches). Buttons may be provided to raise the frame102, lower the frame, articular the patient support deck104, set/pause/reset an exit alarm, zero an occupant weight reading, lockout controls, and to enable other functions. The control panels120,122may have different sets of buttons for different sets of functions, with the attendant's control panel120typically having a wider array of functions available. Other styles of user interface and buttons, such as touch-screen buttons, are also suitable. The user interfaces of the control panels120,122may include indicators, such as printed graphics or graphics on a display, for describing the functions of the buttons or other interface and as well as indicating data related to the patient support100.

It should be emphasized that the patient support100is merely one example of a patient support that may be used with the techniques described herein. Other examples of patient supports that may be so used include ultra-low type height-adjustable beds such as those disclosed in US Patent Publication No. 2011/113556 and U.S. Pat. No. 7,003,828, which are both incorporated herein by reference.

As shown inFIG. 2, one or more linear actuators200are provided to the leg assemblies112,114. Each linear actuator200has an extendable/retractable rod208that is connected to a bearing block202, which slidably engages with a respective guide rod204. The guide rods204are fixed to the frame102. The upper portions of the legs111of each of the leg assemblies112,114are pivotably connected to the respective bearing block202. When the actuators200extend and retract, the bearing blocks202move linearly along the lengths the guide rods204. This linear motion is converted, via the additional constraint of the pivot-connected leg braces116, to motion that raises and lowers the frame102. Also illustrated is one of the elongate structural members206that, together with cross-members (not shown), form the frame102. Although in this embodiment the patient support100has two actuators200for raising and lowering the frame102, it should be understood that one or more actuators200may be used.

Each actuator200may include an actuator position sensor that may output a signal indicative of the position of the actuator200and thus the height of the frame102above the floor. For instance, the actuator position sensor may be a digital rotary encoder that outputs pulses to a control circuit that may comprise a programmable digital controller, which may count the pulses to determine the position of the bearing block202and may further lookup or calculate a height of the frame102based on this count. A single actuator position sensor may be indicative of frame height when more than one actuator200is used. In other examples, other kinds of position or height sensors may be used and these need not be included in the actuator.

The actuators200may also be configured to move the patient support100into other positions, such as the Trendelenburg position (head lower than foot) or the reverse Trendelenburg position (head higher than foot).

FIG. 3shows a block diagram of a system300for controlling the patient support100. Each of the components of the system300may be attached to the patient support100at a suitable location.

The system300includes a controller302that includes a processor304electrically coupled to an input/output interface306and memory308. The controller302may be situated in a control box that is attached or otherwise coupled to the patient support100. The controller302may be physically integrated with another component of the system300, such as the attendant's control panel120.

The processor304may be a microprocessor, such as the kind commercially available from Freescale™ Semiconductor. The processor304may be a single processor or a group of processors that cooperate. The processor304may be a multicore processor. The processor304is capable of executing instructions obtained from the memory308and communicating with the input/output interface306.

The memory308may include one or more of flash memory, dynamic random-access memory, read-only memory, and the like. In addition, the memory308may include a hard drive. The memory308is capable of storing data and instructions for the processor304. Examples of instructions include compiled program code, such as a binary executable, that is directly executable by the processor304and interpreted program code, such as Java® bytecode, that is compiled by the processor304into directly executable instructions. Instructions may take the form programmatic entities such as programs, routines, subroutines, classes, objects, modules, and the like, and such entities will be referred to herein as programs, for the sake of simplicity. The memory308may retain at least some of the instructions stored therein without power.

The memory308stores a program310executable by the processor304to control operations of the patient support100. The controller302comprising the processor304executing the program310, which configures the processor304to perform actions described with reference to the program310may control, for example, the height of the frame102, articulation of the patient support deck104(e.g., upper-body tilt and knee height), exit alarm settings, and the like. The controller302may also be configured to obtain operational data from the patient support100, as will be discussed below. Operational data obtained by the controller302may be used by the processor304and program310to determine control limits for the patient support100.

The memory308also stores data312accessible by the processor304. The data312may include data related to the execution of the program310, such as temporary working data. The data312may additionally or alternatively include data related to properties of the patient support100, such as a patient support serial number, model number, MAC address, IP address, feature set, current configuration, and the like. The data312may additionally or alternatively include operational data obtained from components, such as sensors and actuators, of the patient support100. Operational data may include the height of the frame102, an articulated state of the patient support deck104, a status of the side rails110, an exit alarm setting or status, and an occupant weight. The data312may include historic data, which may be time-stamped. For example, the occupant's weight may be recorded several times a day in association with a timestamp. The data312may be stored in variables, data structures, files, data tables, databases, or the like. Any or all of the data mentioned above may be considered as being related to the patient support100.

The input/output interface306is configured to communicate information between the processor304and components of the system300outside the controller302. The communication may be in the form of a discrete signal, an analog signal, a serial communication signal, or the like. The input/output interface306may include one or more analog-to-digital converters.

In one embodiment, the input/output interface306allows the processor304to send control signals to the other components of the system300and to receive data signals from these components in what may be known as a master-slave arrangement.

The system300further includes components, such as one or more actuators316configured to control the articulation of the patient support deck104, one or more load sensors318(e.g., load cells) positioned to measure the weight of the occupant of the patient support100, one or more side-rail sensors320,321configured to sense the position and/or locked state of a side rail110, the frame-height actuators200, the occupant's control panel122, and the attendant's control panel120. Each of the components may receive control signals from the controller302, send data signals to the controller302, or both.

In this embodiment, the controller302includes the input/output interface306having one or more physical ports322, such as a universal serial bus (USB) port, a memory card slot, an Ethernet jack, a serial port, or the like. The port322includes logic, such as a USB controller or Ethernet adaptor, to allow transfer of data between the controller302and a physically connected external device, such as a memory stick, memory card, portable computer, or similar device. Such physical connections may be made by an appropriate cable, such as a USB cable, Ethernet crossover cable, or the like. When the port includes a network interface, standard network protocols may be used. The port322accepts a physical connection (e.g., a cable or insertion of a card).

A portable memory device324, such as a USB memory stick or flash memory card, or an external computer, such as a portable computer326, may be connected to the port322to communicate data with the patient support100.

As mentioned, the upper-body portion or backrest105of the patient support deck104is variably positionable, and accordingly may be raised and lowered so that the occupant of the patient support100may be provided with, for example, a range of positions between fully prone and sitting upright. As shown inFIG. 4, a backrest support402is pivotably connected to the frame102and supports the backrest105over its range of positions.

A backrest actuator assembly404is connected between the backrest105and the frame102and is configured to raise and lower the backrest105with respect to the frame102. In this example, the backrest actuator assembly404includes an actuator316, which is connected to the frame102. The backrest actuator assembly404further includes a lockable damper406that is connected in series with the actuator316at one end and is pivotably connected to a lever arm408extending from the backrest support402at another end. The lever arm408may also be known as a head gatch bracket. The CPR handle124operates with the above components to form an emergency CPR mechanism.

The actuator316may be an electric motor-driven linear actuator.

The lockable damper406may be a lockable fluid-filled damper, such as a locking hydraulic damper, locking gas spring, or the like. The lockable damper406is configured to provide damping over a range of motion when unlocked and configured to rigidly or nearly rigidly lock at any position on the range of motion. For the linear style damper described herein, range of motion may be known as damper stroke. Dampers may also be known as dampeners or dashpots.

In one example, the lockable damper406includes a cylindrical body though which a piston slides. Each side of the piston has a chamber of fluid that is selectively communicated by pushing an unlocking pin that opens a valve in the piston to allow fluid to move between the chambers. Relative movement between the cylindrical body and a rod extending from the piston may then be damped (valve open) or held rigid (valve closed). In other examples, other kinds of dampers may be used. The lockable damper406may be a BLOC-O-LIFT™ device sold by Stabilus GmbH of Koblenz, Germany.

Each CPR handle124(seeFIG. 1) is connected to the lockable damper406. Each CPR handle124is configured to unlock the lockable damper406when actuated to an unlock position, thereby allowing the damper406to contract without having to operate the actuator316.

During normal operation of the patient support100, the lockable damper406is locked in an extended state and movement of the actuator316causes the lockable damper406to push or pull against the lever arm408to raise or lower the backrest105as commanded by the controller302operated by the bed's occupant or an attendant, such as a nurse or caregiver.

During an emergency, such as a cardiac arrest of the bed's occupant, a CPR handle124may be manually actuated to quickly allow the backrest105to drop due to gravity as shown by arrow E (dropped position shown in phantom line). The rate of drop of the backrest105is controlled at least in part by the damping effect of the damper406as it contracts over its damped range of motion under the weight of the backrest105, backrest support402, attached side rails110, mattress, the occupant's upper body, and any other items in or on the patient support100.

After the CPR handle124has been actuated and while the backrest105is dropping due to gravity, the CPR handle124may be returned to its original position, or lock position, to lock the lockable damper406at its current length and thereby stop the dropping of the backrest105. The backrest105may be stopped at any position along the damped range of motion, which may make for safer bed operation. For example, if the arm of the occupant or that of a person standing near the hospital bed is under the backrest105during a CPR release, the backrest105may be temporarily stopped to reduce the chance of injury.

Once the CPR handle124is pulled and the emergency mechanism is activated to place the patient support in an emergency state, the goal is to allow caregiver's to perform whatever procedures are required to attend to the immediate needs of the patient. Accordingly, a patient supporting surface of the patient support is made flat when in the emergency state and, optionally, the side rails are unlocked through actuation of the release, permitting them to drop out of the way due to gravity. Other actions may also be performed automatically by the patient support when the emergency mechanism is activated to improve access of the caregiver to the patient or otherwise facilitate emergency care.

With reference toFIGS. 5A and 5B, which depict the patient support100in its lowered position, in this embodiment the patient support100has four guard structures in the form of side rails110(only two visible in this view). Two head-end side rails110A are positioned on opposite sides of the patient support100near its head end, and two foot-end side rails110B are positioned on opposite sides of the patient support100at about its midsection, but extending toward the foot end of the bed. Although the side rails are shown having an opening101, in some embodiments this opening may be filled in without affecting function.

Each of the side rails110A,110B comprises a side rail body502pivotally connected to the upper end of two side rail supports504. Each side-rail support504is pivotally connected to the side rail body502and pivotally connected to a side-rail housing506configured for mounting the side rail110to the frame102or backrest105. The side-rail supports504rotate to raise and lower the side rail body502with respect to the frame102, while keeping the side rail body502substantially horizontal and parallel to the frame102or backrest105. The side rail body502, two side-rail supports504, and side-rail housing506may be considered to form a first four-bar linkage. A mechanical release comprising a knob508is provided for each side rail110A,110B to unlock a locking structure510(hidden line) of the side rail110A,110B to allow movement of the side rail110A,110B.

Each of the side rails110A,110B locks when its side rail body502is in a raised position, depicted inFIG. 5A. Each of the side rails110A,110B may be unlocked or released, via manual actuation of the knob508, to unlock the locking structure510and allow movement of the side rail body502into a lowered position, depicted inFIG. 5B. In this embodiment, the side rail110A,110B does not lock in the lowered position. In other embodiments, the side rail110A,110B does lock in the lowered position or, optionally, in other positions.

Each of the side rails110A,110B is configured to automatically move into the lowered position when unlocked. In this embodiment, the center of gravity of the side rail body502, weight and pivoting resistance of the side-rail supports504are selected to allow the side rail body502to move into the lowered position due to the influence of gravity. Thus, when a side rail110A,110B is in the raised position (FIG. 5A) and then unlocked, the side rail110A,110B tends to automatically fall into the lowered position (FIG. 5B) under its own weight.

FIG. 6shows another block diagram of the system300for controlling the patient support100. Electrical couplings are shown by solid connecting lines and mechanical couplings are shown by dashed ones. In this embodiment, the system300further includes electromechanical actuators, for example side-rail unlocking solenoids602, for unlocking the side rails110A,110B, or generally110, and side-rail release buttons604for activating the solenoids602. Although each side rail110is generally provided with one solenoid602and one button604, the button604may be provided on the patient support remote from the side rail110or a single button604may be configured to actuate the release mechanism of a plurality of side rails110.

Each side-rail unlocking solenoid602is electrically coupled to the input/output interface306. The solenoid602may be double acting, spring biased in one direction, or of other design. The solenoid602is configured to electrically actuate and unlock the locking structure510upon activation of a switch via button604. Alternative embodiments of electromechanical actuators may be used in place of the solenoid602, for example linear actuators, etc.

Each side-rail release button604is electrically coupled to the input/output interface306. The button604is connected to a switch, for example a momentary contact switch, and may form part of the occupant's control panel122. The button604is positioned on an inside surface of the side rail110at a location that is readily accessible to the occupant of the patient support100. In other embodiments, a handle, lever, or other device may be used to activate the switch instead of the button604. A side rail release button similar to the button604may be provided in additional or alternative locations, for example on the outside of the side rail, the attendant's control panel, etc.

The side-rail locking structure510is configured to unlock upon electrical actuation of the release via button604. The side-rail locking structure510is configured to mechanically unlock, as mentioned, upon mechanical actuation of the release via knob508. Therefore, the button604is part of an electrical release and the knob508is part of a mechanical release. The electrical and mechanical releases together form a combined release that electrically and mechanically controls the locking structure510. That is, in order to lower the side rail110, an attendant may unlock the side rail110by pressing the knob508or may unlock the side rail110by pressing the button604. The mechanical release may override the electrical release and permit the rail to be unlocked. It is advantageous that the same side-rail locking structure may be unlocked both mechanically and electrically; for example, in the event of power failure.

Side-rail release buttons604may be provided elsewhere on the patient support100to facilitate electrical unlocking of the side rails110. For example, four side-rail release buttons604, one for each side rail110, may be provided at the attendant's control panel120. A side rail release button604may be accessible to an occupant of the bed to electrically actuate the release and unlock the side rail to permit egress from the bed. This may be in addition to or as an alternative to buttons604provided for use by the caregiver or attendant.

The program310may be configured to control side-rail unlocking as follows.

The program310responds to predetermined input at the side-rail release buttons604in order to unlock the side rails110. In one embodiment, three presses of one of the buttons604by an occupant of the bed in quick succession electrically actuates the release and unlocks the respective side rail110. If the program310detects fewer than three presses in an allotted time, then the side rail110is not unlocked, while detection of three or more presses in the allotted time unlocks the side rail110. This may advantageously prevent inadvertent unlocking of the side rails110by the occupant of the patient support100.

The program310may be configured to lock out the side-rail release buttons604. That is, the program310may ignore input at the buttons604under certain circumstances. For example, the attendant's control panel120may include a control lock out button that configures the program310to ignore commands received from the occupant of the patient support100. This may be used when the safety of the occupant is a concern. Additional lockout states may include when the bed is in an unacceptable configuration, for example a Trendelenburg or reverse Trendelenburg orientation, when the backrest or knee is raised above an acceptable level, when a height of the bed is above or below an acceptable level, when a patient support surface or mattress is in an unacceptable orientation, when the caster wheels or brakes are unlocked, etc.

The program310may be configured to automatically electrically actuate the release and unlock any or all of the side-rail locking structures510using the respective solenoids602in the event that the CPR handle124is pulled, thereby putting the patient support in an emergency state. Each CPR handle124includes a switch606that indicates to the controller302that the CPR handle124has been pulled. Among other things, the switch606may provide the controller302with information on the state of the CPR handle124, which the controller302may use, for example, to reset the emergency CPR mechanism. However, regarding the side rails110, the program310may reference the state of each CPR handle switch606and accordingly control the solenoids602to unlock the side-rail locking structures510after one of the CPR handles124has been pulled. Which of the side rails110are to be so unlocked or the sequence in which they are unlocked may be predetermined. In one embodiment, only the two head-end side rails110A are unlocked in an emergency state. In another embodiment, all of the side rails110are unlocked in this way. Electrically unlocking the side rails110during an emergency may advantageously allow the side rails to lower automatically, thereby permitting quicker and less complicated access to the occupant of the patient support100. That is, emergency personnel do not need to first manually lower the side rails110before preforming procedures, such as chest compressions, that require unobstructed access to the occupant. Other actions may be taken by the controller302in an emergency state, for example flattening the patient support surface, triggering lights or alarms indicative of an emergency state, etc.

The program310may be configured to generate an alarm signal in response to unlocking of a side rail110. In one embodiment, the alarm signal is generated when the release is electrically actuated. In another embodiment, each side rail110is provided with a side-rail locking sensor320that senses the locked/unlocked state of the side rail110. The side-rail locking sensors320may comprise limit switches or similar devices. When the program310determines that a side rail110has been unlocked, the program310outputs the alarm signal to a device, such as an alarm device608on the patient support100or a remote monitoring device located at a nurse call station. The alarm device608may include one or more of an audible device, such as a speaker, and a visible device, such as a light or display. The alarm device608may further indicate which of the side rails110has been unlocked. For example, each side rail110may include a light-emitting diode (LED) that flashes when the side rail110is unlocked.

In another embodiment, still with reference toFIG. 6, the program310may be configured to adjust an allowable height of the frame102of the patient support100with reference to the side rails110. Adjusting an allowable height based on the side rails110may reduce a patient falling hazard and/or may reduce the likelihood of damage to the patient support100.

The program310constrains the height-adjusting actuators200to operate according to at least one actuation limit and provides an alarm signal to the alarm device608when the actuation limit is violated. The program310may establish one or more actuation limits corresponding to one or more of a maximum allowable height of the frame102and a minimum allowable height of the frame102. An actuation limit corresponds to a position of an actuator200and may be stored and compared in terms, such as rotary encoder pulse count, that are different from terms (e.g., cm or inches) in which the corresponding allowable height is expressed. An allowable height is enforced by the program310ignoring commands that would cause one or more of the height-adjusting actuators200to violate an actuation limit. Default maximum and minimum allowable heights may be used to stop the actuators200during normal raising and lowering of the patient support100.

The system300may additionally or alternatively include side-rail position sensors321that are electrically coupled to the input/output interface306. Each side-rail position sensor321is configured to detect a position of the side rail110, for example whether the respective side rail110is in the raised position, the lowered position, or optionally another position. The side-rail position sensors321may be limit switches, proximity sensors, optical sensors or similar devices.

The program310may reference one or more of the side-rail locking sensors320and side-rail position sensors321to determine whether an allowable height of the patient support100is to be adjusted. Each kind of sensor320,321may indicate to the program310that the patient support100should not be raised or lowered beyond an allowable height. Other features of the patient support100, such as bed configuration, may be controlled based on input from the sensors320and/or321; for example the bed may be prevented from entering a Trendelenburg or reverse Trendelenburg orientation, the backrest or knee may be prevented from being raised above an acceptable level, a height of the bed may be prevented from being adjusted outside of an acceptable range, a patient support surface or mattress may be prevented from entering an unacceptable orientation, the caster wheels or brakes may be prevented from being unlocked, etc.

The program310may be configured to lower the maximum allowable height of the frame102when a side rail110is unlocked, as determined by the respective side-rail locking sensor320, or when a side rail110is lowered, as determined by the respective side-rail position sensor321. When a side rail110is unlocked or lowered, the program310ignores commands that would cause the frame102to be raised higher than the maximum allowable height. When the program310determines that the frame102is higher than the maximum allowable height, as may be the case when a side rail110is unlocked or lowered after the frame102has been raised, then the program310outputs an alarm via the alarm device608. This may advantageously help reduce injury if the occupant were to fall from the patient support100.

In a numerical example, the default maximum allowable height is 91 cm (or 36 inches) and the maximum allowable height with an unlocked or lowered side rail110is 61 cm (or 24 inches). The patient support100may be raised and lowered below 61 cm irrespective of the side rails110being locked/unlocked or raised/lowered. If a side rail110is unlocked or lowered and an attempt is made to raise the patient support100above 61 cm, then the program310ignores the raise command. If the patient support is already above 61 cm when a side rail110is unlocked or lowered, then the program310issues an alarm and also ignores raise commands.

The program310may be configured to raise the minimum allowable height of the frame102when a side rail110is unlocked, as determined by the respective side-rail locking sensor320, or when a side rail110is lowered, as determined by the respective side-rail position sensor321. When a side rail110is unlocked or lowered, the program310ignores commands that would cause the frame102to be lowered lower than the minimum allowable height. When the program310determines that the frame102is lower than the minimum allowable height, as may be the case when a side rail110is unlocked or lowered after the frame102has been lowered, then the program310outputs an alarm via the alarm device608. This may advantageously help prevent damage to the side rails110or objects on the floor underneath the side rails110.

In a numerical example, the default minimum allowable height is 15 cm (or 6 inches) and the minimum allowable height with an unlocked or lowered side rail110is 20 cm (or 8 inches) or other increased amount sufficient to prevent interference between the side rails110and the floor. The patient support100may be raised and lowered above 20 cm irrespective of the side rails110being locked/unlocked or raised/lowered. If a side rail110is unlocked or lowered and an attempt is made to lower the patient support100below 20 cm, then the program310ignores the lower command. If the patient support is already below 20 cm when a side rail110is unlocked or lowered, then the program310issues an alarm and also ignores lower commands.

The features of the program310described in the embodiments above, and specifically the features regarding electrical unlocking of side rails110, such as control lock out, CPR unlocking, alarms, and allowable height adjustments, may be used independently of each other and may be used together in any suitable combination.

As may be seen from the figures, the mechanical release action of the locking structure510may override the electrical release action of the locking structure510. That is, in some situations, such as power failure, the solenoid602may not be used to unlock the side rail110. However, in such situations, the knob508may always be pushed to unlock the side rail110. Another example of such a situation is a control lock out that disables the side-rail release button604and thus disables electrical unlocking of the side rail110. Again, the knob508may be pushed to unlock the side rail110. This is advantageous in that the side rails110may always be lowered during an emergency, regardless of the state of electrical power at the patient support100, while still providing convenience via electrical side rail unlocking when power is available.

Referring toFIG. 7A, a side rail110is mounted to a side of a frame102of a patient support100. The side rail110is depicted in a raised position and shows various components of the locking mechanism and release in exploded view. The release shown is configured to be both mechanically and electrically actuated, in a manner as will be more fully described hereinafter.

Turning toFIG. 7B, the side rail110comprises a side rail body502pivotally connected to the upper end of two side rail supports504as previously described. The side rail supports504are pivotally connected at their lower end to the housing506that is used to mount the side rail to the frame102or backrest105. Inside the housing506are a pair of lobe shaped members702that are fixedly attached to a shaft (not shown) extended through the housing506at the point of pivotal connection of the side rail supports504to the housing506. For reference, the shaft (not shown) is attached to each lobe shaped member at about the center of the triangle formed by the three screws703. The lobe shaped members702therefore move with the side rail supports504upon pivoting movement of the side rail body502.

Pivotally attached to the outward end of each lobe shaped member702is a side rail cross-bar704that completes a second four-bar linkage of the siderail110. The cross-bar704includes an arcuate slot705with an enlarged circular aperture706at one end thereof. A locking pin707comprises an elongate pin shaft708that is threaded at one end and comprises an enlarged pin head709at the other. The pin head709includes a shoulder710with a diameter corresponding to that of the aperture706. When locked, the shoulder710of the locking pin707rests within the aperture706. Since the shoulder710is larger in size than the arcuate slot705, movement of the cross-bar704is prevented, which concurrently prevents pivoting movement of the rail body due to the action of the second four-bar linkage. When unlocked through actuation of a release, in a manner as will be more thoroughly described hereinafter, the locking pin707moves longitudinally towards the frame102(upward in the orientation ofFIG. 7B) so that the shoulder710disengages from the aperture706. The relatively smaller first diameter of the pin shaft708corresponds in size to the arcuate slot705, thereby permitting movement of the cross bar704and concurrently permitting movement of the side rail body502.

A spring711forms part of the mechanical release and biases the locking pin707outwardly, away from the frame (toward the cross bar704). A knob508for manual actuation of the mechanical release (via pushing towards the frame102) is threaded to the end of the pin shaft708. A washer750is provided to enlarge the surface for engagement of the spring711with the knob508. When unlocked, the shoulder710is able to ride along the outside edge of the arcuate slot705during lowering of the side rail110(represented by movement of the rail body to the right inFIG. 7B), thereby keeping the side rail110in an unlocked state. When the side rail110is raised, the shoulder710eventually encounters the aperture706and snaps into engagement therewith due to the action of the spring711. This locks the rail in the raised position, preventing further movement. Therefore, the arcuate slot705, circular aperture706and locking pin707together form a locking structure510that is configured to lock the rail in the raised position, but permits the rail to be unlocked and free to move when in other positions.

The pin head709comprises a U shaped slot712. A capture plate713with a smaller U shaped slot is mounted to the pin head709. A reciprocating electromechanical actuator in the form of a solenoid602comprises a solenoid actuator714with a solenoid shaft715secured for reciprocating movement therethrough by a solenoid cover plate716attached to the actuator714by a pair of mounting bolts and corresponding nuts717. Referring additionally toFIGS. 8A-B, the solenoid shaft715has a diameter corresponding to the U shaped slot of the capture plate713and includes an enlarged solenoid shaft head718with a diameter roughly corresponding to that of the U shaped slot712. The capture plate therefore prevents the solenoid shaft head718from escaping the U shaped slot712, thereby longitudinally securing the solenoid shaft715to the pin head709while at the same time permitting some misalignment between the longitudinal axes of the solenoid shaft715and the pin shaft708. This is important in that the solenoid602is mounted to the frame102separately from the side rail110and some misalignment due to manufacturing tolerances is to be expected.

Referring toFIG. 8A, when the side rail110is raised, the shoulder710rests within the aperture706, preventing movement of the side rail110. Turning toFIG. 8B, the side rail110is depicted in an unlocked state, achieved either by mechanical actuation of the release (by pushing the knob508inwardly towards the frame102), or by electrical actuation of the release via the solenoid602. Energizing the solenoid actuator714causes the solenoid shaft715to move inwardly towards the frame102, drawing on the pin head709by virtue of the capturing of the solenoid shaft head718within the U shaped slot712by the capture plate713. This causes the shoulder710to disengage from the apertures706, permitting pivoting movement of the side rail110. It should be noted that the spring711acts to bias both the locking pin707and the connected solenoid shaft715outwardly of the frame towards the cross bar704. Therefore, overcoming the spring711by manually pushing on the knob508overrides the electrical actuation (or non-actuation) of the release. This is advantageous in that, in the event of power outage or solenoid failure, the side rail110can still be mechanically unlocked to permit lowering.

Still referring toFIGS. 8A-B, in the embodiment shown the pin shaft708has a slight variation in diameter along its length. The first diameter D1of the pin shaft708corresponds to the arcuate slot and is slightly larger in size than the second diameter D2of the pin shaft. A chamfered transition connects the two diameters. A locking sensor800comprises a longitudinally translatable plunger801oriented at right angles to the pin shaft708. When the locking pin707is in the locked position shown inFIG. 8A, the plunger801is depressed by the larger diameter D1of the pin shaft708, thereby closing a limit switch (not shown) located within the sensor800and connected to the plunger801. When the locking pin707is in the unlocked position shown inFIG. 8B, the plunger801is biased outwardly toward the smaller diameter D2, thereby opening the limit switch within the sensor800. The locking sensor800is thereby able to detect the locking state of the locking structure and to provide a signal indicative of the locking state to the controller.

Referring toFIG. 9B, the release access port902includes a port aperture910and a port cover906. Inside the port aperture910is an actuatable button912that is only accessible to the occupant of the patient support100through the port aperture910when the port cover906is opened. In other embodiments, rather than the button912, a handle or lever may be located inside the port aperture910.

The port cover906slides across the aperture910, for example horizontally, and is resiliently biased to close. Therefore, the port cover906is held open by the occupant with one hand while the button912is pressed to actuate the release. In a variation of this embodiment, the port cover906may temporarily lock in the open position and be released once the button912is pressed. In either case, the port cover906automatically closes following actuation of the release.

FIG. 9Ashows locations1002,1004for releases discussed herein, such as the button604ofFIG. 6and the release access port902ofFIG. 9AB. As may be seen, the location1002is on the inside of the head-end side rail110A and the location1004is on the inside of the foot-end side rail110B. The locations1002,1004are readily accessible to the occupant of the patient support when the side rail110is raised and locked. The release may be a mechanical release similar to the one comprising the knob508or may be an electrical release similar to the one comprising the button604. The release may include a release access port902that is located on an inside surface904of the side rail110that the release unlocks. Alternatively, the release access port902may be located on an inside surface904of a side rail110other than the side rail110that the release unlocks; for example, the access port902may be located on an inside surface904of a head-end side rail, but the release unlocks a foot-end side rail. Releases may also be provided at the occupant's control panel122and the attendant's control panel120.

While the foregoing provides certain non-limiting example embodiments, it should be understood that combinations, subsets, and variations of the foregoing are contemplated. The monopoly sought is defined by the claims.