Patent Publication Number: US-2015086958-A1

Title: Medical treatment simulation devices

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application claims priority to U.S. Patent Application No. 61/882,107, the contents of which are incorporated herein by reference in their entirety. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates generally to medical simulations, and more particularly, to simulation devices for training care providers to provide medical treatment. 
     BACKGROUND OF THE INVENTION 
     Training care providers to administer cardiopulmonary resuscitation (CPR) treatment can be complicated due to the difficulty in simulating the actual conditions in which treatment is required. In particular, encountering a patient who is suffering from serious distress (e.g., panting, sweating, panicking, etc.) may invoke an emotional response in a care provider that can interfere with or overcome the provider&#39;s CPR training. 
     One possibility for overcoming this emotional response is providing training to CPR providers in which a real-life CPR scenario can be simulated. Such training may not be capable of simulation through the use of a conventional training mannequin. Conversely, conventional training programs do not allow for the provision of realistic CPR treatment to a patient actor, as such treatment may cause actual harm to the actor. Accordingly, improved systems and devices are desired for training CPR care providers to provide treatment. 
     SUMMARY OF THE INVENTION 
     Aspects of the present invention are medical treatment simulation devices. In accordance with an aspect of the present invention, a medical treatment simulation device is configured to be secured to a subject and to cover at least a portion of a torso of the subject. The medical treatment simulation device includes a base member, a movable member, and at least one sensor. The movable member is movably coupled to the base member. The movable member is biased to be in a predetermined position relative to the base member. The sensor is configured to detect a movement of the movable member relative to the base member. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention is best understood from the following detailed description when read in connection with the accompanying drawings, with like elements having the same reference numerals. When a plurality of similar elements are present, a single reference numeral may be assigned to the plurality of similar elements with a small letter designation referring to specific elements. When referring to the elements collectively or to a non-specific one or more of the elements, the small letter designation may be dropped. This emphasizes that according to common practice, the various features of the drawings are not drawn to scale unless otherwise indicated. On the contrary, the dimensions of the various features may be expanded or reduced for clarity. Included in the drawings are the following figures: 
         FIG. 1  is an image illustrating an exemplary medical treatment simulation device in accordance with aspects of the present invention; 
         FIG. 2  is a diagram illustrating an exemplary cross-section of the medical treatment simulation device of  FIG. 1 ; 
         FIGS. 3A and 3B  are diagrams illustrating exemplary layouts of the medical treatment simulation device of  FIG. 1  relative to a human subject; 
         FIG. 4  is a diagram illustrating an exemplary base member of the medical treatment simulation device of  FIG. 1 ; 
         FIG. 5  is a diagram illustrating an exemplary movable member of the medical treatment simulation device of  FIG. 1 ; and 
         FIGS. 6A and 6B  are diagrams illustrating exemplary sensor layouts of the medical treatment simulation device of  FIG. 1 . 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Aspects of the invention are described herein with reference to simulating the treatment of patients requiring cardiopulmonary resuscitation (CPR). However, it will be understood by one of ordinary skill in the art that the exemplary devices described herein may be used to simulate treatment of a variety of medical conditions, and is not limited to CPR treatment. Other medical treatments suitable for simulation with the disclosed devices will be known to one of ordinary skill in the art from the description herein. 
     The exemplary devices disclosed herein may be particularly suitable for providing an enhanced level of feedback to the medical care provider relative to conventional training devices. Visual and/or haptic feedback may be provided to the care provider during treatment in order to reinforce proper techniques. Likewise, this feedback may be provided to correct treatment errors that the care provider may otherwise struggled to detect during the simulated treatment. The provision of feedback using the exemplary devices of the present invention may desirably improve the ability of medical care providers to comfortably and effectively treat patients. 
     With reference to the drawings,  FIG. 1  illustrates an exemplary medical treatment simulation device  100  in accordance with aspects of the present invention. Device  100  is usable to train medical care providers to provide CPR treatment to patients. In general, device  100  includes an overlay  110 , a base member  120 , a movable member  130 , and at least one sensor  140 . Additional details of device  100  are described below. 
     Overlay  110  is configured to be positioned overtop of a subject who is playing the role of the patient. When positioned overtop the subject, overlay  110  is configured to cover the subject&#39;s upper torso. In an exemplary embodiment, overlay  110  is shaped like a patient&#39;s upper torso, as shown in  FIG. 1 . Shaping overlay  110  as described above desirably limits the size of overlay  110 , and allows the profile of overlay  110  to closely conform to the body of the subject, thereby allowing the subject to portray a CPR patient. 
     Overlay  110  may be formed from multiple pieces that connect to define an enclosure for the components of device  100 . In an exemplary embodiment, overlay  110  is a housing including a front surface  112  and a rear surface  114 , as shown in  FIG. 2 .  FIG. 2  shows a cross-section illustrating the internal layout of device  100 . Front surface  112  is configured to be removably connected to rear surface  114 , for example, by straps, buttons, snaps, or any other structures known in the art. Inside the surfaces  112  and  114 , base member  120  and movable member  130  are spaced from one another to form a cavity  125 , as described in more detail below. 
     In an exemplary embodiment, front surface  112  of overlay  110  may be formed from a soft and pliable material intended to simulate the patient&#39;s skin (“artificial skin”), which may further include anatomically accurately positioned simulated nipples to facilitate proper hand placement for performing CPR. Likewise, rear surface  114  of overlay  110  may be formed from a soft foam material for providing comfort to the subject wearing device  100 . These surface materials may be coupled to rigid shells designed to house the operational components of device  100  (e.g. sensors and feedback devices), thereby providing protection for these components and conceal wiring and other items. 
     In an exemplary embodiment, the artificial skin of front surface  112  of overlay  110  may include sound dampening material in order to dampen sounds generated within device  100 . The artificial skin may further include memory foam, PVC, and/or elastomeric layers for simulating the patient&#39;s skin. 
     In one embodiment, the artificial skin may comprise a sheet of thermoplastic, such as a 3 mm thick sheet of low temperature thermoplastic manufactured by Allard USA, embedded in a silicone rubber gel, such as made by Smooth-On, Inc. Such a configuration may have a stiffness of several pounds per inch. One method of fabricating a suitable skin overlay comprises molding the thermoset plastic around a human individual&#39;s chest and then allowing it to cool. Another mold may then be created using a lifecasting technique utilizing plaster of Paris. The silicone rubber gel may then be painted onto the plaster of Paris mold in several layers, allowing sufficient curing time (roughly 10 minutes) between coats to ensure thickening of the silicone to avoid unwanted pooling. In one suitable embodiment, after applying three layers of the silicone rubber gel over the mold, the thermoplastic layer was then set in the mold and two additional layers of silicone were applied. 
     It will be understood that the selection, order, and thickness of layers of artificial skin are not limited. Other suitable materials for use in simulating a patient&#39;s skin will be generally known to one of ordinary skill in the art from the description herein. 
     Device  100  may further include a plurality of straps for securing overlay  110  to a subject. In an exemplary embodiment, the rear of device  100  includes a pair of straps  116  configured to encircle the subject&#39;s shoulders. Straps  116  are usable to secure device  100  to the subject during the simulated treatment. Device  100  may further include additional buckles  118  coupled to base member  120  for receiving straps. Buckles  118  can receive straps around the torso of the subject for securing device  100  during simulated treatment. 
     In a preferred embodiment, straps may extend between the upper and lower connections on overlay  110  in a cross-strap pattern. In other words, a strap may be attached to overlay  110  at the upper left and the lower right points, allowing a pair of straps to cross on the back of the subject. This may increase the stability and comfort of device  100  to the subject. 
     Device  100  is preferably designed to assist in distributing the force from chest compressions across device  100 , to minimize force transfer to the subject wearing device  100 . In one exemplary embodiment, overlay  110  extends over the top of the subject&#39;s torso and down the sides of the subject&#39;s torso, as shown in  FIG. 3A . In this embodiment, overlay  110  or base member  120  contacts the floor or other surface on which the subject is lying. This may desirably assist in distributing the force of chest compressions into the floor or underlying structure, and away from the subject. In another exemplary embodiment, overlay  110  extends over substantially all of the subject&#39;s upper torso, as shown in  FIG. 3B . In this embodiment, device  100  is formed with a relatively large surface area, which allows the force from chest compressions to spread out over the subject&#39;s entire upper torso. The embodiment shown in  FIG. 3B  may be preferable to assist in wearability of overlay  110 , and realism of the simulated CPR treatment. 
     In an exemplary embodiment, base member  120  is formed from a rigid material such as metal (e.g. aluminum), plastic (such as polypropylene), or rigid fabric (such as KEVLAR). A layer of cushioning material, such as but not limited to memory foam, may be provided on a rear surface of base member  120  to form rear surface  114  of overlay  110 . Base member and underlying rear surface  114  of device  100  are designed to be positioned against the chest of the subject when device  100  is secured to the subject. One or more coupling devices (such as straps) may be attached to base member  120  to couple device  100  to the subject. 
     A suitable base member  120  for use with one embodiment of the present invention is depicted in  FIG. 4 . In the exemplary embodiment depicted in  FIG. 4 , base member  120  has a Y-shape, as shown in  FIG. 4 . The shape of base member  120  provides support for the additional components (e.g. movable member  130  and sensor  140 ) of device  100 , as will be described below. Additionally, the Y-shape of base member  120  may be desirable for spreading out the applied force to peripheral areas of the subject&#39;s torso, thereby minimizing the force transferred to the subject. To this end, base member  120  has a profile corresponding to the profile of the human thoracic cavity, in order to further provide comfort and force distribution to the subject. Other possible shapes for use with base member  120  include, for example, circular or rectangular shapes. 
     Movable member  130  is movably coupled to base member  120 . Movable member  130  is biased to be in a predetermined position relative to base member  120 . Suitable for biasing movable member  130  will be described in greater detail below. Movable member  130  may be positioned directly against front surface  112  of overlay  110 , such that front surface  112  of overlay  110  is secured to movable member  130 . 
     A suitable movable member  130  for use with the present invention is provided in  FIG. 5  for the purpose of illustration. In an exemplary embodiment, a lower portion of the movable member  130  is shaped like a CPR patient&#39;s sternum. In this embodiment, the shape of movable member  130  may be useful for providing a more realistic feeling or feedback to the care provider using device  100 . During the simulated CPR treatment, the care provider may be then position their hands relative to movable member  130  in a manner corresponding to the appropriate positioning of a care provider&#39;s hands when providing actual CPR treatment to a patient. 
     As shown in  FIG. 5 , movable member  130  has a Y-shape similar to the shape of base member  120 . At the branched upper end, movable member  130  includes a pair of hinges  131  for allowing controlled relative movement between movable member  130  and base member  120 . The control provided by hinges  131  causes the lower end of movable member  130  to move substantially in a single plane toward and away from base member  120 . 
     Movable member  130  comprises a biasing element  132  for biasing movable member to be in the predetermined position. Biasing element  132  biases movable member  130  away from base member  120 . In an exemplary embodiment, biasing element  132  comprises one or more springs coupled between base member  120  and movable member  130 . The one or more springs have a length selected to place movable member  130  in the predetermined position when the springs reach their respective equilibrium lengths. Springs  134   a - 134   c  in part create the spacing between members  120  and  130  that defines cavity  125  within device  100  that acts as the simulated thoracic cavity for the simulated chest compressions. 
     As shown in  FIG. 5 , in an exemplary embodiment, biasing element  132  includes three springs  134   a - 134   c.  The springs are positioned approximately in a line between base member  120  and movable member  130 . In this embodiment, one of the springs  134   a  may have a different spring constant from at least another one of the springs  134   c.  The use of different spring constants among the springs  134   a - 134   c  of biasing element  132  may be desirable in order to accurately simulate the resistive force provided by the overlay against the chest compressions performed by the care provider during simulated CPR treatment. Additional details regarding suitable force profiles for biasing element  132  are provided in greater detail below. 
     In an exemplary embodiment, springs  134   a  and  134   b  have an equilibrium height of between approximately 2.5-3.5 inches and a base diameter of approximately 2-2.5 inches. Spring  134   c  has an equilibrium height of between approximately 2-3 inches, and a base diameter of approximately 1.75-2 inches. In this embodiment, springs  134   a  and  134   b  have a spring constant between approximately 13-15 lbs./in, while spring  134   c  has a spring constant between approximately 11.5-13.5 lbs./in. Between springs  134   a - 134   c  and the natural stiffness from the remaining components (including overlay  110 ) which amount to between 3-6 lbs./in, device  100  incorporating biasing member  132  provides a realistic force curve simulating the force a care provider would experience when providing CPR treatment to an actual patient. 
     While springs  134   a - 134   c  in  FIG. 5  are illustrated as coil springs, it will be understood that the invention is not so limited. Other suitable springs for use as biasing element  132  include, for example, torsional springs, volute springs, or leaf springs. 
     Sensor  140  is coupled to base member  120  and/or movable member  130 . Sensor  140  is configured to detect certain movements of movable member  130  relative to base member  120 . Exemplary embodiments of sensor  140  are set forth below. 
     In one exemplary embodiment, sensor  140  comprises a plurality of optical sensors  142   a,    142   b,    142   c,    142   d,    142   e,  as shown in  FIG. 6A . Optical sensors  142   a - 142   e  are configured to detect the total displacement of movable member  130  from the predetermined position. As shown in  FIG. 6A , optical sensors  142 - 142   e  are arranged approximately in a line, and are positioned to detect movement within a slot or cavity  144  defined by sensor  140 . The slot  144  extends between the movable member  130  and the base member  120 . Optical sensors  142   a - 142   e  may be, for example, a series of infrared LED emitter and detector pairs spanning across slot  144 , as shown in  FIG. 6A . Each of the sensors  142   a - 142   e  may be spaced apart by an equal distance, e.g., between approximately one quarter and one half inch. 
     In this embodiment, movable member  130  comprises a projection  136  on an end thereof. The projection  136  is positioned within the slot  144  defined by sensor  140 . As movable member  130  is moved during compressions by the care provider, projection  136  moves downward within slot  144 , and interrupts the optical beams projected by optical sensors  142   a - 142   e.  The number of optical sensors  142   a - 142   e  triggered by projection  136  can be used to determine the total displacement of movable member  130 . It will be understood that the number of optical sensors  142   a - 142   e  shown in  FIG. 6A  is provided for the purposes of illustration, and is not intended to be limiting. 
     In another exemplary embodiment, sensor  140  comprises a reed switch, as shown in  FIG. 6B , configured to signal when movable member  130  has moved a predetermined amount from the predetermined rest position. As shown in  FIG. 6B , reed switch sensor  140  comprises a magnet  142   f  coupled to base  120  and a reed switch element coupled to projection  136  of movable member  130 . As is known in the art, a reed switch typically comprises a pair (or more) of magnetizable, flexible, metal reeds having end portions separated by a small gap when the switch is open, all hermetically sealed in opposite ends of a tubular glass envelope. The reed switch comprises a circuit that is adapted to change state (i.e. to close if normally open, or to open if normally closed) when the reed switch is in sufficient proximity to a magnetic field. Other technologies for causing an open or closed signal may also be provided in place of the reed switch, with similar functionality. Projection  136  may be a telescoping rod that permits selection of a desired compression depth for the simulated CPR treatment. In an exemplary embodiment, the predetermined amount is between approximately 3-6 cm. 
     In the reed switch embodiment, as movable member  130  is moved during compressions by the care provider, projection  136  moves downward, and the reed switch element mounted thereon passes through or sufficiently close to the magnetic field created by magnet  142   f,  thereby causing electrical contacts in the reed switch to change position, thereby creating a sensible change in an electrical signal. Thus, when triggered, the sensor  140  provides a signal that movable member  130  has moved the predetermined amount. This signal may be used to provide feedback to the care provider, as will be described in greater detail below. It will be understood that the predetermined amount of movement of movable member  130  may be adjusted by adjusting the length of the telescoping rod  136 . 
     The above examples of types and layouts of sensors  140  are provided for the purposes of illustration, and are not intended to be limiting. It will be understood that a combination of the disclosed sensors may be used, and that additional types and layouts of sensors may be used, without departing from the scope of the invention. 
     For example, sensor  140  may comprise an accelerometer for sensing the movement of movable member  130 . The sensed movement could be used to determine the displacement of movable member  130  and the force applied to movable member  130 . Alternatively, sensor  140  may comprise a linear variable differential transformer (LVDT) configured to measure displacement of movable member  130  along a line extending between the predetermined position of movable member  130  and base member  120 . The LVDT could be coupled to base member  120  so that it could be raised or lowered depending on a desired depth of compression/desired length of movement of movable member  130 . 
     Other components usable to detect the movement and displacement of movable member  130  will be known to one of ordinary skill in the art from the description herein. 
     Device  100  is not limited to the above-described components, but can include alternate or additional components as would be understood to one of ordinary skill in the art in view of the examples below. 
     For example, device  100  may include a feedback device  150  to provide feedback to the user of device  100  (i.e. the care provider) based on the movement of movable member  130  detected by sensor  140 . Feedback may be provided based on the movement of movable member  130  caused by the care provider during the compressions that are part of the simulated CPR treatment. 
     In an exemplary embodiment, feedback device  150  is a visual display. The display provides visual feedback to the user during the simulated treatment of the subject. The display may be mounted in the front surface  112  of overlay  110 , in an area not likely to be contacted during simulated CPR treatment. Suitable displays for use as feedback device  150  include, for example, liquid crystal displays. Other display components for use as feedback device  150  will be known to those of ordinary skill in the art from the description herein. 
     In another exemplary embodiment, feedback device  150  is an audible alarm. The alarm generates a sound that can be heard by the user during the simulated treatment of the subject. Suitable loudspeakers for use as the audible alarm will be known to one of ordinary skill in the art from the description herein. Other feedback devices, or combinations thereof, will be known to one of ordinary skill in the art from the description herein. 
     For another example, device  100  may include a microcontroller  160 . In an exemplary embodiment, microcontroller  160  is connected in communication with sensor  140  and feedback device  150 . Microcontroller  160  processes the information detected by sensor  140 , and operates feedback device  150  to provide the user with feedback based on the movement of movable member  130  detected by sensor  140 . Examples of feedback provided by microcontroller  160  using feedback device  150  are set forth below. 
     In one exemplary embodiment, microcontroller  160  is programmed to operate feedback device  150  to display information to the user regarding the total displacement of movable member  130  relative to base member  120 . In this embodiment, device  100  includes the sensor  140  illustrated in  FIG. 6A , and a visual feedback device  150 . Sensor  140  generates a signal representative of the total displacement of movable member  130  relative to base member  120 . The signal is based on the number of optical sensors  142   a - 142   e  triggered by projection  136 . This signal is communicated from sensor  140  to microcontroller  160 . Microcontroller  160  then processes this information, and operates feedback device  150  to display to the user information regarding the displacement of movable member  130 . This information may include, by way of example, the distance moved by movable member  130 , i.e., the depth of the chest compression during the simulated treatment. For another example, the displayed information may include the force exerted on movable member  130  by the user, which microcontroller  160  may be configured to calculate from the distance moved by movable member  130 . This calculation may be performed based on predetermined characteristics of movable member  130  and biasing member  132  (such as spring constants). 
     In another exemplary embodiment, microcontroller  160  is programmed to operate feedback device  150  to display information to the user regarding a frequency of movements of movable member  130  relative to base member  120 . In this embodiment, device  100  may include the sensor  140  illustrated in  FIG. 6B , and may include a visual and/or audio feedback device  150 . Sensor  140  generates a signal representative of movement of movable member  130  a predetermined distance (e.g., an effective compression). This signal is communicated from sensor  140  to microcontroller  160 . Microcontroller  160  then processes this information, and operates feedback device  150  to display to the user information regarding the compressions of movable member  130 . This information may include, by way of example, the frequency of movements of movable member  130  (i.e., the frequency of chest compressions). This frequency may be displayed numerically, or may be broadcast audibly to the user (e.g., as a series of beeps corresponding to the compressions). 
     Additionally or alternatively, microcontroller  160  may operate an audio feedback device  150  to produce sounds corresponding to a desired frequency for the chest compressions (e.g., again, as a series of beeps with which the user should attempt to keep time). In an exemplary embodiment, feedback device  150  may a metronome tuned to emit sounds at the desired frequency, which can be switched on and off either manually (by the user or subject) or automatically (by microcontroller  160 ). 
     The above described medical treatment simulation device provides advantages not found in conventional devices as set forth below. In particular, the disclosed embodiments provide treatment devices that allow a care provider to simulate the provision of CPR treatment to a living patient, as opposed to a non-moving, non-responsive mannequin or dummy. Additionally, the expansive size contouring of the base member, along with the biased connection between the movable member and the base member, allows for the dissipation of force from chest compressions during the simulated treatment, thereby creating a safe environment for the subject. During proper simulated CPR treatment, the disclosed devices will result in a chest pressure well below the pain or danger threshold for the subject, e.g., a PSI of 1.55 or less. 
     Although the invention is illustrated and described herein with reference to specific embodiments, the invention is not intended to be limited to the details shown. Rather, various modifications may be made in the details within the scope and range of equivalents of the claims and without departing from the invention.