Patent Application
20150257968
This application relates to medical devices for treating patients. More particularly, the application relates to soft-robotic devices for wound management.
Generally, bandages are soft materials that are applied to the exterior of the body to provide mechanical support, absorb drained fluids, or act as a barrier between a portion of the body such as a wound and the external environment. Bandages are typically formed from woven textiles, and may include a wide variety of additives such as antiseptics (e.g. polyhexamethylene biguanide), drugs for transdermal delivery (e.g. nicotine, scopolamine, estrogen, etc.), coatings or membranes to prevent adhesion to wounds (e.g. mylar membranes), and/or adhesives to keep the bandage in contact with the skin. Bandages are formed as strips, tubes, sheets, and any other shapes which are suitable for their intended uses. They are typically flexible (capable of being deformed) and/or elastic (tending to return to their unstressed-configurations after being deformed), and are typically deployed so as to apply pressure to at least a portion of the body being treated. Bandages may provide varying degrees of pressure depending on their sizing and elasticity relative to the size of the patient and the area being treated. For some applications, such as the treatment of topical abrasions or lacerations, relatively little pressure is needed. For others, such as the treatment of hemorrhage or orthopedic conditions, more pressure may be called for.
Although the simplicity of currently-used bandages offers certain advantages such as low cost and ease of use, it also constrains their efficacy: existing bandages are most useful in settings where the need for support, absorption, or prevention of infiltration does not change over time. For treatment of conditions that do change over time or that require complex applications of force, a single bandage is generally inadequate, and multiple bandages may be required over time. In addition, bandages that apply substantial pressure may need to be removed in order to ensure that tissues adjacent to the region being treated receive sufficient blood perfusion. For traumatic degloving wounds, burns, compound fractures and similar injuries, traditional bandages may simply be inadequate, particularly if these injuries occur in places like the battlefield in which complex medical care is not readily available. Traditional bandages attach only to the surface of the wound and are not necessarily conformal to its margins, particularly if they are irregular, potentially allowing the loss of blood and other fluids as well as failing to completely prevent external contaminates and infectious particles from entering the wound. These shortcomings may be compounded further if the patient cannot be moved enough to dress the entire wound.
Recent advances in the field of “soft” robotic manipulators, or “soft robots,” have the potential to improve bandage design generally and wound care in particular. (See, for instance, International Patent Application Pub. No. WO2012/148472 by Ilievsky et al. entitled “SOFT ROBOTIC ACUATORS”, the entire disclosure of which is incorporated by reference herein for all purposes). Soft robots comprising elastomeric or extensible bodies and/or flexible polymeric or textile actuators rather than hard plastic or metal ones are remarkably well suited to the manipulation of delicate objects such as injured human tissue. However, in spite of their advantages over existing technologies, soft robots have not yet found widespread use in medicine.
The present invention, in its various embodiments, applies soft robotic technology to address the shortcomings of traditional bandages.
This Summary is provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description. This Summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended as an aid in determining the scope of the claimed subject matter.
An exemplary embodiment of a soft conformal compression medical device for treatment of a wound on a patient's limb in accordance with the present disclosure may include a network of pneumatic actuators and a wound dressing. The pneumatic actuators may be activated by providing a source of a gas to an inlet on the device, which may cause the device to curve, bend, or otherwise deform in a predetermined manner to encircle a patient's limb and urge the wound dressing toward the wound.
A method of treating a wound in accordance with the present disclosure may include placing, adjacent a wound on a portion of a patient's body, a conformal compressive device, the device configured to at least partially encircle the portion of the patient's body and including a wound dressing and a network of pneumatic actuators configured to urge the wound dressing toward the wound when activated, and activating the network of pneumatic actuators.
Aspects of the invention are described below with reference to the following drawings in which like numerals reference like elements, and wherein:
Unless otherwise provided in the following specification, the drawings are not necessarily to scale, with emphasis being placed on illustration of the principles of the invention.
Soft robotic devices for treating wounds and applying pressure to limbs are described herein. The devices preferably comprise networks of pneumatic actuators referred to herein and elsewhere as “Pneu-Nets.” Individual pneumatic actuators within such networks can function in several ways. One category of actuators is flexible and/or compliant at ambient pressure (e.g. 1 atm), becoming rigid when externally pressurized or placed under vacuum internally. These actuators include paired elastomeric beams comprising opposing toothed patterns separated by an open-cell foam. Under vacuum, the dead air within the foam is evacuated, drawing the elastomeric beams together such that the toothed patterns interdigitate, forming a single, relatively rigid beam.
A second type of actuator, described by Ilievsky et al., is substantially linear and/or has a first curvature at a ambient pressure, but becomes (more) curved upon the application of internal pressure or vacuum. Actuators of this type generally comprise a plurality of chambers arranged in an array. The chambers are defined by a plurality of walls, and the various configurations of the actuators are determined in part by the relative flexibility and/or elasticity of the walls. Specifically, walls that are more elastic (e.g. thinner elastomeric walls) will tend to elongate and/or bend as the internal pressure of the chamber increases, while walls that less elastic (e.g. thicker elastomeric walls) will not bend or elongate to the same degree. In addition, some walls can be flexible but not elastic such that, when the internal pressure of the chamber increases, the wall bends without elongating. In some embodiments, the chambers in the array are separated from one another by relatively thick walls. The chambers in the array are further defined by a first side that is covered by a relatively thin elastic membrane capable of expanding in length as the pressure within the chamber increases and a second side, that does not vary significantly in length as the internal pressure of the chamber increases or decreases (referred to by Ilievsky et al. as a “strain-limiting” portion of the chamber). As the pressure increases, the first side expands along with the internal volume of the chamber, thereby causing the chamber to curve about the second side wall. Alternatively or additionally, if the internal pressure within the chamber is reduced below the ambient pressure, the first side wall will buckle, permitting the chamber to curve away from the second side wall. The ultimate shape and action of the device can be tuned, among other ways, by adjusting the relative thicknesses and elasticities of the various walls defining the chambers, and/or by varying these thicknesses and/or elasticities across the array.
More generally, pneumatic elements used in the invention respond to increases in internal pressure by expanding, particularly in the regions that are most compliant or have the lowest stiffness. In devices with homogeneous elastomer structures, the regions that expand the most are those with the thinnest walls (which are the structures with the lowest resistance to stretching). Pressurization and expansion in these regions further thins the walls, and increases the volume of the channel. To accommodate the asymmetric elongation of two opposite walls of the channel, the structure surrounding the expanding volume bends. Upon pressurization, a single channel spanning the length of a rectangular slab causes the slab to bend around the axis of the channel. Multiple channels have an additive effect; upon pressurization, an actuated network of channels can generate complex shapes in elastomeric structures. The choice of materials, coupled with the design of the channels and the speed of inflation, determines the response of the device to applied pressure. The pressure necessary to achieve a particular amplitude of actuation scales with the stiffness of the materials and with the ratio of elastomeric polymer material in the chamber relative to the volume of the chamber.
Passive and active loading capacity of actuators (the maximum sustainable load) correlates to the stiffness of the materials used for fabrication—stronger materials are able to support larger loads, but typically cannot sustain very large strains. Agility—the ability to create intricate movements, and to do so rapidly—requires bending to small radii of curvature, and is thus easier to achieve in materials able to sustain high strains. Composite structures, in which materials with different stiffnesses join to form a channel, are useful for programming the directionality of actuation, and provide properties that benefit from the combined mechanical properties of the different materials. As with single-material devices, the composite channels expand upon pressurization at the most compliant region. Since the different compliances are now not controlled by the channel design, but largely determined by the choice of materials and their layout, regions made from a more elastic material will expand.
Stacking or connecting the components described above creates structures that provide complex motion and require only a single source of pressure. Appropriate distribution, configuration, and size of the Pneu-Net elements determine the resulting movement. Pneumatic and/or hydraulic systems are attractive for medical applications, particularly those performed outside of the clinic, because air has low viscosity, and permits rapid actuation; since air is compressible, it is easy to store, light and environmentally benign; biocompatible hydraulic fluids such as saline are also easy to store and are environmentally benign.
Devices comprising Pneu-Nets can generate a wide variety of movements including gripping, inversion of shape from convex to concave, and undulating shape changes. Additionally, their modular structure allows designers the freedom to design each layer or segment of a Pneu-Net device separately, tailoring the structure of each part to achieve a particular function, and then join them together. For example, a ridged texture may be added to a skin-contacting layer in order to enhance grip. The textured surface is more compliant than a solid surface of the same material and provides more traction. In some embodiments, the textured surface is achieved through the actuation of Pneu-Net actuators: at atmospheric pressure, the surface, and the actuation of the Pneu-Net results in the formation of corrugations, striations, or other surface textures.
Referring now to
The first portion 105, as shown in
Turning to
The CC 200 may further include an inflation mechanism 217, such as a manual inflation bulb (as shown in
As shown in
Turning to
While the foregoing disclosure has focused on the treatment of wounds, CCs according to various embodiments of the invention can also be used to apply pressure or vacuum to limbs or other body parts that are not affected by specific, external wounds. In some embodiments, CCs are configured to provide heat and/or cold therapy to, for instance, injured musculoskeletal tissue. For instance, as shown in
In certain embodiments, a CC in accordance with the present disclosure may be sized and shaped to provide periodic and/or rhythmic chest compressions for cardiopulmonary resuscitation (“CPR”). Currently, providing chest compression for CPR fully occupies one CPR provider, and it is difficult to manually provide sufficient pressure for chest compression without breaking ribs, particularly if chest compressions are performed for an extended period. One advantage of CCs according to the present disclosure is the ability to store such CCs in places where people congregate, such as building lobbies, airport terminals, etc., and to provide simple instructions for use by an untrained or first-time user to place the uninflated CC beneath the patient and inflate and/or deflate the CC to provide chest compression for CPR.
Devices according to the embodiments of the present invention advantageously permit greater control over the pressure applied to a wound than currently-used bandages, and allow varied pressure to be applied to a wound over time, which is not possible using conventional bandages. In addition, various embodiments of the invention have features that are especially advantageous for medical applications, especially those which may be performed by emergency personnel, first responders, or battlefield personnel, including the following:
The phrase “and/or,” as used herein should be understood to mean “either or both” of the elements so conjoined, i.e., elements that are conjunctively present in some cases and disjunctively present in other cases. Other elements may optionally be present other than the elements specifically identified by the “and/or” clause, whether related or unrelated to those elements specifically identified unless clearly indicated to the contrary. Thus, as a non-limiting example, a reference to “A and/or B,” when used in conjunction with open-ended language such as “comprising” can refer, in one embodiment, to A without B (optionally including elements other than B); in another embodiment, to B without A (optionally including elements other than A); in yet another embodiment, to both A and B (optionally including other elements); etc. The term “consists essentially of means excluding other materials that contribute to function, unless otherwise defined herein. Nonetheless, such other materials may be present, collectively or individually, in trace amounts. As used in this specification, the term “substantially” or “approximately” means plus or minus 10% (e.g., by weight or by volume), and in some embodiments, plus or minus 5%. Reference throughout this specification to “one example,” “an example,” “one embodiment,” or “an embodiment” means that a particular feature, structure, or characteristic described in connection with the example is included in at least one example of the present technology. Thus, the occurrences of the phrases “in one example,” “in an example,” “one embodiment,” or “an embodiment” in various places throughout this specification are not necessarily all referring to the same example. Furthermore, the particular features, structures, routines, steps, or characteristics may be combined in any suitable manner in one or more examples of the technology. The headings provided herein are for convenience only and are not intended to limit or interpret the scope or meaning of the claimed technology.
Certain embodiments of the present invention have described above. It is, however, expressly noted that the present invention is not limited to those embodiments, but rather the intention is that additions and modifications to what was expressly described herein are also included within the scope of the invention. Moreover, it is to be understood that the features of the various embodiments described herein were not mutually exclusive and can exist in various combinations and permutations, even if such combinations or permutations were not made express herein, without departing from the spirit and scope of the invention. In fact, variations, modifications, and other implementations of what was described herein will occur to those of ordinary skill in the art without departing from the spirit and the scope of the invention. As such, the invention is not to be defined only by the preceding illustrative description.
| Number | Date | Country | |
|---|---|---|---|
| 61950961 | Mar 2014 | US |
