Vacuum assisted tissue treatment system

ES 2 299 412 T3

DESCRIPTION

Vacuum assisted tissue treatment system.

Technical field

This invention relates generally to tissue treatment systems. Specifically, this invention relates to vacuum assisted treatment systems used in the healing of open wounds.

Background of the technique

The vacuum induction open wound healing process has been gaining popularity in recent years thanks to Kinetic Concepts, Inc. of San Antonio, Texas, with its commercially available VAC® product line. The vacuum induction healing process has been described in commonly assigned US Patent No. 4,969,880 issued November 13, 1990 to Zamierowski, as well as its additions and partial additions, US Pat. USA No. 5,100,396, issued March 31, 1992, US Patent No. 5,261,893, issued November 16, 1993, and US Patent No. 5,527,293 , issued June 18, 1996. Subsequent modifications and enhancements to the vacuum induction healing process are also reflected in US Pat. 6,071,267, issued June 6, 2000 to Zamierowski and US Pat. Nos. 5,636,643 and 5,645,081 issued to Argenta et al, on June 10, 1997 and July 8, 1997, respectively. Additional improvements are also described in US Patent No. 6,142,982, issued May 13, 1998 to Hunt, et al.

In practice, the application of negative manometric pressure to a wound, marketed by the Assignee or its parent under the name of "vacuum assisted closure" therapy (known by its acronym "VAC®") usually involves mechanical contraction. of the wound, accompanied by the removal of excess fluid. In this way, VAC® therapy increases the body's natural inflammatory process, while alleviating many of the known intrinsic side effects, such as the production of edema due to increased blood flow due to the lack of the vascular structure necessary for a adequate venous return. Consequently, VAC therapy^® It has been highly successful in closing open wounds, healing many wounds for which there was no treatment before.

The frequency with which negative pressure is applied to the wound, as well as the frequency of the pressure change, directly influences the degree of wound healing. It is believed that a time-dependent variation in pressure change, which until now devices for vacuum-induced closure therapy have not been able to provide, can significantly increase the degree of wound healing. Likewise, an immediate incorporation to their usual activity by the patient subjected to this type of therapy can also improve the degree of wound healing, since increased physical activity is often accompanied by greater vascular circulation, which it involves increased blood flow to the wound area. One of the drawbacks of incorporation into normal activity is the limited battery life, as a consequence of the energy required by current vacuum-assisted treatment systems for wound healing. Also, the wound site needs to be checked regularly to make sure it is not infected. However, an immediate incorporation into normal activity should not prevent us from taking the necessary precautions during vacuum-assisted therapy therapy in order to avoid inadvertent spillage of fluid suppurated by the wound contained in the tray, or to prevent entry into the pumping mechanism of fluid suppurated by the wound.

There are other limitations in the prior art related to the use of constant frequency oscillating pumps. Said limitations are imposed due to the need for a specific pump size to be able to maintain the desired negative pressure in the wound area and / or due to a shorter battery life since oscillating pumps require this energy for their operation. Oscillating pumps, as we know from the art, are typically intended to operate under limited operating conditions. For example, to take full advantage of low pressure flow at a constant frequency. Generally, the mass and / or hardness of various components is modified to change the resonant frequency of the pump based on design operating conditions. If the pressure is increased through the pump, the hardness of the system is increased by the back pressure that is produced through the diaphragm of the oscillating pump. The resonant frequency of the pump changes and the constant frequency drive does not run the pump at the optimum frequency. As a result, the flow rate drops dramatically, impairing the pump's ability to drive air at high pressure. Therefore, to be able to provide a higher flow at high pressures it is necessary to sacrifice the flow at low pressures, or have a pump that is large enough when using a constant frequency oscillating pump.

For the reasons described above, there is a need for a vacuum assisted wound management system that is capable of automatically changing pressure. Furthermore, there is a need for a more effective vacuum assisted wound management system capable of offering greater mobility to the patient, and minimizing the risks of spilling the suppurated fluid or contaminating the pump.

Therefore, the objective of the present invention is to offer a vacuum-assisted wound treatment system capable of promoting the stimulation of cell growth through variations in pressure change.

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One of the preferred objectives is to be able to offer a system that does not interrupt its operation in the event of a cut in the alternating current electrical supply.

Another preferred objective of the present invention is to provide a cost-effective sanitary environment for sampling fluids drawn from the wound site without removing the tray or disturbing the wound site.

Finally, another of the preferred objectives to be achieved with the present invention is to offer a therapy device for vacuum-assisted wound treatment that can be attached to an object in order to reduce the possibilities of tampering with the device, and that at the same time it can be placed in a practical place where it works normally.

Disclosure of the invention

In accordance with the foregoing objectives, the present invention refers to a system according to claim 1. This system generally consists of a porous pad designed to be inserted mainly in the wound area and a dressing that provides a watertight closure of the pad in the wound area. A distal end of a tube is connected to the dressing to provide negative pressure at the wound site. A fluid sampling hole is prepared in the tube to allow samples of fluid drained from the wound to be drawn through the tube from the wound site. A source of negative pressure is in communication with a proximal end of the tube. A removable cuvette is attached to the tube aimed at collecting fluids from the wound during the application of negative pressure. A first filter fits into an opening in the bowl, while a second filter is positioned between the bowl and the source of negative pressure. As the negative pressure source can be an electric pump powered by alternating current or direct current, an energy management device is incorporated, with its corresponding energy management protocol, in order to maximize battery life when the unit It is powered by direct current. A locking mechanism is used to secure the system to a stationary object, such as a bed rail or a pole such as those used to hang IV bags.

The pad, consisting of a foam with relatively few open cells in contact with the area in which cell growth needs to be stimulated, in order to avoid unwanted adhesions, but at the same time with enough open cells so that negative pressure therapy and drainage can run its course unaffected, it is placed in fluid communication with a vacuum source to stimulate fluid drainage, as we know from the art. The porous pad of the present invention may consist of a polyvinyl alcohol foam. Fluid communication can be established by connecting a tube to a dressing, such as that described in International Application WO 99/13793, entitled "Surgical Drape and Suction Heads for Wound Treatment." ].

Once the pad is placed, a tight seal is formed in the wound area that prevents vacuum losses. Such a seal is achieved by placing a dressing on the wound in such a way that it adheres to the healthy skin around the wound area, while at the same time maintaining a seal on the wound itself.

A conduit or tube is placed in fluid communication with the foam pad, its distal end connected to a fluid drainage basin that is in fluid communication with a vacuum source. The negative pressure varies according to the moment, for a greater stimulation of cell growth, which in turn can reduce the healing process. The negative pressure induced in the wound is adjusted to accommodate a variable target pressure, which ranges from a minimum to a maximum target pressure.

The flow rate of a variable displacement pump is maximized over a range of pressures by varying the frequency of actuation of the pump. A system is responsible for continuously adjusting the optimal drive frequency, as well as periodically and constantly monitoring the pump pressure in order to determine the optimal drive frequency for that pressure. Therefore, the performance of the pump is improved compared to the variable displacement pumps used in the prior art, without having to increase the dimensions or weight of the pump. Also, the performance of a conventional variable displacement pump can be achieved with a smaller pump, which in turn reduces the dimensions and weight of the entire system in order to facilitate use and portability for the patient. Another alternative negative pressure source can also be used, such as a fixed displacement pump, also known as a positive displacement pump.

The power management system is used to maximize battery life when the system is powered by direct current. The power management system includes turning off the backlight of a display terminal, or control panel of a liquid crystal touch screen (LCD), after a predetermined interval has elapsed. Battery life is prolonged when the power management system prevents electrical power from entering an electric motor until the fixed power setting is large enough to start the motor. In such a case the motor is used to provide negative pressure by driving an electric pump as we know from the art.

The foregoing gives a general idea of ​​some of the more important objectives of the present invention. These objectives should be construed as a mere illustration of some of the most prominent features and applications of the invention. Many other beneficial results can be achieved by applying the disclosed invention differently or by modifying the invention as described below. Consequently, they may consider

ES 2 299 412 T3 other objectives and a better understanding of the invention by consulting the following Detailed Description of the Invention, which includes the preferred embodiment.

Brief description of the figures

These and other features and benefits of the invention are described below in connection with the drawings of certain preferred embodiments, intended to illustrate without limiting the invention, according to which similar reference numerals refer to similar components, and in which:

Figure 1 is a schematic block diagram of a tissue treatment system employed in accordance with the present invention.

Figure 2a is a perspective view of a liquid sampling port.

Figure 2b is a perspective view of an alternate representation of a liquid sampling port.

Figure 3a is a perspective view of the rear section of the pump casing.

Figure 3b is a perspective view of the front section of the pump casing.

Figures 4a and 4b are flow charts representing the ideal steps for the implementation of an energy management system.

Figure 5 is a flow chart illustrating the ideal steps for implementing impulse therapy.

Modes of carrying out the invention and Industrial application

Although many of the alternative embodiments will be readily recognized by those of ordinary skill in the art, especially in light of the illustrations included herein, this detailed description is an example of the preferred embodiment of the present invention, which scope is limited only by the claims that are drawn.

The present invention is a vacuum assisted system designed to promote tissue healing.

If we look in particular at Figure 1, we will see that the main components of a system operating according to the present invention are illustrated therein. The present invention 10 includes a foam pad 11 designed to be inserted primarily in the wound area 12 and a dressing 13 to hermetically seal the foam pad 11 in the wound area 12. The foam pad 11 may consist of an open cell polymeric material made of polyvinyl alcohol (PVA), or other similar material with a cell size large enough to facilitate wound healing. It is recommended that the density be greater than 38 pores per linear inch. A pore density between 40 and 50 pores per linear inch would be the most advisable situation. Although the ideal is that the density is greater than 45 pores per linear inch. Said pore density translates to a pore size of approximately 400 microns.

The incorporation of an indicator agent such as crystal violet, methylene blue or other similar agents already known in the art causes a color change in the foam 11 in the presence of a bacterial agent. This enables a user or healthcare professional to easily and immediately determine whether the wound site 12 is infected with it. It is envisaged that the indicator agent can also be placed in conduit 16 between wound site 12 and tray 18. This type of configuration (not shown) would allow to easily and immediately check the presence of contaminating bacteria in the wound area 12, without altering the wound, since a color change would occur almost immediately and the wound infected with bacteria fluid would ooze which would be drawn from wound site 12 and carried through conduit 16 during application of negative pressure.

It is also contemplated that the foam pad 11 may be coated with a bacteriostatic agent. The incorporation of such an agent would serve to limit or reduce the bacterial density in the wound area 12. The foam pad 11 can be impregnated or soaked with the agent prior to insertion into the wound area, just like during a process of packaged with sterilization. Alternatively, the agent may be injected into the foam pad 11 after it is inserted into the wound site 12.

Once inserted into the wound site 12 and sealed by the wound dressing 13, the foam pad is placed in fluid communication with a vacuum source 14 to promote fluid drainage and wound healing, such as those with normal knowledge of the art know. The vacuum source 14 can be a portable, electrically operated pump or a wall-mounted suction unit, which is the most common method in healthcare facilities.

In accordance with the preferred embodiment of the present invention, the foam pad 11, the wound dressing 13, and the vacuum source 14 are applied in accordance with the prior art, except for the modifications described in detail herein.

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The foam pad 11 preferably consists of highly cross-linked open-celled polyurethane or polyester foams so that wound fluids can be effectively impregnated during suctioning tasks. The pad 11 is preferably placed in fluid communication, through a conduit 16 of plastic or similar material, with a bowl 18 and a source of vacuum 14. A first hydrophobic membrane filter 20 is placed between the cuvette 18 and the vacuum source 14, to prevent fluids from the wound from contaminating the vacuum source 14. The first filter 20 can also be used as a fluid fill sensor. the bowl 18. As soon as the liquid comes into contact with the first filter 20, a signal is sent to the vacuum source 14, and this is closed. Preferably, the wound dressing 13 consists of an elastomeric material covered at least peripherally with a pressure sensitive adhesive for application of the seal in the wound area 12, such that a tight seal can be maintained in the area of ​​the wound. the wound 12. The conduit 16 can be placed in fluid communication with the foam 11 through an appendage 17, which can adhere to the dressing 13.

In accordance with the present invention, a second hydrophobic filter 22 is positioned between the first filter 20 and the vacuum source 14. The second filter 22 can be of great help when the first filter 20 is also used as a fill sensor for the bowl 18. In that case, the first filter 20 can act as a fill sensor, while the second filter 22 prevents the vacuum source 14 from being further contaminated with the festering liquids. This separation of functions in a safety and control device (or limitation) allows each device to be designed independently. An odorous fume filter 23, such as a carbon filter, may be placed between the first filter 20 and the second filter 22, to counteract the malodorous vapors emanating from the oozing liquids. In an alternative embodiment (not shown), the odor filter 23 can be placed between the second hydrophobic filter 23 and the vacuum source 14. A second odor filter 15 can be placed between the vacuum source 14 and the orifice of exterior exhaust 25, to further reduce the output of malodorous vapors from the current system. Another representation allows the incorporation of the first filter 20 and the second filter 22 as integral parts of the bowl 18 to ensure that the filters 20, 22, at least one of which is likely to be contaminated during the normal process, are automatically removed in order to limit the exposure of the system to contaminants that may become trapped in filters 20 and 22.

A means for taking samples may also be used through a resealable access port 24 from conduit 16. Port 24 is located between distal end 16a of conduit 16 and distal end 16b of conduit 16. Port 24, as shown described later in Figures 2a and 2b, it is used to be able to extract fluid samples from the wound area 12. Although hole 24 appears as an appendix protruding from conduit 16, it is to be understood that a recessed hole (not shown) can perform the same functions. The hole 24 includes a resealable membrane 26 which, although pierced, for example with a hypodermic needle, the gasket remains watertight. Various rubber-like materials can be used, known in the prior art to maintain their tightness if punctured.

The process by which wound fluids are sampled, according to the present invention, consists of piercing the membrane 26 with a liquid sampler 28, such as a hypodermic needle or syringe. Sampler 28 is inserted through membrane 26 and hole 24 until it comes into contact with wound fluids flowing through interior cavity 30 of conduit 16. As illustrated in Figure 2b and described in more detail in US Patent 6,142,982, issued to Hunt, et al. On May 13, 1998, the inner cavity 30 may be surrounded by one or more outer cavities 31. The outer cavities 31 can be used as pressure sensing conduits capable of detecting pressure variations in the wound area 12. In another embodiment (not shown), the outer cavity or cavities 31 may act as a negative pressure conduit, while the inner cavity 30 may be used as a pressure sensing conduit. In the present invention, the liquid sampling port 24 communicates only with the inner cavity 30, in order not to interfere with the pressure detection that the outer cavities 31 may be carrying out. In another embodiment (not shown), where the outer cavity 31 is used as the negative pressure conduit, the liquid sampling port 24 communicates with the outer cavity 31.

Vacuum source 14 may consist of a portable pump within housing 32, as illustrated in Figures 3a and 3b. A handle 33 may be included or incorporated in the housing 32 so that the user can easily grasp or move the housing 32.

In accordance with the preferred embodiment of the present invention, a clamp-shaped means 34 is provided to secure the housing 32 to a stationary object, such as a pole for hanging bags of intravenous fluids. Clamp 34, which can be a vise, as we know from the art, is retractable so that when not in use it is in a storage position within a recess 36 of housing 32. A hinge mechanism 38 is provided so that clamp 34 can extend outwardly from housing 32 to a 90 degree angle from its storage position. Another representation (not shown) allows clamp 34 to be positioned at an angle of up to 180 degrees from its storage position. When the clamp 34 is fully extended, the hinge mechanism 38 is locked in position so that the housing 32 is suspended from the clamp 34. A clamping device 40, such as a threaded bolt, is inserted through a hole 42 of the clamp 34, so that the clamp 34 can be firmly fitted to various stationary objects of different thicknesses.

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In some cases, the clamping device 40 may consist of a spring-loaded screw or pin, capable of automatically adjusting to various objects of different thickness in section, such as poles for hanging bags of intravenous fluids.

Preferably, the system of the present invention also allows management of the power supply to the vacuum source 14, to maximize battery life when the present invention uses direct current as the power source. In the preferred embodiment, as illustrated in the flow chart of Figure 4a, a motor control 44 determines whether the actual pressure is less than or equal to a target pressure 46. If the actual pressure is less than the target pressure, the provisional motor drive power required to reach the target pressure 48 is calculated. If the provisional motor drive power required to reach the target pressure is greater than or equal to the loss of power 49, the provisional motor drive power is applied to motor 50. If the actual pressure is higher than the target pressure, the provisional motor drive power is reduced and it is decided whether additional power is needed to compensate for the loss of power 52. If it is decided that the provisional power is not sufficient to be able to compensate for the loss of power, provisional power is not supplied to motor 54. If the provisional power is sufficient to compensate for the loss of energy, the provisional power is applied to motor 50. The motor control 44 operates as a closed loop system, so that the actual pressure is constantly measured against the predetermined target pressure. The advantage of this system is that it prevents power being supplied to the motor when it is not needed to maintain the target pressure specified by the VAC therapy. Therefore, the battery life is extended as energy is not wasted unnecessarily by powering the motor when it is not needed.

Battery life is extended, as illustrated in the flow chart in Figure 4b, by providing a means, such as software embedded in a computer processor, that automatically turns off the display screen backlight. 19 of the present invention 10 (as shown in Figure 3b). User input 55, such as desired target pressure or therapy duration, activates 57 a backlight of display screen 19 as shown in Figure 3b. User input 55 can also be made by simply touching the display screen 19, which may be activated by a touch or touch sensitive screen as we know from the art. Activation of an alarm 55 can also activate 57 the backlight of the screen 19. An alarm can be activated automatically if an air leak is detected in the wound area 12. Such a leak can be evident when a decrease or reduction of the pressure in the wound area 12. The backlight remains active until it is decided that the predetermined time interval has expired 58. If the time interval has not elapsed, the backlight remains active 57. If the time interval has elapsed, the backlight turns off automatically 59, until such time as the user enters additional information, or an alarm 55 sounds.

If we look at Figure 1, the battery life is prolonged thanks to a variable frequency pump drive system 80, when the pump 14 is an oscillating pump. The pump drive system 80 consists of a pressure sensor 82, a control system 84, and a variable frequency drive circuit 86. In the preferred embodiment the pressure sensor 82 measures the pressure across the pump, the which is transmitted to the control system 84. The control system 84 determines the optimal drive frequency of the pump 14, as a function of the pressure measured and transmitted by the pressure sensor 82. The optimal drive frequency of the pump 14 is determined by the control system 84 in such a way repeated or continued. Control system 84 adjusts variable frequency drive circuit 86 to drive the pump at an optimal frequency determined by control system 84.

The use of a variable frequency pump drive system 80 allows pump 14 pressure to be maximized. In tests carried out on oscillating pumps, the maximum pressure achieved was doubled only by modifying the drive frequency by 30%. In addition, system 80 maximizes flow over the extended frequency range. As a result, the performance of the pump 14 is greatly improved compared to pumps in existing constant frequency drive systems without the need to increase the size or weight of the pump. Consequently, the battery life is prolonged, allowing the user greater mobility by not having to be tied to a stationary power source. Alternatively, a smaller pump can be achieved, performance similar to that achieved by prior art constant frequency drive pumps. As a result, patient mobility is improved by facilitating the portability of the unit.

The system according to the present invention also increases the stimulation of cell growth through pressure oscillation, as shown in Figure 5. Said pressure oscillation is achieved thanks to a series of algorithms of a software program, used in conjunction with a computerized processing unit to control the function of the vacuum source or pump. The program is initialized when a user, such as a healthcare professional, activates the pulse mode of pump 60. The user sets a maximum value for the target pressure and a minimum value for the target pressure 62. The software then initializes the direction of pressure to "rise" 63. The software then enters a software control loop. In this control loop, the software first determines if the pressure is increasing 64.

If the actual pressure increases in test 64, then it is decided whether a variable target pressure is still below the maximum target pressure 70. If the variable target pressure is still below the maximum target pressure, then the software decides whether actual pressure equated to (increased to) target pressure

ES 2 299 412 T3 rising 66. If the actual pressure has reached the rising target pressure, the software increments the variable target pressure by an interval 68. Otherwise, it refrains from doing so until the actual pressure has equated to the pressure ascending target. If the variable target pressure has reached the maximum target pressure in the block 70 test, the software adjusts the direction of the pressure to "drop" 69 and the variable target pressure begins to move in the downstream part of its oscillatory cycle.

The range can be measured in mmHg or any other common unit of pressure measurement. Preferably, the magnitude of the range is within the range 1-10 mmHg, according to the preferences of the user.

If the actual pressure decreases in test 64, then it is decided if the variable target pressure is still greater than the minimum target pressure 74. If the variable target pressure is still greater than the minimum target pressure, then the software decides if the pressure target has reached (decreased to) the target downstream pressure 76. If the actual pressure has equated to the target downstream pressure, the software decreases the variable target pressure by an interval 72. Otherwise it refrains from doing so until the actual pressure has equaled the target downward pressure. If the variable target pressure has reached the minimum target pressure in the block 74 test, the software adjusts the direction of the pressure to "rise" 73 and the variable target pressure begins to move in the upward portion of its oscillatory cycle. This oscillatory process continues until the user disables the pulse mode.

While the invention has been described herein in relation to certain preferred representations, note that such representations have been presented by way of example only, without limiting the scope of the invention. Accordingly, the scope of the invention will only be limited in accordance with the following claims.