Patent Publication Number: US-2018050137-A1

Title: Wound treatment method and apparatus

Description:
This application claims priority to Korean Patent Application No. 10-2015-0033105 filed on Mar. 10, 2015 in the Korean Intellectual Property Office, the disclosure of which is incorporated herein by reference in its entirety. 
     BACKGROUND 
     1. Field of the Invention 
     The present disclosure relates to a wound treatment method and apparatus, and more particularly, to a wound treatment method and apparatus capable of promoting the treatment of a wound. 
     2. Description of the Related Art 
     A wound treatment method using negative pressure is commonly used in hospitals to promote the treatment of wounds. In the wound treatment method using negative pressure, a curer places a foam dressing at a wound site. 
     Then, the curer seals the wound site by attaching a film dressing onto the skin adjacent to the wound site. Once the wound site is sealed, the curer places one end of a drain tube in communication with the sealed space between the film dressing and the wound site. 
     Thereafter, the curer supplies negative pressure to the sealed space between the film dressing and the wound site by driving a negative pressure generation unit, which is placed in communication with the other end of the drain tube. As a result, exudate from the wound site is absorbed by the foam dressing, and the absorbed exudate is discharged from the sealed space between the film dressing and the wound site through the drain tube. 
     Since the exudate is removed from the wound site, the formation of granulation tissue in the wound site is promoted, and thus, the treatment of the wound site is promoted. However, since the wound site is sealed, the wound site is at the risk of getting infected with pathogens present therein and becoming worse, and research is underway to address this and other issues. 
     SUMMARY 
     Exemplary embodiments of the present disclosure provide a wound treatment method and apparatus capable of promoting the treatment of a wound. 
     However, exemplary embodiments of the present disclosure are not restricted to those set forth herein. The above and other exemplary embodiments of the present disclosure will become more apparent to one of ordinary skill in the art to which the present disclosure pertains by referencing the detailed description of the present disclosure given below. 
     According to an exemplary embodiment of the present disclosure, a wound treatment method comprising: placing a foam dressing at a wound site; sealing the wound site by attaching a film dressing to the skin adjacent to the wound site; lowering pressure in a sealed space, which is formed between the film dressing and the wound site, to a target negative pressure level by supplying negative pressure generated by a negative pressure generation unit to the sealed space; maintaining the pressure in the sealed space at the target negative pressure level for a first setting period; stopping the supply of the negative pressure for a second setting period, which follows the first setting period; and injecting a medication into the wound site within the second setting period. 
     In some embodiments of the present invention, wherein the injecting the medication into the wound site, comprises injecting the medication into the wound site at the same time as the stopping the supply of the negative pressure. 
     In some embodiments of the present invention, wherein the injecting the medication into the wound site, comprises stopping the injection of the medication within the second setting period. 
     In some embodiments of the present invention, wherein the injecting the medication into the wound site, comprises stopping the injection of the medication after the second setting period. 
     In some embodiments of the present invention, wherein the target negative pressure level is set to −125 mmHg or a range including −125 mmHg. 
     In some embodiments of the present invention, wherein the first setting period is longer than the second setting period. 
     In some embodiments of the present invention, wherein the injecting the medication into the wound site, comprises injecting the medication at a volume less than a volume of the wound site. 
     In some embodiments of the present invention, further comprising: measuring a flow rate of a fluid discharged from the sealed space due to the negative pressure supplied to the sealed space; and calculating the volume of the wound site based on the measured flow rate. 
     According to an exemplary embodiment of the present disclosure, a wound treatment apparatus, comprising: a foam dressing placed at a wound site; an irrigator feeding a medication to the wound site; a film dressing attached onto the skin adjacent to the wound site so as to seal the wound site; a negative pressure generation unit generating negative pressure and supplying the negative pressure to a sealed space, which is formed between the film dressing and the wound site; a negative pressure delivery unit connecting the negative pressure generation unit and the sealed space and delivering the negative pressure to the sealed space; and a controller controlling the negative pressure generation unit and the irrigator, wherein the controller controls the negative pressure generation unit and the irrigator such that the supply of the negative pressure is stopped and at the same time, the medication is injected into the wound site. 
     In some embodiments of the present invention, wherein once the pressure in the sealed space reaches the target negative pressure level, the controller controls the negative pressure generation unit to maintain the pressure in the sealed space at the target negative pressure level for a first setting period. 
     In some embodiments of the present invention, wherein the controller controls the negative pressure generation unit to stop the supply of the negative pressure for a second setting period, which follows the first setting period, and controls the irrigator to inject the medication at a time when the supply of the negative pressure is stopped. 
     In some embodiments of the present invention, wherein the controller controls the irrigator to stop the injection of the medication within the second setting period. 
     In some embodiments of the present invention, wherein the controller controls the irrigator to stop the injection of the medication after the second setting period. 
     In some embodiments of the present invention, wherein the first setting period is longer than the second setting period. 
     In some embodiments of the present invention, further comprising: an oxygen supplier supplying oxygen to the medication, which is to be injected into the wound site. 
     In some embodiments of the present invention, wherein the controller controls the irrigator to inject the medication at a volume less than a volume of the wound site. 
     In some embodiments of the present invention, further comprising: a flow sensor measuring a flow rate of a fluid discharged from the sealed space due to the negative pressure, wherein the controller calculates the volume of the wound site based on the flow rate measured by the flow sensor. 
     According to the exemplary embodiments, the cycle of replacement of a foam dressing and a film dressing may be lengthened by discharging exudate from a wound site and injecting a medication into the wound site. 
     Pathogens may be removed from the wound site by discharging the medication from the wound site after irrigating the wound site with the medication. 
     The injection of the medication into the wound site, which is sealed, may be facilitated by stopping the supply of negative pressure to the wound site and at the same time, injecting the medication into the wound site. 
     Other features and aspects will be apparent from the following detailed description, the drawings, and the claims. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The above and other features and advantages of the present invention will become more apparent by describing in detail exemplary embodiments thereof with reference to the attached drawings in which: 
         FIG. 1  is a schematic view illustrating a wound treatment apparatus according to an exemplary embodiment of the present disclosure. 
         FIG. 2  is a flowchart illustrating an operating method of the wound treatment apparatus of  FIG. 1 . 
         FIGS. 3 through 6  are schematic views illustrating how the wound treatment apparatus of  FIG. 1  operates. 
         FIG. 7  is a graph showing variations in the pressure in a sealed space during an operation of the wound treatment apparatus of  FIG. 1 . 
     
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
     The present invention will now be described more fully hereinafter with reference to the accompanying drawings, in which preferred embodiments of the invention are shown. This invention may, however, be embodied in different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. The same reference numbers indicate the same components throughout the specification. In the attached figures, the thickness of layers and regions is exaggerated for clarity. 
     It will also be understood that when a layer is referred to as being “on” another layer or substrate, it can be directly on the other layer or substrate, or intervening layers may also be present. In contrast, when an element is referred to as being “directly on” another element, there are no intervening elements present. 
     Spatially relative terms, such as “beneath,” “below,” “lower,” “above,” “upper” and the like, may be used herein for ease of description to describe one element or feature&#39;s relationship to another element(s) or feature(s) as illustrated in the figures. It will be understood that the spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures is turned over, elements described as “below” or “beneath” other elements or features would then be oriented “above” the other elements or features. Thus, the exemplary term “below” can encompass both an orientation of above and below. The device may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly. 
     The use of the terms “a” and “an” and “the” and similar referents in the context of describing the invention (especially in the context of the following claims) are to be construed to cover both the singular and the plural, unless otherwise indicated herein or clearly contradicted by context. The terms “comprising,” “having,” “including,” and “containing” are to be construed as open-ended terms (i.e., meaning “including, but not limited to,”) unless otherwise noted. 
     Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. It is noted that the use of any and all examples, or exemplary terms provided herein is intended merely to better illuminate the invention and is not a limitation on the scope of the invention unless otherwise specified. Further, unless defined otherwise, all terms defined in generally used dictionaries may not be overly interpreted. 
     The present invention will be described with reference to perspective views, cross-sectional views, and/or plan views, in which preferred embodiments of the invention are shown. Thus, the profile of an exemplary view may be modified according to manufacturing techniques and/or allowances. That is, the embodiments of the invention are not intended to limit the scope of the present invention but cover all changes and modifications that can be caused due to a change in manufacturing process. Thus, regions shown in the drawings are illustrated in schematic form and the shapes of the regions are presented simply by way of illustration and not as a limitation. 
     Exemplary embodiments of the present disclosure will hereinafter be described with reference to the accompanying drawings. 
     The term “negative pressure”, as used herein, may be defined as pressure lower than the atmospheric pressure. Since the atmospheric pressure may differ from one region to another region, the term “negative pressure”, as used herein, may be defined as pressure lower than the atmospheric pressure in the region where a wound treatment apparatus resides. 
       FIG. 1  is a schematic view illustrating a wound treatment apparatus according to an exemplary embodiment of the present disclosure. 
     Referring to  FIG. 1 , a wound treatment apparatus  10  includes a negative pressure output unit  100 , a negative pressure delivery unit  200 , a negative pressure generation unit  300 , a canister  400 , and a medication feeding unit  500 . 
     As illustrated in  FIG. 1 , the negative pressure output unit  100  is placed at a wound site W and seals the wound site W. For convenience, the wound W will hereinafter be described, taking an open wound as an example, but the present disclosure is not limited thereto. 
     The negative pressure output unit  100  includes a foam dressing  110 , which is placed at the wound site W, and a film dressing  120 , which seals the wound site W. 
     The foam dressing  110  is placed at the wound site W and absorbs exudate from the wound site W using negative pressure. 
     To effectively discharge exudate from the wound W, the foam dressing  110  may be formed of polyurethane or polyether, but the present disclosure is not limited thereto. That is, any material capable of effectively discharging exudate may be used to form the foam dressing  110 . For example, the foam dressing  110  may be formed of a polyurethane material, which is a hydrophobic material, in which case, the foam dressing  110  may easily discharge exudate. 
     The foam dressing  110  may include pores, which distribute negative pressure to the wound W and deliver a fluid (such as exudate) discharged from the wound W. For example, the foam dressing  110  may be formed to have an open-cell network structure capable of effectively discharging exudate. 
     The volume of the foam dressing  110  may be varied by negative pressure applied thereto by the negative pressure generation unit  300 . For example, in response to negative pressure being applied to a sealed space S between a film dressing  120  and the wound site W, the foam dressing  110 , the volume of the foam dressing  110  may be reduced so that the foam dressing  110  may be pressed against the surface of the wound site W. Then, in response to the supply of negative pressure to the sealed space S being terminated, the foam dressing  120  may return to its original state due to its restoring force. In this manner, the volume of the foam dressing  110  may be varied by negative pressure. 
     The film dressing  120  is attached onto the skin adjacent to the wound site W and seals the wound site W. As illustrated in  FIG. 1 , the film dressing  120  seals the wound site W except for part of a suction head  210 . 
     In response to the film dressing  120  being attached onto the skin adjacent to the wound site W, the film dressing  120  may form the sealed space S together with the wound site W. 
     The film dressing  120  is formed of a material having elasticity. Accordingly, the film dressing  120  may not be torn or broken even when the pressure in the sealed space S changes. 
     The negative pressure delivery unit  200  delivers negative pressure generated by the negative pressure generation unit  300  to the negative pressure output unit  100 . 
     As illustrated in  FIG. 1 , the negative pressure delivery unit  200  includes the suction head  210 , which is connected to one side of the foam dressing  110 , and a drain tube  220 , which places the suction head  210  and the negative pressure generation unit  300  in communication with each other. 
     The suction head  210  guides, to the drain tube  220 , the exudate absorbed into the foam dressing  110  due to negative pressure. In some exemplary embodiments, the suction head  220  may receive a medication from a connecting tube  530  of the medication feeding unit  500  and may inject the medication into the wound site W. 
     The suction head  210  includes a flange part  211 , which is connected to one side of the foam dressing  110 , a first connecting duct part  212 , which is connected to the drain tube  220 , and a second connecting duct part  213 , which is connected to the first connecting duct part  212  and the connecting tube  530 . 
     The flange part  211  forms a plurality of guide flow paths (not illustrated), which are connected to at least one of the first connecting duct part  212  and the second connecting duct part  213 . The flange part  211  guides the exudate absorbed into the foam dressing  110  to the first connecting duct part  212  through the plurality of guide flow paths. Also, the flange part  211  evenly applies a medication supplied thereto from the medication feeding unit  500  through the second connecting duct part  213  to the wound site W through the plurality of guide flow paths. 
     A first end of the drain tube  220  is connected to the first connecting duct part  212 . Accordingly, the drain tube  220  may be placed in indirect communication with the sealed space S through the suction head  210 . In some exemplary embodiments, the suction head  210  may not be provided, in which case, the first end of the drain tube  220  may be placed in direct communication with the sealed space S through the film dressing  120 . 
     A second end of the drain tube  220  is connected to the canister  400 . The canister  400  is connected to an output terminal  311  of a negative pressure generator  310 , and thus, the drain tube  220  is placed in indirect communication with the negative pressure generator  310  through the canister  400 . 
     Since the drain tube  220  is in communication with both the sealed space S and the negative pressure generator  310 , the drain tube  220  may supply negative pressure generated by the negative pressure generator  310  to the sealed space S. 
     As illustrated in  FIG. 1 , the negative pressure generation unit  300  includes the negative pressure generator  310 , a controller  320 , which controls the negative pressure generator  310 , and a pressure sensor  330 , which senses negative pressure output from the negative pressure generator  310 . 
     The negative pressure generation unit  300  includes the negative pressure generator  310  therein and supplies negative pressure generated by the negative pressure generator  310  to the negative pressure output unit  100  through the negative pressure delivery unit  200 . 
     The negative pressure generator  310  generates negative pressure and supplies the negative pressure to the sealed space S through the drain tube  220 . For example, the negative pressure generator  310  includes a negative pressure motor (not illustrated) therein and supplies negative pressure generated by the negative pressure motor to the sealed space S through the drain tube  220 . 
     The operation of the negative pressure generator  310  is controlled by the controller  320 . For example, the controller  320  may control whether and how long to operate the negative pressure motor and the magnitude of negative pressure to be generated by the negative pressure motor. 
     The negative pressure generated by the negative pressure generator  310  is provided to the drain tube  220  of the negative pressure delivery unit  200  through the output terminal  311 . As illustrated in  FIG. 1 , the output terminal  311  is connected to a second side of the canister  400 . Accordingly, the negative pressure generated by the negative pressure generator  310  is provided to the drain tube  220 , which is connected to a first side of the canister  400 , through the canister  400 . 
     The pressure sensor  330  is connected to the output terminal  311  of the negative pressure generator  310 . 
     The pressure sensor  330  senses the pressure in the sealed space S. For example, the pressure sensor  330  senses the pressure at the output terminal  311 . Since the output terminal  311 , the canister  400 , the drain tube  220  of the negative pressure delivery unit  200 , and the sealed space S form a connected space together, pressure information regarding the sealed space S may be obtained from pressure information sensed from the output terminal  311 . 
     The controller  320  controls the negative pressure generator  310  and an irrigator  510  of the medication feeding unit  500 . The controller  320  will be described later in detail. 
     Although not specifically illustrated in  FIG. 1 , the negative pressure generation unit  300  may also include a hydrophobic filter (not illustrated), which is provided between the canister  400  and the output terminal  311  of the negative pressure generator  310 . The hydrophobic filter prevents a fluid such as exudate discharged from the sealed space S from infiltrating into the negative pressure generator  310 . 
     Although not specifically illustrated in  FIG. 1 , the negative pressure generation unit  300  may also include a power button (not illustrated), which controls the turning on or off of the negative pressure generation unit  300 . In response to the power button being turned on, an operation signal for operating the controller  320  is input to the controller  320 . In response to the power button being turned off, an operation stop signal for stopping the operation of the negative pressure generator  310  is input to the controller  320 . 
     Although not specifically illustrated in  FIG. 1 , the negative pressure generation unit  300  may also include a flow sensor (not illustrated), which measures the flow rate of a fluid discharged from the sealed space S due to negative pressure. The flow sensor may be disposed between the canister  400  and the negative pressure generator  310 . 
     For example, the flow sensor may be connected to the output terminal  311  of the negative pressure generator  310 . Accordingly, the flow sensor may measure the flow rate of a fluid flowing to the negative pressure generator  310  through the canister  400 . 
     The fluid discharged from the sealed space S includes a gas and/or a liquid present in the sealed space S. The liquid present in the sealed space S may include exudate from the wound S. 
     The fluid discharged from the sealed space S flows into the canister  400  through the negative pressure delivery unit  200 . Most of the liquid part of the fluid flowing into the canister  400  is contained in the canister  400  due to the gravity, and most of the gas part of the fluid flowing into the canister  400  flows to the negative pressure generator  310  due to negative pressure. 
     As a result, the flow sensor, which is disposed between the negative pressure delivery unit  200  and the negative pressure generator  310 , can measure the flow rate of the gas present in the sealed space S, and flow rate information obtained by the flow sensor is transmitted to the controller  320 . 
     The medication feeding unit  500  injects a medication into the wound W, which is sealed, and thus promotes the treatment of the wound W. The medication feeding unit  500  includes the irrigator  510 , an oxygen supplier  520 , and the connecting tube  530 . 
     A medication to be injected into the wound site W may include water such as purified water or sterilized water. The medication may also include a treating agent promoting the treatment of the wound W. The medication may also include oxygen supplied by the oxygen supplier  520 . 
     Once the medication is injected into the wound site W, the medication irrigates the wound W and is then discharged by negative pressure provided by the negative pressure generation unit  300 . Accordingly, the medication may remove pathogens from the wound site W. 
     The irrigator  510  may contain a predetermined amount of the medication therein or may receive the medication from an additional container for storing the medication. 
     The irrigator  510  injects the medication into the wound site W. For example, the irrigator  510  may open an electronic valve (not illustrated), under the control of the controller  320 , and may thus inject the medication into the wound site W. Also, the irrigator  510  may close the electronic valve, under the control of the controller  320 , and may thus stop the injection of the medication into the wound site W. 
     In some exemplary embodiments, the irrigator  510  may include a pump (not illustrated). The irrigator  510  drives the pump, under the control of the controller  320 , and may thus inject the medication into the wound site W. Also, the irrigator  510  may stop the driving of the pump and may thus stop the injection of the medication into the wound site W. 
     The irrigator  510  is connected to the connecting tube  530 , which is connected to the second connecting duct part  213  of the suction head  210 . Accordingly, the irrigator  510  may inject the medication into the wound site W through the connecting tube  530 . 
     The irrigator  510  may inject the medication at a volume less than the volume of the wound site W. 
     The oxygen supplier  520  supplies oxygen to the medication to be fed to the wound site W. For example, the oxygen supplier  520  may be disposed above the connecting tube  530  and may supply oxygen to the medication flowing along the connecting tube  530 . 
     The oxygen supplier  520  supplies oxygen to the medication only when the medication is fed to the wound site W under the control of the controller  320 . For example, the oxygen supplier  520  may be driven at the time when the medication is injected, and may thus supply oxygen to the medication. 
     The connecting tube  530  connects the irrigator  510  and the second connecting duct part  213  of the suction head  210 . Accordingly, the connecting tube  530  may deliver the medication of the irrigator  510  to the wound site W. 
     Since the connecting tube  530  of the medication feeding unit  500  is connected to the second connecting duct part  213  of the suction head  210 , the irrigator  510  injects the medication into the wound site W through the suction head  210 . 
     The medication feeding unit  500  is disposed in the sealed space S and also includes an additional injection head (not illustrated), which is connected to the connecting tube  530 . The irrigator  510  injects the medication into the wound site W through the additional injection head. 
     In a case in which the negative pressure generation unit  300  and the irrigator  510  are provided as separate elements, as illustrated in  FIG. 1 , each of the negative pressure generation unit  300  and the irrigator  510  may include a communication part (not illustrated), which transmits control signals. 
     The communication parts of the negative pressure generation unit  300  and the irrigator  510  may be electrically connected by a wired cable (not illustrated) and may transmit control signals to, or receive control signals from, each other. 
     Although not specifically illustrated, each of the communication parts of the negative pressure generation unit  300  and the irrigator  510  may be configured to include a short-range wireless communication module such as a Bluetooth or Wireless Fidelity (WiFi) communication module and may thus be able to wirelessly transmit control signals to, or wirelessly receive control signals from, each other. 
     The controller  320  will hereinafter be described. The controller  320  may control the negative pressure generator  310  to lower the pressure in the sealed space S to a target negative pressure level (P 1  of  FIG. 7 ). 
     Also, once the pressure in the sealed space S has reached the target negative pressure level, the controller  320  may control the negative pressure generator  310  to maintain the pressure in the sealed space S at the target negative pressure level (P 1  of  FIG. 7 ) in a first setting period (from t 1  to t 2  of  FIG. 7 ). 
     In a second setting period (from t 2  to t 3  of  FIG. 7 ), which follows the first setting period (from t 1  to t 2  of  FIG. 7 ), the controller  320  may control the negative pressure generator  310  to stop the supply of negative pressure to the sealed space S. 
     The controller  320  may control the irrigator  510  to inject the medication in the second setting period (from t 2  to t 3  of  FIG. 7 ). 
     Also, the controller  320  may control the irrigator  510  to inject the medication into the wound site W at the time when the supply of negative pressure to the sealed space S is stopped. Since the supply of negative pressure is stopped and at the same time, the medication is injected into the wound site W, the medication may be easily injected into the wound site W due to the negative pressure in the sealed space S. 
     For example, when the supply of negative pressure to the sealed space S is stopped, the pressure in the sealed space S may be at the target negative pressure level (P 1  of  FIG. 7 ), which is substantially a minimum pressure level, and may increase substantially to an atmospheric pressure level (P 0  of  FIG. 7 ). 
     Accordingly, if the supply of negative pressure to the sealed space S is stopped and at the same time, the medication is injected into the wound site W, the medication may be quickly injected into the wound site W due to the pressure in the sealed space S. 
     Since the supply of negative pressure is stopped and at the same time, the medication is injected into the wound site W, the medication may be maintained to be in contact with the wound site W for a longer period of time than the second setting period (from t 2  to t 3  of  FIG. 7 ). 
     Since the medication is maintained to be in contact with the wound site W for a predetermined amount of time, time may be secured for irrigating the wound site W to remove pathogens from the wound W. However, if the second setting period (from t 2  to t 3  of  FIG. 7 ) is longer than necessary, the medication may be placed in contact with the wound site W for too long, so that the wound W may fester or granulation tissue from the wound W may be damaged. 
     Accordingly, the second setting period (from t 2  to t 3  of  FIG. 7 ) may be set to be about 2 minutes, but the present disclosure is not limited thereto. That is, the length of the second setting period (from t 2  to t 3  of  FIG. 7 ) may vary depending on the size and severity of a wound. 
     The first setting period (from t 1  to t 2  of  FIG. 7 ) may be set to be longer than the second setting period (from t 2  to t 3  of  FIG. 7 ). The supply of negative pressure to the sealed space S is mainly for discharging exudate from the wound site W. That is, the supply of negative pressure is basically for the treatment of the wound W. On the other hand, the injection of the medication into the wound site W is mainly for irrigating the wound site W so as to remove pathogens from the wound site W. 
     Accordingly, the first setting period (from t 1  to t 2  of  FIG. 7 ), which corresponds to a wound treatment period, may be preferably set to be longer than the second setting period (from t 2  to t 3  of  FIG. 7 ), which corresponds to a wound irrigation period. For example, the first setting period (from t 1  to t 2  of  FIG. 7 ) may be set to about 13 minutes, and the second setting period (from t 2  to t 3  of  FIG. 7 ) may be set to about 2 minutes. 
     The controller  320  may control the irrigator  510  to stop the injection of the medication into the wound site W in the second setting period (from t 2  to t 3  of  FIG. 7 ). Accordingly, the injection of the medication into the wound site W and the discharge of the medication may be performed at different times. 
     The controller  320  may control the irrigator  510  to stop the injection of the medication into the wound site W after the second setting period (from t 2  to t 3  of  FIG. 7 ). Accordingly, there may be an overlap in time between the injection of the injection of the medication into the wound site W and the discharge of the medication. 
     The controller  320  may determine whether the operation stop signal has been input by, for example, turning off the power button after the second setting period (from t 2  to t 3  of  FIG. 7 ). In response to a determination being made that the operation stop signal has not yet been input, the controller  320  may control the negative pressure generator  310  to supply negative pressure to the sealed space S. In other words, in a case in which the operation stop signal has not yet been input, the controller  320  may drive the negative pressure generator  310  again. 
     Since the controller  320  supplies negative pressure to the sealed space S after the second setting period (from t 2  to t 3  of  FIG. 7 ), the medication injected into the wound site W and a fluid such as exudate from the wound site W may be discharged into the canister  400 . 
     The controller  320  controls the negative pressure generator  310  to lower the pressure in the sealed space S to the target negative pressure level (P 1  of  FIG. 7 ) again. 
     The controller  320  generates control signals for controlling the irrigator  510 . The control signals generated by the controller  320  may include a medication feed signal and a medication feed stop signal. The control signals generated by the controller  320  are transmitted to the irrigator  510  via the communication parts of the negative pressure generation unit  300  and the irrigator  510 . 
     The controller  320  automatically calculates the volume of the wound site based on the flow rate of a flow, measured by the flow sensor (not illustrated). The volume of the wound site, calculated by the controller  320 , may be used to determine the amount of injection of the medication into the wound site W. 
     For example, the controller  320  may calculate the volume of the wound site W by adding up the flow rate of a fluid discharged in the process of pressing the film dressing  120  and the foam dressing  110  against the surface of the wound site W. 
     Alternatively, the controller  320  may calculate the volume of the wound site by adding up the flow rate of a fluid measured from the time when the film dressing is pressed against the foam dressing  110  to the time when the pressure in the sealed space S reaches the target negative pressure level (P 1  of  FIG. 7 ). 
     Alternatively, the controller  320  may calculate the volume of the wound site by adding up the flow rate of a fluid measured from the time when the film dressing is pressed against the foam dressing  110  to the time when the supply of negative pressure to the sealed space S is stopped. 
     Alternatively, the controller  320  may calculate the volume of the wound site by adding up the flow rate of a fluid measured from the time when the rate of change of the flow rate of the fluid exceeds a predetermined threshold level to the time when the pressure in the sealed space S reaches the target negative pressure level (P 1  of  FIG. 7 ). 
     Once the volume of the wound site W is calculated, the controller  320  may automatically control the irrigator  510  to inject the medication at a volume less than the volume of the wound site W. For example, the controller  320  may control the amount of injection of the medication into the wound site W by controlling the electronic valve (not illustrated) or the pump (not illustrated) of the irrigator  510 . 
     The controller  320  may control the irrigator  510  to stop the injection of the medication if the pressure in the sealed space S reaches the atmospheric pressure level (P 0  of  FIG. 7 ) or a predetermined pressure level within the second setting period (from t 2  to t 3  of  FIG. 7 ). Accordingly, the controller  320  may control the amount of injection of the medication according to the pressure in the sealed space S. 
     The controller  320  may control the oxygen supplier  520  to supply oxygen to the medication, which is to be injected into the wound site W. For example, the controller  320  may control the operation of the oxygen supplier  520  through the communication parts of the negative pressure generation unit  300  and the irrigator  510  so as for the oxygen supplier  520  to supply oxygen to the medication at the time when the medication is injected into the wound site W. 
       FIG. 2  is a flowchart illustrating an operating method of the wound treatment apparatus of  FIG. 1 .  FIGS. 3 through 6  are schematic views illustrating how the wound treatment apparatus of  FIG. 1  operates.  FIG. 7  is a graph showing variations in the pressure in a sealed space during an operation of the wound treatment apparatus of  FIG. 1 . 
     Referring to  FIGS. 2 through 7 , a curer places the foam dressing  110  at the wound site W of a patient (S 10 ). The foam dressing  110  placed at the wound site W absorbs exudate from the wound site W. 
     As illustrated in  FIG. 3 , the curer seals the wound site W (S 20 ) by attaching the film dressing  120  onto the skin adjacent to the wound site W. As a result, the sealed space S is formed between the film dressing  120  and the wound site W, as illustrated in  FIG. 1 . 
     Once the wound site W is sealed, the curer supplies negative pressure to the sealed space S (S 30 ) by driving the negative pressure generator  310  of  FIG. 1 . As a result, due to the negative pressure supplied by the negative pressure generator  310 , the pressure in the sealed space S may be reduced from the atmospheric pressure level P 0  to the target negative pressure level P 1 . 
     The controller  320  of  FIG. 1  senses the pressure in the sealed space S using the pressure sensor  330  of  FIG. 1 , and determines whether the pressure in the sealed space S has reached the target negative pressure level P 1  (S 40 ). 
     The target negative pressure level P 1  may be set to −125 mmHg or a range including −125 mmHg. For example, the target negative pressure level P 1  may be set to a range of ±5 mmHg from −125 mmHg. 
     The target negative pressure level P 1  of −125 mmHg may indicate a pressure level 125 mmHg lower than the atmospheric pressure. The atmospheric pressure is generally defined as about 760 mmHg, and the target negative pressure level P 1  may actually be about 635 mmHg, which is 125 mmHg lower than the atmospheric pressure. For convenience, the atmospheric pressure level P 0  may be defined as 0, and the target negative pressure level P 1  may be defined as −125 mmHg. 
     Once the pressure in the sealed space S has reached the target negative pressure level P 1 , the controller  320  maintains the pressure in the sealed space S within a predetermined range from the target negative pressure level P 1  in the first setting period (from t 1  to t 2 ) (S 50 ). 
     The first setting period (from t 1  to t 2 ) may be set to about 13 minutes, but may vary depending on the size and severity of a wound. 
     The controller  320  may uniformly maintain the pressure in the sealed space within a predetermined range by repeatedly turning on or off the negative pressure generator  310  in the first setting period (from t 1  to t 2 ). 
     For example, the controller  320  may repeatedly drive, and stop driving, the negative pressure generator  310  to maintain the pressure in the sealed space S at the target negative pressure level P 1 . In other words, if the pressure in the sealed space S becomes higher than the target negative pressure level P 1 , the controller  320  may drive the negative pressure generator  310  to lower the pressure in the sealed space S, and if the pressure in the sealed space S becomes lower than the target negative pressure level P 1 , the controller  320  may stop driving the negative pressure generator  310  to increase the pressure in the sealed space S. Accordingly, the pressure in the sealed space S may be uniformly maintained at the target negative pressure level P 1 . 
     If the pressure in the sealed space S has not reached the target negative pressure level P 1 , the controller  320  may control the negative pressure generator  310  to supply negative pressure to the sealed space S and thus to allow the pressure in the sealed space S reach the target negative pressure level P 1 . 
     Although not specifically illustrated in  FIG. 2 , the flow sensor (not illustrated) measures the flow rate of a fluid discharged from the sealed space S due to the negative pressure supplied by the negative pressure generation unit  300  to the sealed space S. 
     The flow sensor transmits the measured flow rate to the controller  320 . The controller  320  may calculate the volume of the wound site W based on the measured flow rate transmitted by the flow sensor. 
     For example, as illustrated in  FIG. 4 , the controller  320  may continue to supply negative pressure to the sealed space S even after the film dressing  120  is pressed against the foam dressing  110 . As a result, as illustrated in  FIG. 5 , the film dressing  120  and the foam dressing  110  may be pressed against the surface of the wound site W. That is, the foam dressing  110  with the film dressing  120  pressed thereagainst may be pressed against the surface of the wound site W. 
     A fluid in the sealed space S may be discharged in the process of pressing the film dressing  120  and the foam dressing  110  against the surface of the wound site W. Since the foam dressing  110  is placed at the wound site W, the amount of a fluid discharged in the process of pressing the film dressing  120  and the foam dressing  110  against the surface of the wound site W may substantially correspond to the volume of the wound site W. 
     Accordingly, the controller  320  may calculate the volume of the wound site W by adding up the amount of a fluid discharged in the process of pressing the film dressing  120  and the foam dressing  110  against the surface of the wound site W. 
     Alternatively, as illustrated in  FIG. 3 , in the process of pressing the film dressing  120  against the foam dressing  110 , the tensile force of the film dressing  130  may act as counterforce to negative pressure. 
     On the other hand, as illustrated in  FIGS. 4 and 5 , in the process of pressing the film dressing  120  and the foam dressing  110  against the surface of the wound site W, the tensile force of the film dressing  130  and the compressive force of the foam dressing  110  may both act as counterforce to negative pressure. 
     Since the counterforce to negative pressure in the process of pressing the film dressing  120  and the foam dressing  110  against the surface of the wound site W is stronger than the counterforce to negative pressure in the process of pressing the film dressing  120  against the foam dressing  110 , the amount of a fluid discharged in the in the process of pressing the film dressing  120  and the foam dressing  110  against the surface of the wound site W may be less than the amount of a fluid discharged in the in the process of pressing the film dressing  120  against the foam dressing  110 . Thus, the flow rate of a fluid discharged from the sealed space S may considerably change. 
     Accordingly, the controller  320  may calculate the volume of the wound site W by adding up the amount of a fluid measured from the time when the rate of change of the flow rate of a fluid measured by the flow sensor exceeds a predetermined threshold level. 
     For example, the controller  320  may calculate the volume of the wound site W by adding up the flow rate of a fluid measured from the time when the time when the rate of change of the flow rate of a fluid exceeds the predetermined threshold level to the time when the pressure in the sealed space S reaches the target negative pressure level P 1 . 
     Alternatively, the controller  320  may calculate the volume of the wound site W by adding up the flow rate of a fluid measured from the time when the time when the rate of change of the flow rate of a fluid exceeds the predetermined threshold level to the time when the driving of the negative pressure generator  310  is stopped (i.e., the flow rate of a fluid measured during the first setting period after the pressure in the sealed space S has reached the target negative pressure level P 1 ). 
     In the second setting period (from t 2  to t 3 ), which follows the first setting period (from t 1  to t 2 ), the controller  320  stops the supply of negative pressure generated by the negative pressure generator  310  to the sealed space S (S 60 ). 
     The second setting period (from t 2  to t 3 ) may be set to about 2 minutes, but may vary depending on the size and severity of a wound. 
     As illustrated in  FIG. 6 , the controller  320  controls the irrigator  510  of  FIG. 1  to inject the medication into the wound site W within the second setting period (from t 2  to t 3 ) (S 70 ). 
     The controller  320  may control the irrigator  510  to inject the medicine into the wound site W at the time when the supply of negative pressure to the sealed space S is stopped. Accordingly, the efficiency of the treatment of a wound may be improved by leaving no interval of time between the time when the supply of negative pressure to the sealed space S is stopped and the time when the medication is injected into the wound site W. 
     If the supply of negative pressure is stopped and at the same time, the injection of the medication is injected, the medication may be maintained to be in contact with the wound site W for a longer period of time than the second setting period (from t 2  to t 3 ). 
     Also, the controller  320  may control the irrigator  510  to inject the medication at a volume less than the volume of the wound site W. 
     After the second setting period (from t 2  to t 3 ), the controller  320  determines whether the operation stop signal for stopping the operation of the negative pressure generator  310  has been input (S 80 ). 
     In response to a determination being made that the operation stop signal has not yet been input, the controller  320  drives the negative pressure generator  310  again to supply negative pressure to the sealed space S. That is, after the second setting period (from t 2  to t 3 ), the controller  320  may repeatedly perform the step of lowering the pressure in the sealed space S to the target negative pressure level P 1  until the operation stop signal is input. 
     Since negative pressure is supplied again to the sealed space S, the medication injected into the wound site W may be discharged into the canister  400 . The controller  320  may control the irrigator  510  to stop the injection of the medication into the wound site W during the second setting period (from t 2  to t 3 ), in which case, the injection of the medication and the discharge of the medication may occur at different times. 
     However, as already mentioned above, if the controller  320  controls the irrigator  510  to stop the injection of the medication into the wound site W after the second setting period (from t 2  to t 3 ), there may be an overlap in time between the injection of the medication and the discharge of the medication. 
     In some exemplary embodiments, a cycle of steps ranging from the supply of negative pressure to the sealed space to the injection of the medication into the wound site W may be repeatedly performed a predetermined number of times, and then, the operation of the negative pressure generation unit  300  may be stopped even if no operation stop signal is input. 
     In concluding the detailed description, those skilled in the art will appreciate that many variations and modifications can be made to the preferred embodiments without substantially departing from the principles of the present invention. Therefore, the disclosed preferred embodiments of the invention are used in a generic and descriptive sense only and not for purposes of limitation.