EP4680297A1

EP4680297A1 - Negative pressure wound therapy system

Info

Publication number: EP4680297A1
Application number: EP24706815.8A
Authority: EP
Inventors: Md Abdulla Al MASUD; Zane Johnson; Lindsey L. HINES; Done DEMIRGOZ; Marie D. MANNER; Sarah A. MOUNHO; Chin-Yee Ng; Eric H. TSAI
Original assignee: Solventum Intellectual Properties Co
Current assignee: Solventum Intellectual Properties Co
Priority date: 2023-03-17
Filing date: 2024-02-16
Publication date: 2026-01-21
Also published as: WO2024194701A1

Abstract

The present disclosure relates to a negative pressure wound therapy system comprising a negative pressure dressing, a negative pressure source, a digital camera, an array of acoustic sensors and a controller configured to determine presence and location of a leak of the negative pressure dressing. The present disclosure further relates to a method of detecting a leak in a negative pressure wound therapy system.

Description

NEGATIVE PRESSURE WOUND THERAPY SYSTEM

Cross Reference to Related Application

This application claims the benefit of priority to U.S. Provisional Application No. 63/452,706, filed on March 17, 2023, which is incorporated herein by reference in its entirety.

Technical Field

The present disclosure relates to a negative pressure wound therapy system comprising a negative pressure dressing configured to detect a leak of the negative pressure dressing.

Background

Tissue growth and wound healing of patients has been shown to be accelerated through the use of applying negative pressure, i.e., reduced pressure, to a wound site. Reduced pressure delivery systems operate to form such a reduced pressure at a wound site of a patient. This form of wound healing can be readily integrated into a clinician’s wound healing procedure. Reduced pressure wound therapy optimizes patient care and decreases costs associated with treatment of patients having traumatic and chronic wounds. Reduced pressure therapy can be administered in hospitals, community settings, such as assisted living complexes and convalescent homes, or homes of patients.

Reduced pressure delivery to a wound or tissue site promotes wound healing and/or tissue growth, in part, by removing infectious materials and other fluids from the wound or tissue site. Reduced pressure treatment further promotes tissue growth by imposing forces on the tissue, which is believed to contribute to the development of granulation tissue at the tissue site. The forces imposed on the tissue site by the delivery of reduced pressure further encourages improved blood flow at the tissue site, which futher assists in the growth of new tissue.

Reduced pressure delivery systems generally use a vacuum pump to apply a reduced pressure via a reduced pressure conduit to a wound or tissue site. A manifold is often used at the wound or tissue site to help evenly distribute the reduced pressure. A drape is typically used to cover the manifold and form a seal with surrounding tissue of the tissue site to which the reduced pressure is being applied. In order to maintain the reduced pressure at a relatively constant and accurate reduced pressure to provide optimum wound therapy, the drape is to be interfaced and maintained with the healthy tissue surrounding the tissue site, i.e., the peri-tissue, to minimize the number and severity of the fluid leaks, such as air leaks. In the event that a fluid leak results during installation of the drape or during treatment, clinicians often find it difficult to isolate the precise location of the fluid leak.

When a reduced pressure dressing is applied to a patient’s body, a visual inspection is made to confirm that the constituent parts of the dressing such as, for example, the drape covering a porous pad and a connector for providing the reduced pressure to the porous pad, have been placed correctly to form a leak-free seal over the wound or tissue site. As the therapy device begins applying reduced pressure in operation, the reduced pressure decreases from ambient pressure during a start-up period until a desired target pressure is reached and maintained. The application of reduced pressure causes the reduced pressure dressing to contract in response to the increasing pressure. After the start-up period, a controller regulates the reduced pressure during a therapy period based on the therapy intended for treating the patient. Fluid leaks can occur during the start-up and/or the therapy periods as a result of the initial misplacement of these components or susequent damage to the drape itself. Locating such fluid leaks in reduced pressure dressings can be time-consuming and difficult to correct. If a leak is not corrected, therapy is interrupted, and full potential of the treatment is not realized.

Negative pressure wound therapy removes excess fluid in the wound, prevents bacterial infection, and stimulates tissue regeneration. When a leak occurs in the dressing, the negative pressure cannot be maintained, an alarm sounds, and therapy is interrupted. Leak events are a common occurrence in negative pressure wound therapy and present a serious problem in ensuring a patient receives the continuous therapy prescribed. This is even more significant when therapy is performed at home, when neither doctors or nurses are readily available. Patients are often left to troubleshoot any problems themselves, frequently requiring a call to tech support which amount to significant costs for the negative pressure wound therapy equipment provider.

Even though some drape material may be transparent so that the wound and dressing can be seen by the clinicain, visual inspection through the drape material only helps to locate the largest holes or leaks in the drape or other damage to the dressing that is causing major leaks allowing air to leak into the wound site. While the clinical benefits of reduced-pressure therapy are widely known, the complexity of reduced-pressure therapy can be a limiting factor in its application and further development of reduced- pressure systems which presents significant challenges to manufacturers, healthcare provides, and patients.

US 10,307,516 and US2018/0318475A1 disclose using a microphone for leak detection in negative pressure wound therapy, which requires searching the leak by moving the microphone over various positions of the dressing. Leaks cannot be automatically detected.

US2021/0260258A1 discloses a wound dressing for pressure gradient wound therapy, the wound dressing including a dressing body and an adhesive layer. Sensors are provided associated with the adhesive region, the sensors being configured to monitor one or more conditions indicative of a hermeticity of the seal between the wound dressing and the periphery of the wound site. As the sensors are an element of the dressing itself, the sensors need to be sterile, and this leak detection method requires providing the sensors for each patient or for each dressing, and disposing the sensors after each change of dressing.

There is still a need for readily identifying automatically the location of a leak in negative pressure wound therapy.

As used herein, "a", "an", "the", "at least one" and "one or more" are used interchangeably. The term “comprise” shall include also the terms “consist essentially of’ and “consists of’. Summary

In a first aspect, the present disclosure relates to a negative pressure wound therapy system comprising: a negative pressure dressing configured to be placed over a wound site to create a fluid impermeable seal over the wound site; a negative pressure source configured to be coupled to the negative pressure dressing; a digital camera configured to receive a visual image comprising the negative pressure dressing; and an array of acoustic sensors configured to detect sound produced by at least one sound source, wherein the at least one sound source comprises an airflow associated with a leak of the negative pressure dressing; a controller configured to determine presence and location of a leak of the negative pressure dressing, the controller further configured to: receive the visual image from the digital camera; receive sound from the array of acoustic sensors; receive information about the differences in propagation time of the sound waves of the sound detected by the individual acoustic sensors of the array of acoustic sensors; calculate the local position of the at least one sound source from the differences in propagation time of the sound waves of the sound detected by the individual acoustic sensors of the array of acoustic sensors; compose a locally resolved acoustic image from the calculation of the local position of the at least one sound source; receive information about the relative position of the digital camera and the array of acoustic sensors; and superimpose the visual image with the locally resolved acoustic image to obtain a superimposed image comprising information about presence and location of the leak.

In another aspect, the present disclosure also relates to a method of detecting a leak in a negative pressure wound therapy system comprising a negative pressure dressing, a negative pressure source, an array of acoustic sensors, a digital camera, and a controller, the method comprising: directing the digital camera to the negative pressure dressing, wherein the negative pressure dressing is placed over a wound site to create a fluid impermeable seal over the wound site; by the digital camera, receiving a visual image from the negative pressure dressing; directing the array of acoustic sensors to the negative pressure dressing; aligning the digital camera with the array of acoustic sensors to adjust the local position of the visual image with the local position of the locally resolved acoustic image; utilizing the array of acoustic sensors to detect sound produced by at least one sound source, wherein the at least one sound source comprises an airflow associated with a leak of the negative pressure dressing; by the controller, receiving the visual image from the digital camera; by the controller, receiving sound from the array of acoustic sensors; by the controller, receiving information about the differences in propagation time of the sound waves of the sound detected by the individual acoustic sensors of the array of acoustic sensors; by the controller, calculating the local position of the at least one sound source from the differences in propagation time of the sound waves of the sound detected by the individual acoustic sensors of the array of acoustic sensors; by the controller, composing a locally resolved acoustic image from the calculation of the local position of the at least one sound source; by the controller, superimposing the visual image with the locally resolved acoustic image to obtain a superimposed image comprising information about presence and location of the leak.

The negative pressure wound therapy system and the method disclosed herein allows readily identifying automatically location of a leak in negative pressure wound therapy. Patients can more easily seal leaks without intervention, adherence to therapy can be improved, and the total amount of wound dressing replacements and nursing interventions for the patient can be decreased, decreasing healthcare worker cost, and reducing cost to the negative pressure wound therapy system provider.

There is no need to replace the audio sensors of the leak detection system each time a dressing is replaced, as the audio sensors are not comprised in the negative pressure dressing.

There is no need to move the acoustic sensors around the negative pressure dressing for leak detection. Instead, the array of acoustic sensors is stationary.

In some embodiments of the negative pressure wound therapy system disclosed herein, frequency-based leak detection is performed, i.e., information about the frequencies of the sound waves is used for leak detection. The sound waves detected by the array of acoustic sensors may have different frequency ranges for different sound sources, i.e., for different leaks of the negative pressure dressing or for other sound sources, and the information about the different frequency ranges is used for leak detection.

Brief Description of the Drawings The present disclosure is explained in more detail on the basis of the drawings, in which

Figure 1 schematically shows a first embodiment of a negative pressure wound therapy system as disclosed herein;

Figure 2 schematically shows a second embodiment of a negative pressure wound therapy system as disclosed herein;

Figure 3 schematically shows a third embodiment of a negative pressure wound therapy system as disclosed herein; and

Figure 4 schematically shows the controller, with its input and output, of a negative pressure wound therapy system as disclosed herein.

Detailed Description

Leaks, which can occur at interfaces between tissue and dressing or overlayed dressing components, or in the tubing or component connections in the negative pressure wound therapy system, may be detected and located by the negative pressure wound therapy system disclosed herein.

The negative pressure wound therapy system disclosed herein comprises a negative pressure dressing configured to be placed over a wound site of a patient to create a fluid impermeable seal over the wound site.

The term “fluid” as used herein generally refers to a gas or liquid, but may also include any other flowable material, including but not limited to gels, colloids, and foams. One example of a fluid is air. The term “impermeable” as used herein generally refers to the ability of a membrane, cover, sheet, or other substance to block or slow the transmission of fluids.

The term “negative pressure” or “reduced pressure” as used herein generally refers to a pressure less than the ambient pressure at a wound site that is being subjected to treatment. In most cases, this reduced pressure will be less than the atmosphere pressure at which the patient is located. Alternatively, the reduced pressure may be less than a hydrostatic pressure of tissue at the wound site. Although the terms “vacuum” and “negative pressure” may be used to describe the pressure applied to the wound site, the actual pressure applied to the wound site may be higher than the pressure normally associated with a complete vacuum, but lower than ambient pressure at the wound site. Reduced pressure may initially generate fluid flow in the tube or conduit in the area of the wound site. As the hydrostatic pressure around the wound site approaches the desired reduced pressure, the flow may subside, and the reduced pressure is then maintained.

The term “wound site” as used herein refers to a wound or defect located on or within any tissue, including but not limited to, bone tissue, adipose tissue, muscle tissue, dermal tissue, connective tissue, cartilage, tendons, incision wound, or ligaments. The term “wound site” may further refer to areas of any tissue that are not necessarily wounded or defective but are instead areas in which it is desired to add or promote the growth of additional tissue. For example, reduced pressure wound treatment may be used in certain tissue areas to grow additional tissue that may be harvested and transplanted to another tissue location. The term “clinician” is used herein as meaning any medical professional, user, family member of a patient, or patient who interacts of interfaces with a delivery system.

The term "negative pressure dressing” as used herein refers to a dressing configured to be placed over a wound site to create a fluid impermeable seal over the wound site. The negative pressure dressing is configured to be coupled to the negative pressure source. The negative pressure dressing may comprise a manifold and a drape. The negative pressure dressing may also comprise a negative pressure conduit fluidly coupled between the negative pressure source to the wound site.

The term “manifold” as used herein generally refers to a substance or structure that is provided to assist in applying reduced pressure to, delivering fluids to, or removing fluids from a wound site. A manifold typically includes a plurality of flow channels or pathways that interconnect to improve distribution of fluids provided to and removed from the area of tissue around the manifold. Examples of manifolds may include, without limitation, devices that have structural elements arranged to form slow channels, cellular foams, porous tissue collections, and liquids, gels and foams that include or cure to include flow channels.

The drape may be placed over the wound site and manifold to seal the manifold at the wound site. The drape may be constructed from a flexible material that is impermeable to fluids including gases and liquids to prevent air or other fluids from entering or exiting the wound site during reduced pressure treatment.

As used herein, the term “flexible” refers to an object or material that is able to be bent or flexed. Elastomer materials are typically flexible, but reference to flexible materials herein does not necessarily limit material selection to only elastomers. The use of the term “flexible” in connection with a material or reduced pressure delivery apparatus in accordance with the principles of the present disclosure generally refers to the material’s ability to conform to or closely match the shape of a wound site. For example, the flexible nature of a negative pressure dressing or a drape used to treat a bone defect may allow the dressing or drape to be wrapped or folded around the portion of the bone having the defect. The negative pressure wound therapy system disclosed herein comprises a negative pressure source configured to be fluidly coupled to the negative pressure dressing. The negative pressure source may be fluidly coupled to the negative pressure dressing by a negative pressure conduit or tubing. Negative pressure from the conduit or tubing may be distributed to the wound site via a negative pressure dressing or manifold located at or within the wound site. The negative pressure dressing may also be coupled to a fluid container for collecting bodily fluids from the wound site. The negative pressure source typically comprises a vacuum pump to apply a negative pressure via the negative pressure conduit to the wound site.

The negative pressure wound therapy system disclosed herein comprises a digital camera and an array of acoustic sensors. The digital camera is configured to receive a visual image which comprises the negative pressure dressing. The array of acoustic sensors is configured to detect sound produced by at least one sound source, wherein the at least one sound source comprises an airflow associated with a leak of the negative pressure dressing.

When a leak occurs in a pressurized system such as a negative pressure dressing or a negative pressure wound therapy system, the gas (air) molecules entering the pressurized system will cause turbulence, which causes rapid changes in pressure and flow velocity. These changes may be transmitted as sound waves.

The array of acoustic sensors is configured to detect sound produced by only one sound source or by more than one sound sources, for example by two sound sources, by three sound sources, or by more than three sound sources, such as 4, 5, 6, 7 or 8 sound sources. At least one of the sound sources is an airflow associated with a leak of the negative pressure dressing. It is possible that there is more than one leak (e.g., two leaks, three, four, five or more leaks) in the negative pressure dressing, and in this case an airflow is associated with each of the different leaks, and each of these different airflows of the different leaks is a different sound source, i.e., there is more than one sound source, and each of these sound sources comprises an airflow associated with a leak of the negative pressure dressing, and each of these leaks is different from the other leaks.

It is also possible that a sound source is different from an airflow associated with a leak. A sound source may be noise arising from the negative pressure source or noise from the environment of the patient such noise produced by further medical equipment.

The array of acoustic sensors comprises a plurality of acoustic sensors. The acoustic sensors are able to receive audible sound as well as ultrasonic sound. An example for an acoustic sensor is a microphone. Different types of microphones may be used, such as dynamic microphones, condenser microphones, ribbon microphones, and crystal microphones. The plurality of acoustic sensors is spatially arranged or grouped in a two-dimensional or three-dimensional form. The array of acoustic sensors is formed by the plurality of acoustic sensors being arranged or grouped in a two-dimensional or three-dimensional form. For example, the acoustic sensors of the array of acoustic sensors may be arranged in a plane. The acoustic sensors of the array of acoustic sensors may also be arranged as a series in a row. The acoustic sensors of the array of acoustic sensors may also be arranged in the form of a paraboloid. The arrangement of the plurality of acoustic sensors in the array may be regular or irregular.

The array of acoustic sensors is not comprised in the negative pressure dressing.

The negative pressure wound therapy system disclosed herein comprises a controller. The controller is configured to determine presence and location of a leak of the negative pressure dressing, i.e., the controller is configured to determine if a leak is present in the negative pressure dressing and where such a leak is located. The determination of presence and location of a leak of the negative pressure dressing is explained in more detail below.

The controller is further configured to receive the visual image from the digital camera. The controller is further configured to receive sound from the array of acoustic sensors. This means that the controller is configured to receive sound from each of the individual acoustic sensors of the plurality of acoustic sensors comprised in the array of acoustic sensors.

The sound which is produced by a sound source propagates as a sound wave. The sound wave may be detected by each of the individual acoustic sensors of the plurality of acoustic sensors comprised in the array of acoustic sensors. The propagation time of the sound wave from a sound source to each of the individual acoustic sensors depends on the distance of the sound source to the individual acoustic sensor, which means that the propagation time of the sound wave from a sound source to each of the individual acoustic sensors is different.

The controller is configured to receive information about the differences in propagation time of the sound waves of the sound detected by the individual acoustic sensors of the array of acoustic sensors. Depending on the position of each of the individual acoustic sensors relative to the sound source, the sound is received slightly at different times by each of the individual acoustic sensors. The differences in propagation time allow locating the sound source’s position.

From the relative position of each of the individual acoustic sensors of the array of acoustic sensors, and from the differences in propagation time of the sound waves detected by the individual acoustic sensors of the array of microphones, the local position of the sound source is calculated. The controller is configured to calculate the local position of the at least one sound source from the differences in propagation time of the sound waves of the sound detected by the individual acoustic sensors of the array of acoustic sensors. For this calculation, the controller uses an appropriate algorithm, such as a beamforming algorithm or a digital signal processing speech algorithm.

For each of the at least one sound sources, the controller may calculate its local position. From the local position of each individual sound source of the at least one sound sources, the controller may compose a locally resolved acoustic image. In other words, the controller is configured to compose a locally resolved acoustic image from the calculation of the local position(s) of the at least one sound source(s). The digital camera and the array of acoustic sensors may be arranged in a fixed manner to one another. For example, the digital camera and the array of acoustic sensors may have a firm connection such as a fixed rail. It is also possible that the digital camera and the array of acoustic sensors are not arranged in a fixed manner relative to one another, and that the digital camera and the array of acoustic sensors are positioned at different locations relative to one another before the detection of the sound waves. The controller is configured to receive information about the relative position of the digital camera and the array of acoustic sensors.

The visual image from the digital camera and the locally resolved acoustic image as composed by the controller may be superimposed by the controller and thereby a superimposed image may be obtained which comprises information about presence and location of the at least one sound source. The at least one sound source may comprise an airflow associated with a leak of the negative pressure dressing. The controller is configured to superimpose the visual image with the locally resolved acoustic image to obtain a superimposed image comprising information about presence and location of the at least one sound source. The at least one sound source comprises an airflow associated with a leak of the negative pressure dressing, and the superimposed image comprises information about presence and location of an airflow associated with a leak of the negative pressure dressing, i.e., information about presence and location of a leak.

For superimposing the visual image with the locally resolved acoustic image, the visual image and the locally resolved acoustic image need to be adjusted to each other. This adjustment may be accomplished, for example, by one or more point sound sources such as a piezo sounder and by matching the visual image and the locally resolved acoustic image of the one or more point sound sources. The adjustment needs to be performed only one time if there is a fixed mechanical relation between the digital camera and the array of acoustic sensors. If there is no fixed mechanical relation between the digital camera and the array of acoustic sensors, the adjustment needs to be performed before each measurement, i.e., before each detection of sound waves by the array of acoustic sensors. By superimposing the visual image from the digital camera and the locally resolved acoustic image, a superimposed image is obtained which comprises information about presence and location of a leak of the negative pressure dressing.

The controller may be further configured to receive information about the amplitudes of the sound waves detected by the individual acoustic sensors of the array of acoustic sensors; and calculate the sound intensity from the amplitudes of the sound waves detected by the individual acoustic sensors of the array of acoustic sensors.

The superimposed image may further comprise information about the sound intensity of at least one sound source.

The locally resolved acoustic image, and the superimposed image of the locally resolved acoustic image with the visual image from the digital camera, represent the locally resolved amplitude of the sound waves of the sound detected by the individual acoustic sensors of the array of acoustic sensors. This means that the locally resolved acoustic image, and the superimposed image, may comprise locally resolved information about the sound intensity, i.e., the loudness (measured in decibel (dB)).

The controller may be further configured to receive information about the frequencies of the sound waves detected by the individual acoustic sensors of the array of acoustic sensors.

The superimposed image may further comprise information about the frequencies of the sound waves of the sound of at least one sound source.

The sound waves of the sound detected by the individual acoustic sensors of the array of acoustic sensors may have different frequency ranges for different sound sources which are an airflow associated with a leak of the negative pressure dressing, i.e., for different leaks of the negative pressure dressing, and also for other sound sources. Different frequency ranges may arise depending on the leak rate of the leak and depending on the size of the leak. Different frequency ranges may also arise from different materials of the negative pressure dressing.

The locally resolved acoustic image, and the superimposed image of the locally resolved acoustic image with the visual image from the digital camera, may also comprise locally resolved information about the frequency of the sound waves of the sound detected by the individual acoustic sensors of the array of acoustic sensors.

The properties of the leak influence frequency and amplitude of the sound waves detected by the individual acoustic sensors of the array of acoustic sensors. The inventors of the present disclosure have found that if both frequency and amplitude of the sound waves are analyzed, a detailed description of the leak is obtained, i.e., information about presence, location, and size of an airflow associated with a leak of the negative pressure dressing. Sound intensity (loudness) and frequency are correlated with the size of a leak.

This means that the controller is configured to determine presence, location and size of a leak of the negative pressure dressing, and the superimposed image comprises information about presence, location and size of the leak.

The controller is also configured to determine presence, location and size of a sound source other than an airflow associated with a leak of the negative pressure dressing, such as noise arising from the negative pressure source or noise from the environment of the patient such noise produced by further medical equipment, and the superimposed image also comprises information about presence, location and size of this sound source other than an airflow associated with a leak of the negative pressure dressing.

Typically, the array of acoustic sensors comprises at least 3 acoustic sensors.

The array of acoustic sensors may comprise from 3 to 256, or from 4 to 256, or from 8 to 256, or from 16 to 256, or from 64 to 256 acoustic sensors. The array of acoustic sensors may also comprise more than 256 acoustic sensors.

The frequency of the sound waves of the sound detected by the individual acoustic sensors of the array of acoustic sensors, and by the array of acoustic sensors, may be in the range of from 10 Hz to up to 200 kHz, or from 10 Hz to 100 kHz, or from 10 Hz to up to 80 kHz, or from 10 Hz to 40 kHz, or from 10 Hz to 30 kHz, or from 10 Hz to 20 kHz, or from 1 kHz to 60 kHz, or from 10 kHz to 15 kHz, or from 10 kHz to 20 kHz, or from 10 kHz to 30 kHz, or from 10 kHz to 35 kHz, or from 10 kHz to 50 kHz, or from 10 kHz to 55 kHz.

One or more frequency intervals may be selected from the frequency range of the sound waves of the sound detected by the individual acoustic sensors of the array of acoustic sensors, and by the array of acoustic sensors.

Different frequency intervals may correspond to different leak rates. As used herein, the leak rate is the volumetric flow rate of an airflow associated with a leak of the negative pressure dressing, i.e., the volume of airflow which passes per unit time. For example, three frequency intervals with frequency ranges from 10 kHz to 20 kHz, 10 kHz to 35 kHz and 10 kHz to 50 kHz may be selected. With these frequency intervals, leaks orginating from the dressing may be detected. The frequency interval of 10 kHz to 20 kHz may correspond to a leak with a leak rate of 0. 1 L/min, the frequency interval of 10 kHz to 35 kHz may correspond to a leak with a leak rate of 0.3 L/min, and the frequency interval of 10 kHz to 50 kHz may correspond to a leak with a leak rate of 0.5 L/min.

As another example, four frequency intervals with frequency ranges from 10 kHz to 15 kHz, 10 kHz to 30 kHz, 10 kHz to 35 kHz and 10 kHz to 55 kHz may be selected. With these frequency intervals, leaks originating from the tubing may be detected. The frequency interval of 10 kHz to 15 kHz may correspond to a leak with a leak rate of 0.25 L/min, the frequency interval of 10 kHz to 30 kHz may correspond to a leak with a leak rate of 0.7 L/min, the frequency interval of 10 kHz to 35 kHz may correspond to a leak with a leak rate of 1.2 L/min, and the frequency interval of 10 kHz to 55 kHz may correspond to a leak with a leak rate of 1.8 L/min.

As a further example, two leaks may be identified in a knee ankle wound by selecting two different frequency intervals of from 24 kHz to 32 kHz and from 20 kHz to 28 kHz. The two different leaks can be identified by selecting these two different frequency intervals, and they can be located by the superimposed image.

As a further example, a leak may be identified even when the negative pressure source (such as a ActiV.A.C.™ therapy unit, available from 3M Company) is present nearby. Two different frequency intervals may be selected of from 8 kHz to 15 kHz and from 20 kHz to 40 kHz. Above the 15 kHz frequency, the negative pressure source was found to not make any sound and the sound in the frequency interval of from 20 kHz to 40 kHz was coming only from the leak. It is also possible to use only one frequency interval of from 8 kHz to 40 kHz, and the sound from the leak and from the negative pressure source are both detectable by the superimposed image.

The controller may be further configured to perform a spectral analysis of the sound waves of the sound detected by the individual acoustic sensors of the array of acoustic sensors. The spectral analysis may be performed for at least one local point of the locally resolved acoustic image.

As used herein, “spectral analysis” means an analysis of the sound waves in terms of the spectrum of frequencies. By the spectral analysis, an x-y diagram of the amplitude as a function of the frequency of the sound waves is obtained.

The sound waves of sound from different sound sources typically have different frequency intervals. By performing a spectral analysis of the sound waves of the sound detected by the individual acoustic sensors of the array of acoustic sensors, different sound sources may be detected and distinguished.

The spectral analysis of the sound waves of the sound may be used to separate sound produced by a sound source different from an airflow associated with a leak of the negative pressure dressing. A sound source different from an airflow associated with a leak of the negative pressure dressing may be noise arising from the negative pressure source or noise from the environment of the patient such noise produced by further medical equipment.

The sound waves of sound produced by a sound source different from an airflow associated with a leak of the negative pressure dressing typically has a frequency interval different from the frequency interval of the sound waves originating from an airflow associated with a leak of the negative pressure dressing. By performing a spectral analysis of the sound waves of the sound detected by the individual acoustic sensors of the array of acoustic sensors, sound produced by a sound source different from an airflow associated with a leak of the negative pressure dressing may be separated and suppressed. The controller then creates a superimposed image combining both acoustic and digital camera information to inform the user about the presence and location of the leak, i.e., the superimposed image comprises information about presence and location of the leak.

For determining presence and location of an airflow associated with a leak of the negative pressure dressing in presence of another sound source such as noise from the negative pressure source, a spectral analysis may only be required if the other sound sources is very loud or near the leak.

Otherwise, the information about presence and location of the airflow associated with the leak of the negative pressure dressing may be obtained from the superimposed image without performing a spectral analysis.

This means that the controller may be configured to determine presence and location of a leak of the negative pressure dressing in presence of sound arising from a sound source different from the airflow associated with the leak of the negative pressure dressing.

The spectral analysis may also be used to separate sound produced by different leaks of the negative pressure dressing, i.e., by different airflows associated with a leak of the negative pressure dressing. For example, the spectral analysis of the sound waves of the sound may be used to separate sound of a first and a second leak of the negative pressure dressing, wherein the first leak is at a first location of the negative pressure dressing, and wherein the second leak is at a second location of the negative pressure dressing, and wherein the first location is different from the second location.

Different leaks, such as the first and second leak of the above example, typically produce sound corresponding to different frequency intervals, i.e., the first leak produces sound corresponding to a first frequency interval and the second leak produces sound corresponding to a second frequency interval. As a consequence, it is possible to separate sound produced by different leaks of the negative pressure dressing by performing a spectral analysis of the sound waves, for example to separate sound produced by the first and the second leak. Information about presence and location of the different leaks such as for the first and second leak of the above example, is obtained from the superimposed image.

This means that the controller may be configured to determine presence and location of a first and a second leak of the negative pressure dressing, wherein the first leak is at a first location of the negative pressure dressing, and wherein the second leak is at a second location of the negative pressure dressing, and wherein the first location is different from the second location. The spectral analysis of the sound waves of the sound may be used to obtain information about the leak rate, i.e., the volumetric flow rate of an airflow associated with a leak of the negative pressure dressing. As different frequency intervals may correspond to different leak rates, the spectral analysis of the sound waves can be used to obtain information about the leak rate, i.e., the volumetric flow rate of an airflow associated with a leak. This information may be obtained at each point of the locally resolved acoustic image and the superimposed image, i.e., the information about the volumetric flow rate of an airflow associated with a leak comprises information about the local position of the leak.

Further disclosed herein is also a method of detecting a leak in a negative pressure wound therapy system comprising a negative pressure dressing, a negative pressure source, an array of acoustic sensors, a digital camera, and a controller, the method comprising: directing the digital camera to the negative pressure dressing, wherein the negative pressure dressing is placed over a wound site to create a fluid impermeable seal over the wound site; by the digital camera, receiving a visual image from the negative pressure dressing; directing the array of acoustic sensors to the negative pressure dressing; aligning the digital camera with the array of acoustic sensors to adjust the local position of the visual image with the local position of the locally resolved acoustic image; utilizing the array of acoustic sensors to detect sound produced by at least one sound source, wherein the at least one sound source comprises an airflow associated with a leak of the negative pressure dressing; by the controller, receiving the visual image from the digital camera; by the controller, receiving sound from the array of acoustic sensors; by the controller, receiving information about the differences in propagation time of the sound waves of the sound detected by the individual acoustic sensors of the array of acoustic sensors; by the controller, calculating the local position of the at least one sound source from the differences in propagation time of the sound waves of the sound detected by the individual acoustic sensors of the array of acoustic sensors; by the controller, composing a locally resolved acoustic image from the calculation of the local position of the at least one sound source; by the controller, superimposing the visual image with the locally resolved acoustic image to obtain a superimposed image comprising information about presence and location of the leak.

All the particular and preferred aspects relating to, in particular, the negative pressure dressing, the negative pressure source, the array of acoustic sensors, the digital camera and the controller which were described hereinabove in the context of the negative pressure wound therapy system, are fully applicable to the method as described above.

After directing the digital camera and the array of acoustic sensors to the negative pressure dressing, the digital camera is aligned with the array of acoustic sensors. By aligning the digital camera with the array of acoustic sensors, the local position of the visual image is adjusted with the local position of the locally resolved acoustic image. The alignment or adjustment may be accomplished by one or more point sound sources such as a piezo sounder and by matching the visual image and the locally resolved acoustic image of the one or more point sound sources.

The array of acoustic sensors is not moved around the negative pressure dressing for leak detection. The array of acoustic sensors is stationary.

The method disclosed herein may further comprise by the controller, performing a spectral analysis of the sound waves of the sound detected by the individual acoustic sensors of the array of acoustic sensors.

The spectral analysis is performed for at least one local point of the locally resolved acoustic image.

Performing the spectral analysis of the sound waves of the sound may comprise separating sound produced by a sound source different from an airflow associated with a leak of the negative pressure dressing.

A sound source different from an airflow associated with a leak of the negative pressure dressing may be noise arising from the negative pressure source or noise from the environment of the patient such noise produced by further medical equipment.

The sound waves of sound produced by a sound source different from an airflow associated with a leak of the negative pressure dressing typically has a frequency interval different from the frequency interval of the sound waves originating from an airflow associated with a leak of the negative pressure dressing. By performing a spectral analysis of the sound waves of the sound detected by the individual acoustic sensors of the array of acoustic sensors, sound produced by a sound source different from an airflow associated with a leak of the negative pressure dressing may be separated. Information about presence and location of the leak is obtained from the superimposed image.

By performing a spectral analysis of the sound waves, sound produced by a sound source different from an airflow associated with a leak of the negative pressure dressing may be separated even if the different sound source is at the same local position as the leak, or if the different sound source is very close to the local position of the leak, and even if the different sound source, such as the negative pressure source, is much louder and has a much higher amplitude of the sound wave than the airflow associated with the leak. Performing the spectral analysis of the sound may comprise separating sound produced by different leaks of the negative pressure dressing, i.e., by different airflows associated with a leak of the negative pressure dressing. Different leaks typically produce sound corresponding to different frequency intervals. As a consequence, it is possible to separate sound produced by different leaks of the negative pressure dressing by performing a spectral analysis of the sound waves. Information about presence and location of the different leaks is obtained from the superimposed image.

For example, performing the spectral analysis of the sound waves of the sound may comprise separating sound produced by a first and a second leak of the negative pressure dressing, wherein the first leak is at a first location of the negative pressure dressing, and wherein the second leak is at a second location of the negative pressure dressing, and wherein the first location is different from the second location. The first and the second leak produce sound corresponding to a first and a second frequency intervals. The first and the second frequency interval typically are different from one another. As a consequence, it is possible to separate sound produced by the first and the second leak of the negative pressure dressing by performing a spectral analysis of the sound waves. Information about presence and location of the first and second leak is obtained from the superimposed image.

By performing the spectral analysis of the sound, information about the leak rate, i.e., the volumetric flow rate of an airflow associated with a leak of the negative pressure dressing, may be obtained. As the leak rate is dependent on the frequency, i.e., as different frequency intervals correspond to different leak rates, it is possible to obtain information about the leak rate by performing a spectral analysis of the sound. This information may be obtained at each point of the locally resolved acoustic image and the superimposed image, i.e., the information about the leak rate of an airflow associated with a leak comprises information about the local position of the leak.

In some embodiments, the negative pressure wound therapy system disclosed herein further comprises an ultrasound generating device, and the method disclosed herein further comprises performing wound debridement by using the ultrasound generating device.

By using an ultrasound generating device for wound debridement and by combining wound debridement with leak detection in negative pressure wound therapy, a faster or enhanced healing can be achieved instead, compared to using the two techniques of wound debridement and leak detection separately as usually performed.

Negative pressure wound therapy and wound debridement by using an ultrasound generating device, i.e., ultrasound debridement, both have the purpose of cleaning and healing of a wound site. Negative pressure pumps out wound exudate, whereas the ultrasound debridement actively removes devitalized wound through microstreaming and cavitation.

The ultrasound generating device may have a frequency of between 20 kHz and 4 MHz, for example. Detecting presence and location of a leak and performing wound debridement by using an ultrasound generating device may be performed altematingly. For example, the ultrasound generating device may be placed in the controller, and in this case detecting presence and location of a leak and performing wound debridement by using an ultrasound generating device need to be performed altematingly. Wound debridement may be performed before preparing the dressing or in between changing the dressing.

Detecting presence and location of a leak and performing wound debridement may also be performed simultaneously. For example, the ultrasound generating device may be placed in a manifold such as a foam that is used to assist in applying reduced pressure to, delivering fluids to, or removing fluids from the wound site. In this case, detecting presence and location of a leak and performing wound debridement by using an ultrasound generating device may be performed simultaneously.

In some embodiments, the negative pressure wound therapy system disclosed herein further comprises an ultrasound generating device, and the method disclosed herein further comprises identifying leaks by the sound generated using the ultrasound generating device. In these embodiments, the ultrasound generating device may also be used to assist in leak detection, i.e., to identify leaks by the sound generated using the ultrasound generating device. The ultrasound generating device may be placed within the negative pressure dressing, and ultrasonic waves sourced from the ultrasound generating device will propagate through existing leak paths and be more detectable at these leak paths by the array of acoustic sensors. As the ultrasonic waves are directly generated by the ultrasound generating device and its frequencies can be set as desired, controller processing and environmental noise filtering is simplified.

In Figure 1, a first embodiment of a negative pressure wound therapy system 1 as disclosed herein is shown schematically. A negative pressure dressing 2 is placed over a wound site to create a fluid impermeable seal over the wound site. A negative pressure source 3 such as a vacuum pump is fluidly coupled to the negative pressure dressing 2 by a negative pressure conduit or tubing 4. Negative pressure from the conduit or tubing may be distributed to the wound site via the negative pressure dressing 2 or via a manifold (not shown) located at or within the wound site. The negative pressure dressing 2 may also be coupled to a fluid container (not shown) for collecting bodily fluids from the wound site. A portable device 5 comprises a digital camera 6 and an array of acoustic sensors 7 (both located at the backside of the device), and a controller 8 (inside the device). The digital camera 6 is directed to and receives a visual image from the negative pressure dressing 2. The array of acoustic sensors 7 is directed to the negative pressure dressing 2. The controller 8 calculates the local position of a leak 10 of the negative pressure dressing 2 from the differences in propagation time of the sound waves of the sound detected by the individual acoustic sensors of the array of acoustic sensors 7. The controller 8 composes a locally resolved acoustic image from the calculation of the local position of the leak 10. The controller 8 receives information about the relative position of the digital camera 6 and the array of acoustic sensors 7. The controller 8 has a display 9 showing a superimposed image with the location of the leak 10. The superimposed image is superimposed from the locally resolved acoustic image and the visual image of the digital camera. In Figure 2, a second embodiment of a negative pressure wound therapy system 1 as disclosed herein is shown schematically. A negative pressure dressing 2 is placed over a wound site to create a fluid impermeable seal over the wound site. A negative pressure source 3 (included in the device 11) such as a vacuum pump is fluidly coupled to the negative pressure dressing 2 by a negative pressure conduit or tubing 4. Negative pressure from the conduit or tubing may be distributed to the wound site via the negative pressure dressing 2 or via a manifold (not shown) located at or within the wound site. The negative pressure dressing 2 may also be coupled to a fluid container (not shown) for collecting bodily fluids from the wound site. The negative pressure source 3 is included in the device 11 which also includes a digital camera 6 and an array of acoustic sensors 7 (both located at the backside of the device), and a controller 8 (inside the device). The digital camera 6 in the device 11 is directed to and receives a visual image from the negative pressure dressing 2. The array of acoustic sensors 7 in the device 11 is directed to the negative pressure dressing 2. The controller 8 in the device 11 calculates the local position of a leak 10 of the negative pressure dressing 2 from the differences in propagation time of the sound waves of the sound detected by the individual acoustic sensors of the array of acoustic sensors 7. The controller 8 in the device 11 composes a locally resolved acoustic image from the calculation of the local position of the leak 10. The controller 8 in the device 11 receives information about the relative position of the digital camera 6 and the array of acoustic sensors 7. The controller 8 in the device 11 has a display 9 showing a superimposed image with the location of the leak 10. The superimposed image is superimposed from the locally resolved acoustic image and the visual image of the digital camera.

In Figure 3, a third embodiment of a negative pressure wound therapy system 1 as disclosed herein is shown schematically. A negative pressure dressing 2 is placed over a wound site to create a fluid impermeable seal over the wound site. A negative pressure source 3 such as a vacuum pump is fluidly coupled to the negative pressure dressing 2 by a negative pressure conduit or tubing 4. Negative pressure from the conduit or tubing may be distributed to the wound site via the negative pressure dressing 2 or via a manifold (not shown) located at or within the wound site. The negative pressure dressing 2 may also be coupled to a fluid container (not shown) for collecting bodily fluids from the wound site. One or several units 13 are stationary fixed in the environment of the negative pressure dressing 2. The units 13 comprise a digital camera 6 and an array of acoustic sensors 7. Several units 13 instead of only one unit 13 may be used for large wound sites or for wound sites which cannot easily be shown in a single visual image. The digital camera 6 in the unit 13 is directed to and receives a visual image from the negative pressure dressing 2. The array of acoustic sensors 7 in the unit 13 is directed to the negative pressure dressing 2. A controller 8 is included in the device 12. The controller 8 calculates the local position of a leak 10 of the negative pressure dressing 2 from the differences in propagation time of the sound waves of the sound detected by the individual acoustic sensors of the array of acoustic sensors 7. The controller 8 in the device 12 composes a locally resolved acoustic image from the calculation of the local position of the leak 10. The controller 8 in the device 12 receives information about the relative position of the digital camera 6 and the array of acoustic sensors 7. The controller 8 in the device 12 has a display 9 showing a superimposed image with the location of the leak 10. The superimposed image is superimposed from the locally resolved acoustic image and the visual image of the digital camera. The controller 8 shows a superimposed image for each of the units 13 which are stationary fixed in the environment of the negative pressure dressing 2.

Figure 4 schematically shows the controller 8 of a negative pressure wound therapy system as disclosed herein. The controller 8 takes input from a plurality of individual acoustic sensors 14 and a digital camera 6 and algorithmically combines the input. The plurality of acoustic sensors 14 is spatially arranged in a two-dimensional or three-dimensional form, thus forming an array 7 of acoustic sensors. In the example of Figure 4, the number of individual acoustic sensors in the array of acoustic sensors is four; however, the number of individual acoustic sensors in the array of acoustic sensors may also be three or higher than four and may be up to 256 or higher. The controller 8 receives a visual image from the digital camera 6 and receives sound from the array 7 of acoustic sensors. The controller 8 also receives information about the differences in propagation time of the sound waves of the sound detected by the individual acoustic sensors 14 of the array 7 of acoustic sensors. The controller 8 calculates the local position of at least one sound source (such as an airflow associated with a leak of a negative pressure dressing) from the differences in propagation time of the sound waves of the sound detected by the individual acoustic sensors 14 of the array 7 of acoustic sensors. The controller 8 composes a locally resolved acoustic image from the calculation of the local position of the at least one sound source. The controller 8 superimposes the visual image with the locally resolved acoustic image to obtain a superimposed image comprising information about presence and location of the leak. The controller 8 could be run locally on a physical device or hosted on cloud services. The controller 8 outputs the superimposed image which combines digital camera and acoustic sensor information, which the user can view on a display 9.

Claims

1. A negative pressure wound therapy system (1) comprising: a negative pressure dressing (2) configured to be placed over a wound site to create a fluid impermeable seal over the wound site; a negative pressure source (3) configured to be coupled to the negative pressure dressing (2); a digital camera (6) configured to receive a visual image comprising the negative pressure dressing (2); and an array (7) of acoustic sensors configured to detect sound produced by at least one sound source, wherein the at least one sound source comprises an airflow associated with a leak (10) of the negative pressure dressing (2); a controller (8) configured to determine presence and location of a leak of the negative pressure dressing (2), the controller (8) further configured to: receive the visual image from the digital camera (6); receive sound from the array (7) of acoustic sensors; receive information about the differences in propagation time of the sound waves of the sound detected by the individual acoustic sensors (14) of the array (7) of acoustic sensors; calculate the local position of the at least one sound source from the differences in propagation time of the sound waves of the sound detected by the individual acoustic sensors (14) of the array (7) of acoustic sensors; compose a locally resolved acoustic image from the calculation of the local position of the at least one sound source; receive information about the relative position of the digital camera (6) and the array (7) of acoustic sensors; and superimpose the visual image with the locally resolved acoustic image to obtain a superimposed image comprising information about presence and location of the leak (10).

2. The negative pressure wound therapy system (1) of claim 1, wherein the controller (8) is further configured to receive information about the amplitudes of the sound waves detected by the individual acoustic sensors (14) of the array (7) of acoustic sensors; and calculate the sound intensity from the amplitudes of the sound waves detected by the individual acoustic sensors (14) of the array (7) of acoustic sensors; wherein the superimposed image further comprises information about the sound intensity of the at least one sound source.

3. The negative pressure wound therapy system (1) of claim 1 or 2, wherein the controller (8) is further configured to receive information about the frequencies of the sound waves detected by the individual acoustic sensors (14) of the array (7) of acoustic sensors; wherein the superimposed image further comprises information about the frequencies of the sound waves of the sound of the at least one sound source.

4. The negative pressure wound therapy system (1) of any of claims 1 to 3, wherein the controller (8) is configured to determine presence, location and size of a leak (10) of the negative pressure dressing (2), and wherein the superimposed image comprises information about presence, location and size of the leak (10).

5. The negative pressure wound therapy system (1) of any of claims 1 to 4, wherein the at least one sound source comprises noise produced by the negative pressure source (3) and/or noise produced by further medical equipment.

6. The negative pressure wound therapy system (1) of any of claims 1 to 5, wherein the array (7) of acoustic sensors comprises at least 3 acoustic sensors (14).

7. The negative pressure wound therapy system (1) of any of claims 1 to 6, wherein the array (7) of acoustic sensors comprises from 3 to 256 acoustic sensors (14).

8. The negative pressure wound therapy system of any of claims 1 to 7, wherein the frequency of the sound waves of the sound detected by the individual acoustic sensors of the array of acoustic sensors is in the range of from 10 Hz to up to 200 kHz.

9. The negative pressure wound therapy system (1) of any of claims 1 to 8, wherein one or more frequency intervals are selected from the frequency range of the sound waves of the sound detected by the individual acoustic sensors (14) of the array (7) of acoustic sensors.

10. The negative pressure wound therapy system (1) of any of claims 1 to 9, wherein the acoustic sensors (14) of the array (7) of acoustic sensors are arranged in a plane.

11. The negative pressure wound therapy system (1) of any of claims 1 to 10, wherein the acoustic sensors (14) of the array (7) of acoustic sensors are arranged in the form of a paraboloid.

12. The negative pressure wound therapy system (1) of any of claims 1 to 11, wherein the controller (8) is further configured to perform a spectral analysis of the sound waves of the sound detected by the individual acoustic sensors (14) of the array (7) of acoustic sensors, and wherein the spectral analysis is performed for at least one local point of the locally resolved acoustic image.

13. The negative pressure wound therapy system (1) of claim 12, wherein the spectral analysis of the sound waves of the sound is used to separate sound produced by a sound source different from an airflow associated with a leak (10) of the negative pressure dressing (2).

14. The negative pressure wound therapy system (1) of claim 12, wherein the spectral analysis of the sound waves of the sound is used to separate sound of a first and a second leak of the negative pressure dressing (2), wherein the first leak is at a first location of the negative pressure dressing (2), and wherein the second leak is at a second location of the negative pressure dressing (2), and wherein the first location is different from the second location.

15. The negative pressure wound therapy system (1) of claim 12, wherein the spectral analysis of the sound waves of the sound is used to obtain information about the leak rate, wherein the leak rate is the volumetric flow rate of an airflow associated with a leak (10) of the negative pressure dressing (2).

16. A method of detecting a leak in a negative pressure wound therapy system (1) comprising a negative pressure dressing (2), a negative pressure source (3), an array (7) of acoustic sensors, a digital camera (6), and a controller (8), the method comprising: directing the digital camera (6) to the negative pressure dressing (2), wherein the negative pressure dressing (2) is placed over a wound site to create a fluid impermeable seal over the wound site; by the digital camera (6), receiving a visual image from the negative pressure dressing (2); directing the array (7) of acoustic sensors to the negative pressure dressing (2); aligning the digital camera (6) with the array (7) of acoustic sensors to adjust the local position of the visual image with the local position of the locally resolved acoustic image; utilizing the array (7) of acoustic sensors to detect sound produced by at least one sound source, wherein the at least one sound source comprises an airflow associated with a leak (10) of the negative pressure dressing (2); by the controller (8), receiving the visual image from the digital camera (6); by the controller (8), receiving sound from the array (7) of acoustic sensors; by the controller (8), receiving information about the differences in propagation time of the sound waves of the sound detected by the individual acoustic sensors (14) of the array (7) of acoustic sensors; by the controller (8), calculating the local position of the at least one sound source from the differences in propagation time of the sound waves of the sound detected by the individual acoustic sensors of the array of acoustic sensors; by the controller (8), composing a locally resolved acoustic image from the calculation of the local position of the at least one sound source; by the controller (8), superimposing the visual image with the locally resolved acoustic image to obtain a superimposed image comprising information about presence and location of the leak (10).

17. The method of claim 16, further comprising by the controller (8), performing a spectral analysis of the sound waves of the sound detected by the individual acoustic sensors (14) of the array (7) of acoustic sensors, wherein the spectral analysis is performed for at least one local point of the locally resolved acoustic image.

18. The method of claim 17, wherein performing the spectral analysis of the sound waves of the sound comprises separating sound produced by a sound source different from an airflow associated with a leak (10) of the negative pressure dressing (2).

19. The method of claim 17, wherein performing the spectral analysis of the sound waves of the sound may comprise separating sound produced by a first and a second leak of the negative pressure dressing (2), wherein the first leak is at a first location of the negative pressure dressing (2), and wherein the second leak is at a second location of the negative pressure dressing (2), and wherein the first location is different from the second location.

20. The method of claim 17, wherein performing the spectral analysis of the sound waves of the sound comprises obtaining information about the leak rate, wherein the leak rate is the volumetric flow rate of an airflow associated with a leak (10) of the negative pressure dressing (2).

21. The method of any of claims 16 to 20, wherein the negative pressure wound therapy system (1) further comprises an ultrasound generating device, and wherein the method further comprises performing wound debridement by using the ultrasound generating device.

22. The method of claim 21, wherein detecting presence and location of the leak (10) and performing wound debridement by using the ultrasound generating device are performed altematingly.

23. The method of any of claims 16 to 20, wherein the negative pressure wound therapy system (1) further comprises an ultrasound generating device, and wherein the method further comprises identifying leaks by the sound generated using the ultrasound generating device.