Patent Application
20210259888
This disclosure relates to a wound dressing system having an integral sensor for monitoring and treating a wound.
A major requirement for effective wound care management is the need to monitor and change wound dressings to provide optimal conditions for tissue healing. Most known methods of wound monitoring and care require manual and/or subjective analysis of a range of parameters such as wound temperature and wound dressing saturation/age which usually involves disturbing the patient and/or removing the dressing for inspection. For example, it is recognized that wound temperature is a quantitative measurement that has the potential to assist in assessing and diagnosing chronic deep wound and surrounding skin infection. Indeed, studies have shown that incorporating quantitative skin temperature measurement into routine wound assessment provides a timely and reliable method for a clinician to quantify the heat associated with deep wound and surrounding skin infection (e.g. elevated local temperatures above 37° C. are an indication of wound infection) and to monitor ongoing wound status.
Similarly, it is known that, as healing occurs, the amount of exudate produced usually decreases. The volume of exudate is related to the surface area of the wound and large wounds often produce higher volumes of exudate. However, although a moist wound environment is necessary for optimal wound healing, over- or under-production of exudate may adversely affect healing. Any factor that increases capillary leakage or predisposes a patient to the development of tissue oedema (e.g. inflammation, bacterial contamination or limb dependency) may boost exudate production while low exudate production may indicate a systemic problem (e.g. dehydration, hypovolemic shock and microangiopathy) or may be a feature of ischaemic ulcers. Accordingly, it is essential to accurately determine and evaluate the factors contributing to the production of too much or too little exudate.
However, currently, measurement and assessment of the aforementioned and other wound parameters are generally performed manually using subjective visual inspections and/or equipment such as thermometers or moisture meters resulting in suboptimal dressing changing frequency, clinical timewasting, patient discomfort, increased dressing cost and increased wound healing time.
Accordingly, various attempts have been made to develop smart dressings in which sensors such as a moisture sensor and an associated electronic module communicable with a clinician have been incorporated into the dressings. However, the placement of the sensor and module, as well as the construction of the dressing itself, can negatively impact on the performance of the smart dressing. More particularly, diffusion of wound exudate in a typical dressing takes place initially by vertical diffusion from a wound, through the dressing layers as far as a super-absorbent fibre (SAF) layer where fast lateral diffusion then takes place and the surface of this layer, which is generally in contact with the (moisture) sensor, gets rapidly wet. As a result, moisture is wicked across the dressing very rapidly into contact with the (moisture) sensor which is then activated (i.e. shows a sudden and significant change in measurand) and saturates earlier than desired for wound monitoring purposes i.e. before 50% of the dressing capacity is reached. As a result, it is not possible to measure or map the progress of the wound exudate through the dressing. The measurand can be, for example resistance, impedance, capacitance and/or optical properties.
It has also been found that dressing performance can be compromised by the presence of the electronic module and associated sensor in the dressing e.g. typically electronic modules are placed over the absorbent layers giving rise to pressure being generated by the electronic module on the absorbent layers in the dressing which can change the diffusion/wicking properties of the dressing so that the dressing does not perform as originally intended. Importantly, the placement of the electronic modules over the absorbent layers can also severely compromise the breathability of the dressings which is highly undesirable resulting in negative consequences for the healing process.
PCT Patent Specification No. WO 2017/195038 describes a dressing system for a wound comprising various sensors and an absorbent pad. However, the sensor(s) of the dressing system are not moisture sensors adapted to measure the progress of wound exudate across the dressing. Similarly, PCT Patent Specification No. WO 2017/129194 describes a dressing having a matrix of temperature sensors unsuitable for mapping wound exudate in the dressing, while US Patent Specification No. 2014/928927 describes a separate sensing device for attachment to a dressing in which the non-integral external sensing device has a plurality of separate moisture sensors which are arranged in such a way that progress of exudate across the dressing cannot be mapped.
It is therefore an object to provide an improved dressing system to overcome at least one of the above mentioned problems
The invention generally relates to a dressing system for a wound comprising:
Accordingly, according to a first aspect of the invention there is provided a dressing system for a wound comprising:
Preferably, the moisture sensor array comprises a plurality of moisture sensors.
Suitably, the moisture sensor array is located on the absorbent pad. Alternatively or in addition, the moisture sensor array is located in the absorbent pad.
Preferably, the sensor comprises a peripheral sensor located towards a periphery of the absorbent pad. Suitably, the peripheral sensor is located beyond the periphery of the absorbent pad.
Preferably, the dressing system further comprises a diffusion barrier to delay diffusion of wound exudate towards the sensor. More preferably, the diffusion barrier comprises a delay channel defined in the absorbent pad. Alternatively, the absorbent pad comprises a first superabsorbent layer and the diffusion barrier comprises a second superabsorbent layer between the sensor and the first superabsorbent layer. Advantageously, the first and second superabsorbent layers comprise superabsorbent fibre layers.
Preferably, the moisture sensor is offset with respect to the centre of the absorbent pad so that activation of the sensor is delayed until after about 50% of the dressing system capacity is reached. More particularly, the moisture sensors of the moisture sensor array are offset with respect to the centre of the absorbent pad so that activation of the moisture sensors is delayed until after about 50% of the dressing system capacity is reached.
In a further embodiment, the sensor can further comprise a pH sensor, a pressure sensor, a bacterial sensor, a temperature sensor or an inertial sensor.
Preferably, the electronic module is offset with respect to the absorbent pad. More preferably, the electronic module is located towards a periphery of the absorbent pad. Most preferably, the electronic module is located beyond the periphery of the absorbent pad.
In a preferred embodiment of the invention, the electronic module is located beyond the periphery of the absorbent pad on a substrate.
Preferably, the electronic module comprises a communications module for communicating the wound data from the electronic module to a clinician. More preferably, the communications module comprises a wireless communications module.
Preferably, the electronic module further comprises a power source for powering the electronic module. More preferably, the power source comprises a battery.
Suitably, the dressing system further comprises a backing film on the absorbent pad.
The invention therefore results in a smart or intelligent wound dressing for the intelligent monitoring of wound health and dressing condition having integral moisture sensors adapted to map the progress of exudate in the dressing—i.e. the moisture sensors form part of the dressing (in particular the absorbent pad) or are located internally within the dressing The radially offset position of the (moisture) sensors can delay activation of the sensors by diffusing exudate until after about 50% of the dressing capacity is reached. In addition, by locating an array of the (moisture) sensors in a radial manner i.e. both centrally and offset from the centre of the absorbent towards the periphery of the dressing, exudate progress across the dressing can be measured or mapped to give a time-dependent indication of the saturation levels of the dressing.
Moreover, offset positioning of the electronic module ensures that dressing performance is not compromised by the presence of the electronic module. In particular, the offset electronic module does not impede or impinge upon exudate diffusion in the dressing. Although the Applicant does not wish to be bound by any theorem, it is believed that additional pressure created by centrally positioned electronic modules on the absorbent foam in previous dressings can alter the diffusive/wicking properties of the absorbent pad so that the dressing does not perform as intended. The offset position of the electronic module of the present invention eliminates any such additional pressures in the dressing and improves breathability.
The dressing of the invention is a laminated or multi-layer dressing adapted to rapidly absorb exudates and interstitial fluids and optimize conditions for healing at the wound-dressing interface. A primary wicking or absorbent pad provides a rapid capillary action response to quickly distribute absorbed exudate throughout the dressing and create a sustained movement of fluid away from wound beds.
The dressing of the invention facilitates the monitoring of individual and multiple sensor readings of a wound in real-time and/or the provision of time specific updates. The data generated from the dressing provides a constant and/or time specific update to an app and/or software available to a clinician. Each sensor reading provides a specific reading that is easily interpreted for ease of use and understanding.
In addition to the moisture sensors, pH sensors can be employed in the dressing system to facilitate the measurement of exudate pH to reflect the condition of a wound bed and aid in monitoring and determining the wound's response to treatment. Pressure sensors can also be employed to provide clinicians with key evidence describing pressure applied on wounds during critical healing stages. Temperature sensors can also be employed to monitor healing. Similarly, bacterial sensors can be used to assist in detecting infection. Inertial sensors can be adapted to monitor patient orientation, motion and/or activity.
The dressing of the invention provides a sealing arrangement preventing any bodily fluids or other material that may cause infection and/or impact sensor readings from reaching a wound. The waterproof sealing arrangement also enables the patient to wash and shower without damaging or obstructing the dressing. This is particularly beneficial when the dressing is employed on long term wounds.
Data generated from the dressing is used for the prediction of wound healing to help clinicians adopt a more specific management strategy, at the right time, to achieve healing. The use of the sensed parameters (e.g. moisture, pH and temperature) in combination provides essential information that improves future patient care.
Data transferred to a downloaded app on a handheld device can be used to provide clinicians with continuous data for monitoring and analysing wounds with the app enabling real-time bi-directional communication between patient and clinician.
The invention will now be described, by way of example only, with reference to the accompanying drawings in which:
The absorbent pad 2 is substantially square in shape and is made up of a substantially square lower wound face 10 for contacting a wound having four side walls 11,12,13,14 upstanding therefrom and an upper face 15 disposed towards the non-absorbent layer 4 and the SAF layer 5.
The dressing system 1 has a (moisture) sensor 16 centrally positioned with respect to the sidewalls 11,12,13,14 on top of the absorbent foam pad 2 and under the backing film 6 at the SAF layer 5. Accordingly, in practice, the centrally positioned moisture sensor 16 of the dressing system 1 is located directly above the exudate 3 source i.e. the wound. The dressing system 1 can also have additional moisture sensors 16 as required.
The dressing system 1 of
As shown in
The fast lateral diffusion wicks moisture across the dressing system 1 very rapidly, and into contact with the moisture sensors which 16 which are then activated (i.e. show a sudden and significant drop in resistance where resistance moisture sensors 16 are employed) and saturate earlier than desired i.e. well before about 50% of the dressing capacity is reached. Alternatively any other type of sensor can be used that shows a change in measurand upon contact with or proximity to exudate.
More particularly, in the present embodiment, the moisture sensor 16 is located at the corner of the absorbent pad 2 defined between the sidewalls 12,13. However, the dressing system 1 is further provided with a diffusion/wicking barrier 18 to delay diffusion of exudate 3 towards the moisture sensor 16 to in turn to delay activation of the moisture sensor 16. In the present embodiment, the diffusion barrier 18 is a delay line or channel 19 defined in and across the absorbent foam pad 2 including the non-absorbent layer 4 and the SAF layer 5 adjacent the moisture sensor 16. The delay channel 19 is cut into absorbent foam pad 2, the non-absorbent layer 4 and the SAF layer 5 to partially diffusively isolate the moisture sensor 16 from the absorbent pad 2 (and hence the exudate 3) so that diffusion of exudate 3 to the moisture sensor 16 is delayed until after about 50% of the dressing capacity is reached. As the moisture sensor 16 is only partially diffusively isolated by the delay channel 19, the delay channel 19 extends only partially across the absorbent pad 2, the non-absorbent layer 4 and the SAF layer 5 so that the moisture sensor 16 remains diffusively communicable with exudate 3 in use.
As shown in the drawing, in the present embodiment, the dressing system 1 is provided with radially offset peripheral moisture sensors 16 as previously described disposed towards the periphery of the dressing system 1. The offset moisture sensors 16 are positioned adjacent the corners of the side walls 11,12,13,14 of the absorbent pad 2 on peripheral tabs 26 connected to the absorbent pad 2. However, additionally, the dressing system 1 is provided with a further array 27 of moisture sensors 16. The moisture sensors 16 of the array 27 are radially offset from and/or spaced apart across the centre of the absorbent pad 2 between the side walls 11,12 towards the periphery of the dressing system 1 so that exudate 3 diffusion rates across the dressing system 1 can be measured by the array 27 of sensors 16.
The electronic module 17 on the substrate 22 can include a processor for processing data from the sensors 16, memory for storing data and programmes, a communications module 24 (e.g. a BLE, NFC, WiFi (Trade Mark) or narrowband IoT based communications module) for communicating the sensor data to a base station attended by a clinician, batteries 25 and an actuator for controlling actuation of the dressing system 1. The module can be made up of several sections electrically linked as appropriate. Other components can use an inertial sensor for patient activity monitoring, voltage regulators, switches, LED indicators etc. As shown in the drawing, all the aforementioned components can be accommodated on the electronic module substrate 22 in a fully offset position without overlying the absorbent pad 2.
The absorbent pad 2 is formed from a die-cut adhesive bandage material which allows for sufficient transfer of oxygen to a wound site while effectively preventing passage of microbes to the wound. The backing film 6 can be formed from a polymer such as acrylic or polyurethane while the release film 9 can be formed from polyethylene terephthalate (PET).
The electronic module 17 of the dressing system of the invention includes a communications module such as a wireless communications module for communicating wound data from the electronic module to a clinician and a power source such as a battery for powering the electronic module.
The dressing system 1 can be manufactured in any suitable size as required in accordance with wound sizes. Typical dressing sizes are 10 cm×10 cm, 7.5 cm ×7.5 cm, 20 cm×10 cm and 20 cm×20 cm.
The dressing system 1 is sterilised to kill microorganisms transferred during the manufacturing process. A suitable sterilization method is an ethylene oxide (EtO) sterilisation method which protects the sensors 16 and electronic module 17 from damage. This method of sterilisation is also preferred due to its handling ease, versatility and suitability for use with delicate medical dressings which could be damaged by other sterilisation methods such as heat sterilisation.
In use, data from the sensors 16 is harvested and processed for optimal wound monitoring and healing. Other sensor types can be employed in the dressing system 1 in addition to the moisture sensors 16 as required e.g. pressure sensors, bacterial sensors, temperature sensors and pH sensors. The sensors 16 can be offset from the centre of the absorbent pad 16 as hereinbefore described and can also be included in the offset electronic module 17 if desired. Various data processing methods can be employed as necessary.
The invention is not limited to the embodiments herein described which may be varied in construction and detail without departing from the scope of the invention.
| Number | Date | Country | Kind |
|---|---|---|---|
| 1810531.2 | Jun 2018 | GB | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP19/66975 | 6/26/2019 | WO | 00 |
