US20090143773A1

US20090143773A1 - Device for assistance in the wound healing processes

Info

Publication number: US20090143773A1
Application number: US12/270,237
Authority: US
Inventors: Alban Gosse; Sylvain Giraud; Gwenaelle Iarmarcovai; Alain Cornil; Alexandre Capon; Patrick Peronne
Original assignee: Ekkyo
Current assignee: Vivatech Co
Priority date: 2007-12-03
Filing date: 2008-11-13
Publication date: 2009-06-04
Also published as: US8556887B2; EP2237731A1; ES2573079T3; EP2237731B1; FR2924327B1; WO2009071592A1; FR2924327A1; US20100305554A1; PL2237731T3

Abstract

A device that assists in the wound healing process that takes into account the different skin types that are laser-treated in order to optimise the effectiveness of the wound-healing processes and to avoid any burning. The device comprises a laser source suitable for emitting a beam whose wavelength is between approximately 800 nanometres and approximately 820 nanometres and includes a control module suitable for controlling the laser source according to data regarding the skin type of the patient to be treated.

Description

FIELD OF THE INVENTION

The invention is related to the field of assistance in skin wound healing, and in particular to assistance in wound healing processes using a laser beam.

PRIOR ART

Various solutions are known in the prior art, consisting of promoting wound healing by using an external energy source. These solutions consist of treating the tissue with light energy emitted by a laser source onto the tissues in order to selectively heat specific parts of the skin, during a very short laser firing time (less than one second). The selective nature of the treatment means temperature elevation in the irradiated tissue areas is restricted.
In European patent application EP265470, for example, a device is known, which is used for uniting the lips of a wound. It includes a laser whose emission wavelength is chosen such that it can perform tissue bonding and unite the lips of the wound, and a holding piece suitable for being secured to the tissue around the wound so as to hold the lips of said wound in contact, at least while the wound is exposed to said laser radiation.
The key idea is to unite both skin and vessels, by using sufficient laser energy to achieve an increase in tissue temperature beyond 60° C., suitable for denaturing and achieving interdigitation of the collagen fibres. This temperature is currently acknowledged to be the level above which irreversible heat damage is caused if tissue is heated for longer than one second, leading to tissue coagulation and necrosis through burning, such as to slow and reduce the quality of the healing process.
Nevertheless, the solutions known the prior art invariably use identical firing power values, regardless of the skin type on which the treatment is carried out. However, the effects of a laser beam on the skin vary substantially from one skin type to another. Incorrect choices with regard to laser settings can thus lead to ineffective treatment or to burns.

DISCLOSURE OF THE INVENTION

The aim of the present invention is to solve the aforementioned problem, by offering a device for assistance in the wound healing process that takes into account the different skin types that are laser-treated in order to optimise the effectiveness of the wound-healing processes and to avoid any burning.
To this end, the invention provides a device for assistance in the skin wound healing process, comprising a laser source suitable for emitting a beam whose wavelength is between approximately 800 nanometres and approximately 820 nanometres.
The device of the invention includes a control module suitable for controlling the laser source according to data regarding the skin type of the patient to be treated.
“Laser source” is here understood to refer to the device emitting the beam that is focused on the skin to be treated. The laser source includes, in particular, the laser diode(s) and the optical means used to shape the radiation emitted therefrom.
“Control” is here understood to refer to any type of control or command influencing the characteristics of the beam focused on the skin. Such characteristics may for instance include the power, duration, shape or speed of movement of the laser beam.
In a first embodiment of the invention, the control module is suitable for controlling the laser source according to the skin phototype of the patient to be treated.
More particularly, the control module is suitable for controlling a laser source such that it emits, for a duration of less than 20 seconds, a fluence of:

- between approximately 80 J/cm²and approximately 130 J/cm²when the skin phototype is of category I, II or III,
- between approximately 60 J/cm²and approximately 100 J/cm²when the skin phototype is of category IV, and
- between approximately 20 J/cm²and approximately 60 J/cm²when the skin phototype is of category V or VI.

In a preferred variant of the invention, the control module is suitable for controlling a laser source such that it emits radiation for a duration that varies according to the phototype, whereby the duration will, in particular, decrease as the phototype number (category) increases.
More particularly, the control module is suitable for controlling a laser source such that it emits:

- for approximately 5 seconds to approximately 15 seconds when the skin phototype is of category I, II III or IV, and
- for a duration of greater than 10 seconds and less than 20 seconds when the skin phototype is of category V or VI.

In a second embodiment of the invention, the control module is suitable for controlling the laser source according to the lightness of the skin area to be treated. The parameter L* (for lightness) is part of the L*a*b* colour space description created by the International Commission on Illumination. The parameter L* is a non-linear function of luminance and does not have a measurement unit. L*=0 represents the colour black and L*=100 represents the colour white.
More particularly, the control module is suitable for controlling a laser source such that it emits, for a duration of less than 20 seconds, a fluence of:

- between approximately 110 J/cm²and approximately 130 J/cm²when the lightness of the skin area to be treated is greater than 80,
- between approximately 100 J/cm²and approximately 110 J/cm²when the lightness of the skin area to be treated is between approximately 75 and approximately 80,
- between approximately 80 J/cm²and approximately 100 J/cm²when the lightness of the skin area to be treated is between approximately 70 and approximately 75,
- between approximately 60 J/cm²and approximately 80 J/cm²when the lightness of the skin area to be treated is between approximately 65 and approximately 70,
- between approximately 40 J/cm²and approximately 60 J/cm²when the lightness of the skin area to be treated is between approximately 55 and approximately 65,
- between approximately 30 J/cm²and approximately 50 J/cm²when the lightness of the skin area to be treated is between approximately 45 and approximately 55, and
- between approximately 20 J/cm²and approximately 30 J/cm²when the lightness of the skin area to be treated is less than 45,

In a preferred variant, the control module is suitable for controlling a laser source such that it emits radiation for a duration that varies according to the lightness value of the skin area to be treated, whereby the duration will, in particular, increase as the lightness value increases.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will best be understood through reading the following description, given purely by way of example, referring to the appended illustrations, wherein:

FIG. 1 is a graph illustrating a logarithmic relationship between exposure time and temperature for inducing a heat shock response,

FIG. 2 is a graph illustrating the different phases of healing for a cutaneous wound,

FIG. 3 is a graph illustrating the different absorption coefficients of the main chromophores, as a function of laser source wavelength,

FIG. 4 is a graph illustrating the skin penetration (percentage depth) of a laser beam as a function of wavelength,

FIG. 5 is a graph illustrating the influence of skin phototype on skin temperature elevation,

FIG. 6 is a graph illustrating the influence of skin lightness on skin temperature elevation,

FIG. 7 is a graph showing a conventional laser beam profile and a laser beam profile as claimed in the invention,

FIG. 8 gives a schematic illustration of a laser beam conversion device as claimed in the invention,

FIGS. 9 and 10 are diagrams illustrating a dermatological treatment device as claimed in the invention,

FIG. 11 is a simplified diagram of a safety strip as claimed in the invention,

FIG. 12 illustrates the design that could be printed on a safety strip as claimed in the invention,

FIG. 13 is a schematic representation of the communications between an RFID component and the two microcontrollers in a device as claimed in the invention,

FIGS. 14 a to 14 c are graphs illustrating various temperature increase scenarios on the surface of an area of treated tissue, and

FIGS. 15 and 16 are logic flowcharts showing the processes at work in the microcontrollers in a device as claimed in the invention.

DETAILED DESCRIPTION OF THE INVENTION

The invention is based on moderate heating to provide heat treatment to a limited volume of cutaneous tissue surrounding and including a present or future cutaneous lesion (a future lesion, for instance, in the case of surgical incisions). As stated above, the invention does not provide for the selective heating of one or more skin constituents, but describes heating the whole of a volume located throughout the thickness of the skin (epidermis, dermis, upper layer of the subcutaneous tissue) in order to generate a biological response to the heat stress or thermal conditioning throughout the tissue. The choice of beam and all related parameters is therefore based on these specifications.
FIG. 1 illustrates a logarithmic relationship between exposure time on the y-axis (units in seconds) and the temperature for inducing a heat shock response along the x-axis (units in degree Celsius). Heat shock response is a cellular mechanism used to maintain stability when a shock (e.g. heat shock) is undergone. The heat shock response often involves the production of heat shock proteins (HSP), a protein group that can help accelerate the healing process.
The invention does not aim to alter the cell structure, but to influence the healing process by inducing HSP production. Indeed, uncontrolled hyperthermia can quickly lead to tissue damage and consequently to tissue denaturing and destruction. Using thermal conditioning, the invention provides for induction of a localised fever whose maximum temperature is controlled to prevent tissue damage.
By directing a source of electromagnetic energy such as a laser at the wounded tissue zone, thermal conditioning is induced such as to alter the inflammatory process. The link between a controlled temperature increase (moderate hyperthermia), HSP production and the inflammation process has been established in the prior art.
Referring to FIG. 2, the healing process involves three phases following the initial thrombosis:

- inflammation (21),
- proliferation (22) and,
- remodelling (23).

The x-axis of this graph shows the time since start of healing and the y-axis shows a level of response to a given heat shock and hence a level of HSP production.
A laser beam skin wound treatment process consists of directing light energy onto the tissue with the aim of generating moderate and controlled hyperthermia as early as possible in the healing process in order to prevent scarring and accelerate tissue regeneration, rather than correcting this scarring once the scar itself has appeared. The time at which the wound is treated must therefore be selected carefully with respect to the inflammation phase.
An optimum treatment window should be defined, to ensure that the peak of HSP production coincides with the inflammation phase. Since the HSP production peak may occur up to 24 hours after heat stress has been undergone, the conditioning treatment may take place up to 24 hours before the lesion appears.

Beam Selection:

The choice of beam and all related parameters is based on precise specifications. A digital simulation model was used, based on the finite element method, taking into account interactions between the light and the main chromophores in the treatment region, in order to confirm the theoretical choices.

Wavelength Selection:

FIG. 3 is a graph with three curves showing the energy absorption coefficient (y-axis) as a function of the energy wavelength (x-axis) for the following skin constituents: melanin, shown as curve 301, haemoglobin, shown as curve 302, and water, shown as curve 303.
FIG. 4 is a graph showing the rate of absorption of each skin layer for various wavelengths.
Referring to these figures, it can be observed that light absorption by the various chromophores can vary considerably according to wavelength.
Since the melanocytes are located in the basal layer of the epidermis, the wavelength must be greater than 800 nm in order to pass through this layer without being fully absorbed. At wavelengths of less than 590 nm, haemoglobin is the predominant chromophore and is therefore highly absorbent. However, at red and near-infrared wavelengths (between 600 nm and 1000 nm), there is relatively little absorption since neither water nor blood absorb energy at these wavelengths. Finally, for wavelengths greater than 1800 nm, absorption in water is extremely high and this absorption becomes the predominant factor.
The range of wavelengths to be used must therefore be between 800 nm and 1800 nm. In a preferred embodiment, the wavelength will be 810 nm or 910 nm. Advantageously, wavelengths of 1200 nm would minimise the absorption by melanin, but current technology does not provide a sufficiently powerful beam from laser diode source at this wavelength.

Laser Fluence Selection

FIGS. 5 and 6 illustrate the influence of skin type on the temperature reached by said skin under laser illumination at a wavelength of 810 nanometres.
FIG. 5 shows skin temperature curves as a function of laser fluence in joules per cm²for patient with different skin phototypes. The fluence of the beam is the energy transmitted per cm².
These curves were obtained in experiments involving patients with different skin phototypes, whereby curve C1 describes skin of phototype V, curve C2 describes skin of phototype IV, curves C3, C4 and C6 all describe skins of phototype III and curve C5 describes skin of phototype II.
Phototype is a numerical classification of skin type that is well known in the field of dermatology. It takes into account a person's genetic disposition, reaction to sun exposure and tanning habits. Skin phototype, as determined by the score given in the Fitzpatrick skin typing test, is commonly used by healthcare professionals and can help support various diagnostic and treatment procedures for the skin.
As can be seen from FIG. 5, skin heating depends heavily on skin phototype. Moreover, a spread of behaviours is observable even within a single phototype category, as illustrated by curves C3, C4 and C6.
The inventors thus observed that, for a wavelength of between 800 nanometres and 820 nanometres, the following ranges of fluence values provide for an effective process of wound healing, as sought, whilst avoiding any burning due to overexposure:

- fluence between approximately 80 J/cm²and approximately 130 J/cm²when the skin phototype is of category I, II or III,
- fluence between approximately 60 J/cm²and approximately 100 J/cm²when the skin phototype is of category IV, and
- fluence between approximately 20 J/cm²and approximately 60 J/cm²when the skin phototype is of category IV.

Outside of this range of fluence values, a reduced healing effect or burning may be observed, or wholly ineffective treatment.
In addition, the fluence should be transmitted for a duration that is less than a specified threshold, in order to promote effective skin heating, leading to the desired healing effect. A maximum fluence transmission time of less than 20 seconds is suitable for achieving the desired heating effect. Beyond this duration, the heating is too shallow. The exposure time can, for example, be managed by controlling the duration of the laser pulses.
The spread of temperature values observed in a group of people with the same phototype may have various causes. The Fitzpatrick skin typing test does not only take into account skin colour, but also considers criteria such as eye and hair colour, skin reaction to sunlight or tanning habits. Although phototype values given by the Fitzpatrick test are a good indicator, enabling the fluence of the laser treatment to be adjusted without requiring any specific equipment for detecting skin type, the precision of the phototype scale remains somewhat limited.
FIG. 6 shows skin temperature curves as a function of laser fluence in joules per cm2 for skins with different lightness values, as measured with a conventional chromameter.
As can be seen from curves C7, C8 and C9, obtained from experiments on skin with the same phototype but with lightness values of 70, 73 and 77 respectively, temperature elevation is heavily dependent of the lightness of said skin.
The inventors thus observed that, for a wavelength of between 800 nanometres and 820 nanometres, the following ranges of fluence values provide for an effective process of wound healing, as sought, whilst avoiding any burning due to overexposure:

- fluence between approximately 110 J/cm²and approximately 130 J/cm²when the lightness of the skin area to be treated is greater than 80,
- fluence between approximately 100 J/cm²and approximately 110 J/cm²when the lightness of the skin area to be treated is between approximately 75 and approximately 80,
- fluence between approximately 80 J/cm²and approximately 100 J/cm²when the lightness of the skin area to be treated is between approximately 70 and approximately 75,
- fluence between approximately 60 J/cm²and approximately 80 J/cm²when the lightness of the skin area to be treated is between approximately 65 and approximately 70,
- between approximately 40 J/cm²and approximately 60 J/cm²when the lightness of the skin area to be treated is between approximately 55 and approximately 65,
- between approximately 30 J/cm²and approximately 50 J/cm²when the lightness of the skin area to be treated is between approximately 45 and approximately 55, and
- between approximately 20 J/cm²and approximately 30 J/cm²when the lightness of the skin area to be treated is less than 45.

Analogously to what has described above, said fluence should be transmitted for a duration of less than 20 seconds in order to produce the desired healing effect.
Moreover, the inventors also noted that the darker the skin is, the longer the duration of fluence transmission that should be applied. Indeed, with dark skins, the transmission of light energy over a short duration has the effect of heating surface layers of the skin rather than heating in depth. If the illumination is spread over time, the skin is heated by thermal diffusion.
Notably, the laser beam is controlled such that its duration varies according to the phototype, whereby the duration will in particular decrease as the phototype number (category) increases. More particularly, once the fluence has been determined according to skin phototype, it is preferable to have illumination for approximately 5 seconds to approximately 15 seconds when the skin phototype is of category I, II, III or IV and illumination for a duration of greater than 10 seconds and less than 20 seconds when the skin phototype is of category V or VI.
Analogously, the laser beam is controlled such that it varies according to the lightness value of the skin area to be treated, whereby the duration will in particular increase as lightness increases.

Spot Shape Selection:

The shape of the laser spot must also be studied in order to provide deep heating and stimulate all tissues involved in the skin wound healing process: the subcutaneous tissue, dermis, and epidermis. Since depth is near-proportional to the laser spot diameter, a diameter greater than or equal to 3 mm will be preferred in the case of a round spot. Ideally, the spot shape could also be tailored to the geometry of the area to be treated, to enable the most homogeneous distribution possible of light energy within the target tissue. In a preferred embodiment, a rectangular spot shape whose width is at least 3 mm and whose length may be several centimetres will be selected, in order to treat linear wounds.

Temperature Precision in the Heated Volume and Laser Beam Profile:

The invention additionally relates to the temperature precision achieved within the heated volume. The digital model developed can be used to optimise all parameters and achieve a minimum temperature of 45° C. (temperature required to induce heat stress) and a maximum temperature of 55° C. As described in the prior art, temperatures in excess of 60° C. can induce protein denaturing and therefore counteract the desired effect. The maximum temperature of 55° C. means that this threshold value will not be exceeded.
For these reasons, and as shown in FIG. 7, which illustrates both a conventional Gaussian beam profile (curve 512) and the beam profile of a device as claimed in a possible embodiment of the invention (curve 510), a conventional Gaussian beam profile is not the most suitable profile. Indeed, as the name suggests, the energy distribution is similar to a Gaussian function, which has the direct effect of heating the skin surface in a non-uniform manner, with a major temperature peak in the centre of the irradiated zone. The temperature gradient will therefore be too great with respect to the temperature range in which it is desirable to operate.
A flat-top (or top-hat) profile (510) is consequently to be preferred to a Gaussian profile in order to ensure the skin surface temperature is homogenised, as is the temperature of the heated volume. This flat-top power profile, shown as curve 510, gives a more homogeneous heating effect throughout the heated area, rather than a selective heating action. This profile is defined by three components:

- the ratio of wavefront width (515) to full-width half-maximum (FWHM) (514),
- the rate of variation (516) along the wavefront width (515),
- the nominal power (518) which is the mean power along the wavefront width (515).

One feature of a flat-top profile is a minimal rate of variation (516) along the wavefront width, with a maximal wavefront width-to-FWHM ratio. Advantageously, a flat-top profile will have a rate of variation of less than 5% and a ratio of wavefront width-to-FWHM of greater than 90%.
The spot shape will depend on the medical indication. In a preferred embodiment and in a configuration chosen for treating incisions, the spot dimensions will be 20 mm by 4 mm, and the rate of variation less than +/−20% of nominal power (518).
In order to achieve this particular profile, the invention provides a means for shaping the laser beam emitted by the diode (since on output from the diode the laser beam has a Gaussian profile). An example of such a system is shown in FIG. 8.
In one possible embodiment of the invention therefore, the laser beam shaping means (61) is positioned downstream of a laser diode (62), advantageously characterised in that its emission width is 200 μm by 5 μm and its divergence is 8×35°. An optical fibre (63) positioned in front of the diode acts as a cylindrical lens to reduce divergence of the diode's fast axis advantageously to approximately 5°. The laser beam then passes through the laser beam shaping means (61), which includes a system of two lens arrays (64) and a cylindrical lens (66), which splits the original beam into as many beams as there are lenses in the lens array (64). Each sub-beam is focused at the desired distance and all these beams are then superimposed to achieve a flat-top profile.
The beam's focal distance depends chiefly on the focal length of the cylindrical lens. The homogeneous nature of the profile depends however both on the focal length of the cylindrical lens and on the focal length of the two lens arrays. Furthermore, to achieve the most homogeneous flat-top beam profile possible, the input beam must strike as many lenses in the array as possible (the greater the number of sub-beams formed, the more likely the sub-beams are to tend towards a flat-top profile when combined). There is, therefore, a balance to be struck between the distance between the diode and the first lens array and the angle of divergence, in order to maximise homogeneity of the flat-top profile, whilst reducing the length of the final system.

PREFERRED EMBODIMENTS

In order for the technique to be accessible to as many users as possible, the device is designed to be easy and safe to use under all circumstances and in all locations in which it may be used, from a general practitioner's surgery to the sterile environment of an operating theatre. Since users may travel or make regular visits, the size and portability of the device is also a key factor. In addition, as described above, the invention provides that the light source is applied as early as possible in the healing process in order to prevent the appearance of scarring, rather than correcting this once the scar has appeared. For this purpose, users need a medical device that can enable early intervention, i.e. directly in the operating theatre in a sterile environment.
The medical device should therefore be designed to be small, portable, easy to use with one hand and autonomous (wireless) and further designed to avoid jeopardising the cleanliness or sterility of the environment in which it is used.
One embodiment of a device as claimed in the invention will now be described, referring to FIGS. 9 and 10.
A dermatological treatment device (70) as claimed in the invention includes a closed optical unit (722), including at least one laser system (72) comprising a power laser diode whose wavelength is between 800 nm and 820 nm, preferably equal to 810 nanometres and whose power is greater than 1 W and less than 25 W, and conversion means (74) consisting of a lens array or a phase array. The laser system (72) and conversion means (74) are designed to emit a laser beam with the aforementioned advantageous characteristics. Optical unit (722) may also include a sighting laser (73), whose power is less than 1 mW for instance, in order for said sighting laser to provide comfort in use and not generate any biological response. In order to ensure this sighting laser (73) is visible, its wavelength may for instance be between 480 nm and 650 nm (red colour).
The invention provides that optical unit (722) is removable and interchangeable in order to facilitate maintenance of treatment device (70) and ensure its flexibility (ability to change diode type according to the desired treatment type). The invention therefore provides the device user (e.g. medical practitioner) with a selection of optical units, each of which will have different configurations and all of which comply with the safety-related constraints (the user cannot change the settings himself).
Treatment device (70) also comprises an energy source (battery) (71) for full autonomy. This battery may be interchangeable.
Treatment device (70) includes one or more electronic circuits (710) whose function is to manage power supply to the device and the various components in the device.
The treatment device includes an RFID reader (711) (e.g. RFID antenna), used to make the device safe by ensuring that the laser only fires when it is in the vicinity of an RFID component (tag) affixed close to the treatment area, thus preventing any risk of harm for the user, patient and other nearby persons. This system also enhances treatment safety by reading pre-recorded settings from the tag, meaning that the practitioner cannot accidentally change any potentially dangerous parameter (chiefly laser power and firing time). The laser settings are controlled on the basis of information transmitted by the RFID component, which contains configuration data that can adjust the firing power, firing time and number of pulses, according to the user's choices, in order to obtain the fluence values described above according to the skin phototype of the patient to be treated.
The user will select the attachment element according to the nature of the treatment to be performed, and the selected tag will transmit a signal or information which will control the laser emissions. The attachment element consists for instance of a patch formed by a piece of adhesive fabric that includes a radio frequency identification (RFID) tag, consisting of an antenna design that enables inductive coupling for power supply to a high frequency component and transmission of a high frequency signal emitted by said component.
The attachment element must be placed close to the treatment zone such that treatment device (70) is within interaction range of the tag throughout the duration of treatment.
These RFID components are widely described in the prior art. However, the invention provides that the RFID component also plays a role in automating the process. The RFID component has an identifier which refers to a settings table in the laser software. This table contains preset values for firing power and firing time and also the type of patient to be treated (for a safety check by the practitioner). When using the device, the user simply selects a safety strip (containing RFID components) based on the patient's skin phototype and indication (wound, acne treatment, skin remodelling etc.). Unlike other laser systems on the market, the user cannot adjust the operating settings. Treatment parameters are therefore based solely on the choice of strip containing the treatment identifier.
Advantageously, the distance between the RFID component and the treatment device (70) is between one and fifteen centimetres. This distance is assessed by the limited range of the interaction means between said component and treatment device (70) or by a range-finder, for instance an ultrasound range-finder integrated in the device.
The treatment device also includes a pyrometer (712), used to monitor the temperature increase that can cause superficial burning (temperature greater than 60° C.). The pyrometer (712) is used to set up a closed loop on the laser beam. Pyrometer (712) is in fact a safety component that monitors skin surface temperature. It operates to “lock down” or deactivate laser firing if the temperature reaches a preset threshold value. Pyrometer (712) can also be used in a more advanced way within a closed control loop in order to readjust the laser settings.
In general, the temperature at the surface and deeper in the epidermis will depend on a variety of parameters such as:
1—wavelength, which is a key factor in the absorption and scattering of light by the various chromophores (water, haemoglobin, melanin),
2—laser power, causing heating to a greater or lesser depth,
3—spot shape and size, which influence the heat distribution at depth,
4—beam profile, which has a direct impact on the temperature gradient across a beam cross-section (Gaussian profile, flat-top profile),
5—firing time which, at a given power, the longer it is promotes a thermal diffusion heating system,
6—finally, parameters directly related to the patient, the most significant of which is likely to be the skin phototype.
There may not therefore be a general correlation between the surface temperature of the epidermis and the temperature of lower layers. However, if all laser-related parameters (points 1 to 5) are fixed, it is possible to “predict” the temperature increase in the tissue on the basis of a human factor, for instance the phototype.
In addition, a transparent optical window (713) in the wavelength range between 480 nm and 1.4 μm shall be provided. In a preferred embodiment, potassium bromide that is transparent from wavelengths from 450 nm to 10 μm could be chosen.
A standby system could be also added to the device, to operate when the device is not used for a preset length of time. Standby mode is interrupted as soon as user presses either of the fire buttons. This type of system saves battery power, on the one hand, but in particular prevents the sighting laser (even a low power laser) from causing eye damage.
In addition, the treatment device could include a cooling system comprising an internal radiator (714) connected directly or via a heat pipe to the laser diode. Furthermore, one possible embodiment of the invention provides a natural and/or forced ventilation device to extract heat generated by the laser diode from the device in a sterile manner in order to avoid jeopardising the sterility of the operating area in which the treatment device (70) is used.
Advantageously, the device could be fitted with a user interface to provide the user with information on the operating parameters (wavelength, settings contained in the RFID component and read by the RFID treatment device, temperature measured by the pyrometer).
Details of the user interface on a treatment device as claimed in the invention will now be given. Advantageously, the user interface on a treatment device of the invention includes the following items:

- an LCD screen (75), feeding back information to the user on the operating settings and parameters of the device of the invention (the LCD screen may be a touch-screen),
- an emergency stop button (76), which the user can activate to quickly shut down (20) the device in a emergency,
- an on/off button (77) to switch the device on or off,
- a double button system (88) to safely fire the laser. The double button system (two buttons, one on either side) makes the firing operation safe in that the laser can only fire when both buttons are held down by the user. As soon as the user releases either button, the laser immediately stops firing. Consequently, if the handpiece were to be inopportunely placed on a work surface and one of the buttons was resting on an item on the work surface, the laser could not fire.
- an indicator light (89) to show the user that the device is operating,
- a buzzer (717) to warn the user of a problem (battery problem, high temperature measured by the pyrometer).

Advantageously, a possible embodiment of the invention provides a removable sterile sleeve (80) designed to contain the device and isolate it from the external environment. This sleeve can be understood as a sterile casing in which the device is placed in order to ensure that the area in which the device is used remains sterile. Advantageously, removable sleeve (80) is designed not to interfere with the laser beam. For this purpose the device shall have a window that is transparent to the predefined wavelengths, in order to allow a beam whose wavelength is within the range of preset wavelengths to pass through. Removable sleeve (80) is further designed not to interfere with pyrometer (712) or RFID reader (711) operation. Removable sleeve (80) also allows heat extraction without causing a detrimental effect on the sterile environment in which treatment device (70) is used. Using this sleeve, the laser can be fired without altering the sterility of the sleeve's outside surfaces.
The sleeve must obviously be sealed and have a sealed closure system, in order to provide a microbial barrier between the device and its external surroundings. Nevertheless, this sterile barrier must not hinder the extraction of heat generated by the device. The sleeve therefore contains at least two filters (an air inlet and air outlet filter) to allow air circulation inside the sleeve.
Moreover, the sleeve must not hinder access to the device controls (firing buttons, switch, emergency stop button), prevent information from being read (LCD screen, indicator lights) or the device from being gripped. In a preferred embodiment, the sleeve shall therefore comprise a rigid section at the bottom of the device for correct positioning and a flexible transparent upper section covering the rest of the device.
Since surfaces (81) and (82) are in contact with the patient, the risk that the sleeve could come into contact with blood, particularly when treating an incision, should not be ignored. Indeed, if the sleeve is in contact with blood, the blood can accumulate on it as the sleeve is moved across the rest of the incision. Since the laser beam passes through the sleeve, it could be absorbed by these traces and consequently lose part of the treatment energy in this zone. In a preferred embodiment, treatment device (70) and the lower rigid part (87) of sleeve (80) in contact with the treatment area both include a recess (83) opposite the laser beam output, ensuring there is no direct contact with the patient and therefore no fouling or contamination. This design also ensures a distance between the beam shaping system output and the tissue zone to be treated.
The sleeve therefore comprises one rigid section and one flexible section (to be handheld and for easy use of the buttons). It is intended that both sections be made of PVC, with a thickness of between 2 and 3 tenths of a millimetre for the flexible section and a few millimetres for the rigid section.

RFID Component

Referring to FIG. 11, and as described above, the treatment shall be made safe and controlled by means of a safety strip (90) containing an RFID chip which will transmit the various operating settings to the laser device, on the basis of the medical indication and skin phototype of the patient to be treated. Said safety strip (90), which may be produced in several different lengths (e.g. 4, 10 and 20 cm), is affixed approximately 5 mm away from the zone to be treated.
The safety strip comprises two adhesive attachment elements: one double-sided adhesive element (91) and another single-sided adhesive element (93). These two elements sandwich the RFID components (92), which are arranged every 2 cm. The safety strip may, for instance, be 2 cm wide.
Lower adhesive element (91) is in contact with the patient's skin. It must therefore be biocompatible and offer appropriate adhesion to the skin during use. Lower adhesive element (91) must stick to the patient's skin and also bond correctly with both the RFID component and upper adhesive element (93). The lower adhesive element is therefore a double-sided adhesive.
The safety strip manufacturing process shall include a sterilisation stage.
Upper adhesive sub-element (93) must be a single-sided adhesive in order to be assembled with RFID component (92) and lower adhesive element (91). As shown in FIG. 12, information shall be printed on upper section (93), such as skin phototype, the company name, product number and a scale to help the practitioner gauge progress of the treatment.
Upper adhesive element (93) is designed not to interfere with RFID communication between the RFID reader (711) (see FIG. 9) in the device and the (25) RIFD components (92). The RFID components (92) must comply with the ISO 15693-3 standard. The mandatory and optional sections, as defined by said standard, are to be implemented. Since the RFID transmission range is critical, RFID components (92) as claimed in the invention shall be such that this value can be fixed once the “RFID component-RFID reader” pair has been selected. The size of said RFID components may for instance be 14 mm×14 mm and the thickness less than 1 mm. The EEPROM storage capacity of the RFID component shall be at least 1024 bytes. The production process shall also include sterilisation with ethylene oxide.

Communication Process Between the RFID Component and the Device

As shown in FIG. 13, the device comprises two microcontrollers (111 and 112). One microcontroller (111) manages the laser, energy, thermal control and the user interface. The other microcontroller (112) manages the safety strips (90). Responsibility for managing the laser firing is shared by both microcontrollers (111 and 112). The laser may be stopped due to excessive temperature (15) (managed by microcontroller 111) or an emergency stop request (microcontroller 111). If the stoppage conditions still apply, laser treatment cannot resume.
Referring to FIGS. 14 a, 14 b and 14 c, a pyrometer (712) (see FIG. 7) stops the laser if the skin temperature exceeds a critical temperature, for instance 60° C. (managed by microcontroller 111). These figures are graphs which show temperature curves 120, 121 and 122 (temperature in degree Celsius on the Y-axis) as a function of heating time (TC, on the X-axis). TC1, TC2 and TC3 represent the times at which the laser is stopped. If the laser has been stopped (25) by the pyrometer (712), it can be authorised to operated once more only, after a safety delay (e.g. 5 seconds), if during the first laser emission, the firing time was less than or equal to half the preset firing time (as managed by microcontroller 112). This is the case in FIG. 14 c. The figures therefore illustrate the following scenarios:

- FIG. 14 a illustrates a scenario in which the laser is stopped (TC1) after 50% of the preset firing time has elapsed; in this case the laser treatment cannot be resumed,
- FIG. 14 b illustrates a scenario in which the laser is not stopped before the end of the preset firing time (TC2),
- FIG. 14 c illustrates a scenario in which the laser is stopped (TC3) before 50% of the preset firing time has elapsed; in this case the laser treatment may be resumed.

If the pyrometer (712) trips after 50% or more of the normal firing time has elapsed (FIG. 14 a), the end of normal firing should be indicated with a beep (microcontroller 111). If the pyrometer (712) trips before 50% of the time has elapsed, a display on the user interface shall indicate to the user that the laser treatment may be resumed.
If the user stops the laser voluntarily or otherwise and the elapsed time is less than or equal to 75% of the preset firing time, the laser treatment may be allowed to resume once only, after a 5 second delay. This re-authorisation is valid for a 60 minute period.
If the emergency stop system is activated (FIG. 9, button 76), a checking procedure could be provided.
The presence of an RFID component (92) is indicated by the TTL pin (113) on the microcontroller (112). The presence of an RFID component (92) gives no information regarding its status. To find out the status of RFID component (92), a “read settings” message must be sent to microcontroller (112). This command requests information on the treatment status of RFID component (92), which is in range of RFID reader (711). The status of an RFID component (92) may be one of the following:

- Treated,
- OK (Not Treated),
- Immediate resume (identical to not treated),
- Wait then resume (5 seconds),

Microcontroller (111) recognises five messages from microcontroller (112):

- INIT: Initialising clock and device identification,
- PARAM: Retrieve information on RFID component (92) status, firing power and firing time (firing only allowed if status is OK),
- START: Start firing,
- STOP: Stop firing,
- PAUSE: Prematurely stop firing.

When the device starts, microcontroller (111) initialises the clock in microcontroller (112) with the INIT message. Both clocks are synchronised. At the rising edge of the TTL pin (113) on microcontroller (112), microcontroller (111) requests the laser settings via the PARAM message. Depending on the reply message from microcontroller (112), the user interface is updated and firing is authorised. During laser emission, microcontroller (111) indicates progress to microcontroller (112) with the messages START, STOP and PAUSE. Microcontroller (112) updates the information in the RFID components (92) according to these messages. The device clock is managed by microcontroller (111). It does not contain the exact date and time, but dating information related to the device start-up. It operates as a timer. The device clock may be reinitialised following extended battery power loss. In this case, if an RFID component (92) has been treated, its treatment start date is later than the current date. Even if treatment has not been completed, RFID component (92) is considered as treated.
FIG. 15 illustrates a logic flowchart for microcontroller (111). Thus box (1301) shows detection of the presence or otherwise of an RIFD component. If not detected, the user interface will indicate that no RFID component was found (box 1302). If an RFID component is detected, the “read settings” command is initiated (box 1303) to diagnose RFID component status (box 1304). If status is OK, the device indicates via the user interface that it is “ready” (box 1305), and if the trigger is activated (box 1306), then microcontroller (111) sends microcontroller (112) the START message (box 1307) to indicate that laser emission should be started. The laser is switched on (box 1308). If the message is WAIT, the device will indicate that it is on “standby” (box 1309) and the process goes back to the start of the flowchart. If the message is TRT OK (treated), the device indicates that the zone has been treated (box 1310) and the process goes back to the start of the flowchart.
If firing is initiated (box A), temperature measurement (box 1311) is performed. If the temperature is greater than 60° C., a time measurement (box 1312) is also performed. If this time value is less than 50% of the preset firing time, a PAUSE message (box 1313) is sent to microcontroller (112) and the laser is switched off (box 1314).
If the temperature measured (box 1311) is less than 60° C., a time measurement (box 1315) is also performed. If this time value is less than 75% of the preset firing time, a further temperature measurement (box 1311) is performed. If, on the other hand, the time value is greater than 75% of the preset firing time TC, a STOP message (box 1316) is sent to microcontroller (112). A temperature measurement is then performed (box 1317), and if temperature is less than 60° C., the firing time is checked (box 1318). If the actual firing time is less than the preset firing time TC (meaning that the laser treatment has not yet finished), a further temperature check is performed (back to box 1317). This loop continues until the temperature exceeds 60° C. or until the firing time reaches or exceeds TC. In either case, the laser is turned off (box 1320), and a beep (box 1321) (or any other user interface signal) is sent to advise user that treatment has finished in this zone, and an end of treatment message is displayed (box 1322). Coming back to box 1312, if the actual firing time is greater than 50% of TC, a STOP message is sent to the microcontroller (box 1319) and the laser is turned off (box 1320). If the actual firing time is less than or equal to 50% of TC, a PAUSE message is sent to microcontroller (box 1314) and the laser is turned off.
Referring to FIG. 15, a firing authorisation management logic flowchart for microcontroller (112) will now be described. If an RFID tag is detected (box 1401), microcontroller (111) waits for a message (box 1402). When a message (box 1403) is received, said message is analysed. If the message is START, and the laser was last fired less than 5 seconds ago (box 1405), microcontroller (111) sends the WAIT message (box 1406). If, on the other hand, the laser was last fired more than 5 seconds ago, the totaLstart variable (indicating the number of times the laser has fired) is increased by one increment (box 1407) and the last_start variable (indicating the date at which the laser last fired) is updated (box 1408). Finally an OK message is sent (box 1409).
If the message received is STOP, the totaLstart variable is set to a predetermined maximum (box 1410) and the OK message is sent (box 1411).
If the message received is PAUSE, the end of firing date is recorded (box 1413).
Finally, if the message received is PARAM, the totaLstart variable (box 1414) is analysed. If this variable is lower than the specified maximum, the TREATED message is sent (box 1415). If not, the last_start variable (box 1416) is analysed. If this variable is greater than 60 minutes, the TREATED message is sent (box 1415). If not, a check is performed to see whether the laser was last fired more than 5 seconds ago (box 1417). If not, the WAIT message is sent (box 1418). If, on the other hand, the laser was last fired more than 5 seconds ago, the OK message is sent and the settings are read (box 1419). The information in the RFID component could be selected from the following possibilities: unique RFID component identifier, manufacturing date, expiry date, device settings identifier based on skin type, safety strip manufacturing batch number.
Obviously, all the numerical values in this description (e.g. percentages, temperature etc.) are given simply for reference in order to guide production of the invention. Other values could be used for instance as determined by experimentation, whilst still remaining within the scope of the invention.
In a possible embodiment of the invention, the adhesive attachment element shall have a threefold safety role:

- making the device safe by immediately stopping the device from operating when the RFID component (92) in the adhesive attachment element (90) is no longer within range of the RFID reader (711) in the device.
- defining the treatment settings. The user selects the adhesive attachment element according to the patient's skin type, and the pre-programmed RFID components (92) within adhesive attachment element (90) directly transmit the appropriate information to the device.
- protecting integrity (single use). When in use, the device records information about treatment status on the RFID components (92) in the adhesive attachment element. Treatment status may be as follows: zone not treated, zone being treated, and zone treated. Once treatment is completed, the device, upon receiving information about the status of the zone to be treated, has means of preventing reuse of any adhesive attachment element (90) whose identification means has already been used once for treating a treatment zone. This RFID component locking principle ensures that each adhesive attachment element can be used only once. The direct benefit of this system is that it prevents:
  - a repeated treatment in the same place (overdose risk prevention)
  - reuse of a used adhesive attachment element (which was sterile when delivered)

The means of preventing reuse of adhesive attachment element (90) could directly be included in the RFID component itself.
A preferred embodiment has been described in which microcontrollers 111 and 112 control the laser power and firing time on the basis of data contained in the RFID tags in a strip chosen by the practitioner following a Fitzpatrick skin typing test to ascertain the patient's phototype. The laser control settings can be used to ensure the fluence values are within a range determined by the skin phototype, as described above, in order to achieve a suitable wound healing effect, whilst avoiding any burning, in a safe environment, secured by the use of such strips.
In a variant, the laser has a chromameter connected to microcontroller (111). In this case, skin lightness is used as the basis for selecting the laser power and firing time, in order to ensure the fluence values are within a range determined by the lightness value, as described above.

Claims

1. Device for assistance in the skin wound healing process, comprising a laser source suitable for emitting a beam whose wavelength is between approximately 800 nanometres and approximately 820 nanometres, wherein it includes a control module suitable for controlling the laser source according to data regarding the skin type of the patient to be treated.

2. Device for assistance in the skin wound healing process, as claimed in claim 1, wherein the control module is suitable for controlling the laser source according to the skin phototype of the patient to be treated.

3. Device for assistance in the skin wound healing process, as claimed in claim 2, wherein the control module is suitable for controlling the laser source such that it emits, for a duration of less than 20 seconds, a fluence of between approximately 80 J/cm²and approximately 130 J/cm²when the skin phototype is of category I, II or III.

4. Device for assistance in the skin wound healing process, as claimed in claim 2, wherein the control module is suitable for controlling the laser source such that it emits, for a duration of less than 20 seconds, a fluence of between approximately 60 J/cm²and approximately 100 J/cm²when the skin phototype is of category IV.

5. Device for assistance in the skin wound healing process, as claimed in claim 2, wherein the control module is suitable for controlling the laser source such that it emits, for a duration of less than 20 seconds, a fluence of between approximately 20 J/cm²and approximately 60 J/cm²when the skin phototype is of category V or VI.

6. Device for assistance in the skin wound healing process, as claimed in claim 2, wherein the control module is suitable for controlling the laser source such that it emits radiation for a duration that varies according to the phototype, whereby the duration will, in particular, decrease as the phototype number (category) increases.

7. Device for assistance in the skin wound healing process, as claimed in claim 6, wherein the control module is suitable for controlling the laser source such that it emits for approximately 5 seconds to approximately 15 seconds when the skin phototype is of category I, II, III or IV.

8. Device for assistance in the skin wound healing process, as claimed in claim 6, wherein the control module is suitable for controlling the laser source such that it emits for a duration of greater than 10 seconds and less than 20 seconds when the skin phototype is of category V or VI.

9. Device as claimed in claim 1, wherein the control module is suitable for controlling the laser source according to the lightness of the skin area to be treated.

10. Device for assistance in the skin wound healing process, as claimed in claim 9, wherein the control module is suitable for controlling the laser source such that it emits, for a duration of less than 20 seconds, a fluence of between approximately 110 J/cm²and approximately 130 J/cm²when the lightness of the skin area to be treated is greater than 80.

11. Device for assistance in the skin wound healing process, as claimed in claim 9, wherein the control module is suitable for controlling the laser source such that it emits, for a duration of less than 20 seconds, a fluence of between approximately 100 J/cm²and approximately 110 J/cm²when the lightness of the skin area to be treated is between approximately 75 and approximately 80.

12. Device for assistance in the skin wound healing process, as claimed in claim 9, wherein the control module is suitable for controlling the laser source such that it emits, for a duration of less than 20 seconds, a fluence of between approximately 80 J/cm²and approximately 100 J/cm²when the lightness of the skin area to be treated is between approximately 70 and approximately 75.

13. Device for assistance in the skin wound healing process, as claimed in claim 9, wherein the control module is suitable for controlling the laser source such that it emits, for a duration of less than 20 seconds, a fluence of between approximately 60 J/cm²and approximately 80 J/cm²when the lightness of the skin area to be treated is between approximately 65 and approximately 70.

14. Device for assistance in the skin wound healing process, as claimed in claim 9, wherein the control module is suitable for controlling the laser source such that it emits, for a duration of less than 20 seconds, a fluence of between approximately 40 J/cm²and approximately 60 J/cm²when the lightness of the skin area to be treated is between approximately 55 and approximately 65.

15. Device for assistance in the skin wound healing process, as claimed in claim 9, wherein the control module is suitable for controlling the laser source such that it emits, for a duration of less than 20 seconds, a fluence of between approximately 30 J/cm²and approximately 50 J/cm²when the lightness of the skin area to be treated is between approximately 45 and approximately 55.

16. Device for assistance in the skin wound healing process, as claimed in claim 9, wherein the control module is suitable for controlling the laser source such that it emits, for a duration of less than 20 seconds, a fluence of between approximately 20 J/cm²and approximately 30 J/cm²when the lightness of the skin area to be treated is less than 45.

17. Device for assistance in the skin wound healing process, as claimed in claim 9, wherein the control module is suitable for controlling the laser source such that it emits radiation for a duration that varies according to the lightness of the skin area to be treated, whereby the duration will, in particular, increase as the lightness increases.