Patent Application
20090048590
The present invention relates to methods and systems for treatment of nail-bed infections. More specifically, the present invention relates to methods and systems for treatment of nail-bed fungus involving the application of thermal energy.
Nail disorders comprise about ten percent of all skin disorders and fungal nail infections (onychomycosis) account for approximately fifty percent of all nail problems. It is estimated that two to three percent of the United States population has onychomycosis. The disorder is twice as frequent among men and increases with age.
Onychomycosis, which causes the nails to become thickened, hard to cut and often painful, is worsened by moisture, warmth, trauma, communal bathing, and other activities that lead to the exposure to fungi. Common complaints of the disorder are pain, deformed nails, and interference with daily activities such as walking, typing, or playing a musical instrument. Those who suffer from onychomycosis cite a substantial negative effect on their quality of life. Fingernail infections have a significant effect on the life of infected individuals. Embarrassment may prevent patients from taking part in social situations because they feel unwilling to show their hands or feet.
While Onychomycosis typically refers to the invasion of the nail bed by a fungus, the infection may be due to a fungus, a mold, or non-dermatophyte yeast. The group of fungi most commonly responsible for causing infection of the nail bed are known as dermatophytes and include the genera Trichophyton, Microsporum, and Epidermophyton. Infections can also be caused by Candida species, which are yeasts. The most common Candida species causing infection is Candida alicats. The most common non-dermatophyte molds associated with nail disease are Scopulariopsis, Scytalidium, Fulsarium, Aspergillus and Onychocola canadensis.
Until now, the methods and devices for treating onychomycosis have included treatment with topical antifungal agents, oral antifungal drugs, thinning or partial removal of the nail, and permanent removal of the nail. Often, these techniques take up to year to no longer see the symptoms of onychomycosis.
It has been demonstrated that the application of heat at various time and temperature combinations reliably kills the P. acnes and Staphylococcus aureus bacteria, as well as the HSV1 virus. The necessary temperature range to kill bacteria is generally above 47 degrees Celsius. but below the bum or discomfort threshold for human skin. Depending on the area of skin and the area of surface contact, this upper threshold is in the range of 51 degrees Celsius. A treatment method using a rapid, transient heat application, has been suggested for the treatment of onychomycosis (Chato, J. C., Thermal Therapy of Toe Nail Fungus, Int'l Mech. Eng. Congress and Exposition 2000, Nov. 11-16, 2000, Orlando, Fla.). This method employed the use of hot water, heated to a temperature of 50 degrees Celsius, applied near the base of the nail for a period of 4 to 5 seconds repeated three times, approximately 15 seconds apart. Because of the thick nail plate and possible separation of the nail plate from the nail bed, this rapid, transient heat application is unlikely to have any appreciable effect on the fungal infection.
This invention relates to the use of a regulated heat source that can be applied to a nail bed infection, such as onychomycosis, in order to initiate and/or accelerate the death of the bacteria, dermatophyte, mold, virus, or non-dermatophyte yeast causing the nail bed infection and thereby speed the recovery process.
In one embodiment, a device for treating nail bed fungus is described. The device includes a thermal delivery surface designed to be placed in contact with the nail plate. The thermal delivery surface is adapted to transfer thermal energy from the device to the nail bed. There may also be a thermal transfer medium that is attached to the nail plate. The thermal transfer medium is designed to be flexible, deformable, and highly conductive and is used to improved the transfer of thermal energy from the thermal delivery surface to the nail bed. Thermal transfer from the thermal deliver surface may further be enhanced by a spring tensioning system used to apply a downward pressure on the thermal delivery surface according to embodiments of the invention. In situations were the nail plate has separate from the nail bed, a thermal gel can be applied to the air gap formed between the nail plate and nail bed. The combination of the thermal delivery surface, thermal transfer medium, thermal gel, and downward force of the spring tensioning system provide greatly improved thermal energy transfer.
In another embodiments the thermal delivery surface is attached to the nail plate using a flexible strap. The flexible strap may be made of an elastic material and a fastening system is used to apply the thermal transfer surface to the nail plate. The flexible nature of the strap allows tension to be applied to the strap to produce a downward pressure on the thermal transfer surface. As discussed above, the transfer of thermal energy can also be improved by the use of a thermal transfer medium and thermal gel.
The foregoing has outlined rather broadly the features and technical advantages of the present invention in order that the detailed description of the invention that follows may be better understood. Additional features and advantages of the invention will be described hereinafter which form the subject of the claims of the invention. It should be appreciated by those skilled in the art that the conception and specific embodiment disclosed may be readily utilized as a basis for modifying or designing other structures for carrying out the same purposes of the present invention. It should also be realized by those skilled in the art that such equivalent constructions do not depart from the spirit and scope of the invention as set forth in the appended claims. The novel features which are believed to be characteristic of the invention, both as to its organization and method of operation, together with further objects and advantages will be better understood from the following description when considered in connection with the accompanying figures. It is to be expressly understood, however, that each of the figures is provided for the purpose of illustration and description only and is not intended as a definition of the limits of the present invention.
The following drawings form part of the present specification and are included to further demonstrate certain aspects of the present invention. The invention may be better understood by reference to one or more of these drawings in combination with the detailed description of specific embodiments presented herein.
An embodiment of a device for treating or preventing nail bed infections is shown in
Treatment device 100 comprises a nail cover 112 connected by spring tensioning system 116 to housing 118. Thermal delivery surface 113 located under nail cover 112 also preferably includes a temperature sensor, not shown. Housing 118 comprises a protective cover to hold the internal electrical components of treatment device 100 (a preferred embodiment of which is shown and described below with respect to
Nail cover 112, thermal delivery surface 113, and spring tensions system 116 are replaceable according to embodiments of the invention. Nail cover 112 and thermal delivery surface 113 can be changed as necessary to accommodate the various differences in the size of the patent's digits (length of nail, width of nail, thickness of digit). Additionally, spring tensioning system 116 can be exchanged with various spring strengths as necessary for patient comfort.
Thermal delivery surface 113 contains a heating element which is electrically connected to treatment device 100. Examples of heating elements include resistance heaters, etch foil heaters, silicone rubber heaters, heat cables, fiberglass heating tapes, wire wound flexible heaters, electric heating tape, cable heaters, tape heaters. Treatment device 100 provides electrical current to the heating element of thermal delivery surface 113 by means of rechargeable batteries. The heating element of thermal delivery surface 113 produces heat through electrical resistance, which, in turn, is monitored by treatment device 100. The temperature of thermal delivery surface 113 is monitored by a temperature sensor, which may be a thermistor or other electrical device that measures or monitors heat. Treatment device 100 is able to adjust the power provided to thermal delivery surface 113 so as to maintain thermal delivery surface 113 at or near a set temperature chosen for the treatment.
As noted above, housing 118 holds the internal electrical components and the power source, such as rechargeable batteries. While treatment device 100 is described as using rechargeable batteries as the preferred power source, any suitable power source may be used, including receiving power from an ordinary household power plug and socket connection. A speaker, not shown, is also housed in housing 118.
Treatment device 100 of the illustrated embodiment includes a battery charge port 130 and a data port 132. Battery charge port 130 is used to plug in a charger to charge the internal batteries or, in some embodiments, to power the device from line power. Data port 132 allows treatment device 100 to communicate with another device, such as a computer or PDA, and allows the internal electrical components to receive new programs or new data to be used in treatment device 100. Data that can be communicated from the device to a computer or PDA includes, but is not limited to, number of treatments, duration of treatment, temperature of treatment, date and time of treatment. Additionally, a computer or PDA can be used to chance treatment settings such as duration, temperature, etc. Although the embodiment shown in
User interface 120 of the illustrated embodiment includes power button 122, treatment button 124, and light emitting diodes (LEDs) 188. Power button 122 of one embodiment is used to turn treatment device 110 on and off. Treatment button 124 of the aforementioned embodiment is used to initiate and/or cancel treatments. Treatment button 124 can include LEDs 188 that indicate whether treatment device 10 is ready to begin a treatment. While the illustrated embodiment is shown using LEDs as a display, any display technology such as LCDs or other display may be used without departing from the concepts described herein. For example. LEDs 188 could include an amber light to indicate that the device is not ready to begin a treatment and a green light to indicate that treatment device 100 is ready to begin a treatment. Treatment device 100 may comprise additional LEDs not shown to provide additional visual information to the user, such as the charge remaining in the battery and any other information which may be useful or interesting to the user. The speaker can be used to provide audible information to the user such as the amount of time remaining in the treatment, an error condition, low battery charge, and any other audible information that might be useful or interesting to the user. Additionally, other user interlaces may also be used, including touch screens, slide controls, keyboards, light pens, microphones, speech recognition, pointing devices (mouse, track ball, etc.), and gesture devices.
Referring now to
As shown in
In operation according to a preferred embodiment, thermal gel pack 406 is applied to the nail plate 402, air gap 304 of
Now referring to
Thermal delivery surface 502 contains a heating element which is electrically connected to the treatment device. Preferably, thermal delivery surface 502 comprises a flexible material and flexible heating element also designed to conform to the irregular shape of nail plates. Examples of flexible heating elements include etch foil heaters, silicone rubber heaters, heat cables, fiberglass heating tapes, wire wound flexible heaters, electric heating tape, cable heaters, tape heaters.
The heating element of thermal delivery surface 502 of the embodiments is electrically connected to a treatment device similar to treatment device 100 of
Referring now to
A memory element 616 may also mounted on circuit board 610. Memory element 616 can be any combination of processing and memory elements utilized to store and implement thermal delivery surface specific functions. Memory element 616 of the embodiments is used to store thermal delivery surface specific information. For example, memory element 616 of the illustrated embodiment may include calibration information for its associated thermal delivery surface. As the individual components used in particular thermal delivery surface may have their own variances from their marked values, each thermal delivery surface is calibrated during manufacturing to provide calibration information stored in memory element 616 and used to adjust the heating algorithm of treatment device 100 to account for the particular values of the components in the thermal delivery surface.
The memory element 616 can also store treatment variables such as treatment cycle duration, treatment temperature and treatment frequency, as well as other information that aids the treatment device in its operation. Such information can, for example, be information that identifies the type of thermal delivery surface and the intended treatment protocols, as well as algorithm information used during a treatment cycle.
An electrical diagram showing an embodiment of the electrical system 610 of treatment device 100 of
Microprocessor 620 is also in electrical communication with thermal delivery surface 113 of
Microprocessor 620 of the embodiments is programmed with a control algorithm referred to as a proportional, integral, derivative or PID. A PID is a control algorithm which uses three modes of operation: the proportional action is used to dampen the system response, the integral corrects for droop, and the derivative prevents overshoot and undershoot. The PID algorithm implemented in microprocessor 620 operates to bring the thermal delivery surface 113 to the desired operating temperature as quickly as possible with minimal overshoot, and also operates to respond to changes in the temperature of thermal delivery surface 113 during the treatment cycle that are caused by the heat sink effect of the treatment area.
In addition to being connected to FET 634, resistors 612 are connected to battery 622 through thermal interlock 618. Battery 622, which can be comprised of one or more individual cells, is charged by battery charger 624 when battery charger 624 is connected to external power supply 626. External power supply 626 can be any type of power supply, but is normally an AC to DC converter connected between battery charger 624 and an ordinary wall outlet. According to embodiments, the output voltage of battery 622 is directly related to the amount of charge left in battery 622, therefore, by a monitoring the voltage across battery 622 microprocessor 620 can determine the amount of charge remaining in battery 622 and convey this information to the user using LEDs 646 or speaker 630. Other methods of determining battery voltages or charge for different battery technologies can also be used and are well within the scope of the present invention.
Referring now to
In response to the temperature sensor input and information from memory element 716, firmware 700 controls FET 734 to regulate the temperature of the thermal delivery surface according to the PID algorithm programmed into firmware 700. Firmware 700 also controls speaker 730 to provide audible feedback to the user and LEDs 702 and 704 which are subsets of LEDs 646 from
Referring now to
During the heating state 816 the thermal delivery surface is heated using resistors 612 from
In addition to the expiration of the timer, the treatment device powers down by transitioning to the Suspended state if the power button is pressed, or the battery voltage falls below a threshold, and indication of the fault is provided to the user through visual and/or audible signals. If the thermal delivery surface successfully reaches the operating temperature within the designated time the state transitions to Ready state 818. A timer is started upon entering the Ready state 818. If the timer expires or the power button is pressed while in the Ready state 818, the state transitions to the Suspended state 810.
If the treatment button is pressed while in Ready state 818 the state transitions to Treatment state 820. Two timers, a treatment timer and a safety timer, are started upon entering the Treatment state 820+The safety timer is slightly longer than the treatment timer so that if there is a failure in the treatment timer the safety timer will expire and transition the state to the Power Reset state 824 before transitioning to the Suspended state 810. The state also transitions from Treatment state 820 to Suspended state 810 if the power button is pressed during a treatment cycle.
As a treatment cycle can be a relatively long period of time, the treatment device can also be programmed to provide visual and/or audible indications of the progress of the treatment timer. For example, speaker 630 of
When the treatment timer expires, or if the treatment button is pressed, the state transitions from Treatment state 820 to Wait state 822 which forces an inter-treatment delay. If the power button is pressed or the thermal delivery surface removed during the Wait state, the state transitions to Suspended state 810. After the expiration of the inter-treatment delay the state transitions back to Ready state 818. In addition to the inter-treatment delay, the Wait state 822 can be used to force a temporal treatment limit. While the inter-treatment delay forces a relatively brief delay between treatment cycles, the temporal treatment limit acts to limit the number of treatments that can be performed in specified period. For example, if the treatment cycle is two and a half minutes and the inter-treatment delay is 10 seconds, a temporal treatment limit of 30 minutes could be used to limit the device to approximately 10 to 11 consecutive treatments before a forced interval is imposed.
In another embodiment of the treatment device 100, an antibacterial, antiseptic, or antifungal compound may be introduced at air gap between the nail plate and nail bed, adding to the killing effect provided by the thermal energy. In turn, the heat created by thermal delivery surface 113 will aid in the dispersing and absorbing of such compounds creating a synergistic effect.
Although the preferred embodiments described above disclose the use of a temperature sensor which measures the temperature of the thermal deliver surface, other locations of the temperature sensor are well within the scope of this invention. Other locations include a temperature sensor located in the thermal transfer medium, such as thermal gel pack 502 of
Preferred Set Temperature and Treatment Time
To determine the preferred set temperature and treatment time, two factors should be considered. First, the set temperature and treatment time should be sufficient to cause a thermal reaction or response in the fungus, virus or bacteria detrimentally affecting the skin surface. Second, the set temperature and treatment time should be below the threshold that would damage the skin being treated. The first factor is discussed with reference to Examples 1-3 below using exemplary infectious agents. Based on Examples 1-3 a set temperature of 121 degrees Fahrenheit (49.44 degrees Celsius) for a period of 150 seconds proves to be effective for a variety of infectious agent and irritants. While a set temperature of 121 degrees Fahrenheit and a treatment time of 150 seconds are chosen for an embodiment of the present invention, other embodiments using combinations of set temperatures and treatment times which depart significantly from the described embodiment are well within the scope of the present invention.
To ensure that the described embodiment of a set time and temperature do not cause burn damage to the treatment area, modeling can be performed against previous research done into burn injuries. The modeling assumes that the skin surface in contact with the applicator immediately reaches the applicator temperature of 121 degrees Fahrenheit and remains at that temperature for the entire 150 seconds. First, the set temperature and treatment time are plotted against the Time-Surface Temperature Thresholds plot represented in
Based on the data of Moritz and Henriques cited above, Xu and Qian in an article entitled “Analysis of Thermal Injury Process Based on Enzyme Deactivation Mechanisms,” in Journal of Biomechanical Engineering, Transactions of the ASME, Vol. 117, pp. 462-465 (1995), the disclosure of which is incorporated by reference, developed an equation for a damage function, 6, based on enzyme deactivation concepts.
where z=1-305.65/T ° K. and t is in seconds
In this model T=322.59° K. and is constant, therefore,
Ω=4.947*10−3*Δt=0.742 for 150 seconds.
Temperature dependent death curves for P. acnes.
While the bacteria P. acnes is not normally present in the nail bed, nor the cause of onychomycosis, the reaction of P. acnes to heating can he considered illustrative of the expected reactions of those infection agents which are responsible for onychomycosis and other nail bed infections treatable by the device described herein.
Materials and Methods: The bacterial strain P. acnes was purchased from The American Type Culture Collection ATCC No. 11827, Lot 419571, Manassas, Va.). The cultures were stored in KWIK-STIK lyophilized preparations. The lyophillized cells (P. acnes) were rehydrated according to the manufacturers recommendations and initially grown on a streak plate to isolate individual colonies under anaerobic conditions. These plates were then incubated overnight at 37 degrees Celsius in an anaerobic chamber. Individual colonies were then isolated and inoculated into TSB-growth media with medium agitation overnight. From these aliquots of 0.1 ml of TSB broth culture was added to the 0.9 ml of PBS sterile buffer. This mixture was then transferred to thin-walled Eppendorf 1.5 ml tubes and placed in a heating block at various times and temperatures. The cultures after specific incubation times were removed and 0.1 ml of the material was plated onto TSA plates. This mixture was then spread with a sterile hockey-stick and then allowed to incubate at 37 degrees Celsius for 5 days in anaerobic conditions. The plates were then removed and colonies were counted and recorded. The results are demonstrated in
Results: A general trend of reduction of required time to kill the bacterial strain is seen at higher temperature incubations. Also of note is the temporal thermal threshold where the number of colonies drops off in a very steep fashion. By using the curves generated by such experiments the optimal thermal output and the timing for each temperature can be extrapolated for a localized heating device. The in vitro data shown demonstrates significant sensitivity of P. acnes bacterial cells to the effects of sustained low-level heat. Temperatures of 55 degrees Celsius result in the death of substantially all of the bacteria after 3½ minutes. Temperatures of 58 and 59 decrees Celsius result in the death of substantially all of the bacteria after 2 minutes. These curves demonstrate that P. acnes can be rendered largely non-viable by treatment under the conditions shown by the death curves.
Again, though acne is a skin condition, the treatment of skin lesions using heat is considered to be illustrative of utility of heat treatment for onychomycosis and other nail bed infections using the concepts described herein.
Treatment of acne lesions in human subjects. The inventors have performed preliminary studies on over 100 volunteers experiencing outbreaks of acne lesions. All subjects reported being satisfied with the results obtained. The results showed a clear response to treatment in approximately 90% of subjects treated. No subject reported any serious adverse effects due to treatment. Furthermore, we have discovered that a treated lesion heals more than 80% faster than untreated lesions.
The electrical device used in the present study had an interface of approximately 0.4 cm2. The interface of the device was heated to a constant temperature of approximately 48-50 degrees Celsius prior to application of the device to the skin surface, and the temperature was maintained during the treatment period. Each of the subjects was given instructions on how to use the device and was monitored during the treatment. The treatment consisted of a 2½ minute application of the device to the lesion site. The study called for the application of two treatment cycles to each patient, with the second treatment cycle being administered 12 hours after the first. In practice, however, the treatments were frequently only conducted once on each subject because twelve hours after the first treatment many of the lesions had healed to an extent that they did not require any further treatment.
Results of experiments performed on volunteer subjects are listed in Table 1. Members of the control group were not treated. Members of the treatment group were treated as described above. Both groups either examined or self-reported the results of treatment over the following 14 days. Only results from study participants who reported data for 14 days were included in the table. The data is reported in terms of the size of the lesion prior to treatment. A lesion size of 100% indicates that the lesion size was unchanged. Lesion size was approximated in increments of 10%. A lesion size of 0% indicates that the lesion had fully healed.
The inventors have tested prototype devices on multiple oral herpes lesions of human volunteers, and the results have shown a complete termination of the herpetic lesion after two applications of the device at 2½ minutes per treatment, 12 hours apart as described in Example 2. The volunteers reported a marked decrease in healing time after treatment versus the usual healing cycle for lesions of this type.
All of the compositions and methods disclosed and claimed herein can be made and executed without undue experimentation in light of the present disclosure. While the compositions and methods of this invention have been described in terms of preferred embodiments, it will be apparent to those of skill in the art that variations can be applied to the devices or methods and in the steps or in the sequence of steps of the methods described herein without departing from the concept, spirit and scope of the invention. More specifically, it will be apparent that certain mechanical elements related to those described above can be substituted for the mechanical elements described herein to achieve the same or similar results. All such similar substitutes and modifications apparent to those skilled in the art are deemed to be within the spirit, scope and concept of the invention as defined by the appended claim.
Although the present invention and its advantages have been described in detail, it should be understood that various changes, substitutions and alterations can be made herein without departing from the spirit and scope of the invention as defined by the appended claims. Moreover, the scope of the present application is not intended to be limited to the particular embodiments of the process, machine, manufacture, composition of matter, means, methods and steps described in the specification. As one of ordinary skill in the art will readily appreciate from the disclosure of the present invention, processes, machines, manufacture, compositions of matter, means, methods, or steps, presently existing or later to be developed that perform substantially the same function or achieve substantially the same result as the corresponding embodiments described herein may be utilized according to the present invention. Accordingly, the appended claims are intended to include within their scope such processes, machines, manufacture, compositions of matter, means, methods, or steps.
