Patent Application
20060276861
1. Field of the Invention
This invention relates to method and system for the treatment of snoring, sleep apnea and nasal obstruction, particularly for shrinkage of soft tissue by a laser.
2. Prior Art
Snoring is caused by irregular air flow of the nose which results in non-controllable vibration of the uvula or soft palate. Various methods have been used to treat snoring. These prior arts include the use of anti-snoring solution, such as U.S. Pat. No. 6,790,465, or anti-snoring device such as U.S. Pat. No. 6,748,951. Bipolar cautery and radio frequency (RF) somnoplasty have been used commercially, which requires the use of needle electrode and delivery of 200 to 500 J in each treated spot. Surgical method using a carbon dioxide laser has been used to remove (ablate) a portion of the uvula or palate soft tissue. This prior art (ablative surgery) is invasive, painful having delayed bleeding or synechia formation, and requires a long healing time and it is not recommended for sleep apnea.
Thermal lasers have been used for the treatment of hyperopia, such as U.S. Pat. No. 5,484,432, using wavelength of 1.8 to 2.2 micron and a shallow absorption depth of the corneal tissue about 0.45 mm. There is no commercially available thermal laser for snoring treatment which requires a much deeper depth about 2 to 5 mm.
One objective of this invention is to provide a non-invasive laser method and system to obviate drawbacks of prior arts and improve the treatment efficacy.
It is yet another objective of this invention is to define the optimal laser parameters and the area and depth for various soft tissues to be treated for the treatment of snoring, sleep apnea and nasal obstruction.
It is yet another objective of this invention is to include the disclosure of integrated system design including optical fiber delivery, focusing optics and multi-wavelength mixture.
It is yet another objective of this invention is to include the disclosure of the laser tissue interaction mechanism behind the treatment, for the criteria of wavelength selection.
In comparing to a RF device, the laser method of this invention offers the following advantages: less invasive, much smaller energy (about 5 to 50 J) is needed in each treated spot; faster procedure using adjustable laser spot size of 1 to 5 mm (versus a penetrating needle about 0.5 mm in RF); both contact and non-contact mode treatment (versus a penetrating needle in RF device); penetration depth controllable by laser wavelength selected; and multi-wavelength laser output for optimal outcome (not available in RF device).
The preferred embodiment of this invention includes the laser shrinkage of uvula or soft palate (for snoring), tongue base (for sleep apnea) or nasal turbinate (for nasal obstruction).
It is yet another preferred embodiment is that the treated area is locally heated without damaging the surrounding tissue, where the localized temperature is raised to about 65 to 85 degree Celsius (C.), most preferable about 75 to 80 degree C., to cause efficient thermal shrinkage of the treated area
It is yet another preferred embodiment includes a heating penetration depth on the treated area about 2 to 5 mm governed by the power and wavelength of the laser and treated tissues.
It is yet another preferred embodiment includes a fiber-delivered laser beam applied to the treated area in either contact or non-contact mode.
It is yet another preferred embodiment includes a laser having a wavelength in the infrared of 0.7 to 1.85 microns, such as semiconductor laser (0.7 to 1.85 microns), Nd:glass (at 1.54 micron), Nd:YAG or Nd:YLF (at 1.3 or 1.4 micron); pulse width of 100 microsecond to about 5 seconds, or operated at free-running normal mode, or a continuous wave (CW).
It is yet another preferred embodiment includes a fiber bundle having the same wavelength diode or 2 to 3 different wavelengths selected from a group consisting of about 0.8, 0.9, 0.94, 0.98, 1.3, 1.45, 1.54 and 1.85 microns.
Further preferred embodiments of the present invention will become apparent from the description of the invention that follows.
As shown in
When a laser is used, we also require efficient localized tissue heating with minimal thermal damage to the non-treated tissue. Therefore, the preferred laser spectrum of this invention is the region where the treated tissues including soft palate, uvula, nasal turbinate or tongue base (containing blood, melanin or water) have certain absorption, but not too strong, in order to penetrate deep into the selected area for maximal shrinkage. Based on these criteria, the preferred laser spectrum includes infrared (IR) laser at about 0.7 to 1.85 microns. Other ranges of spectrum with very strong tissue absorption such as carbon dioxide laser (at 10.6 microns) or other IR laser about 1.9 to 2.2, or about 2.8 to 3.2 microns, visible laser of 0.4 to 0.69 microns or UV laser of 193 to 300 nm should be excluded. These ‘ablation-type” lasers, excluded in the present invention, are required in the prior arts which use laser to remove (ablate) tissues, rather than thermal shrinking. For lasers in the above selected IR range, the preferred pulsed duration is longer than 100 microseconds, or a continuous wave (CW) mode at low peak power (less than 500 W), comparing to the prior arts of ablation procedure which requires very high peak power (over 100 KW).
The preferred lasers of this invention include solid-state or diode lasers at about 0.7 to 1.85 microns. The most preferable laser spectra are at about 0.75, 0.8, 0.94, 0.98, 1.3, 1.45, 1.54 and 1.85 microns from semiconductor diode lasers, or Nd:glass (at 1.54 micron), or Nd;YAG or Nd:YLF (at 1.3 or 1.4 micron). The preferred laser pulse width is about 100 microseconds to 5 second, operated at CW or quasi-CW mode.
The preferred embodiment of this invention further includes the use of multiple spots on each of the treated area, where each spot also includes multiple pulses of about 1 to 10. It also includes a multiple treatments of about 1 to 5, depending on area treated and applications, over a period of about 2 to 10 weeks. In comparison, when a RF device is used, a typical energy delivery time for each spot is about 80 to 200 seconds which is much longer than that of a laser is used in this invention (about 5 to 30 seconds). In addition, only about 5 to 50 J laser energy is needed in each treated spot for each treatment, which is much smaller than 200 to 500 J of RF energy when a RF device is used.
It was previously known (for example: Bargeon et al. “Calculated and measured endothelial temperature histories of excised rabbit cornea explored to IR radiation”, Exp. Eye Research, vol. 32, 241-250, 1981; Stringer et al. “Shrinkage temperature of eye collagen”, Nature, vol. 204, 1307, 1964) that collagen fiber may contract to about one-third of their linear dimension when it is heated to about 60 to 70 degree Celsius. This thermal shrinkage in corneal tissue shall also occur similarly to the treated soft tissues proposed in this invention. In Lin's proposed “laser induced” thermal shrinkage (LTS), there is a minimal amount of thermal energy needed in order to cause sufficient LTS. LTS is further governed by the localized temperature (T) of the treated tissue. Depending on the types of soft tissue (uvula, nasal turbinate, palate or tongue), the preferred T=(65 to 85) degree Celsius, most preferable of 75 to 80 degree Celsius, and shall not be too high to cause permanent tissue damage or evaporation. Given a laser energy (E), T is proportional to W=Et, where t is the laser treating time and W is the average power (in Watt) applied to the tissue. To cause effective LTS of the tissue, only those lasers with appropriate spectra can be used, such that the laser energy can be localized absorbed by the treated tissue via the melanin, blood or water content of the tissue.
We note that without the above theoretical analysis, it would be very difficult to predict the clinical outcome. Our method in this invention and the parameters for the proposed device and clinical techniques are based upon the above analysis relating to the absorption depth, and temperature required for efficient shrinkage.
As shown in
The preferred lasers of this invention include solid-state or diode lasers at about 0.7 to 1.85 microns. The most preferable laser spectra are at about 0.8, 0.9, 0.94, 0.98, 1.3, 1.45, 1.54 and 1.85 microns from semiconductor diode lasers, or Nd:glass (at 1.54 micron), or Nd;YAG or Nd:YLF (at about 1.3 or 1.4 micron). The preferred laser pulse width is about 100 microseconds to 5 second, operated at CW or quasi-CW mode. The preferred energy beam spot size (in non-contact mode) or the size of the fiber tip (for contact mode) is about 2 to 5 mm on the treated surface. The preferred average power at each of the treated spot is about 2 to 20 W, depending on spot size, spectra and power of the laser beam and the types of tissues treated. For example, a power of 20 W needed for a spot size of 5 mm will be reduced to about 3 W when a small spot of 2 mm is used. This is based on our theory that the laser-induced temperature increase of the soft tissue is proportional to the fluency (F) times the treated period of each spot, where F is the energy per unit area and area is proportional to square of the spot diameter. Greater details will be disclosed later.
The preferred diode laser chips or arrays shown in
Another preferred embodiment of this invention includes that, as shown by
Another preferred embodiment of this invention includes that the output beam 12 having a spot of about 2 to 5 mm is used to treat (using multiple spots) an area of about 5 to 15 mm of the soft palate, uvula or tonsils.
The preferred embodiment of this invention includes that the diode array having the same wavelength or a combination of more than one wavelength selected from a group of wavelength in the IR about 0.7 to 1.85 microns depending on the treated areas. For deeper laser penetration, wavelength shorter than about 1.3 micron is preferred, and for shallow laser penetration, stronger absorption spectra of about 1.4 to 1.85 microns are preferred. The preferred laser penetration depth includes about 0.5 to 8 mm (most preferable of about 1 to 2 mm) for thermal shrinkage of soft palate, 2 to 3 mm for uvula, and 2 to 4 mm for tongue base or nasal turbinate. We note that the degree of shrinkage (or volume reduction of the treated area) is proportional to the volume (area x depth) of laser penetration, or the volume (area) where the temperature profile above the shrinkage threshold temperature, about 55 to 60 degree Celsius. The preferred laser penetration depths (PD) for various treated tissues disclosed in this invention (governed by the laser wavelength) are based on clinically preferred condition of maximal depth with a minimal pain. For example, soft palate is thinner than other tissues, but needs a larger treated area, therefore, shallower PD is preferred. In comparison, uvula has a smaller, but thicker area, which needs a deeper PD to achieve effective shrinkage.
While the invention has been shown and described with reference to the preferred embodiments thereof, it will be understood by those skilled in the art that the foregoing and other changes and variations in form and detail may be made therein without departing from the spirit, scope and teaching of the invention. Accordingly, threshold and apparatus, the ophthalmic applications herein disclosed are to be considered merely as illustrative and the invention is to be limited only as set forth in the claims.
