Patent Application
20110015621
The invention relates to methods and device soft tissue thermal treatment.
Liposuction remains the number one cosmetic surgery procedure in North America. Liposuction is performed by inserting fenestrated cannulas into fat and removing the fat under vacuum pressure through the fenestrated openings in the cannula. Fat may also be destroyed by inserted ultrasonic probes directly into the fat causing cavitation or by using a reciprocating probe inserted into the fat.
Recently laser assisted liposuction has gained broad popularity due to the following combined effects created by laser:
Fat destruction
Blood vessel coagulation
Thermal collagen contraction
These allow performing more gentle aspiration with less bleeding and post surgery skin tightening.
Laser liposuction is based on thermal fat destruction, blood coagulation and collagen contraction induced by laser radiation delivered to the subcutaneous tissue through the optical fiber imbedded into the treatment cannula. U.S. Pat. No. 6,206,873 describes a method of lipolysis using laser radiation delivered through an optical fiber inserted into the hollow needle. Where the needle pierces the skin of a patient and bringing tip of the optical fiber into a subcutaneous adipose layer of the patient.
U.S. Patent application Publication No. US 20040034341 describes a method where laser radiation used for fat treatment is absorbed in the adipose tissue more than in water based tissue.
U.S. Patent application Publication No. US 20090076489 describes the use of an accelerometer for tracking position of the laser hand piece during the laser-assisted liposuction.
U.S. Patent application Publication No. US 20080306476 describes a method of skin and subcutaneous tissue heating using laser radiation and molding it to the new shape.
U.S. Patent application Publication No. US 20080188835 describes a device for cellulite and adipose tissue treatment where a laser fiber is incorporated into the aspiration cannula.
U.S. Pat. No. 6,206,873 describes method fat removing from the body where liposuction cannula is assembled with laser fiber for cutting adipose tissue and an irrigating system for cooling the fiber.
All above mentioned devices and methods are based on adipose tissue treatment by laser energy delivered through an optical fiber. Typical fiber diameter used for laser-assisted liposuction is in the range of 400-1000 microns that at 30W output power providing power density from about 4 kW/cm2 to 24 kW/cm. Such high power density creates very high temperature in vicinity of the fiber and carbonization of the tissue that prevents energy propagation. Also high energy density may cause accidental skin burn if the laser fiber gets too close to the dermis.
Adipose tissue in the near infrared range (700 nm-1500 nm) has a low scattering coefficient and radiation propagates along the fiber axis for a few millimeters before it is absorbed. Tumescent anesthesia used in liposuction is based on saline which is also has low scattering properties and favors the directional propagation of light. Because fiber during the procedure is displaced in the same direction the fat volume over the fiber canal is over treated while surrounding tissue is not affected.
A device is provided for thermal fat destruction and collagen remodeling of a body. The device has a cannula with at least one optical channel For delivering optical energy in the form of light into the body. A light emitting tip is connected to the cannula. The light emitting tip has a light emitting area larger than the cross-sectional area of the optical channel. A light source is connected to the cannula for providing light with a power sufficient to coagulate tissue in the vicinity of the light emitting tip.
The light source may be a laser.
The light source may be connected to the cannula with optical fiber.
The light generated by the light source may be in the spectral range of from 400 nm to 20 nm.
Light emitting tip may have a light emitting area in the range of 2 mm2 to 200 mm2.
The light emitting tip may be configured to direct at least pan of the light in a preferred direction different from a longitudinal axis of the cannula.
The light emitting tip may be configured to diffuse the optical energy over the tip of the light emitting surface.
The cannula may include a lumen for vacuum suction of coagulated tissue.
The cannula may include a thermal sensor.
In order to understand the invention and to see how it may be carried out in practice, a preferred embodiment will now be described, by way of non-limiting example only, with reference to the accompanying drawings, in which:
A device according to the present invention is generally indicated by reference 10 in
The tip 14 is configured to direct a light beam 32 emanating from the optical fiber 33 in a direction generally transverse to the axis of the cannula. Various arrangements may be used to cause the direction of the light beam 32. As illustrated in
In using the system to treat subcutaneous adipose tissue and collect collagen the following exemplary parameter values may be selected:
In general, the tip of the cannula has a light emitting are a larger than the cross-sectional area of the optical fiber 33 which delivers light to the tip 14.
The device may be used in a minimally invasive procedure where at least one optical fiber light guide is inserted into the soft tissue to he treated. The area of the light-emitting tip is configured to create an energy density sufficient to cause tissue coagulation but below that which would cause carbonization. The light energy density should be sufficient to create thermal damage to adipose tissue. The applied optical energy should be high enough to create adipocyte damage and/or collagen contraction in the region surrounding the tip 14 of the cannula. Destroying the tissue around the tip minimizes the amount of mechanical action required for the liposuction.
In the
Optical energy may be delivered in pulse mode to create fractional coagulation or ablation of the dermis to create dermis collagen remodeling and skin tightening. For fractional dermis treatment, the wavelengths used should preferably be absorbing in dermis but non-absorbing in fat.
In another embodiment, the light may have a different preferred direction than discussed above. For example, light may be directed into the body depth for treatment of deeper tissue such as facial. In the
The parameters of the light energy may be adjusted depending on the intended application. As mentioned above, light energy can be delivered as a sequence of pulses or in continuous mode. Although the spectral range of optical energy is in the range of 400 nm to 2,000 mm, the preferable range of wavelengths is in the near infrared range of 700 nm to 1600 nm. The optical power should be sufficient to heat tissue volumes from a few cubic centimeters for facial treatments up to a few liters for body fat treatment. Accordingly, optical power should be in the range of 1-30 W for treatment of delicate areas such as face, neck and knees. Optical power should be in the range of 30-200 W for abdominal area and other areas with larger volume.
The method of the invention may be used for example to achieve a reduction in body weight, local fat reduction, lipolysis, body reshaping, cellulite reduction, loose skin reduction, wrinkle treatment, body surface tightening, skin tightening and collagen remodeling.
The treated body zone may be protruded using vacuum suction or mechanically to localize the region being treated thereby reducing the risk of mechanical and thermal damage to deeper tissue structures.
The temperature required for collagen remodeling depends on heating time. For short millisecond range pulses the required temperature is 60-70° C. If treatment time is a few minutes, then the temperature should be in the range of 40-45° C. as required to cause collage remodeling without skin damage. Accordingly, the cannula may be provided with temperature sensors for measuring the temperature of the treated tissue to provide the required thermal effect and prevent it from overheating.
The cannula 11 may be connected through the optical fiber or light guide to a laser, a light emitting diode, a gas discharge lamp or an incandescent tamp. Lamp radiation may be passed through an optical filter to optimize the light spectrum. The light source may be located in the separate console or in the handle of the handpiece. Preferably, the light source is a diode laser but it may be other types of laser or light sources.
Light may be emitted in continuous wave, burst or pulse manner. Optical energy may be adjusted according to thermal sensor measurements.
As mentioned, the cannula 11 may have a temperature sensor for measuring tissue temperature in the vicinity of the tip 14 of the cannula. The signal from the temperature sensor may be used to adjust optical energy according to the measured temperature. For example, power may be switched off when a target tissue temperature is reached and switched on when the cannula is moved to a new locations with a lower temperature.
The cannula may have a lumen and vent hole in the vicinity of the treatment tip 14 for aspiration of coagulated tissue using a vacuum pump connected to the cannula 11.
The above description is intended in an illustrative rather than a restrictive sense. Variations to the described structures and methods may be apparent to persons of relevant skill in the art without departing from the spirit and scope of the invention as defined by the claims set out below.
