Serum lipid changes following laser lipolysis.

BACKGROUND: Laser lipolysis allows the removal of small volumes of fat with concurrent sub-dermal tissue contraction. However, the physiologic consequences of this procedure are not well documented. The possible effects on serum lipids are not well established. OBJECTIVE: This study was undertaken to determine what changes, if any, occurred in serum lipid profiles at different intervals (1 day, 7 days, 2 weeks and 1 month) after the procedure. METHODS: Four consecutive patients were included in the study. In all patients, the right and left hips were treated with a 980-nm diode laser (Osyris Medical, Hellemmes, France). Power was tuned at 18 W. Cumulative energies varied from 22 000 J to 50 150 J. Fasting blood samples were obtained before the procedure and 1 day, 3 days, 2 weeks and 1 month after. A standard lipid profile (total cholesterol, HDL cholesterol, LDL cholesterol and triglycerides) was done using the same laboratory facility for all tests. RESULTS: Serum cholesterol and triglyceride levels remained in the normal range after laser lipolysis. CONCLUSION: Two hypotheses can be proposed: (i) fat elimination is so gradual that an increase in circulating lipid levels is not measurable; (ii) the damaged adipocytes are undergoing apoptosis and being removed by phagocytosis, presumably via activated macrophages.

Lipolysis using a 980-nm diode laser: a retrospective analysis of 534 procedures.

BACKGROUND: The safety and efficacy of the 980-nm diode laser for laser lipolysis were evaluated in different body areas. METHODS: From June 2005 to June 2007, 334 subjects underwent laser lipolysis. The treatment was performed using a 980-nm diode laser (OSYRIS, Hellemmes, France). After tumescent anesthesia, a 1-mm-diameter microcannula housing a 600-mum optical fiber was inserted into the subcutaneous fat. The cannula was moved back and forth in a predetermined manner to get a homogeneous distribution of energy at the treated area. Laser settings (power and cumulative energy) were selected in relation to individual body areas: 6 W (chin, arm, knee), 10 W (abdomen, back), and 15 W (thigh, hips, buttock). Patient satisfaction was evaluated and side effects were recorded. The laser energy counter incrementally counted the energy used; then the cumulative energy used for each treatment was recorded. Ultrasound imaging was used to control tumescent anesthesia infiltration, cannula position prior to laser emission,and postoperative fat liquefaction. RESULTS: Five hundred thirty-four (534) laser lipolysis procedures were performed on 334 patients. Different areas were treated: hips (197), inner thighs (86), abdomen (86), knees (61), flanks (57), buttocks (28), chin (22), arms (18), back (4). Mean cumulative energy was area-dependent, ranging from a minimum of 2200 J (knee) to a maximum of 51,000 J (abdomen). Contour correction and skin retraction were observed almost immediately in most patients. There was no scarring, infection, burns, hypopigmentation, bruising, swelling, or edema. Ecchymoses were observed in almost all patients but resolved in under 1 week for 322 patients. Patient satisfaction was very high. Because laser lipolysis is an outpatient procedure, patients were able to resume normal daily activities after 24 h. Ultrasound imaging confirmed that the thermal effect generated by the laser results in melting and rupture of the collagenous and subdermal bands. CONCLUSION: This clinical study demonstrates that the removal of small volumes of fat with concurrent subdermal tissue contraction can be performed safely and effectively using a 980-nm diode laser. Additional benefits include excellent patient tolerance and quick recovery time. This study also confirms that enough accumulated energy must be delivered to achieve sufficient lipolysis throughout different fat layers.

Mathematical modeling of laser lipolysis.

BACKGROUND AND OBJECTIVES: Liposuction continues to be one of the most popular procedures performed in cosmetic surgery. As the public's demand for body contouring continues, laser lipolysis has been proposed to improve results, minimize risk, optimize patient comfort, and reduce the recovery period. Mathematical modeling of laser lipolysis could provide a better understanding of the laser lipolysis process and could determine the optimal dosage as a function of fat volume to be removed. STUDY DESIGN/MATERIALS AND METHODS: An Optical-Thermal-Damage Model was formulated using finite-element modeling software (Femlab 3.1, Comsol Inc). The general model simulated light distribution using the diffusion approximation of the transport theory, temperature rise using the bioheat equation and laser-induced injury using the Arrhenius damage model. Biological tissue was represented by two homogenous regions (dermis and fat layer) with a nonlinear air-tissue boundary condition including free convection. Video recordings were used to gain a better understanding of the back and forth movement of the cannula during laser lipolysis in order to consider them in our mathematical model. Infrared video recordings were also performed in order to compare the actual surface temperatures to our calculations. The reduction in fat volume was determined as a function of the total applied energy and subsequently compared to clinical data reported in the literature. RESULTS: In patients, when using cooled tumescent anesthesia, 1064 nm Nd:YAG laser or 980 nm diode laser: (6 W, back and forth motion: 100 mm/s) give similar skin surface temperature (max: 41 degrees C). These measurements are in accordance with those obtained by mathematical modeling performed with a 1 mm cannula inserted inside the hypodermis layer at 0.8 cm below the surface. Similarly, the fat volume reduction observed in patients at 6-month follow up can be determined by mathematical modeling. This fat reduction depends on the applied energy, typically 5 cm3 for 3000 J. At last, skin retraction was observed in patients at 6-month follow up. This observation can be easily explained by mathematical modeling showing that the temperature increase inside the lower dermis is sufficient (48-50 degrees C) to induce skin tightening DISCUSSION AND CONCLUSION: Laser lipolysis can be described by a theoretical model. Fat volume reduction observed in patients is in accordance with model calculations. Due to heat diffusion, temperature elevation is also produced inside the lower reticular dermis. This interesting observation can explain remodeling of the collagenous tissue, with clinically evident skin tightening. In conclusion, while the heat generated by interstitial laser irradiation provides stimulate lipolysis of the fat cells, the collagen and elastin are also stimulated resulting in a tightening in the skin. This mathematical model should serve as a useful tool to simulate and better understand the mechanism of action of the laser lipolysis.