Subdermal Temperature Measurement During Laser-Assisted Lipolysis: Proper Technique and Temperature Sensor Design
8Pages

Subdermal Temperature Measurement During Laser-Assisted Lipolysis: Proper Technique and Temperature Sensor Design Cheryl Deguara, PhD and James L. Hobart, PhD. Sciton, Inc., Palo Alto, California Abstract Maximizing patient outcomes, avoiding complications and increasing control of laser-assisted lipolysis procedures are all benefits that can be achieved with real time, subdermal, internal temperature measurement. Improper technique can obviate the benefits of internal temperature monitoring, thus proper use of internal temperature monitors must be employed. This paper highlights the proper technique for the use of subdermal, realtime temperature monitoring during laser-assisted lipolysis. In addition, an optimal design for the TempASSURE™ cannula and temperature sensor are described. Background Clinical observation and experimental evidence have demonstrated that spurious temperature measurements can result from incorrect use of subdermal, internal temperature monitoring for laser-assisted lipolysis. Understanding how anomalistic temperature readings can occur is the key to understanding and performing proper technique and in assessing the optimal temperature sensor design. The Basics of Internal Temperature Measurement Subdermal, internal temperature monitors are designed to make real-time measurements while performing laser-assisted lipolysis. The temperature monitor is designed as follows: the temperature sensor is a thermocouple which is the junction of two dissimilar wires. The wires extend along the outside of the cannula to within a few millimeters of the end of the cannula at the point where the laser fiber exits the cannula and emits light, termed distal end (Figure 1). Thermocouple Wire Temperature Sensor Fiber Laser light Figure 1:The distal end of a cannula with a temperature sensor. 1 | SCITON Technical White Paper

Subdermal Temperature Measurement During Laser-assisted Lipolysis: Proper Technique and Temperature Sensor Design A small amount of energy is scattered in all directions from the fiber tip. The amount of scattered light that is absorbed by the distal end of the cannula can vary and lead to unusually high temperature readings under certain conditions (Figures 2 and 4). Both temperature sensor design and technique can contribute to inaccurate temperature readings. Low Level Light Scattering from Fiber Tip Figure 2: Scattering from the distal end can heat the cannula. Improper techniques...

Subdermal Temperature Measurement During Laser-assisted Lipolysis: Proper Technique and Temperature Sensor Design resulting backscatter can increase dramatically. Thus, it is critically important to know proper fiber cutting technique and how to adequately assess the quality of the cut. To avoid this all together, the most reliable and recommended method is to use a new fiber for each case. Clean, Uncontaminated Fiber Tip It is inevitable that there are situations when biological material may adhere to the distal end of the laser fiber and cannula. This material can become carbonized and...

Subdermal Temperature Measurement During Laser-assisted Lipolysis: Proper Technique and Temperature Sensor Design light is essentially eliminated and the high temperature reading artifacts are negligible. However, in a situation where the cannula may be in an air pocket or moving through dense scar tissue, the temperature readings can spike due to the reflected light. The practitioner should pay close attention to the temperature as the laser is firing. When the temperature reading is within target or a few degrees higher, he should stop firing the laser, stroke the cannula a few seconds...

Subdermal Temperature Measurement During Laser-assisted Lipolysis: Proper Technique and Temperature Sensor Design backscattered light by moving the temperature sensor further from the cannula end. The scattered light intensity at this position is greatly reduced, so that the sensor temperature is identical to the tissue temperature. The modified design in shown in Figure 4. The optimized design of Sciton’s TempASSURE minimizes aberrant temperature readings, improving the physician’s ability to safely and effectively provide the best clinical outcomes. Summary Proper technique and optimal...

Subdermal Temperature Measurement During Laser-assisted Lipolysis: Proper Technique and Temperature Sensor Design Appendix A: Thermal Time Constant of the TempASSURE Cannula The thermal time constant of a system is its thermal impedance times its heat capacity. The sensor insulator has a thermal impedance of 2.5 kelvin/watt. The sensor heat capacity is 0.09 joule/kelvin. The time constant is then 0.23 second. This is the time for the sensor to move two-thirds of the way to a new outside temperature. To give a concrete example: Let the sensor be initially in a medium at 30 °C. It is then...

Subdermal Temperature Measurement During Laser-assisted Lipolysis: Proper Technique and Temperature Sensor Design Appendix B TempASSURE Specifications Temperature Range Temperature Accuracy Measurements (LxWxH) Monitor Type LCD 4.3 inch, 480 x 272 pixel (WQVGA) Power Source Rechargeable Lithium-ion Battery Cannula Length 7 | SCITON Technical White Paper

925 Commercial Street, Palo Alto, California 94303 Phone: 888 646 6999 • Email: info@sciton.com ©2011 Sciton, Inc. All rights reserved. Sciton is a registered trademark and Temp/4SSL/RE is