title: Numerical simulation of endovenous laser treatment of the incompetent great saphenous vein with external air cooling.
abstract: Endovenous laser treatment (ELT) has been proposed as an alternative in the treatment of reflux of the great saphenous vein. Before the procedure, peri-saphenous subcutaneous tumescent saline solution infiltration is usually performed. However, diffusion of this tumescent fluid is rapidly observed and can potentially reduce the efficacy as a heat sink. External skin cooling with cold air was proposed as an alternative solution. The objective of this study is to compare endovenous laser treatment without and with air cooling by realistic numerical simulations. An optical-thermal damage model was formulated and implemented using finite element modeling. 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. Parameters, used in clinical procedures, were considered: power, 15 W; pulse duration, 1 s; fiber pull back, 3-mm increments every second; cold air applied in continuous mode during ELT; and no tumescent anesthesia. Simulations were performed for vein locations at 5, 10, and 15 mm in depth, with and without air cooling. For a vein located at 15 mm in depth, no significant difference was observed with and without cooling. For a vein located at 10 mm in depth, surface temperature increase up to 45 °C is observed without cooling. For a vein located at 5 mm, without cooling, temperature increase leads to irreversible damage of dermis and epidermis. Conversely, with air cooling, surface temperature reaches a maximum of 38 °C in accordance with recordings performed on patients. ELT of the incompetent great saphenous vein with external air cooling system is a promising therapy technique. Use of cold air on the skin continuously flowing in the area of laser shot decreased significantly the heat extent and the thermal damage in the perivenous tissues and the skin.
authors: INSERM-U703, Université Lille Nord de France, Lille University Hospital, 152, rue du Dr. Yersin, Loos, 59120, Lille, France.
authors: Mohamad Feras
authors: MF
authors: Marqa
authors: Serge
authors: S
authors: Mordon
authors: Esteban
authors: E
authors: Hernández-Osma
authors: Mario
authors: M
authors: Trelles
authors: Nacim
authors: N
authors: Betrouni
mesh_terms: D003198:Computer Simulation; D017679:Cryotherapy / Q000379:methods; D057510:Endovascular Procedures / Q000009:adverse effects / Q000379:methods*; D020342:Finite Element Analysis; D006358:Hot Temperature / Q000009:adverse effects; D006801:Humans; D053685:Laser Therapy / Q000009:adverse effects / Q000379:methods*; D008954:Models, Biological; D012501:Saphenous Vein / Q000293:injuries / Q000601:surgery*; D012881:Skin Temperature; D014689:Venous Insufficiency / Q000601:surgery*