In vivo comparison of near infrared lasers for skin welding

Abstract

The skin closure abilities of near infrared lasers and suturing were compared by histological examination and mechanical tensile tests during a 21-day healing period. One-centimeter incisions on the dorsal skin of Wistar rats were treated by one of the closing techniques: (a) soldering, using an 809 nm diode laser (0.5 W, 5 s) with 25% bovine serum albumin (BSA) and 2.5 mg/ml indocyanine green (ICG); (b) direct welding with a 980 nm diode laser (0.5 W, 5 s); (c) direct welding with a 1,070 nm fiber laser (0.5 W, 5 s); (d) suturing. Six spots (79.61 J/cm(2) for each spot) were applied through the incisions. Healing was inspected on the 1st, 4th, 7th, 14th, and 21st post-operative days. The closure index (CI), thermally altered area (TAA), granulation area (GA) and epidermal thickness (ET) were determined by histological examination. Tensile tests were performed at a 5 mm/min crosshead speed up to the first opening along the incision. Immediate superficial closure with high CI values was found for the laser-irradiated incisions at the early phase of recovery. Clear welds without thermal damage were observed for the group irradiated at 1,070 nm. For the sutured group, the incisions remained unclosed for the first day, and openings through the incision were observed. At the end of the 21-day recovery period, no differences between experimental groups were observed in terms of the CI, GA and ET values. However, the tensile strength of the groups irradiated at 980 nm and 1,070 nm was found to be higher than that of the sutured incisions. The laser welding techniques were found to be reliable in terms of immediate and mechanically strong closure compared with suturing. Of them, 1,070 nm laser welding yielded noticeably stronger bonds, with minimal scarring at the end of the 21-days of recovery.

Closure of skin incisions by laser-welding with a combination of two near-infrared diode lasers: preliminary study for determination of optimal parameters

“…The major disadvantage is thermal damage to the surrounding tissue which should be minimized with the correct selection of laser wavelength, operation mode, and irradiation dose. 17,18 In the present study, aiming to achieve a full-thickness closure of incision, the ability and efficiency of skin welding with a combination of two near-infrared lasers (980 and 1064-nm lasers) was investigated using rat skin models, which have been widely used to simulate human conditions, [14][15][16]18 and compared with the suturing technique.…”

“…The laser parameters selected here refer to previous literatures. 13,15,16 First, 18 rats were divided equally into six groups, and each rat had three pairs of incisions on the dorsal side parallel with the spine. Then we welded skin incisions with combined lasers in different irradiationdoses and combinationmodes.…”

“…Then, histological examinations were performed as described in previous works. [14][15][16] For tensile strength measurements, 20 rats (10 from each group: laser welding and suture) were anesthetized with ketamine, and 1 cm×3 cm strips with the incisions in the center were cut off. Then, the measurements were performed immediately (within 10 min after the cut) in order to minimize drying of the tissues.…”

“…13 The skinwelding ability of a 980-nm diode laser was investigated because of its relatively higher absorption by water than other near infrared lasers, and good closure ability was reported in the early days of the healing period. [14][15][16] In all of these previous works, however, a good deal of attention was paid to the skinwelding ability of a single laser, and little was paid to skin welding with more than one laser, as far as we know.…”

“…16 Their results showed that 980-nm diode laser was suitable for superficial welding, while a 1070-nm laser was suitable for deep welding because of its relatively deeper optical penetration. Since the tissue optical properties of a 1064-nm laser are similar to those of a 1070 nm laser, we expect to achieve more effective welding with full-thickness closure and stronger tissue-bonding with 980 and 1064-nm diode lasers simultaneously.…”