Ação da fototerapia na cicatrização de queimaduras em pele: Análise clínica e histológica

Abstract

Burns are considered a serious public health problem worldwide. Among these lesions, third degree burns are considered the most serious ones, since they cause the destruction of all layers of the skin, which can also reach muscles, ligaments, tendons, and bones. Currently, among the new studied therapies that aim to accelerate and optimize the healing process of these injuries, there is the phototherapy with the use of Light Emitting Diode (LED) at different wavelengths. The objective of this study was to evaluate the effects of red and blue LED photobiomodulation on the healing of third degree burns in rat skin, through clinical and histological parameters. 60 Wistar male rats were randomly divided into three groups: control (CTR) (n = 20), red LED (RED) (n = 20) and blue LED (BLUE), with subgroups (n = 5) for each time of euthanasia (7, 14, 21 and 28 days). The red (630 ± 10nm, 300 mW, 9 J/cm2 per point, 30 seconds) and blue LED applications (470 nm, 1W, 12.5 J/cm2 per point, 28 seconds) were performed daily in contact with four points of the wounds (total: 36 J/cm2 in the RED and 50 J/cm2 in the BLUE), except on the day of euthanasia. The food consumption of the animals was measured every two days in the 3 groups, with the aid of an analytical balance. After euthanasia of the animals at the pre-established times, the Wound Retention Index (WRI) and removal of the specimen were performed and the sections were stained in Hematoxylin-Eosin (HE) and Masson's Trichrome (MT). At 7 days, it was observed that the WRI of the CTR was greater than the RED (p = 0.01) and there were no statistically significant differences between the BLUE and CTR groups (p> 0.05) in all evaluated periods. The Angiogenic Index (AI) of CTR was lower when compared to RED (p = 0.02) and BLUE (p = 0.01) in 7 days, and higher when compared to RED in 21 days (0.04). The CTR animals consumed less food than the RED ones at 7, 14 and 28 days (p <0.05) and the BLUE at 14, 21 and 28 days (p <0.05). At 28 days, all groups presented a predominance of chronic inflammatory infiltrate of mild intensity, all cases of the RED group presented complete re-epithelialization and BLUE, in the same period, incomplete re- epithelialization. This study suggests that LED, in the dosimetry used, contributes to important steps in the healing of third degree burns, stimulating re-epithelialization, angiogenesis, attenuation of the inflammatory response and possible analgesic effects in the initial stages. Based on the findings of this research, future studies will be important to deepen the knowledge about the effects of photobiomodulation of these two types of LED in the healing of these injuries