Methodological parameters to induction of second-degree thermal injuries in experimental model

Sabrina de Oliveira Capella , Mariana Teixeira Tillmann , Cristina Gevehr Fernandes , Márcio Fernando Weber Brito , Gabriela Morais Santana , Anelize de Oliveira Campelo Félix and Márcia de Oliveira Nobre

Abstract
Thermal injuries present a high severity potential, affecting adjacent organs with functional loss and even methabolic, cardiovascular and pulmonary disorders that can lead the animal to death. Over time, companion animals started to share smaller spaces and living very close to humans, due to these changes cases of thermal burns have been increasing. Therefore, studies embracing this area are needed, considering the skin tissue and its attachments loss have repercussions in thequality of the wound healing. The complexity of this kind of skin injuries does not allow in vitro experiments to clarify its pathophysiology, being necessary to use experimental animals to replicate a thermal injury corectly, in the same way that we have a diversity of methodologies for inducing termal burns, and yet there is no such padronization for the development of a type of injury. In this scenario, the purpose of the study is to stablish methodological parameters for the induction of second-degree thermal lesions. Six Wistar rats were used, creating, with the help of cubic-tipped metallic device, two lesions on the back of each animal, one in the thoracic region and the other in the abdominal region. Different temperatures (90 ^oC and 100 ^oC) were applied in different times of contact with the skin (10 s, 15 s and 20 s), each animal received a temperature and time of exposure for both lesion sites. After three days the animals were euthanized, a photographic record was created and the injured skin sites were collected to evaluate the extent of the lesion by digital planimetry. Skin samples were processed and stained with hematoxicillin-eosin. It was observed that lesions in the abdominal region with higher temperature (100 ^oC) and longer exposure time (15 s and 20 s) showed an expansion in the diameter of the initial thermal lesion, whereas lesions of the thoracic region with lower temperature (90 ^oC) and time of exposure (10 s) showed a reduction related to the initial lesion size. Regarding the histopathological parameters, it was determined that wounds performed in the thoracic region and that remained longer in contact to high temperatures (90 ^oC and 100 ^oC) presented greater severity, whereas lesions located in the abdomen and with a shorter time of exposure to high temperatures were lower. Thus, it is concluded that to obtain standardized second-degree wounds it must be applied temperatures between 90 ^oC and 100 ^oC, for 15 s or 20 s, in the thoracic region.

Keywords
Thermal injuries; Rats; Necrosis; Temperature; Lesion site.

DOI
10.21472/bjbs.051113

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