Morphometric analysis of lungs parameters under conditions of simulated burn injury

Abstract

Thermal burns are one of the most traumatic and physically exhausting injuries. Among the many factors that are decisive for a burn injury, the relationship between the temperature of the damaging agent and the duration of exposure is important. The term of exposure and high temperature determine the depth of the lesion. During burns, hypoxic, hemodynamic and metabolic disorders occur, which lead to changes in the structures and functions of internal organs. There are various ways of developing the respiratory system disorders after a burn injury to the skin: direct thermal damage to the respiratory tract, damage to the lungs by toxins of endogenous origin. After thermal exposure, there is a reorganization of the airiness of the lung tissue, its increase and combination with the phenomena of bronchospasm. A complex of morphological changes develops in the lungs, which includes degenerative changes in the walls of blood vessels and their permeability, a violation of the typical structure of the alveoli, the appearance of foci of distelectases and atelectasis, signs of inflammatory reactions, as well as the detection of areas of clusters of alveolar macrophages in places of hemorrhages. The aim of our study was to establish changes in the morphometric parameters of the lungs during experimental thermal injury to the skin. The results of the morphometric analysis showed that in the early stages (1st, 7th days) after experimental thermal injury to the skin, there is a reorganization of the structural components of the lungs with signs of an adaptive and compensatory nature, as well as destructive changes. It was established that the average values of the area of bronchi, lymphoid tissue statistically significantly increased from the indicators of the intact group animals, while the percentage of unchanged lung tissue significantly decreased in the respiratory portion. It was found that in the late stages of the experiment (14th, 21st days), inflammatory and sclerotic changes in the components of the respiratory portion occurred, which were manifested by a significant increase in the average values of dys- and atelectasis and the relative areas of emphysematously changed lung tissue relative to the indicators of the intact group. The values of the relative fractions of unchanged lung tissue were significantly reduced, which indicated deep degenerative-destructive changes in the organ.