Mucosal fluid evaporation is not the method of heat dissipation from fourth-degree laryngopharyngeal burns.

This study was designed to explore whether mucosal fluid evaporation represents a method of heat dissipation from thermal air inhalation injury and to assess laryngopharyngeal tissue damage according to heat quantity changes of dry air and vapour. Fifteen adult male beagles were divided into five groups to inhale heated air or vapour for 10 min as follows: control group (ordinary air), group I (91-110 °C heated air), group II (148-175 °C heated air), group III (209-227 °C heated air), and group IV (96 °C saturated vapour). The heat quantity changes of the dry air and vapour were calculated via thermodynamic formulas. The macroscopic and histological features of the laryngopharynxes were examined and assessed by various tissue damage grading systems. Group IV exhibited the most serious laryngopharyngeal damage, including cilia exfoliation, submucosal thrombosis, glandular atrophy, and chondrocyte degeneration, which is indicative of fourth-degree injury. The quality, heat quantity, and proportional reduction of heat quantity of vapour in group IV were all higher than those in the other groups. Furthermore, we found that mucosal fluid evaporation is not the method of heat dissipation from thermal air inhalation injury used by the airways. Laryngopharyngeal tissue damage depends chiefly on the heat quantity of vapour in the air.

The Preparation of Acellular Dermal Matrices by Freeze-Thawing and Ultrasonication Process and the Evaluation of Its Antigenicity.

Antigenicity is the biggest obstacle of xenogeneic acellular dermal matrices (ADM) as dermal scaffold in treatment of large-area skin defect. We prepared ADM by repeated freezing and thawing and ultrasonic process, and then injected the ADM homogenate and degradation product into porcine skin to evaluate the effectiveness of the decellularized method and the antigenicity of porcine ADM. In this work, chinese miniature pigs (n = 10) were sensitized by subcutaneous injection with human ADM degradation products on days 0, 7, and 14. After 21 days, their abdominal skin was divided into five regions for intradermal injection of porcine ADM homogenate (PADM), PADM degradation products, human ADM homogenate (HADM), HADM degradation products, and physiological saline (negative control). Positive controls (n = 2) were processed with fresh human skin homogenate by the same method. The skin manifestations in related areas were observed at 24 and 48 h and then the skin was subjected to histopathological and immunohistochemical analysis. The results showed that skin erythema and hydroderma were not observed in all groups but in positive control group. The histopathological and immunohistochemical results confirmed that no inflammatory cell infiltration, irregular extracellular matrix, IL-2, and IFN-γ expression were observed in all four test groups. Our results suggest that the combination with repeated freeze-thawing and ultrasonication can be an effective method to prepare ADM, which has great potential in clinical application.