Abstract
The authors of this experimental study tested a murine model using heat and cold injury that did not involve direct contact in order to compare cellular changes between each mechanism. Forty mice were anesthetized while their body temperatures were maintained at 37°C. Their ears were stretched in a similar fashion and exposed to 117°C air for 1 second at a distance of 1 mm or −196°C liquid nitrogen for 1.5 seconds at a distance of 3 mm. Fluorescent microscopy was used to compare cellular changes between each model prior to injury and at day 1, 3, 7, and 12.
Microscopic examination of the surrounding tissue demonstrated destruction of cells and the surrounding collagen matrix in the burns, while the matrix was retained after frostbite. Cellular changes were observed and showed a statistically significant difference between the 2 injury types, including a 5% increase in angiogenesis by day 7 in frostbite, an increase in function vessel density by day 7 in frostbite, increased edema by day 7 in burn injury, and increased leukocyte density by day 12 in frostbite injury.
The authors acknowledge that this article is a preliminary step in comparing these 2 injury mechanisms. They propose using this model for future investigations to more accurately parallel the real injury pathway in frostbite because of the absence of direct contact to the mouse ears. The main limitation I see with a direct comparison is delineating the changes due to injury mechanism as opposed to the amplitude of injury.
(J Surg Res. 2011;167:e395–e401) O Goertz, T Hirsch, B Buschhaus, et al.
Prepared By Anil Menon, MD, UTMB/NASA Aerospace Medicine Fellow, Galveston, TX, USA