Effects of Three Anesthetic Regimens on Bioengineering Methods Conducted on Ventral Abdominal Skin of Weanling Swine

Abstract

Background/Purpose: A weanling swine model was previously developed to study healing of cutaneous injuries induced by the blistering chemical warfare agent sulfur mustard. Noninvasive bioengineering methods are used in the model to monitor the progress of wound healing and evaluate the efficacy of treatments. It is necessary to anesthetize the animals to facilitate bioengineering data collection from ventral abdominal wound sites. As anesthetic agents affect cardiac output and deep vascular and cutaneous microcirculation in many species, there was a need to identify an anesthetic regimen with minimal effects on baseline measurements. The effects of three anesthetic regimens on reflectance colorimetry, transepidermal water loss, and laser Doppler perfusion imaging were studied in unexposed control animals. Methods: The following regimens were tested on six female Yorkshire swine (weanlings, 8–11 kg): repeated, separate intramuscular (i.m.) injections of ketamine HCl and xylazine HCl (K/X, at 20 ± 2 mg/kg and 2 ± 0.2 mg/kg, respectively), repeated i.m. injections of a tiletamine HCl/zolazepam HCl/xylazine HCl combination (T/X, at 2.2 mg/kg, 2.2 mg/kg, and 4.4 mg/kg, respectively), and the tiletamine HCl/zolazepam HCl/xylazine HCl combination as a preanesthetic and isoflurane inhalation to maintain anesthesia (T/X/Iso; dosage of tiletamine HCl/zolazepam HCl/xylazine HCl was the same as listed above, with 2.5–3.0% isoflurane in oxygen at an initial flow rate of 2 L/min, reduced to 1.0%–1.5% at 0.8–1.0 L/min for maintenance). Each regimen was administered in three iterations within a week (every other day), with a minimum 1‐week washout period between regimens. Results: The effect of the anesthetic regimens on bioengineering assessments of ventral abdominal skin was evaluated. For reflectance colorimetry, regimens T/X and K/X had a narrower range of readings over the three testing days than T/X/Iso. Either T/X or K/X was suitable, with T/X preferred because of a lesser blanching effect. T/X or T/X/Iso were preferred for transepidermal water loss readings, because overall they depressed transepidermal water loss rates less than did K/X. T/X, T/X/Iso, and K/X all affected cutaneous blood flow, with no clear preference. Conclusions: Overall, T/X produced the most consistent results with the fewest anesthetic effects.