Determination of the minimum anesthetic concentration of isoflurane and sevoflurane in Magellanic penguins (Spheniscus magellanicus) and evaluation of anesthesia under different fractions of inspired oxygen

Abstract

The Magellanic Penguin is very common specie present in Brazilian waters and frequently found in the marine animals clinics, mainly due to environmental accidents. This study aims to establish the Minimum Anesthetic Concentration (MAC) of isoflurane and sevoflurane in Magellanic penguins (Spheniscus magellanicus), through the challenge of electrical stimulation. Moreover, we will evaluate the influence of different concentrations of O2 inspired fraction in the anesthesia these two drugs. Fifteen adult, healthy and without sex distinction will be used. In a first step, the animals will be anesthetized with sevoflurane using a facemask and avalvular circuit in order to stablish the MAC. The establishment of MAC will be conducted in accordance with the design "quantal study design", each animal will be exposed once and for a definite period followed by an application of an electrical stimulus. The anesthetic concentration will be pre-determined by a pilot study. According to the observed response, the next animal will be subjected to an increase or decrease of 10% expired fraction of sevoflurane EFiso and EFSEVO. To carry out the second step, all animals will be two anesthetic procedures with 1.5 MAC, corresponding to the first phase. The anesthetic agent will be diluted in O2 fractions of 21%, 40% and 60%. After the stabilization period, the animals will be kept in anesthesia for 60 minutes. The exchange of O2 fraction will occur every 20 minutes randomly by lot and following a Latin square model. Heart rate, respiratory rate, arterial systolic, diastolic, and mean pressures, temperature, pH, HCO3-, PaCO2 and PaO2, electrolytes (Na+ and K+) and lactate will me evaluated. It is believed that the results obtained in this study may standardize the use of both isoflurane and sevoflurane in this specie, as well as a correlation between lung capacity and endurance to different fractions of inspired O2. (AU)