Elimination of Intracardiac Shunting Provides Stable Gas Anesthesia in Tortoises. Issue 1 (December 2018)

• Record Type: Journal Article
• Authors: Greunz, Eva; Williams, Catherine; Ringgaard, Steffen; Hansen, Kasper; Wang, Tobias; Bertelsen, Mads
• Is Part Of: Scientific reports. Volume 8:Issue 1(2018)
• Page Start: 1
• Page End: 6
• Publication Date: 2018-12
• Subjects: Natural history -- Research -- Periodicals; Biology -- Research -- Periodicals; Physical sciences -- Research -- Periodicals; Earth sciences -- Research -- Periodicals; Environmental sciences -- Research -- Periodicals; 502.85
• DOI: 10.1038/s41598-018-35588-w
• Languages: English
• ISSNs: 2045-2322

Abstract

Abstract Inhalant anesthesia is challenging in chelonians due to a great capacity for breath-holding and an incomplete separation of the cardiac ventricle. Deoxygenated blood can recirculate back into systemic circulation by bypassing the lung in a process referred to as intracardiac right to left (R-L) shunting. Via electrocardiogram gated magnetic resonance imaging, a novel modality to investigate arterial flows in reptiles, intracardiac shunting and its elimination via atropine during gas anesthesia in tortoises (Chelonoidis carbonaria ) was demonstrated. The great vessels of the heart were visualized confirming that after shunt-elimination, the flow (mean ± sd) in the pulmonary arteries increased significantly (54.6 ± 9.5 mL min−1 kg−1 vs 10.8 ± 3.4 mL min−1 kg−1 ; P < 0.008). Consequently, animals required significantly lower concentrations of inhaled anesthetics to maintain a stable anesthesia. To that end, the minimum anesthetic concentration (MAC) of isoflurane needed to maintain surgical anesthesia was measured. A significantly lower MAC was found after administration of atropine (mean MAC ± sd 2.2 ± 0.3% vs 3.2 ± 0.4%; P < 0.002). Previously, MAC has been indeterminable in chelonians likely due to intracardiac shunting, so this report constitutes the first MAC study performed in a tortoise.