Ketamine Attenuates the ACTH Response to Hypoxia in Late-Gestation Ovine Fetus

Ketamine, a noncompetitive N-Methyl-D-aspartate (NMDA) receptor antagonist, is a commonly used dissociative anesthetic in neonatology. We have proposed that ketamine reduces fetal stress responsiveness to stimuli that involve reduced oxygen supply to the fetal brain. Previously, we have shown that ketamine inhibits plasma ACTH levels in late-gestation fetal sheep subjected to brachiocephalic artery occlusion (BCO), an ischemic hypoxia model that might activate some of the same direct and reflex responses as hypoxia.