Inhalant anesthetics and inspired oxygen: implications for anesthesia in birds

A number of factors cause respiratory depression in anesthetized birds. Hypoventilation can be due to anesthetic-induced depression of the central nervous system, muscular relaxation of the muscles of respiration, and effects on central and peripheral chemoreceptors. Compared to mammals, respiratory function in birds may be more sensitive to the effects of inhalant anesthetics because of their effect on unique carbon dioxide (CO2)-sensitive intrapulmonary chemoreceptors located within the avian lung. High fractions of inspired oxygen also contribute to hypoventilation, possibly by depressing oxygen-sensitive chemoreceptors. This article is a review of the factors that cause respiratory depression in anesthetized birds.