In their descriptions of the hydrate theory of anesthetic action Pauling and Miller suggested that the action of two anesthetic gases might be synergistic if one gas formed a structure I and the other a structure II hydrate. The correlation of anesthetic potency and lipid solubility, however, suggests that combinations of anesthetics should result in an additive effect rather than synergism. We compared the anesthetic requirements, as defined by MAC, for xenon (structure I hydrate) and for halothane (structure II hydrate) with MAC values for xenon-halothane mixtures in man. The results indicate that xenon and halothane in combination have an additive rather than a synergistic anesthetic effect.
(C) 1969 American Society of Anesthesiologists, Inc.