Maturational influences on suppression of vocal cord function by anesthesia

Vocal cord abduction is a complex action that occurs with inspiration and is controlled by the respiratory center in the brainstem. A study was conducted to evaluate the maturational influences on the effect of anesthesia on vocal cord movement. Rabbits aged 15, 30, 45, and 60 days were used to study this problem. The animals were equilibrated to varying concentrations of halothane, and vocal cord movements were documented. In all age groups the vocal cord motion increased with increasing concentration of halothane. The amount of vocal cord movement also increased with the increasing age of the animal. These effects, however, were independent of each other. There did not appear to be any interaction between the concentration of halothane and the age of the animal. These findings are discussed in light of the apparent absence of active vocal cord motion observed in some children under a general anesthetic.