Controlled ventilation with the Mapleson D system A theoretical and experimental study.

A theoretical analysis has been performed to show the interrelationships between alveolar carbon dioxide concentration, carbon dioxide output, alveolar ventilation and fresh gas flow during controlled ventilation with the Mapleson D system. The model and forms of equation used have been substantiated by experiments in which dogs were ventilated through a coaxial version of the Mapleson D system at varying levels of fresh gas flow and alveolar ventilation. By assuming that man ventilated with this system behaves as does the dog, a nomogram has been produced to predict alveolar carbon dioxide concentrations at any levels of fresh gas flow and minute volume.