Preliminary evaluation of the Enclosed Magill Breathing System.

The Enclosed Magill anaesthetic breathing system may be used for both spontaneous ventilation and controlled ventilation with similar fresh gas flows. During spontaneous ventilation, a fresh gas flow between estimated alveolar ventilation and minute ventilation is adequate and the system performs as a Mapleson A type breathing system. For controlled ventilation, a fresh gas flow of 70-100 ml kg-1 min-1 produces normocapnia in most subjects, as demonstrated in this limited study. These values are similar to those demonstrated for type D breathing systems. It is suggested from this preliminary study that the breathing system conforms to the requirements of a universal breathing system in as much as similar fresh gas flows are used in both modes of ventilation.