Controlled ventilation with a Mapleson A (Magill) breathing system: reassessment using a lung model.

We have used a lung model to reassess the efficiency of the Magill attachment during controlled ventilation in which the pattern of ventilation, tidal volume and fresh gas flows were varied. Adjustment of the inspiratory:expiratory ratio to ensure a prolonged expiratory phase is recommended, to improve efficiency and predictability of the system, if its use is necessary for short periods during controlled ventilation in clinical practice.