Modified parallel 'Lack' breathing system for use in dental anaesthesia

A twin-tube breathing system for inhalational anaesthesia in dental surgery is described. The system is a modification of a parallel Mapleson 'A' breathing system and is suitable for use with continuous flow anaesthetic machines. Resistance to airflow has been evaluated and is within the recommended ranges at all flows likely to be experienced in normal clinical conditions. The system is suitable for children and adults, easy to use and efficient. The expiratory valve is located remote from the face and the system is suitable for scavenging by active, assisted or passive systems.