The systems are designated A through F. They can be broadly categorized based on the location of the APL valve relative to the patient and the fresh gas inlet.
While the circle absorber system has largely replaced breathing circuits in routine surgical anesthesia, the Mapleson systems remain indispensable backup and specialty tools. The Mapleson A stands as the most efficient circuit for the spontaneously breathing patient, while the Mapleson D (and its Bain modification) is the workhorse for controlled ventilation and transport. A thorough understanding of the flow dynamics within these circuits is essential for every anesthetist to prevent the catastrophic complication of hypercapnia due to unintended rebreathing. mapleson circuit