The Mapleson D circuit design includes which feature?

The Mapleson D circuit design includes which feature?

• A. Proximal fresh gas inflow and distal overflow valve
• B. Distal fresh gas inflow and proximal overflow valve
• C. A venturi scavenging port
• D. A sealed reservoir bag only

Answer: (A)

Mapleson circuits differ by where fresh gas enters the system and where exhaled gas is vented. In the D configuration, fresh gas is delivered near the patient's airway (proximal end), so the inspired mixture is dominated by new gas. Exhaled gas is directed out through a distal overflow valve, away from the patient, and toward the scavenging system. This setup minimizes rebreathing during spontaneous ventilation and keeps the circuit simple, with the reservoir bag located on the machine side rather than forming a closed, sealed bag in the patient limb. The design does not rely on a venturi scavenging port, and it is not a sealed reservoir bag only.

Mapleson circuits differ by where fresh gas enters the system and where exhaled gas is vented. In the D configuration, fresh gas is delivered near the patient's airway (proximal end), so the inspired mixture is dominated by new gas. Exhaled gas is directed out through a distal overflow valve, away from the patient, and toward the scavenging system. This setup minimizes rebreathing during spontaneous ventilation and keeps the circuit simple, with the reservoir bag located on the machine side rather than forming a closed, sealed bag in the patient limb. The design does not rely on a venturi scavenging port, and it is not a sealed reservoir bag only.