Cylinder & Anesthesia Machine
All of the following are suitable anaesthetic circuits for both controlled and assisted ventilation, except:
|B||Mapleson B & C|
a. D & C are no more used in anaesthesia practice but if the characteristic of these circuits are seen they are almost equally effective for controlled and spontaneous ventilation, similarly E & F (although E is primarily used for spontaneous but controlled ventilation is possible by intermittently occluding and sealing the end of tube) can be used for controlled and spontaneous ventilation.
b. Type D (Bain) requires high flow for spontaneous but does work efficiently for spontaneous also.
c. Mapleson A (Magill) is circuit of choice for spontaneous respiration, for controlled ventilation it may require very high flows (may be > 3 times minute volume or > 20 L by some studies) and in spite of that prevention of rebreathing is unpredicted-table, so Mapleson A should not used for controlled ventilation.