Which circuits are not suitable for IPPV?

• A. Circle, T-piece, Bain, Humphreys
• B. Mini lack, Lac, Magill
• C. Bain, Circle
• D. Humphreys, Magill

Answer: (B)

Intermittent Positive Pressure Ventilation relies on delivering controlled breaths through a circuit that provides a reservoir and proper gas flow control so you can compress the bag to deliver a set tidal volume without allowing gas to leak or backflow. Some circuits simply aren’t built for this kind of controlled ventilation because they lack a reservoir, valves, or the necessary configuration for safe, repeatable positive pressure breaths.

The options not suitable for IPPV are those that are small, open-ended, or lack a proper reservoir and valve system. Mini lack and Lac circuits fall into this category because their design does not provide a reliable reservoir or the necessary valve arrangement to deliver consistent, controlled breaths. The Magill circuit is a short, open non-rebreathing circuit typically used for quick, hands-on ventilation during direct laryngoscopy rather than for controlled, ongoing IPPV; its design does not support reliable positive pressure ventilation.

In contrast, circuits like circle, Bain, and Humphrey’s incorporate reservoir bags and appropriate valve configurations that enable accurate, controllable IPPV, making them suitable choices for delivering intermittent positive pressure breaths.