Which type of breathing circuit is associated with hypothermia risk under general anesthesia?

• A. Re-breathing circuit
• B. Circle circuit
• C. Non re-breathing circuit
• D. Breathing circuit with heated humidification

Answer: (C)

Heat and moisture exchange in breathing circuits is the key idea. A non-rebreathing circuit delivers fresh gas at high flow and does not reuse exhaled gas, so the inspired gas is typically dry and cooler. This increases evaporative and conductive heat loss from the airway and skin, and since anesthesia impairs the body’s ability to regulate temperature, the overall risk of hypothermia rises. In contrast, circle (rebreathing) circuits recycle some exhaled gas, which is warmed and humidified within the circuit, helping to conserve heat and moisture and better preserve body temperature. If heated humidification is used, this further reduces hypothermia risk. So the non-rebreathing circuit is the one associated with greater hypothermia risk.