Anesthesia Technologist Practice Exam

Under which conditions may rebreathing occur during anesthesia?

1. During high fresh gas flows

2. During low fresh gas flows

3. During controlled ventilation

4. During spontaneous breathing

The correct answer is: During low fresh gas flows

Rebreathing during anesthesia typically occurs under conditions of low fresh gas flows. This situation arises when the fresh gas flow from the anesthesia machine is insufficient to adequately clear exhaled carbon dioxide (CO2) from the breathing circuit or reservoir. At low flow rates, the exhaled gases, which include CO2, can mix with the fresh gas and be inspired again by the patient, leading to rebreathing of CO2. In scenarios where fresh gas flows are high, there is generally an adequate supply of fresh anesthetic gases that helps to dilute and wash out the exhaled gases, minimizing the risk of rebreathing. Controlled ventilation and spontaneous breathing are methods of delivering anesthesia; however, rebreathing itself is a function of fresh gas flow rates rather than the method of ventilation. Thus, the occurrence of rebreathing is primarily influenced by the fresh gas flow conditions present during anesthesia administration.