Anesthesia Technologist Practice Exam

Which gas flow could lead to a higher risk of rebreathing?

1. High fresh gas flow

2. Zero fresh gas flow

3. Medium fresh gas flow

4. Low fresh gas flow

The correct answer is: Low fresh gas flow

Rebreathing occurs when exhaled gases are inhaled again, which can lead to a decrease in the effectiveness of gas exchange and can result in the inhalation of carbon dioxide along with a reduction in oxygen levels. Low fresh gas flow increases the risk of rebreathing because it limits the amount of fresh anesthetic gas being delivered to the patient. In a system with low fresh gas flow, the volume of gases exhaled can accumulate in the circuit and may not be effectively expelled, especially if the breathing circuit is poorly ventilated or has high compliance. This growing concentration of exhaled gases can lead to the patient inhaling these gases again during the next breath. Consequently, in situations where the fresh gas flow is insufficient to dilute or replace the exhaled gases adequately, the likelihood of rebreathing becomes significantly higher. Conversely, high fresh gas flow rates promptly eliminate the potential for rebreathing by continuously flushing the circuit with fresh gases, while zero fresh gas flow would typically lead to ventilatory failure, making the patient unable to breathe adequately. Medium fresh gas flow may provide a balance but is more effective than low flow in preventing rebreathing. Thus, low fresh gas flow is indeed associated with an increased risk