Abstract: An anesthesia system includes a main output and an auxiliary output. The main output and the auxiliary output are configured to operate independently of each other. The main output may provide a first mixture of gases and an anesthetic agent to a patient. The auxiliary output may provide a second mixture of gases to the patient. A user may selectively mix oxygen and at least one other gas such that the second mixture of gases is provided to the auxiliary output at a desired flow rate and such that the second mixture of gases includes a desired oxygen percentage level. The second mixture of gases provided through the auxiliary output is prevented from flowing back into the anesthesia system to reduce or prevent contamination of the gases provided through the main output.