Comparison of AGC (Automatic Gas Control) Mode and Manually Controlled Minimal Flow Anesthesia in Breast Surgery

Modern anesthesia machines use circular systems in which ventilated gas re-circulates to a certain degree and is therefore reused, preserving temperature, and humidity. The rebreathing fraction is increased by a reduction in fresh gas flow, which leads to a considerable decrease in consumption of fresh gas and volatile anesthetics, resulting in reductions in cost and atmospheric pollution. In a closed ventilation system, only the patient's requirements for oxygen and anesthetic agents are supplemented. A fresh gas flow-rate of 0.5 l/min is defined as the minimal-flow technique. The oxygen and anesthetic gas titration can be manually controlled by the anesthetist. To assure safe and appropriate anesthesia, manually controlled anesthesia requires constant monitoring and numerous adjustments to the gas dosage by the anesthetist, especially for low- and minimalflow anesthesia. Oxygen flow and volatile anesthetics can also be automatically controlled by anesthesia machines using end-tidal control (such as AGC mode of Maquet FLOW-i anesthesia machine), which ensures constant end-tidal concentration of oxygen and anesthetic gas via feedback and continuous automatic adjustment mechanisms. Anesthesiologists needing to make fewer interventions during a case may have clinical importance in terms of distraction, record keeping and patient safety. In addition to this advantage, we wanted to compare the AGC mode and manually controlled minimal-flow anesthesia for volatile anesthetic consumption, hemodynamic parameters, and recovery from anesthesia.