Comparison of Automated Control Anesthesia and Manual Control Anesthesia in Minimal Flow Anesthesia

In the manual technique, the inspired and exhaled gas concentrations are regulated by the anesthetists manually by the fresh gas flow during general anaesthesia. When administered manually, low-flow anesthesia requires the attention and time of the anesthesiologist, especially the difference between the gas concentrations set in the anesthesia machine and the respiratory system, and the delay between changes in fresh gas concentrations and the end tidal fraction (EtAA) of the anesthetic agent. The most important risks of manually controlled low-flow anesthesia are hypoxia and awareness that may occur due to low doses of inhaler anesthetic agents.

In the automatic controlled anesthesia technique, it is a method in which the values desired by the anesthetists during general anesthesia are determined at the beginning of anesthesia and automatically adjusted by the anesthesia device without any additional intervention. After intubation, anesthetists set 3 parameters on the anesthesia device: inspiratory or expiratory oxygen fraction (FiO2- End tidal O2 concentration), anesthetic agent concentration (MAC or End-tidal Anesthetic agent concentration) and fresh gas flow amount. With this method, it is aimed to provide safer and more stable anesthesia. In addition, it has been stated in many previous studies that automatic control anesthesia technique reduces anesthetic gas consumption and less anesthesiologist intervention is needed to reach target values.

In our study, we aimed to compare the safety, efficiency and cost aspects of automatic controlled anesthesia and manual control methods in achieving intraoperative target anesthetic and oxygen concentrations. We hypothesized that anesthesia applied with the end-tidal control method would have a lower cost, less workload, and similar anesthetic depth with the manual control method.

Inclusion criteria

• Between 18-75 year-old
• ASA 1-3
• Will undergo gynecological operation
• Expected surgery time (>1 hour)

Exclusion criteria

• ❖ BMI >30

• Chronic opioid use
• Contraindication to any of the anesthetic agents to be used
• Neurological disorders
• Surgery lasting <1 hour