Automated gas control with the Maquet FLOW-i

Area of Science:

• Anesthesiology
• Medical Devices
• Pharmacology

Background:

• The FLOW-i anesthesia machine features Automated Gas Control (AGC) for precise management of inspired oxygen concentration (FIO2) and end-expired anesthetic concentration (FA).
• AGC utilizes automated low flow techniques with target-controlled delivery of potent inhaled anesthetics like sevoflurane.
• Understanding AGC's performance and quantitative aspects is crucial for optimizing anesthetic delivery and resource utilization.

Purpose of the Study:

• To evaluate the performance and quantitative characteristics of the Automated Gas Control (AGC) feature on the FLOW-i anesthesia machine.
• To compare the impact of different AGC speed settings on anesthetic agent usage, physiological parameters, and time to target concentration.
• To assess the potential of AGC to reduce anesthetic waste, cost, and environmental pollution.

Main Methods:

• Twenty-four ASA I-II patients undergoing abdominal or gynecological surgery received sevoflurane anesthesia with AGC.
• Patients were randomized into three groups (n=8 each) assigned to AGC speeds 2, 4, or 6.
• Key parameters including FIO2, end-expired sevoflurane (FAsevo), BIS values, vital signs, and sevoflurane consumption were monitored over 60 minutes.

Main Results:

• Target FIO2 was achieved within 1-2 minutes in all groups. Target FAsevo was reached more rapidly with higher AGC speeds.
• FAsevo reached 1.8-1.9% within 6-15 minutes across groups. No significant differences in blood pressure, heart rate, or BIS values were observed.
• Cumulative sevoflurane usage was significantly lower with lower AGC speeds, particularly after 30 minutes and between 35-60 minutes for the slowest speed.

Conclusions:

• Automated Gas Control (AGC) on the FLOW-i anesthesia machine effectively controls FIO2 and FAsevo, with faster speeds achieving targets sooner.
• Lower AGC speeds significantly reduce sevoflurane consumption, approaching near closed-circuit conditions with maintenance fresh gas flow of 300 mL/min.
• AGC offers a valuable tool for reducing anesthetic waste, cost, and pollution while simplifying low-flow anesthesia management.