Automated gas control with the Maquet FLOW-i

Abstract

The FLOW-i anesthesia machine (Maquet, Solna, Sweden) can be equipped with automated gas control (AGC), an automated low flow tool with target control of the inspired oxygen concentration (FIO2) and end-expired concentration (FA) of a potent inhaled anesthetic. We examined the performance and quantitative aspects of the AGC. After IRB approval and individual informed consent, anesthesia in 24 ASA I-II patients undergoing abdominal or gynecological surgery was maintained with sevoflurane in O2/air with a target FIO2 of 40 % and a target sevoflurane FA (FAsevo) of 2.0 %. The AGC tool also allows the user to select 1 out of 9 different speeds with which the target FAsevo can be reached (with 9 being the fastest speed). Eight patients each were randomly assigned to speed 2, 4, and 6 (= group 2, group 4, and group 6, respectively); these three speeds were chosen arbitrarily. AGC was activated immediately after securing the airway, which defined the start of the study, and the study ended 60 min later. The following parameters were compared among the three groups: age, height, weight, FIO2, FAsevo, BIS values, heart rate, mean arterial blood pressure, fresh gas flow, and sevoflurane usage. Agent usage as reported by the FLOW-i was compared among the three groups. Patient demographics and maintenance FGF did not differ among groups. A very short-lived very high FGF (≈20 L min(-1) for 8-12 s) ensured that the target FIO2 was attained within 1-2 min in all patients. FAsevo was 1.8 % after 15, 10, and 6 min, and 1.9 % after 30, 20 and 15 min in groups 2, 4, and 6, respectively. Blood pressure, heart rate, and BIS values did not differ among the three groups. BIS values remained acceptable in all patients, even with the slowest speed. Cumulative agent usage differed among all three groups between 2 and 30 min (lower with the lower speed), and between group 2 and 6 between 35 and 60 min. AGC combines an exponentially decreasing FGF pattern with a choice of ramp functions for the end-expired target concentration of the inhaled anesthetic. Consequently, both FGF and the choice of speed become factors that influence agent usage. After 15 min, a 300 mL min(-1) maintenance FGF reduces agent usage to near closed-circuit conditions. This new addition to our automated low flow armamentarium helps to reduce anesthetic waste, cost, and pollution, while minimizing the ergonomic burden of low flow anesthesia.

Context-sensitive decrement times for inhaled anesthetics in obese patients explored with Gas Man®

“…Because of a lack in theoretical and clinical data to characterize the alterations of pharmacokinetics of volatile anesthetics in obese patients, these systems may have errors in their prediction. End-tidal control delivery machines like Zeus® (Dräger Medical), Aisys EtControl™ (GE Healthcare, Madison, WI, USA) and the FLOW-i (Maquet, Getinge AB, Getinge, Sweden) adjust the vaporizer output and fresh gas flow (FGF) automatically to reach and maintain a previously set end-tidal volatile anesthetics' concentration [21][22][23] and will be less or not-at-all affected by model errors.…”

Saving sevoflurane: Automated gas control can reduce consumption of anesthetic vapor by one‐third in pediatric anesthesia

“…The software aims to have both financial and environmental benefits; however, it can come at an additional cost from the manufacturer. The benefits have been documented in the adult setting but there is no quantification of the benefit in pediatric anesthesia.…”

Desflurane consumption with automated vapour control systems in two different anaesthesia machines. A randomized controlled study

“…One explanation could be the set-up of speed 6 in TA B L E 2 Desflurane consumption (mL liquid) after 9, 30 and 60 min our study as Carette et al observed that the volatile anaesthetic consumption in Flow-I AGC is higher for speed 6 compared to speed 2. 17 It is unclear whether the chosen speed for the Flow-I AGC had an impact on our results.…”

“…14 However, since the introduction of automated gas control delivery systems only a few studies have investigated functionality and effects on volatile anaesthetic consumption. [14][15][16][17][18][19][20] The aim of this study was to compare the consumption of desflurane delivered with and without the use of automated gas control (AGC) Flow-I or end-tidal gas control Aisys gas control delivery systems. We also compared volatile anaesthetic consumption between the two different automated anaesthetic gas control systems used in the study, the time it took to reach a minimum alveolar concentration of 0.7 and the time to reach a FGF of 0.5 L/min.…”