scholarly journals The theoretical ideal fresh‐gas flow sequence at the start of low‐flow anaesthesia

Anaesthesia ◽  
1998 ◽  
Vol 53 (3) ◽  
pp. 264-272 ◽  
Author(s):  
W. W. Mapleson
Keyword(s):  
Gas Flow ◽  
Low Flow ◽  
Low Flow Anaesthesia

Effect of Fresh Gas Flow on Isoflurane Concentrations during Low-flow Anaesthesia

2005 ◽  
Vol 33 (5) ◽  
pp. 513-519 ◽  
Author(s):  
J-Y Park ◽  
J-H Kim ◽  
W-Y Kim ◽  
M-S Chang ◽  
J-Y Kim ◽  
...  
Keyword(s):  
Gas Flow ◽  
Low Flow ◽  
Physical Status ◽  
Closed Circle ◽  
Haemodynamic Changes ◽  
Low Flow Anaesthesia ◽  
Baseline Values ◽  
American Society ◽  
End Tidal ◽  
Closed Circle System

The effect of fresh gas flow (FGF) on isoflurane concentrations at given vaporizer settings during low-flow anaesthesia was investigated. Ninety patients (American Society of Anaesthesiologists physical status I or II) were randomly allocated to three groups (FGF 1 l/min, FGF 2 l/min and FGF 4 l/min). Anaesthesia was maintained for 10 min with vaporizer setting isoflurane 2 vol% and FGF 4 l/min for full-tissue anaesthetic uptake in a semi-closed circle system. Low-flow anaesthesia was maintained for 20 min with end-tidal isoflurane 1.5 vol% and FGF 2 l/min. FGF was then changed to FGF 1 l/min, FGF 2 l/min or FGF 4 l/min. Measurements during the 20-min period showed that inspired and end-tidal isoflurane concentrations decreased in the FGF 1-l/min group but increased in the FGF 4-l/min group compared with baseline values. No haemodynamic changes were observed. Monitoring of anaesthetic concentrations and appropriate control of vaporizer settings are necessary during low-flow anaesthesia.

scholarly journals Promoting low-flow anaesthesia and volatile anaesthetic agent choice

2019 ◽  
Vol 8 (3) ◽  
pp. e000479 ◽  
Author(s):  
Louise A Carter ◽  
Molola Oyewole ◽  
Eleanor Bates ◽  
Kate Sherratt
Keyword(s):  
Gas Flow ◽  
Anaesthetic Agent ◽  
Cost Effective ◽  
Low Flow ◽  
Volatile Agent ◽  
Monthly Basis ◽  
Improvement Project ◽  
Effective Manner ◽  
Low Flow Anaesthesia ◽  
Volatile Agents

BackgroundAs doctors, we are increasingly aware of the financial implications of our practice. The need to work in a more conscientious, efficacious and cost-effective manner is greater than ever before. Environmental and financial benefits can be seen through employing the use of low-flow anaesthesia.AimsThis quality improvement project aimed to make anaesthetic practice more environmentally friendly and to reduce departmental spending. This could be achieved by promoting the use of low-flow anaesthesia and by encouraging isoflurane use where appropriate.MethodsAll anaesthetic consultants and trainees were invited to fill out an initial questionnaire relating to their personal preferences and practices when conducting anaesthesia. There were specific questions relating to low-flow anaesthesia and isoflurane use. Our main measure of improvement was any decrease in the number of bottles of volatile agent ordered by the department from pharmacy. Monthly spot audits were conducted to assess gas flow rates and volatile agent use in theatre. Departmental spending figures relating to the purchase of volatile agent bottles were obtained from pharmacy. Information was then disseminated to anaesthetists on a monthly basis via a ‘low-flow board’, which showed pictorial and graphical representations of differing gas flows and volatile agent usage in relation to cost.ResultsOur project showed a trend for the increased use of low-flow anaesthesia within the department. We also showed a decrease in the number of bottles of volatile agent ordered: 18% fewer bottles ordered compared with the same period the previous year. This represented a 25% decrease in total departmental expenditure on volatile agents despite an increase in theatre activity.ConclusionIncreasing awareness regarding anaesthetic choices and promoting low-flow anaesthesia and isoflurane use, translated into an overall decreased departmental spend on volatile agents without affecting patient care.

scholarly journals Cost-effectiveness of Basal Flow Sevoflurane Anaesthesia Using the Komesaroff Vaporizer inside the Circle System

2005 ◽  
Vol 33 (5) ◽  
pp. 609-615 ◽  
Author(s):  
S. P. Nandalan ◽  
R. J. Eltringham ◽  
Q. W. Fan
Keyword(s):  
Gas Flow ◽  
Low Flow ◽  
Gas Flows ◽  
Physical Status ◽  
Mechanically Ventilated ◽  
Sevoflurane Anaesthesia ◽  
Inspiratory Limb ◽  
Low Flow Anaesthesia ◽  
Induction Of Anaesthesia ◽  
Basal Flow

After ethics committee approval, 51 consenting ASA physical status 1 or 2 adult patients were given basal flow sevoflurane anaesthesia using fresh gas flows of 150 to 300 ml.min-1 oxygen. A Komesaroff vaporizer was placed on the inspiratory limb of the circle system. Basal flows were introduced immediately following intravenous induction of anaesthesia. The vaporizer was set to deliver the maximum concentration until the inspired sevoflurane concentration (FSI) reached 3%. The dial was then adjusted to maintain the FSI at 3%. After every 60 minutes, the circuit was washed out with 100% oxygen at a flow rate of 10 l.min-1 for one minute. The FSI reached 3% after an average of 8.5 (3.8) [mean (SD)] minutes. The trends in FSI and the expired sevoflurane concentrations were significantly different (P<0.05) between the mechanically ventilated patients (n=21) and the spontaneously ventilating patients (n=30) and demonstrated a more gradual build-up in the former group. The consumption of sevoflurane was found to be 9.2 (2.8) ml.h-1. This represented a 52.5% cost saving over the clinical application of the Mapleson's ideal fresh gas flow sequence for low-flow anaesthesia.

scholarly journals The fresh-gas flow sequence at the start of low-flow anaesthesia

Anaesthesia ◽  
2001 ◽  
Vol 56 (4) ◽  
pp. 379-380 ◽  
Author(s):  
D. P. Sobreira ◽  
M. M. Jreige ◽  
R. &Aring. Saraiva
Keyword(s):  
Gas Flow ◽  
Low Flow ◽  
Low Flow Anaesthesia

scholarly journals Wash-in and wash-out of sevoflurane in a test-lung model: A comparison between Aisys and FLOW-i

F1000Research ◽  
2017 ◽  
Vol 6 ◽  
pp. 389 ◽  
Author(s):  
Petter Jakobsson ◽  
Madleine Lindgren ◽  
Jan G. Jakobsson
Keyword(s):  
Gas Flow ◽  
Anaesthetic Machine ◽  
Flow Time ◽  
Lung Model ◽  
Low Flow ◽  
Major Influence ◽  
Test Lung ◽  
Depth Of Anaesthesia ◽  
Low Flow Anaesthesia ◽  
End Tidal

Background:Modern anaesthesia workstations are reassuringly tight and are equipped with effective gas monitoring, thus providing good opportunities for low/minimal flow anaesthesia. A prerequisite for effective low flow anaesthesia is the possibility to rapidly increase and decrease gas concentrations in the circle system, thereby controlling the depth of anaesthesia. Methods:We studied the wash-in and wash-out of sevoflurane in the circle system with fixed fresh gas flow and vaporizer setting. We compared two modern anaesthesia work stations, the Aisys (GE, Madison, WI, USA) and FLOW-i (Maquet, Solna, Sweden) in a test lung model. Results: We found fresh-gas flow to have, as expected, a major influence on wash-in, as well as wash-out of sevoflurane. The wash-in time to reach a stable circle 1 MAC (2.1%) decreased from an average of 547 ± 83 seconds with a constant fresh gas flow of 300 ml/min and vaporizer setting of 8%, to a mean of 38 ± 6 seconds at a fresh gas flow of 4 L/min. There were only minor differences between the two works-stations tested; the Aisys was slightly faster at both 300 and 4 L/min flow. Time to further increase circle end-tidal concentration from 1-1.5 MAC showed likewise significant associations to fresh gas and decreased from 330 ± 24 seconds at 300 ml/min. to less than a minute at constant 4 L/min (17 ± 11 seconds), without anaesthetic machine difference. Wash-out was also fresh gas flow dependent and plateaued at 7.5 L/min. Conclusions: Circle system wash-in and wash-out show clear fresh gas dependency and varies somewhat between the Aisys and Flow-i. The circle saturation, reaching 1 MAC end-tidal or increasing from 1-1.5 MAC can be achieved with both work-stations within 1.5 minutes at a constant fresh gas flow of 2 and 4 L/min. Wash-out plateaued at 7.5 L/min.

scholarly journals Wash-in and wash-out of sevoflurane in a test-lung model: A comparison between Aisys and FLOW-i

F1000Research ◽  
2017 ◽  
Vol 6 ◽  
pp. 389 ◽  
Author(s):  
Petter Jakobsson ◽  
Madleine Lindgren ◽  
Jan G. Jakobsson
Keyword(s):  
Gas Flow ◽  
Anaesthetic Machine ◽  
Flow Time ◽  
Lung Model ◽  
Low Flow ◽  
Major Influence ◽  
Test Lung ◽  
Depth Of Anaesthesia ◽  
Low Flow Anaesthesia ◽  
End Tidal

Background:Modern anaesthesia workstations are reassuringly tight and are equipped with effective gas monitoring, thus providing good opportunities for low/minimal flow anaesthesia. A prerequisite for effective low flow anaesthesia is the possibility to rapidly increase and decrease gas concentrations in the circle system, thereby controlling the depth of anaesthesia. Methods:We studied the wash-in and wash-out of sevoflurane in the circle system with fixed fresh gas flow and vaporizer setting. We compared two modern anaesthesia work stations, the Aisys (GE, Madison, WI, USA) and FLOW-i (Maquet, Solna, Sweden) in a test lung model. Results: We found fresh-gas flow to have, as expected, a major influence on wash-in, as well as wash-out of sevoflurane. The wash-in time to reach a stable circle 1 MAC (2.1%) decreased from an average of 547 ± 83 seconds with a constant fresh gas flow of 300 ml/min and vaporizer setting of 8%, to a mean of 38 ± 6 seconds at a fresh gas flow of 4 L/min. There were only minor differences between the two works-stations tested; the Aisys was slightly faster at both 300 and 4 L/min flow. Time to further increase circle end-tidal concentration from 1-1.5 MAC showed likewise significant associations to fresh gas and decreased from 330 ± 24 seconds at 300 ml/L to less than a minute at constant 4 L/min (17 ± 11 seconds), without anaesthetic machine difference. Wash-out was also fresh gas flow dependent and plateaued at 7.5 L/min. Conclusions: Circle system wash-in and wash-out show clear fresh gas dependency and varies somewhat between the Aisys and Flow-i. The circle saturation, reaching 1 MAC end-tidal or increasing from 1-1.5 MAC can be achieved with both work-stations within 1.5 minutes at a constant fresh gas flow of 2 and 4 L/min. Wash-out plateaued at 7.5 L/min.

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