1. General Anaesthesiology

Title: Efficiency of consumption of anaesthetic agents within the department, while using low flow circle anaesthesia
Author(s): Anatolyeva M., Kumar N.
Institute(s): NHS Grampian, Dept of Anaesthesiology, Aberdeen, United Kingdom

Text:
Background:

It is important to use circle breathing systems for the delivery of volatile anaesthesia in a safe, efficient and cost effective manner. The implications are environmental pollution and the cost of anaesthetic agents.

Methods of study:

A. To interrogate Drager anaesthetic machines in the main theatres, Aberdeen Royal Infirmary(ARI), over the period of 2 weeks in February 2015 and to get a snap-shot of information like: duration of the case, gases used, amount of carrier gases used, fresh gas flow rate (FGF, L/Min), volatile agent consumption(mls), volatile agent uptake(mls), per case.
B. To calculate the Volatile Ratio(VR) - agent consumption:agent uptake, i.e. what is evaporated:what is consumed by the patient and eventually absorbed by soda lime. The higher the Volatile Ratio is, the more inefficient usage of agents during the case.
C. To compare the collected data with the proposed standards[1]: 75% of anaesthetics with a duration less than 1 hour to have a VR less than 3, 75% of anaesthetics with a duration more than 1 hour to have a VR less than 2.
D.To identify suggestions for improvement, with potential to carry Phase II Audit.

Results:

In total, 230 anaesthetic cases were interrogated. Cases lasting less than 1 hour, or 1 hour sharp constituted 77 out of 230, and 153 cases lasted longer than 1 hour. Out of 77 short cases, VR was less or equal 3 only on 29 occasions, which is 37.66% in the group. Out of 153 longer lasting cases, VR was less or equal 2 on 41 occasions, which is 26.8% in this group. The correlation of VR with FGF was also identified. These data were re-audited in September 2015 - 80 cases considered, 28
short and 52 long cases. Out of 28 short cases VR was less or equal 3 on 17 occasions(60.7%), out of 52 long cases VR was less or equal 2 on 14 occasions(26.9%).

Conclusion(s):

Overall, the efficiency of consumption of anaesthetic gases did not meet the proposed standards and suggestions for improvement were made: reminder to use low flow circle anaesthesia, with FGF of 1L/min or less, also advise would be to set vapouriser to 2 times desired end-tidal agent concentration initially, so the desired concentration of the agent is reached very rapidly.
On re-auditing there was an improvement in the managing short cases.
We would encourage anaesthetists to review log-books on anaesthetic machines for self-learning.

Reference:
http://www.draeger.com/sites/assets/PublishingImages/Generic/sidebar-teaser/MEA/how-low-canyou-
flow.pdf
Preferred Presentation
Type: Clinical or experimental study
Conference: Euroanaesthesia