An audit of anaesthetic fresh-gas flow rates and volatile anaesthetic use in a teaching hospital

N Z Med J. 2003 May 16;116(1174):U438.


Aim: The large number of anaesthetics administered means that the total cost to a hospital of inhalational anaesthetic agent such as isoflurane or sevoflurane can be considerable. The total anaesthetic gas flow is a major determinant of the use of these agents. Modern anaesthetic machines and monitoring facilitate reduced gas flows, which can significantly reduce wastage of these anaesthetic agents. The purpose of this study was to audit gas flow rates and volatile anaesthetic use.

Methods: We audited gas flows and choice of anaesthetic agent over two one-month periods in one theatre at Christchurch Hospital. Data were collected directly from the anaesthetic machine using a computer. The second study period was clearly advised and followed widespread discussion of results from the first study period.

Results: Average fresh-gas flow was approximately 2 l/min (Month 1 = 2.0 l/min, Month 2 = 2.1 l/min). Use of the more expensive agent, sevoflurane, increased but gas flows with this agent decreased.

Conclusions: Given the low flows used, the small difference between study periods was not surprising. The gas flows recorded represent responsible use of anaesthetic agents and are at least as good as flows achieved in previous studies that employed various methods to encourage their reduction.

MeSH terms

  • Anesthesia, Closed-Circuit* / economics
  • Anesthesia, Closed-Circuit* / instrumentation
  • Anesthetics, Inhalation*
  • Hospitals, Teaching
  • Isoflurane*
  • Medical Audit
  • Methyl Ethers*
  • New Zealand
  • Sevoflurane
  • Signal Processing, Computer-Assisted


  • Anesthetics, Inhalation
  • Methyl Ethers
  • Sevoflurane
  • Isoflurane