Monday, August 13, 2012

Minimal Fresh Gas Flow: "A Reassuringly Safe Anesthetic Technique".

Image 1: Minimal FGF on the FLOW-i anesthesia delivery system

In this months Canadian Journal of Anesthesia authors of the article "Brief Review: Theory and Practice of Minimal Fresh Gas Flow Anesthesia", conclude that with newer anesthesia delivery systems that using minimal fresh gas flow and third generation of inhaled anesthetic agents is a safe technique with many benefits [1]. 

The authors review advantages, potential limitations, and safety considerations when utilizing minimal fresh gas flow technique (mFGF). 
Benefits mFGF
  1. Maintaining temperature and humidity.
  2. Cost savings regarding inhaled anesthetic agents (see "Save $200,000" for a case study).
  3. Decrease in environmental exposure to anesthetic agents. 
Image 2: Example of a patient's temperature maintained during minimal flow anesthesia. 

Potential Limitations mFGF

  1. Leaks in the circle system- This is highly monitored in newer devices with the system checkout and feedback alarms.
  2. CO2 absorbency & desiccation- new soda lime contains 0% potassium hydroxide (KOH) a known alkali that results in carbon monoxide production.
Image 3: Example of a system check out, checking for leaks (highlighted in yellow). 

Safety considerations with mFGF

Patient monitoring- newer devices have precise gas analyzers which monitor both inhaled and exhaled anesthetic gas.
A few machines have an additional gas analyzer which can safely turn off the vaporizer, preventing a over dose of anesthetic agent.


[1]. Brattwell et. al. (2012). Brief Review: Theory and Practice of Minimal Fresh Gas Flow Anesthesia. Canadian Journal of Anesthesia. 59 (8): 785-797. 


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