Expert: Dr Ian Jackson - please note UK based - 11/6/2008

Question
Hi Dr Jackson, do you have any knowledge of what general anesthetic is made up of and how it sends you to sleep?
Thanks much

Answer
Sophie
There are lots of different general anaesthetic agents and they work in different ways. Much of it is still unkown however.
For example volatile agents (anaesthetics that you breath in) seem to work by causing changes to cell membranes in your brain. It is interesting to know that most gases can achive the same effect but under differing circumstances. Xenon which is extremely rare is quite a good anaesthetic but is much too costly. Nitrogen puts people to sleep when they are under increased atmospheric pressure. This is what happens to divers if they dive too deep using air - they get drunk and then fall asleep (Nitrogen Narcosis). It is thought the nitrogen dissolves in increasing amounts as the pressure increases leading to the same changes in the brain cell membranes.
Hence they use a mixture of Helium and Oxyrgen (Helox) when diving to deep depths. Helium is less soluble and so they can dive far deeper before they run into problems.
Then there are other anaesthetics that are given intravenously that seem to act on certain receptors in the brain e.g. GABA receptors.
All in all it is a complex subject but no one can tell you exactly what is happening with anaesthesia.
Hope this helps a bit
Dr Ian Jackson