Revision has now begun in earnest, which in practical terms means that I write concise summaries of all my previous lecture notes. This is in many ways therapeutic and I have certainly found myself sleeping considerably better (perhaps a potential cure for insomnia?), although perhaps falling asleep over one's notes is not the best indication of future success in examination... Any offers to take the first BM part II's in my stead? You can even wear my unbelievably cool scholar's gown! No? Oh, well, I suppose I shall have to muddle my way through them like I did last time...

There is one excellent benefit of revision, however, and that is that it allows one a sense of perspective over an entire subject area. There are fewer areas of medicine worse understood than neuroscience and I would like to discuss one particularly interesting field of applied neuroscience, which has as its central tenets an astonishing degree of incomprehension: general anaesthetics.

For any patient lying down on an operating table, it must give them a sense of relief to know that the gases and fluids being pumped into them have been used for decades and the mechanisms underlying their actions have been fully elucidated...poor, naive patient!
One of the most useful classes of clinical hypnotic is the volatile anaesthetics including notably N2O (nitrous oxide), halothane and isofluorane. The most basic question one could ask about this large fraction of hypotic agents is where do they act...
Hmmm...cue sheepish grins from anaesthetists (including my tutor, who is a consultant anaesthetist)... Well, we're pretty sure they work somewhere in the membrane of neurons somewhere in the brain, perhaps a centre of global consciousness such as the locus coeruleus.
What evidence is there for this? Essentially if one examines a table of anaesthetic agents, one notices immediately that there is a correlation between the lipid (fat) solubility of anaesthetic agents and their efficacy. This seems to suggest that the drugs are working in membranes (i.e. fatty areas of cells) and are perhaps (perhaps!) altering nearby proteins or ion channels...

General anaesthetic agents are very good at killing patients if anaesthetists are not careful (hence anaesthetists are the highest paid doctors so that they can afford to pay the court costs of the inevitable trials brought against them!).
Halothane in particular has a wonderful habit of inducing ventricular fibrillation (i.e. the chambers of the heart twitch rapidly instead of beating strongly as they should).
In addition to their cardiotoxic effects, GAs have an interesting tendancy to blunt the response of the body to high CO2 levels and completely abolish any response to low oxygen levels. This can result in the hugely dangerous situation where a patient has almost fatal oxygen saturation levels but is not stimulated to breathe spontaneously. Several anaesthetists have been surprised to come back and find that their patient has turned completely blue! Oops!

Anyway, enough of that! Perhaps if I wish to avoid revision tomorrow as well I may even summarise the pitfalls of another facet of medicine...there are just so many to choose from...