91 lines
5.0 KiB
Plaintext
91 lines
5.0 KiB
Plaintext
In article <1992Oct5.135942.23068@linus.mitre.org> lewis@aera8700.mitre.org (Keith Lewis) writes:
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>I've seen the claim that N2O does not react chemically more than once on
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>this network, yet nobody seems to be able to explain why it gives you a
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>buzz. This sounds a bit fishy to me.
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According to _Introduction to Anesthesia_, Dripps, Eckenhoff, Vandam,
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the action of inhalation anesthetics is still not totally understood, but
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there are several theories and possible explanations:
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"The basic principle that lipid solubility of anesthetics governs anesthetic
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action remains viable. Specifically, the narcotic action of a drug
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correlates strongly with its solubility in biologic membranes. Interactions
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of anesthetics with biologic membranes cause expansion of the membrane.
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Membrane expansion by a critical volume of 0.4 per cent results in
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anesthesia. Evidence is available to show that anesthetics selectively
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combine with hydrophobic groups in biologic proteins, whether purified or
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membrane-associated. Perhaps these alterations in membrane structure affect
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synaptic transmission in the brain, giving rise to anesthesia."
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Another possible method is changes in membrane protein structure altering
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ion flow. Action on membranes in mitochondria and endoplasmic reticulum
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might also be responsible.
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The primary anesthetic action seems to be the synapse. Anesthetics may
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alter the binding of neurotransmitter to specific receptor proteins.
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The section concludes that the mechanisms are not necessarily exclusive of
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one another. Multiple mechanisms may be responsible for anesthesia.
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Ken Shirriff shirriff@sprite.Berkeley.EDU
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=============================================================================
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A FEW WORDS ON METHOD OF ACTION...
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N20 is a weak anaesthetic gas that has been in use since the
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late 18th century both in surgery and at parties. It is also used in
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the dairy industry as a mixing and foaming agent as it is non-flammable,
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bacteriostatic (stops bacteria from growing) and leaves no taste or
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odour on the food.
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N2O does not combine with haemoglobin, but is carried free in
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the blood and excreted unchanged through the lungs. The risk of hypoxia
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comes not from any interaction between N2O and O2 in the blood or brain,
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but from simply not inhaling oxygen often enough. The vast majority of
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deaths from N2O abuse have been through stupidity (tying a plastic bag
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full of N2O round the head, letting off a tank in a airtight place, that
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sort of thing). There have been a few cases of malignant
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hyperthermia (raised body temperature),and this is considered a
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potentially serious threat to those with the genetic requirement (check
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out your family history - look for deaths during surgery, both minor and
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major).
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There are 4 stages of general anaesthesia. The first is
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drowsiness, confusion and analgesia. The second stage involves
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excitement, euphoria, spontaneous muscle movements, hallucinations
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(auditory and visual). The third stage is loss of consciousness, and the
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fourth stage is heading into coma, where the patient stops breathing.
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Anaesthetists generally aim for the upper levels of stage three, which
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is why some people 'wake up' during the operation - they've drifted up
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into stage two. From personal experience, I think that recreational use
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of inhalational anaesthetics (N2O and ether) induce stage 2 and
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sometimes stage 3, depending on the pattern of use.
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General Anaesthetics can give nausea and vomiting as a side
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effect, the risk of this is increased if you have been drinking alcohol.
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Not only is this a bit unpleasant but there is a risk of inhaling your
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own vomit if you are a bit confused or temporarily unconscious.
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Reverse tolerance has been reported in the literature, and this
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seems to be confirmed by my own personal experiences. Reverse tolerance
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is getting more intense or prolonged feelings with the same or lower
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quantities of a drug. Most psychoactive substances don't work this way,
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I don't know why N2O does. As all traces of the gas are excreted from
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the body within an hour after cessation of use, it's not due to fat
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stores being reintroduced to the blood (as can happen with marijuana).
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Be very careful of home made N2O. In some states of the US,
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there is a leaflet floating around with instructions on how to make your
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own, but you are almost guaranteed to end up with a lungful of assorted
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rubbish like NO2, H2NO3, and other yummy toxic things. REF: Annals of
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Internal Medicine, Vol 96, 3,Mar 1982,pp333-334:Home made Nitrous Oxide:
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No laughing matter.
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Nitrous oxide will dissolve out of blood into air filled spaces
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eg the intestines, the middle ear. N2O in the gut will just give you a
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gut pain, but if you have ever had middle ear disease, or damaged ear
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drums, you could be in for permanent hearing loss. There are also some
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cases of transient hearing loss, but I don't know much about this.
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There isn't very much in the medical literature about
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recreational use of N2O, which is a different pattern to surgical use.
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Next time I get a tank, I'll run a few tests and observations on my
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friends just to see what's really happening.
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Karen
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