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Anesthesia (AE), also
anaesthesia (BE), is the process of blocking the
perception of pain and other sensations.
This allows patients to undergo surgery and other procedures without the distress and
pain they would otherwise experience. There are several forms of anesthesia:
Doctors specialising in the administration of anesthetics are known
as anesthesiologists (AE) or anaesthetists (BE). Nurses specialising in the
administration of anesthetics are known as nurse anesthetists
(AE).
History
Non pharmacological methods
Hypnotism and Acupuncture
have a long history of use as anaesthetic techniques.
Herbal derivatives
The first herbal anaesthesia was administered in prehistory. Opium and hemp
were two of the most important herbs used. They were ingested or burned and the smoke inhaled. Alcohol was also used, its vasodilatory properties being unknown. In China,
Taoist medical practitioners developed anaesthesia by means of acupuncture. In South America preparations from datura, effectively scopolamine, were used as was coca. In Medieval
Europe various preparations of mandrake were tried as was
henbane (hyoscyamine).
Early gases and vapours
The development of effective anaesthetics in the 19th century was, with Listerian techniques, one of the keys to successful
surgery. Henry Hill
Hickman experimented with carbon dioxide in the 1820s. The
anaesthetic qualities of nitrous oxide (isolated by Joseph Priestley) were discovered by the British chemist Humphry Davy about 1795 when he was an
assistant to Thomas Beddoes
and reported in a paper in 1800. But initially the medical uses of laughing gas were
limited - its main role was in entertainment. It was used in December 1844 for painless
tooth extraction by American dentist Horace Wells. Demonstrating it the
following year, at Massachusetts General Hospital, he made a mistake and the extractee suffered considerable pain. This lost
Wells any support.
Another dentist, William
E. Clarke, performed an extraction in January, 1842 using a different chemical,
ether (discovered in 1540). In March, 1842 in
Danielsville, Georgia, Dr. Crawford Williamson Long was the first to use anaesthesia
during an operation; giving it to a boy before excising a cyst from his neck. In October 1846 yet another dentist, William Thomas
Green Morton, removed a tumour from an patient under ether. Despite Morton's claims of a new gas called 'Letheon' the use of
ether spread to Europe in late 1846. Here respected surgeons including Liston, Dieffenbach, Pirogoff, and Syme undertook numerous
operations with ether.
Ether had a number of drawbacks and was quickly replaced with chloroform.
Discovered in 1831 its use in anaesthesia is usually linked to James Young Simpson. Who, in a wide-ranging study of organic compounds, found
chloroform's efficacy in 1847. Its use spread quickly and gained royal approval in 1853
when John Snow gave it to Queen Victoria during the birth of Prince Leopold.
Local anaesthetics
The first effective local anaesthetic was cocaine. Isolated in 1859 it was first
used by Karl Koller in ophthalmic
surgery in 1884. Halsted. Prior to that doctors had used a salt and ice mix for the numbing effects of cold - which could only
have limited application. Similar numbing was also induced by a spray of ether or ethyl chloride. Cocaine soon produced a number
of derivatives and safer replacements, including procaine (1905), Eucaine (1900), Stovaine (1904), lidocaine (1943).
Early opioids
Opioids were first used by Racoviceanu-Pitesti, who reported his work in 1901.
The twentieth century
- MAC (minimum alveolar concentration) % atm - methoxyflurane 0.16
- Thiopental (first used 1934
- intravenous, Benzodiazepine)
- Curare (1942)
- Fentanyl (d 1960 Paul Jannsen) fentanyl citrate
- Halothane (d 1951 Charles W. Suckling, 1956 James Raventos)
MAC, non-explosive/inflammable. Halothane hepatitis, malignant hyperthermia, hepatotoxic
- Succinylcholine
- Enflurane (d 1963 u 1972), Isoflurane (d 1965 u 1971), Desflurane, Sevoflurane
- New synthetic opioids - meperidine, alfentanil, sufentanil (1981),
- Neurosteroids
Choice of anesthetic technique
The choice of anesthetic technique is a complex one, requiring consideration of both patient and surgical factors.
However, when either technique is possible, regional
anesthesia is about 30% safer than general anesthesia.
Neuraxial blockade
reduces the risk of deep vein thrombosis, pulmonary embolism, transfusion, pneumonia, respiratory depression, myocardial infarction and renal
failure[1] .
Related topics
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