Anaesthesia or anaesthesis is a state of insensibility to pain, formerly produced by inhaling chloroform, now by the application of other anaesthetic agents, such as morphine. Research Anaesthesia
Anaesthetics are medical agents employed for the removal of pain, especially in surgical operations, by suspending sensibility either locally or generally. Various agents have been employed for both of these purposes from the earliest times, but the scientific use of anaesthetics may be said to date from 1800, when Sir Humphry Davy made experiments on the anaesthetic properties of nitrous oxide, and recommended its use in surgery.
In 1818 Faraday established the anaesthetic properties of sulphuric ether, but this agent made no advance beyond the region of experiment, until 1844, when Dr. Wells, a dentist of Hartford, Connecticut, applied the inhalation of sulphuric ether in the extraction of teeth, but owing to some misadventure did not persevere with it. The example was followed in 1846 by Dr. Morton, a Boston dentist, who also extended the use of ether to other surgical operations. The practice was soon after introduced into England by Mr. Listen, and a London dentist, Mr. Robinson. A few weeks later Sir James Simpson made the first application of ether in a case of midwifery. This was early in 1847. Towards the end of the same year Simpson had his attention called to the anaesthetic efficacy of chloroform, and announced it as a superior agent to ether. This agent was at the start of the 20th century the most extensively used anaesthetic, though the use of ether still largely prevailed in the United States. In their general effects ether and chloroform are very similar; but the latter tends to enfeeble the action of the heart more readily than the former. For this reason great caution has to be used in administering chloroform where there is weak heart action from disease. Local anaesthesia is produced by isolating the part of the body to be operated upon, and producing insensibility of the nerves in that locality. Dr. Richardson's method was to apply the spray of ether, which, by its rapid evaporation, chills and freezes the tissues and produces complete anaesthesia. This mode of treatment, besides its use in minor surgical operations, has recently begun to have important remedial applications. Around 1905 a new valuable local anaesthetic, cocaine was introduced which is now the prevalent local anaesthetic in use.
In 1933 the first barbiturate general anaesthetic was used, hexobarbitone, other barbiturates are now used, most commonly thiopentone and also propofol and ketamine which have effects lasting a shorter period of time and less of a hangover effect on the patient. Chloroform and ether not being used since the introduction of barbiturates due to the reduction of complications, though barbiturates are still dangerous and premedication is widely used with them. Research Anaesthetics
Cyclopropane is an anaesthetic gas. It is very explosive, is extremely powerful and rapid in its action, has no smell and is expensive. Only very small quantities of it need to be used and a special apparatus is necessary to regulate and measure the exact quantity being given to avoid the risk of overdose. The great advantage of cyclopropane is that it will produce muscular relaxation. It is very useful therefore combined with nitrous oxide to give a greater depth of anaesthesia without using an irritant gas, such as ether. Cyclopropane has largely lost its usefulness since the introduction of special relaxing drugs such as tubocurarine. Research Cyclolpropane
An error of development of the duodenum may result in a portion of the tube being completely obliterated or very constricted. This obstruction gives rise to persistent vomiting in the neonatal period. The diagnosis is confirmed by x-ray examination and surgical operation is essential. This may be performed under local anaesthesia, as for Rammstedt's operation, but it is more usual to employ general anaesthesia. The pre- operative and post-operative treatment is similar and usually gastro-enterostomy is performed. Babies with this condition are often premature and almost always in a very bad condition; the operative risk is great. Research Duodenal Atresia and Stenosis
Endoscopy is the examination of internal parts of the body using special instruments known as endoscopes. The simplest method of instrumental examination is that employed for the analcanal and rectum. A 'speculum' (proctoscope) which is in fact a simple tube with a handle, is introduced through the analcanal and the surgeon examines the rectal wall through the tube. To facilitate the introduction of the instrument, there is a shaped conical stopper which is known as the 'obturator.' This same principle of a shaped introducer is used on many instruments which have an open tubular end. Sigmoidoscopy is the examination of the upper regions of the rectum and the sigmoid or pelvic colon with a longer tubular speculum. Because the folds of mucousmembrane fall against the end of the instrument and obstruct the view, air inflation is used for the introduction of the sigmoidoscope so that the lumen of the bowel is distended. The surgeon inserts the instrument under direct vision, inspecting the wall of the bowel as far as 25 cm. from the anus.
The oesophagoscope is a similar instrument passed down the oesophagus through the mouth, thus enabling the surgeon to inspect the whole length of the gullet. The inside of the stomach is examined by the gastroscope, using air inflation. Through a very small incision in the abdominal wall the surgeon may introduce another viewing instrument, the peritoneoscope, and with this he may inspect the inside of the peritoneal cavity and obtain infonnation to enable him to reach a decision without open operation. In order to separate the coils of intestine from one another and allow the satisfactory inspection of the viscera, the peritoneal cavity is inflated with air through a separate cannula. Endoscopic instruments, except for the simpler forms of proctoscope, carry their own miniature lamps which draw electric current either from a battery or the mains through a transformer to reduce the voltage. The bladder and urethra are inspected with the cytoscope and urethroscope. The urinary tract is distended with water instead of air for the inspection, but air inflation is sometimes used for the lower part of the urethra. Various forms of speculum are used for the vagina and these are usually illuminated by direct light, although some forms carry a lamp of their own. Operations for the removal of tissue for microscopic examination (biopsy) are performed through some of the tubular instruments, and for this purpose there are special long forceps and diathermy electrodes. Examinations carried out with endoscopic instruments may be made with local or general anaesthesia and in the case of the rectum and colon, without anaesthesia. Research Endoscopy
Evipan is an anaesthetic which was discovered in the 1930s. It is the sodiumsalt of N-methyl-cyclo- hexenyl- methyl-barbituric acid and was administered by intravenous injection providing surgical anaesthesia for around 20 minutes. Research Evipan
A general anaesthetic is a drug producing anaesthesia of the entire body, with loss of consciousness. There is always the risk of the patient entering a coma or dying with a general anaesthetic, which is why increasingly local anaesthetics are being used. Research General Anaesthetic
Leprsosy is an infective disease which runs a very chronic course, and occurs in different forms. In nodular leprosy there are bouts of fever, with nodules in the skin and mucous membranes. In anaesthetic leprosy there are at first areas of redness over the body, with a macular rash, malaise, chills and vague pains, and later areas of anaesthesia develop, with insensibility to touch, heat and cold, and pain. In later cases of both types ulceration is common, and in anaesthetic leprosy there may be loss of fingers and toes or other parts from gangrene. In nodular
leprosy the mucousmembrane of the nose and mouth is involved, with loss of speech, and ulceration and scarring of the lips and tongue. The skin becomes dry like parchment, and the general expression is grave and heavy. The disease is very chronic and the two types often become merged, with symptoms of both types. There may be remissions or arrest of symptoms, but more commonly death occurs from tuberculosis, exhaustion, or renal failure after twenty years or more. Research Leprosy
Morphine sulphate (Astramorph, Duramorph, MS Contin, MSIR, Roxanol SR, Roxanol 100, RMS) blocks pain messages to the brain and spinal cord. It is a respiratory depressive and causes miosis. It is injected, or administered orally in a suspension to relieve moderate to severe acute and chronic pain and to facilitate the induction of anaesthesia. Research Morphine Sulphate
The Probert Encyclopaedia was designed, edited and programed by
Matt and Leela Probert
Abbreviations
Research Anaesthesia
