Before the discovery of anaesthetics, an operation used to be an agonizing experience for the patient. Even though different agents like herbs, gases, oils and drugs were used for relieving pain, the patient sometimes died from pain and shock. It was only with the discovery of modern anaesthetics that a major break-through was achieved in the field of surgery.
An anaesthetic is a substance that causes a loss of sensation or feeling in the body. The history of its discovery is very interesting. In 1799, the British chemist, Sir Humphry Davy inhaled some ‘laughing gas’ (nitrous oxide) and found that it produced unconsciousness. Davy published this experience and in 1844 in the United States Horace Wells performed the first dental operation using nitrous oxide as an anaesthetic. Two years earlier, i.e. in 1842, the first painless operation had been carried out by Craw Ford W. Long, using ether as an anaesthetic. In 1847, chloroform was reported to have similar anaesthetic effect. At last surgeons had found a method of overcoming pain to carry out lengthy operations without undue haste.
Today, many new types of anaesthetics have been developed. Their application is of two types: local and general. Local anaesthetics are used to numb a particular part of the body. They act by blocking the transmission of electrical impulses along nerve cells, and are usually injected around the nerves that normally carry impulses from the area to be operated upon. The first of these anaesthetics was cocaine. This was superseded by another drug called procaine in 1905. Numerous drugs related to procaine such as lignocaine are nowadays used.
General anaesthetics render the entire body unconscious. Nitrous oxide, ether and chloroform are included in this category, together with a more recently developed drug, halothane. Once inhaled, they act within seconds but recovery starts immediately after the drug is withdrawn. Halothane has been found to have side effects on liver. Now it has been replaced by ethrane.
Under general anaesthesia, the patient’s respiration may be controlled externally. There are two reasons for this. First, general anaesthesia depresses the area of the brain that controls respiration. Second, for many operations the patient’s muscles need to be released which is achieved by giving a drug called curare.
A person called an anaesthetist is trained to give proper amounts of anaesthetic to patients being operated for different ailments. At least one anaesthetist is always present in the operation room during the surgery.