Anesthesia
Written by Rhiana Devadasan
KEYWORD: Analgesia = the inability to feel pain.
16) Anesthesia - history. Definition. Types.
17) Local anesthesia - types, agents, indications, technique, complications.
Anesthesia = the insensitivity to pain, mainly referring to artificially-induced anesthesia by the administration of gases or the injection of drugs called anaesthetics before surgical operations in order to control pain. Controls your breathing, BP, blood flow, HR and rhythm
Alternative definition: a reversible state of pharmacologically controlled sleep with reduction in cortical activity. At sufficient anaesthetic depth there is absence of conscious awareness and recall, and no sensory, motor or autonomic response to stimulation.
History
- Pre-anesthesia
- Previously there were many attempts to relieve pain throughout the centuries.
- E.g. loss of consciousness produced by blows to the patient’s head or by compression of the carotid arteries, the use of elaborate potions like alcohol and various plant extracts.
- Opium was widely used, particularly in China.
- Pain relief in an arm or a leg was produced by squeezing the nerves in the upper part of the limb and also by applying cold water, ice, or snow.
- The first successful demonstration of general anesthesia
- Took place at the Massachusetts General Hospital in Boston, USA on in 1846
- William Morton, a local dentist, administered ETHYL ETHER so that a vascular tumour on the patient’s neck could be operated. He discovered that the inhalation of ethyl ether caused patients to pass out and become unresponsive.
- News of the operation reached England later that year in University College Hospital, London, where a leg was amputated through the thigh under ether anaesthesia.
- James Simpson Chloroform was later introduced as an alternative to ether, as it didn't have a pungent smell, irritation of the throat & nasal passage.
- Anaesthesia produced by nerve block, or regional anaesthesia, became possible after cocaine was isolated from the coca plant in 1860.
- Later on the introduction of halothane saw the disappearance of ether and chloroform from most operating rooms occurred.
- John Snow - first anaesthesiologist, he studied & calculated dosages for the use of ether and chloroform as surgical anaesthetics. He wrote a description of the stages of anaesthesia based on patient responsiveness. He designed an apparatus to safely administer ether & a mask for chloroform.
- The modern era of anaesthesia
- Began in the 1960’s, with the development of new drugs and the availability of new monitoring techniques and equipment. Surgery was extended to increasingly complex