Intro to anaesthesia

• Practice locations of Anesthesiologists


  • Operating rooms
  • Intensive care units
  • Labour and delivery suite
  • Pain clinic
  • Radiology
  • Gastroenterology suite
  • Ambulatory care centers
  • Psychiatry Electroconvulsive Therapy (ECT) unit
• Anaesthesia


  A state of controlled, temporary loss of sensation or awareness induced for medical purposes, may include analgesia, paralysis, amnesia, or unconsciousness
• Components of anaesthesia

  • Analgesia
  • Paralysis
  • Amnesia
  • Unconsciousness
• Drugs used in Anaesthesiology


  • Inhaled anaesthetics
  • Local anaesthetics
  • Induction agents
  • Muscle relaxants
  • Opioids
  • NMDA antagonists
  • Anticholinergics
  • Anticholinesterases etc
• Hippocrates (460-377 BC) had little sympathy for patients undergoing surgery
• Anaesthesia

  Insensitivity to pain, especially as artificially induced by the administration of gases or injection of drugs before surgical operations
• Fanny Burney(1752-1840): 'Received a wine cordial as her sole anaesthetic, had seven male assistants to hold her down for her mastectomy in Paris on September 1811'
• Anaesthesia origin

  Greek (anaisthesia): An- without, Aisthesis- sensation, Modern Latin- anaesthesia
• Anesthesiology began 170 years ago with greatest advances since 1950
• Expertise of Anesthesiologists

  • Airway management
  • Pharmacology
  • Resuscitation
  • Fluid replacement
  • Postoperative pain control
  • Regional anaesthesia
  • Oxygen transport
  • Operative stress reduction
  • Applied Clinical and Basic Research
  • Patient safety
• A person under the effects of anaesthetic drugs is referred to as being anaesthetized
• Surgery has been practiced for thousands of years
• Ancient Americans trephined the skull
• Hippocrates lived

  460-377 BC
• Greatest advances since 1950
• In 1853, the discovery of the hypodermic needle, the syringe, and the injection of morphine are innovations made possible by Alexander Wood. He invented a hollow needle that fits on the end of a piston-style syringe and used the device to successfully treat pain by morphine injection
• Hippocrates: 'Little sympathy for the patient under surgery. Advice to patient was “to accommodate the operator…. and maintain the figure and position of the part operated on….and avoid shrinking from or turning away”'
• Oliver Wendell Holmes, Sr. proposed naming the state produced “anesthesia” and the procedure an “anesthetic” in a letter to Morton
• Chloroform was administered by Dr John Snow to Queen Victoria during the birth of the last two of her nine children (Leopold in 1853 and Beatrice in 1857). Before this time, it was regarded as unethical by many physicians and even the Church of England
• In 1275, Raymundus Lullius discovered ether. Valerius Cordus synthesized ether in 1540. Sir Humphry Davy & Nitrous oxide
• Horace Wells tried to publicly demonstrate nitrous oxide anaesthesia at Harvard in 1844 but failed. The patient groaned during extraction of a wisdom tooth
• William Thomas Green Morton performed the 1st successful public demonstration of anaesthesia
• Beginning of Anaesthesia: 1842. Ether known centuries before 16th century. Paracelsus observed ether to put chickens to sleep and awaken unharmed. No jumps made to using this in humans. Crawford W. Long used diethyl ether for surgical anaesthesia to remove a neck tumour on March 30, 1842, but never published results until 1849
• Theodoric of Lucca induced unconsciousness prior to surgery by holding sponges soaked with opium, mandrake, and hemlock under the patient's nose in the 13th century
• Compression Anaesthesia

  By applying pressure to major nerve trunks, anaesthesia can be produced. But the compression itself causes pain! Early version of Bier Block
• Cocaine may well have been used as a topical anaesthetic
• “As nitrous oxide in its extensive operation appears capable of destroying physical pain, it may probably be used with advantage during surgical operations in which no great effusion of blood takes place” 1800
• Chloroform was first developed as an anaesthetic by James Young Simpson, a Scottish doctor, professor of obstetrics, and physician to Queen Victoria
• Unsatisfactory inhaled Anaesthetics

  • Ethyl chloride- flammable
  • Ethylene 1923- Explosive
  • Divinyl ether- flammable and never widely used
  • Cyclopropane – introduced in 1934, briefly popular but violently explosive
  • Trichloroethylene 1935-decompose to toxic
• WTG Morton brought “Letheon” (diethyl ether) to Harvard in 1846. After performing experiments on himself and his pet animals, George Abbot had a vascular tumour of the neck. 1st successful public demonstration of anaesthesia on 16 October 1846
• Spinal Anaesthesia developments

  • Procaine - 1905
  • Lidocaine – 1948
  • Heinrich Quinke introduced lumbar puncture in 1891
• Femoral Nerve Block under ultrasound Guidance

  21st Century
• Patient-controlled Analgesia is a precision drug delivery technology enabled by an electronically controlled infusion pump with AI application
• Muscle Relaxants

  • Suxamethonium synthesized by Nobel winner, Bovet in 1949
  • Distinction between depolarizing and nondepolarizing in 1956
  • Pancuronium released in 1964
  • Vecuronium released in 1970
  • Rocuronium released in 1994
• Research focus on new drugs, new delivery routes, and new delivery systems for advancements in anaesthesia
• Local Anaesthesia history

  Discovered in 1884 with injectable cocaine by William Halsted
• Muscle relaxants introduced in the 1940s revolutionised anesthesia practice
• Regional anaesthesia types

  1. Infiltrative anaesthesia

  2. Peripheral nerve block

  3. Intravenous regional anaesthesia

  4. Central nerve blockade (spinal, epidural, and caudal anaesthesia)

  5. Topical anaesthesia e.g. EMLA patches

  6. Tumescent anaesthesia e.g. during liposuction
• Safety advancements: Pulse oximetry in 1990, End-tidal CO2 monitoring in 1996, TransEsophagealEchocardiography use by anesthesiologists dates to the late 1980s with first guidelines published in 1996
• Unsatisfactory inhaled Anaesthetics

  • Ethyl chloride- flammable
  • Ethylene 1923- Explosive
  • Divinyl ether- flammable and never widely used
  • Cyclopropane – introduced in 1934, briefly popular but violently explosive
  • Trichloroethylene 1935-decompose to toxic nerve gas dechloroacetylene with soda lime and to phosgene with electrocautery