The document provides an introduction to anesthesia. It discusses the definition of anesthesia and the two main types: general anesthesia and regional (local) anesthesia. General anesthesia involves unconsciousness and is usually required for major surgery, while regional anesthesia blocks sensation in a restricted area of the body and is commonly used for minor procedures and surgery. The document outlines the mechanisms, stages, drugs, and equipment involved in general anesthesia, as well as various regional anesthesia techniques like spinal blocks. It also discusses the scope of practice for anesthesiologists, which includes perioperative care, intensive care, resuscitation, pain management, research, and teaching.

1. Meron Abrar ( MSc Anesthetist)
Addis Ababa University
Health Sciences College
School of Anesthesia
7/25/2021
1
INTRODUCTION TO
ANESTHESIA

3. The name anesthesia (Greekan,“without, and
esthesia,“sensation”) .
 The propose use of the term anesthesia to denote
the state that incorporates Amnesia, analgesia, and
hypnosis to make painless surgery possible.
Anesthesia is the use of medicine to prevent the
feeling of pain or another sensation during surgery or
other procedures that might be painful

4. Introduction to anesthesia
 Anesthesia:- Definition
 is a state of controlled,
temporary loss of sensation
or awareness that is induced
for medical purpose .

5. Types of anesthesia
 There are mainly two types of
anesthesia:-
1-General anesthesia
2- Regional (local
anesthesia)

6. 1- General anesthesia (GA)
 Anesthesia that complete and
affecting the entire body with loss
of consciousness when the
anesthetics acts up on the brain.
 This type of anesthesia is usually
accomplished following
administration of inhalational or Iv
anesthetics commonly used for
surgical procedures.

7.  General anesthesia acts primarily on the
central nervous system to make the patient
unconscious and unaware.
 It is administered via the patient's circulatory
system by a combination of inhaled gas and
injected drugs.
After the initial injection, anesthesia is
maintained with inhaled gas anesthetics and
additional drugs through an intravenous line
(IV).
It can broadly be defined as a drug-induced
reversible depression of the central nervous
system (CNS) resulting in the loss of response
to and perception of all external stimuli

8. Where in the Central Nervous
System do Anesthetics Work?
 The biochemical mechanism of action of
general anesthetics is not well understood.
 To induce unconsciousness, anesthetics have
myriad sites of action and affect the central
nervous system (CNS) at multiple levels.
 Common areas of the central nervous system
whose functions are interrupted
or changed during general anesthesia include
-cerebral cortex,
-thalamus,
-reticular activating system, and
-spinal cord

9. Cont…
 Potential pharmacologic targets of
general anesthetics are
-GABA,
-Glutamate receptors,
-voltage-gated ion channels, and
-Glycine and serotonin receptors

10. The cardinal features of general
anesthesia are
 sleep (unconsciousness)→hypnosis and
amnesia
 loss of all sensation( analgesia)
 muscle relaxation (abolition of reflexes)
Triad of General anaesthesia
Hypnosis
Analgesi
a
Muscle
relaxation(Areflexia)

11. 1.Hypnosis :Unconsciousness is a state which occurs
when the ability to maintain an awareness of self and
environment is lost.
 It involves a complete or near-complete lack of
responsiveness to people and other environmental
stimuli.
2.Amnesia: Amnesia can be caused temporarily by
the use of various sedatives and hypnotic drugs.
 Essentially, amnesia is loss of memory.
3.Analgesia: An analgesic or pain killer is any
member of the group of drugs used to achieve
analgesia, relief from pain.
 Analgesic drugs act in various ways on the
peripheral and central nervous systems
4.Immobielity ;loss of motor reflexes
5.Decreasion the autonomic response to noxious
stimulate .

12. 1- General anesthesia (GA)
 In the modern practice of balanced
anesthesia, these modalities are
achieved by using combination of
drugs, each drug for a specific
purpose. Look at the following.

13. Amnesia
sedation
Hypnosis
Coma
Death
Awake
1- Hypnosis

14. Stages of Anesthesia
Stage I:
 This period begins with induction of anesthesia and
continues to loss of consciousness.
Stage II : Delirium
 This period characterized by not reserved excitation and
potentially injurious responses to noxious stimuli, including
vomiting, tachycardia ,hypertension and uncontrolled
movement.
 The pupils are often dilated…… .
Stage III : Surgical anesthesia
 In this target depth for anesthesia, the gaze is central,
pupils are constricted, and respirations are regular.
Stage IV : Over dosage
 Commonly described as too deep

15. 1. Hypnotic drugs-intravenous
 Thiopentone
 Propofol
 Etomidate
 Benzodiazepines
 Ketamine

16. Hypnotic drugs-Inhalational
anaesthetics
 Nitrous oxide-weak
 Isoflurane
 Sevoflurane
 Desflurane
 Halothane

17. 2-Analgesia
 Good analgesia= good anaesthesia
 Opiates
 Local anaesthetics
 NSAIDS
 Paracetamol

18. Analgesia-NSAIDS
 Gold standard- aspirin
 Ibuprofen
 Diclofenac
 Cox-2 inhibitors

19. Analgesia-Opiates
 Gold standard – morphine
 Derivatives- diamorphine, codeine
 Synthetic agents
- Pethidine
- Fentanyl/Alfentanil-short acting
- Remifentanil-ultra short acting

20. 3-Muscle
relaxation(RELAXATION)
 Aids intubation
 Helps surgeon/surgery
 Surgery of long duration

21. Muscle relaxants
Two types
 Depolarising-short acting
e.g;suxmethonium
 Non-depolarising- medium/long acting
- Tracurium
- Vecuronium
- Rocuronium
- pancronium

22. Prerequisites
 Oxygen
 Suction
 Tilting trolley
 Resuscitation drugs
 Monitoring
 Anaesthetist
 Skilled assistance
 Drugs and machine

23. Regional anaesthesia(local
anesthesia)
 Local anesthetics
Drugs which upon topical application or local
injection cause reversible loss of sensory
perception, especially of pain in a restricted area of
the body.
block generation and conduction of nerve impulse
with out causing any structural damage .
Sensory & motor impulses are interrupted when a
local anesthesia .

24. Major types of regional anesthesia
include:
 Central neural blockade refers to
either epidural or spinal anesthesia.
Spinal anesthesia- often used for
lower abdominal, pelvic, rectal, or lower
extremity surgery.
This type of anesthetic involves
injecting a single dose of the anesthetic
agent directly into the spinal cord in the
lower back, causing numbness in the
lower body.

25. Epidural, and caudal anesthesia - this
anesthetic is similar to a spinal anesthesia
and also is commonly used for surgery of
the lower limbs and during labor and
childbirth
This type of anesthesia involves
continually infusing drugs through a thin
catheter that has been placed into the
space that surrounds the spinal cord in the
lower back/ Epidural space , causing
numbness in the lower body
Caudal anesthesia is a common
regional
Technique in pediatric patients.

26. Nerve blocks - A local anesthetic is
injected near a specific nerve or group of
nerves to block pain from the area of the
body supplied by the nerve.
Nerve blocks are most commonly used
for
procedures on the hands, arms, feet, legs,
or face.
Example - A Brachial Plexus block
may be used
to provide anesthesia to the entire arm and
shoulder

27. Regional anaesthesia
 Spinal/epidural
- surgery below umbilicus
- Provides analgesia/muscle relaxation
 Plexus blocks eg brachial plexus
 Intravenous- Bier’s block

28. Regional anaesthesia
Analgesia Muscle relaxation

29. Local anaesthetics
 Lignocaine- quick/short acting
 Bupivacaine/levobupicvacaine- slow
and long action
 Ropivacaine- as above
 Amethocaine- topical
 Prilocaine- intravenous

30. Comparative features of GA &
LA
features General anesthesia Local anesthesia
Site of action CNS Peripheral nerves
Area of body involved Whole body Restricted area
Consciousness Lost unaltered
Care of vital functional Essential Usually not needed
Physiological effect High Low
Poor health patient Risky Safer
Use in non-cooperative
patient
Possible Not possible
Major surgery Preferred Can not be used
Minor surgery Not preferred Preferred

31. Contraindications for regional
Anesthesia
Patient refusal
Lack of resuscitative equipment
Lack of knowledge of procedure
Coagulopathy
Previous back surgery (relative)
Raised intracranial press
Infection on injection site

32. The Scope of Anesthesia
* Providing general or regional anesthesia
inside and outside the operating room
* Intensive care units
* Respiratory therapy departments
(Anesthetist is respiratory physiologist and
experts at managing ventilatory
inadequacy.)
* Recovery room management
9

33. The Scope of Anesthesia
* Cardiopulmonary resuscitation
* Postoperative pain relief
* Anesthetic research, teaching medical
students, and assuming administrative
and leadership positions on the medical
staffs of many hospitals and ambulatory
care facilities.
10

34. The Scope of Anesthesia
 Blood, Fluid and electrolyte
replacement during operation is
supervised by anesthetist.
 Anesthetist arrange the schedule,
interview and instruct patients
before the day of operation, admit
and examine them, anesthetize,
supervise recovery, and discharge
them.

35. The Scope of Anaesthesia
 Participate in opportunities for
researches in anesthesia.
 Anesthetist, ridges the gap between
basic and clinical sciences,
participate in teaching of basic
science, anesthesia practice &skill.
 Anesthetists are pharmachologists

36. Definition of the practice of
anaesthesia
1)Assessing, consulting, and preparing
patients for anaesthesia
2)Rendering patients insensible to pain
during surgical obstetric, therapeutic, and
diagnostic procedures
13

37. Definition of the practice of
anaesthesiology
3)Monitoring and restoring
homeostasis in perioperative and
critically patients
4)Diagnosing and treating painful
syndromes
14

38. Definition of the practice of
anaesthesiology
5)Managing and teaching of cardiac and
pulmonary resuscitation
6)Evaluating respiratory function and applying
respiratory therapy
7)Teaching, supervising, and evaluating the
performance of medical and paramedical
personnel involved in anaesthesia,respiratory
care, and critical care
15

39. Definition of the practice of
anaesthesiology
8)Conducting research at the basic and clinical
science levels to explain and improve the care of
patients in terms of physiologic function and
drug response
9)Involvement in the administration of hospitals,
medical schools, and outpatient facilities as
necessary to implement these responsibilities
16

41. Quiz- 1
1. Mention cardinal features of GA
2. Mention Types of muscle relaxant
3. Benefits of RA over GA

42. Why study the History of Anesthesia
 An understanding of our past guides our
future
 The history of surgery is inextricably linked
to the development of appropriate
anesthetic
techniques and so the history of surgery
follows
the history of anesthesia.

43. History of Anesthesia
Pre-1846 - the foundations of
anesthesia
1846 - 1900 - establishment of
anesthesia
20th Century - consolidation and
growth
21st Century - the future

44. THE FOUNDATIONS OF
ANESTHESIA
Pre-1846

45. Pre 1846 - The Foundations of
Anesthesia
 ..so the Lord God caused him to fall into a
deep sleep. While the man was sleeping,
the Lord God took out one of his ribs. He
closed up the opening that was in his
side…(Genesis 2:21 )

46. Cont…
 Arabian employ techniques such as ;
 ‘SOPORIFIC SPONGE’: soaked with hashish,
opium & herbs.
 when required for surgery it would be
moistened and held over the face inducing a
state of unconsciousness.

51. The Sumerians were the first to
cultivate the poppy.
Papaver somniferous meaning the
poppy of sleep.
When the walls of opium poppy are
incised a latex like substance is secreted
,from which many of useful products are
derived including opium and alkaloid
derivatives morphine, codeine
,papaverine.. ……

53. The Foundations of Anaesthesia
Drug methods
 Alcohol
 Opium (poppy)
 Hyoscine (Mandrake)
 Cannabis (Hemp)
 Cocaine (New World)
Non-drug methods
 Cold
 Concussion
 Carotid compression
 Nerve compression
 Hypnosis
 Blood letting

54. History of Anesthesia

55. The Foundations of Anaesthesia
Status of surgery
 Barber shop surgeons
Types of surgery
 Amputations dental
extractions
 No antisepsis
 Appalling mortality
Indications
 Unbearable pain
 Crippling deformity
 Imminent death

56. Change / Evolution
1772: Joseph Priestley discovered N2o
 Humphrey Davy, the Pneumatic Institute
 Recognized analgesic properties of N2O
and
name it laughing gas
 first tentatively suggested a use during
surgery
 as nitrous oxide in its extensive operation
appear capable of destroying physical pain
it may be used with advantage during

57. Gas Therapy in Illness
Nitrous oxide
Ether

58. Nitrous oxide
 1800 Davys thesis
 1834 Colton anaesthetized 6 Red Indians
by
mistake
 1844 Horace Wells had his own tooth
pulled under N2O - a new era in tooth
pulling
 1845 Wells failed to demonstrate N2O at
MGH

59. Ether
 1540 synthesized and named sweet oil of
vitriol by Valerius Cordus
 Renamed ether by Frobenius
 1744 Matthew Turner published essay
suggesting its inhalation in certain types
of pain
 late 1790s research at Pneumatic Institute

60. Ether
 1818 Michael Faraday (1791-1867)
described narcotic effects of ether
 1821 Benjamin Brodie (1783-1862)
demonstrated to Royal College of
Surgeons that ether inhalation could
induce insensibility in a guinea pig - ether
acted like a narcotic poison

61. 1846-1900 -The Establishment of Anesthesia
General Anaesthesia
 Ether -spread to Europe
 Nitrous oxide
Chloroform
 James Young Simpson
 John Snow
Local Anaesthesia
 anaesthesia without sleep
New techniques
 early landmarks

62. Ether
 1842 first use as clinical anesthetic in
USA
 16th October 1846 first public
demonstration of ether anesthesia in
Boston, Mass.
William T G Morton
 Inventor and Revealer of Inhalational
Anesthesia Before Whom, in All Time,
Surgery
was Agony By Whom, Pain in Surgery

63. Ether
 16th October 1846 first public demonstration of
ether anesthesia in Boston, Mass.
 Ether - the news spreads
 17th Dec 1846 Boott received letter and
arranged
with dentist James Robinson to experiment with
ether inhalation
 19th Dec 1846 ether administered by James
Robinson to a Miss Lonsdale for molar
extraction
at Bootts home
 21st Dec 1846 Robert Liston, Professor of
Surgery at University of London publicly

64. Nitrous oxide
 1847 Horace Wells published paper - A
History on the Discovery of the Application
of Nitrous Oxide Gas, Ether and Other
Vapors to Surgical
Operations
 1863 Colton reintroduced N2O, primarily for
dental surgery
 1865 N2O cylinders available in London
 1881 pain relief in labour
 1887 Hewitt gas and oxygen machine

65. Chloroform
 1831 Chloroform synthesized
 1833 Cynthia Guthrie accidentally
anaesthetized herself!
 1847 Anesthetic properties
recognized
 1847 First clinical use, St Bart's,
London
 1847 James Young Simpson used
chloroform for obstetric anesthesia

66. James Young Simpson (1811-
1870)
 Professor of Midwifery in Edinburgh from
1840
 Tried chloroform on himself and friends at
suggestion of David Waldie, a chemist
 Secured and popularised chloroform as
clinical anaesthetic, esp. in Obstetrics

68. John Snow (1813-1858)
 Born in York in 1813
 became interested in anesthesia via work
in
toxicology
 apprenticed in Newcastle, then worked in
London 1836-1858 until his death
 acknowledged as first full-time anesthetist
developing ways to improve methods of
ether and chloroform administration

69. John Snow
 By using Chloroform
 Prince Leopold
 born 7th April 1853
 Princess Beatrice
 born 14th April 1857
 helped to overcome religious and moral
objections to analgesia for childbirth

70. Local Anaesthesia in the 19th
cent
 1884 Cocaine
 1885 Spinal analgesia for pain relief -
Corning
 1890 Oil of cloves (Eugenol)
 1891 Tropocaine
 1892 Infiltration LA
 1898 Spinal anesthesia for surgery - Bier

71. History of anesthesia
 The following is summery to the Milestone of the history of
anesthesia
 - Valerius cordus synthesized ether.
 - Joseph priestly discovered oxygen and his next discovery was
 that of nitrous oxide during 1772
 - Sir Humphrey davy discovered the analgesic and exhilarating
 effects of N2O.
 - Crawford Williamson long administered ether to James
 Venable on March 30,1842 for excision of a small tumor of the
 neck.
 - Horace wells received N2O from G.Q.colten for a tooth
 extraction performed by John Riggs on Dec, 11.
 1846 -William T.G.Morton publicly demonstrated ether anesthesia in
 an operation performed by J.C.Warren at the Massachusetts
 general hospital. October 16,the patient was Gilbert Abbott.

72. History of Anesthesia

73. History of Anesthesia

74. History of Anesthesia

75.  1847 - Sir James Simpson introduced analgesia for childbirth.
 - Jon snow the 1st physician anesthetist began the use of ether at
 St. George’s hospital, London &published a book on ether.
 -Jon snow gave chloroform to Queen Victoria for the birth of
 Prince Leopold, making the administration of analgesia to
 women in labour a socially acceptable medical activity.
 -Claude Bernard suggested preanesthetic medications with
 morphine.
 - Carl Kohler used cocaine topically in the eye.
 -Halsted introduced conduction anesthesia with cocaine.
 - Heinrich Quincke demonstrated lumbar puncture.
 - E.A Codman &Harvey Cushing began keeping records of P/R
 during anesthesia.
 - Alfred Einhorn synthesized procaine.
 -Buchanan was appointed 1st as professor of anesthesia at New
 York medical college.

76. History of Anesthesia

77. History of Anesthesia
 Endotracheal tube discovered in 1878
 Local anesthesia with cocaine in 1885
 Thiopental first used in 1934
 Curare first used in 1942 - opened the
“Age of Anesthesia”