2. OUTLINE
• Brief history of Anaesthesia
• Definition of Anaesthesia
• Drugs Definition and classification
Premedications
Induction Agents
Muscle Relaxants
Reversal Agents
Analgesics
Local Anaethetics
• Conclusion
3. HISTORY
• WTG Morton on the 16th of October in 1846 performed the first
public demonstration of anaesthesia.
4. DEFINITION
•Anaesthesia is a branch of medicine
that deals with reversible loss of
consciousness and pain control.
5. PREMEDICATIONS
• Reduction of anxiety and pain
• Promotion of amnesia
• Reduction of secretions
• Reduction of volume and increase PH of gastric contents
• Reduction of postoperative nausea and vomiting
• Enhancing the hypnotic effects of general anaesthesia
• Reduction of vagal reflexes to intubation
• Prophylaxis against allergic reactions
7. GLYCOPYROLATE
• Anticholinergic used as premedicant
• Reduces salivary and sweat gland activity therefore used as
antisialogogue
• Used with acetylcholinesterase inhibitors to prevent muscarinic
effects
8. ATROPINE
• Used for premedication
• Used to reduce muscarinic effects of acetylcholinesterase
• Used for treatment of bradycardia and asystole
• It should be avoided in pyrexial patients
9. TYPES OF ANAESTHESIA
• General
• Regional – Neuraxial : Subarachnoid Block
Epidural Anaesthesia
Nerve Block
• Local Anaesthesia
11. INTRAVENOUS ANAESTHETICS
• These are drugs expected to cause loss of consciousness in “one arm brain circulation”
• Characteristics of Ideal Intravenous Anaesthetics
Simple preparation
Painless on administration
High potency and efficacy
Rapid and predictable offset of effect
Absence of toxic effects or adverse properties
Compactible with other agents and IV fluids
Depression of airway reflexes for intubation
Rapid metabolism and minimal hangover
14. THIOPENTONE
• This is an ultra-short acting barbiturate with a rapid onset
• Used for induction of anaesthesia and the preferred drug of use in
Neuroanesthesia because it reduces cerebral blood flow and
intracranial pressure.
• Potent anaesthetic, weak analgesic effect with little muscle relaxation
• Usually comes in 5 or10% solution and has to be constituted to 2.5%
before use.
• Causes laryngospasm and not ideal for asthmatics
• Causes respiratory and circulatory depression
15. PROPOFOL
• Usually comes as a white emulsion of 1 or 2%
• Good for induction and maintenance of anaesthesia with a
short duration of action, safe for use in day-case surgery.
• It causes pain on injection
• Causes more respiratory and cardiovascular depression than
barbiturates
• Has anti –emetic properties
16. KETAMINE
• Causes ‘dissociative’ anaesthesia, has a slow onset
• Causes amnesia without loss of consciousness
• Has analgesic properties
• Causes cardiovascular stimulation therefore it is Useful for
patients with Hypotension but no respiratory depression
17.
18. INHALATIONAL ANAESTHETICS
• Vapors used for induction and maintenance of anaesthesia.
They are delivered to the respiratory system to produce
anaesthesia.
19. PHYSICAL PROPERTIES OF AN IDEAL
INHALATIONAL ANAESTHETIC AGENT
1. Non-flammable, non-explosive at room temperature
2. Stable in light.
3. Liquid and vaporisable at room temperature i.e. low latent heat of vaporisation.
4. Stable at room temperature, with a long shelf life
5. Stable with soda lime, as well as plastics and metals
6. Environmentally friendly - no ozone depletion
7. Cheap and easy to manufacture
20. BIOLOGICAL PROPERTIES OF AN IDEAL
INHALATIONAL ANAESTHETIC AGENT
1. Pleasant to inhale, non-irritant, induces bronchodilatation
2. Low blood: gas solubility - i.e. fast onset
3. High oil: water solubility - i.e. high potency
4. Minimal effects on other systems - e.g. cardiovascular, respiratory,
hepatic, renal or endocrine
5. No biotransformation - should be excreted ideally via the lungs, unchanged
6. Non-toxic to operating theatre personnel
21. NITROUS OXIDE
• Colourless, odourless gas at room temperature
• Stored in blue cylinders
• Causes rapid induction of anaesthesia and rapid emergence.
• it has weak anesthetic and powerful analgesic effects
• Used as an adjunct to supplement other inhalationals
• Risk of bone-marrow suppression with prolonged
administration.
22. HALOTHANE
• Volatile liquid at room temperature
• Light sensitive
• High fat solubility
• Excreted unchanged through the lungs
• Stored in amber colored bottles with thymols as the
preservative
• Causes reduced myocardial contractility and cause hypotension
23. ISOFLURANE
• Has a pungent smell therefore not ideal for induction of
anaesthesia
• Causes a progressive respiratory depression and hypotension.
• Useful for cardiac anaesthesia
24. SEVOFLURANE
• It has a pleasant smell, non-irritant and good for use in
paediatrics, cardiac and neuroanaesthesia.
• Produces a fast induction and emergence.
• Fairly expensive therefore not readily used in our environment
25. MUSCLE RELAXANTS
• Divided into two
Depolarising – Suxamethonium
Non – Depolarising : Divided into 2
1. Aminosteriods – Rocuronium,
Vecuronium, Pancuronium
2. Benzylisoquinoloniums – Atracurium,
Cisatracurium,
Mivacurium.
26. SUXAMETHONIUM
• The depolarising neuromuscular blocker of choice
• It is widely used due to rapid onset and short duration of action
• Ideal for Rapid Sequence Induction
• The depolarising effect causes fasciculation and flaccid
paralysis
• Paralysis occurs one minute after administration and lasts 7 –
12minutes
• Metabolised by plasma pseudocholinesterase
27. ATRACURIUM
• An intermediate acting muscle relaxant with onset of 60 -90
seconds
• Effect lasts 20 – 30 minutes
• Causes histamine release
• The drug of choice in renal and hepatic impairment
28. PANCURONIUM
• Can be used to aid tracheal intubation after 2 – 3 minutes
• The effect lasts 40 – 60 minutes
• May increase heart rate, BP and cardiac output by vagolytic and
sympathomimetic actions.
• Elimination is delayed in renal and hepatic impairment
therefore avoided in them.
29. VECURONIUM
• Provides intubating condition in 90seconds
• Relaxation is 20 – 30 minutes but can last up to 80minutes with
a dose 250mcg/kg
• Has minimal effect on Bp and pulse
• Metabolised in the liver to an active form of 3-
deactylvecuronium
30. REVERSAL AGENTS/ANTICHOLINESTERASE
• NEOSTIGMINE
Reverses non depolarising muscle blockade
Used with atropine or glycopyrrolate to reduce the muscarinic
effects it causes
Active within 1 minute of injection and lasts up to 20 –
30minutes
32. PARACETAMOL
• Also called Acetaminophen
• Inhibits central prostaglandin synthesis and has a central
antipyretic
• Used to treat minor pain
• Rapidly absorbed with oral administration
• Side effects includes nausea, vomiting and rashes.
33. DICLOFENAC
• Useful for post-op analgesia thereby reducing requirements for
opioids
• 1mg/kg IM up to 75mg or IV over 15minutes
• Can also begiven rectally
• Could be used with caution in renal impairment and
asthsmatics
34. MORPHINE
• Used for premedication and as analgesic
• Causes CNS depression
• Induces vomiting
• Releases histamine
• Should be used with caution in renal and hepatic impairment
35. FENTANYL
• 100 times more potent than morphine
• Used for premedication, induction and sedation in ICU
• Onset is 1-2 minutes and duration of action of 20-60minutes.
• Causes post operative respiratory depression especially with
large doses
• Causes minimal histamine release or cardiovascular changes
36. LOCAL ANAESTHETICS
• Can be given in the following forms
Topical
Superficial injection ( infiltration)
Nerve Block
Intravenous
Epidural
Spinal
37. DIVISION OF LA’S
• Ester – they are hydrolysed by blood esterases with a short
half-life.
Examples include Procaine, Cocaine, Benzocaine, Tetracaine,
Chlorprocaine.
• Amides – they are metabolized in the liver and usually have a
long half-life.
Examples include Bupivacaine, Lignocaine, Ropivacaine,
Prilocaine, Articaine.
38. BUPIVACAINE
• A local anaesthetic agent of longer duration compared to
lidocaine
• For epidural anaesthesia, lasts 3-4 hours and up to 12hours for
nerve blocks
• Usually comes as 0.5%
• Also used for SAB
• Tend to cause more cardiotoxicity compared to neurotoxicity
39. LIDOCAINE
• Onset is rapid by all routes
• Usual duration of action is 1hour but increases to about 2hours
with the addition of adrenaline
• Used as a local anaesthetic, for nerve blocks, SAB and epidural
anaesthesia.
• Used to depress laryngeal and tracheal reflexes
• Causes more of neurotoxic effects when given in high doses
40.
41. QUESTIONS
• 1. which of the following will not cause respiration depression
• (a) Propofol
• (b) Ketamine
• (c) Thiopentone
• (d) Midazolam
• (e) Fentanyl
42. • 2. which of the following has a sweet smell
(a)Nitrous oxide
(b)Halothane
(c)Isoflurane
(d)Desflurane
(e)oxygen
43. • 3. which on of the following is a depolarising muscle relaxant
(a)Atracurium
(b)Pancuronium
(c)Vecuronium
(d)Suxamethonium
(e)mivacurium
44. • 4. which of the following is a good post-operative analgesic
• (a) ibuprofen
• (b) acetaminophen
• (c)diclofenac
• (d) cocodamol
• (e) lignocaine
45. • 5. which one of the following is an amide local anaesthetic
(a)Lignocaine
(b)Procaine
(c)benzocaine
(d)chloroprocaine
(e)cocaine
46. THEORY
• What are the 6 A’s of premedication
• Write short note on propofol
