1. Anesthesiology
[Gk . an-, not + aisthesis-, perception
+ logia, study]

2. General Anaesthesia
An artificial state of
unresponsiveness, followed by
amnesia, maintained by the
continuing presence of
chemical agents in the brain

3. Pharmacology
1. Intravenous Agents
2. Inhalational Agents
3. ( Analgesics )
4. Muscle Relaxants

5. Intravenous anaesthetics
1. Thiopentone
2. Propofol
3. Ketamine

6. Thiopentone
• Proven track record
• Rapid onset of action with fast recovery
due to redistribution
• Repeated doses need to be smaller as
accumulation occurs
• Extravasation may cause necrosis
• Potent anticonvulsant

7. Propofol
• Fast onset of action with rapid recovery
due to redistribution and high clearance
• Clear headed recovery
• Low incidence of nausea and vomiting
• Suitable for short procedures especially
day surgery
• Pain on injection and occasional
involuntary movements

8. Target-controlled Infusion
(TCI)

11. Inhalational anaesthetics
1. Nitrous oxide
2. Volatile anaesthetics
- Sevoflurane
- Desflurane
- Isoflurane
- Enflurane
- Halothane

12. Nitrous oxide
• “ Laughing Gas”
• Gaseous anaesthetic.
• Piped gas supply or blue cylinders.

13. Isoflurane
• Volatile anaesthetic
• Require vaporiser
• Isoflurane commonly used
• Faster recovery compared to halothane
and enflurane
• Irritating vapour, therefore not commonly
used for induction.

15. Newer agents
• Sevoflurane
- Fast onset and offset of effect
- Non-irritating, useful for
inhalational induction,
especially in children.
• Desflurane
- Boiling point near room temperature
- Need special vaporiser

16. Older agents
• Halothane
- May cause arrhythmias
intraoperatively and hepatitis
postoperatively
• Enflurane
- May cause seizures and renal
impairment

18. Muscle relaxants
• Useful for aiding insertion of
Endotracheal tube and ventilation
• Will cause apnoea, therefore assisted
ventilation mandatory.

19. Muscle relaxants
• Suxamethonium
- Rapid onset of action
- Used in rapid sequence induction
- Potential problems include
arrhythmias

20. Muscle relaxants
• Non-depolarising muscle relaxants -
- Atracurium
- Vecuronium
- Mivacurium
- Rocuronium
• Fast onset with intermediate duration of
action

21. Reversal of neuromuscular
blockade
• Neostigmine :
- Anticholinesterase
- Used for reversal of muscle
relaxation by non-depolarising
muscle relaxants
- Atropine given together to counter
bradycardia

22. Anaesthetic Technique
1. Induction
2. Maintenance
3. Reversal

23. Induction of Anaesthesia
• Intravenous hypnotic ± narcotic, or
• Inhalational anaesthetic ± narcotic
± Muscle relaxant if required

24. Maintenance of
Anaesthesia
• Inhalational anaesthetic ± analgesic,
or
• Intravenous anaesthetic ± analgesic,
or
• Inhalational anaesthetic + Intravenous
anaesthetic ± analgesic
± Muscle relaxant if required

25. Reversal of Anaesthetic
• Switch off Inhalational /
Intravenous
Anaesthetic
• Reverse neuromuscular blockage
• Consider other specific antagonists if
necessary - Naloxone,
Flumazenil

26. Complications of
General Anaesthesia
1. Central Nervous System
2. Cardiovascular System
3. Respiratory System

27. Effects
Central Nervous System
1. Depression
- loss of consciousness
- Cardiovascular depression
- Respiratory depression
2. Stimulation - seizures

28. Effects
Cardiovascular System
1. Myocardial depression
2. Vasodilatation
3. Arrhythmias
hypotension, decreased perfusion

29. Effects
Respiratory System
1. Decreased Rate & Apnoea
2. Decreased Tidal Volume
3. Ventilation – Perfusion mismatch
4. Increased Work of Breathing
hypoventilation, hypoxia

31. Intraoperative Monitoring
1. Clinical
2. Cardiovascular System
3. Respiratory System

32. Monitoring
Clinical
1. Pulse rate, Blood Pressure
2. Respiratory rate
3. Colour:
- Pallor, cyanosis
4. Perfusion:
- Capillary refill, Temperature
- Urine output

33. Monitoring
Cardiovascular System
1. Non-invasive:
- ECG
- Pulse rate,
Heart rate
- Blood pressure
2. Invasive:
- Intra-arterial
pressure
- Central Venous
Pressure, PCWP

34. Monitoring
Respiratory System
1. Pressure / Flow monitors:
- Tidal volume, Airway pressure
2. Gas analyser:
- Inspiratory O 2 concentration,
- End-tidal CO 2 partial pressure,
- Anaesthetic gas concentration
3. Pulse Oximeter - Arterial O 2 saturation

35. Ventilation
• Spontaneous ventilation
• Intermittent positive pressure
ventilation - IPPV

36. Ventilation - IPPV
• Requires endotracheal intubation in most
cases
• Useful when needed to:
- protect the lungs from aspiration of
material from stomach or
upper airways
- ensure adequate ventilation of the
lungs

37. Ventilation - IPPV
• Ventilator generates a positive pressure
which drives gas / oxygen mixture into
lungs
• Dangers include:
- failure of intubation / ventilation
leading to hypoxia
- injury to lungs if airway pressure is
excessive