Regarding General Anaesthesia.

1. Types of Anaesthesia

2. Objectives
Short History
Definition/types of anaesthesia
General anaesthesia/drugs
Phases of GA
Regional anaesthesia

3. Early history
Ancient/Medieval period
Opium
Alcohol
Cannabis
-
-
-

4. History
1845- Horace Wells- N2O
1846- William Morton- Ether
1847- Simpson- Chloroform
1853-John Snow
1878- ETT
1884- Cocaine
1895-98- Spinal analgesia/anaesthesia

5. History
1921- Epidurals
1934- Thiopentone, cyclopropane
1942- Curare
1946- Lignocaine
1951- Suxamethonium
1952- IPPV
1956-Halothane

6. Definition
‘Loss of sensation’
General
Regional
Local

7. Triad of General
anaesthesia
Hypnosis
Analgesia Muscle relaxation

8. Death
Coma
Hypnosis
sedation
Amnesia
Awake
Hypnosis

9. Hypnotic drugs-intravenous
Gold standard- thiopentone
Propofol
others
Etomidate
Benzodiazepines
Ketamine

10. Inhalational anaesthetics
Nitrous oxide-weak
Isoflurane
Sevoflurane
Desflurane
Halothane

11. Analgesia
Good analgesia= good anaesthesia
Hypnotic sparing effect
Opiates
Local anaesthetics
NSAIDS
Paracetamol

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

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

14. Muscle relaxation
Aids intubation
Helps surgeon/surgery
Surgery of long duration
Reduces maintenance dose of
anaesthetics agents

15. Muscle relaxants
Two types
Depolarising-short acting
eg;suxmethonium
Non-depolarising- medium/long acting
-
-
- Tracurium
Vecuronium
Rocuronium

16. Prerequisites
Oxygen
Suction
Tilting trolley
Resuscitation drugs
Monitoring
Anaesthetist
Skilled assistance
Drugs and machine

17. Phases of
general anaesthesia
Induction
Maintenance
Recovery

18. Induction
Intravenous- majority
Inhalational- children, needle phobics
Monitoring
Preoxygenation
Hypnotic/analgesic and or relaxant
Mask/LMA/ET tube

19. Stages of anaesthesia
1.Dizzy, delightful
2.Drunk, disorderly
3.Dead drunk
4.Dangerously deep
Alcohol General Anaesthesia
1.Amnesia, analgesia
2.Uninhibited
response to stimuli
3.Surgical anaesthesia
4.Vital centre
depression

20. Maintenance
Intravenous or inhalational
Oxygen –40%-100%
Nitrous oxide
Muscle relaxant
Analgesia

21. Recovery
Turn off agent
Reverse relaxation
Cough reflex
Extubate when awake
Recovery position
Monitor until discharge

22. Advantages
No absolute contraindications
Quick to establish
Never fails to work

23. Disadvantages
Polypharmacy
Effects on various systems
Allergic reactions
Recovery profile
Post operative Nausia &Vomiting
Awareness

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

26. Regional anaesthesia
Analgesia Muscle relaxation

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

28. Advantages
Effective alternative to GA
Avoids polypharmacy
Allergic reactions
Extended analgesia
Patient can remain awake
Early drink/feed

29. Disadvantages
Limited scope
Higher failure rate
Time constraints
Anticoagulants/Bleeding diathesis
Risk of neural injury