1. Thanks to Drs Rob Stephens, James Holding and Maryam Jadidi
Intro
Handbook has more details
Anaesthesia unusual - doctors give the drugs - and see the results, instant feedback
No doses - titrate to effect
Dr Claire Frith
Thanks to Drs Rob Stephens, James Holding and Maryam Jadidi

2. Contents Introduction – the classical triad General principles
Hypnotic Agents
Neuromuscular Paralysis
Reversal of Neuromuscular Paralysis
Analgesia
Cardiovascular Drugs – up and down
Fluids and Gasses are drugs too!

3. Introduction ‘Anaesthesia’ classical triad: Hypnosis
Analgesia Muscle relaxation
Induction, Maintenance, Emergence, Recovery

4. Introduction - Principles
Pharmacokinetics
What the body does to the drug
Absorption, distribution, metabolism, elimination
Pharmacodynamics
What the drug does to the body – ie it’s effects
CVS, RS, GI, NS, Other , Side effects

5. 2015 Anaesthesia Intravenous induction
Short acting opiate - e.g. fentanyl
Hypnotic ‘anaesthetic’ - e.g. propofol
Set up of anaesthetic maintenance - e.g. sevoflurane vapour in oxygen and air
Specific muscle paralysis may be needed
Definitive analgesia
Anti-emetic
Others

6. Hypnosis: Propofol

7. Maintenance Sevoflurane (SEVO) – MAC = 2.2
Concepts of partial pressure and MAC
Sevoflurane (SEVO) – MAC = 2.2
Used for gaseous induction.
Isoflurane (ISO) – MAC = 1.1
Desflurane (DES) – MAC = 6
The most insoluble – so the fastest to equilibrate – but a respiratory irritant, so unsuitable for gaseous induction.
Nitrous Oxide – a gas. MAC = 105
Oxygen /Air
Propofol and Remifentanil
Inhalational agents are administered by concentration rather than dose, as the concentration equilibrates between alveolus, blood and brain it must achieve a sufficient concentration within the CNS to have an effect.
Minimum alveolar concentration = that concentration of anaesthetic agent that will prevent reflex response to a skin incision in 50% population. It is therefore a useful measure of depth of anaesthesia. The concentration of the anaesthetic agent in the expired gases is used to display a MAC value.
Partial pressure – is the driving force behind gas transfer, In a mixture of gases, each gas has a partial pressure which is the hypothetical pressure of that gas if it alone occupied the volume of the mixture at the same temperature
Anaesthetic vapours are halogenated ethers, they have a carbon skeleton and changing the halogenation e.g. fluroide/chloride alters the pharmacological and physical properties.

8. Muscle Paralysis
Curare, compleltely and irreversibly bind nicotinic AcH receptors causing death by asphyxiation due to paralsysis of the diaphragm

9. Neuromuscular blockers
Depolarising
Suxamethonium
Non-depolarising
Atracurium
Vecuronium
Rocuronium
Non-depolarising can be further divided into aminosteroids – Vec/Roc, and benzylisoquinolinium compounds – like atracurium

10. Nicotinic ACh Receptor

11. Reversal of Paralysis Neostigmine Sugammadex Blocks cholinesterase
Stimulates nicotinic and muscarinic
Given with an anticholinergic
Sugammadex
Just have to wait for sux to wear off
Non-depolarisers can be ‘reversed’

12. Analgesia Systemic Regional – spinal / epidural / blocks
Simple- paracetamol 1g
NSAID – Diclofenac etc
Opioids eg morphine 2mg bolus
Others – Ketamine
Regional – spinal / epidural / blocks
Local - infiltration

13. Opiates
Morphine
Diamorphine
Fentanyl
Alfentanil
Remifentanil
Tramadol

14. Uppers Anticholinergics Symatheto-mimetics Atropine
Glycopyrrolate μg
Symatheto-mimetics

 agonists
Phenylepherine
Metaraminol mg
Ephedrine
A mixed  and  adreno agonist
3mg
The anti-cholinergics atropine and glycopyrrolate are used to reduce vagaly mediated bradycardia, and to dry secretions. Unlike atropine, glycopyrulate does not cross the blood-brain barrier, and does not cause sedation.

15. Downers More anaesthetic or opiate / analgesia
Short acting -blockers (labetalol, esmolol)
GTN
Clonidine - 2 agonist clonidine

16. Antiemetics High rates in anaesthesia - up to 30%
Avoid triggers - N2O, opiates
Complex system - various brain areas - various targets - H, mACh, 5HT, DA

17. Antiemetics Cyclizine anti-histamine
S/E – tachycardia and other anti-cholinergic effects
Ondansetron 5-HT3 receptor antagonists
S/E – constipation + long QT
Prochlorperazine (‘Stematil’) –
DA and mACh receptor antagonist
S/E – extrapyramidal
Dexamethasone glucocorticoid
S/E – deranged glucose control

18. Fluids and Gases are drugs too!
Oxygen is a ‘drug’
Intravenous fluids
Colloids
Crystalloids
Blood and products

19. General Advice Can always give more – can’t take away Caution in
Unwell
Elderly
Hypovolaemic
Lots of ways to anaesthetise- don’t worry

20. Summary
Classical Triad Anaesthesia
Temporal sequence
Usual sequence