Transcript Anaesthetic Drugs

Dr Rob Stephens
Thanks to Drs James Holding and Maryam Jadidi
Contents
Introduction – the classical triad
Introduction – general principles
Hypnotic Agents
Neuromuscular Paralysis
Reversal of Neuromuscular Paralysis
Analgesia
Cardiovascular Drugs – up and down
Fluids and Gasses are drugs too!
Introduction
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‘Anaesthesia’ classically
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Hypnotic agent- unconsciousness
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Gas or IV
Analgesia
Neuromuscular Paralysis
Induction, Maintenance, Emergence,
Recovery
Introduction - Principles
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Pharmacokinetics
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What the body does to the drug
Absorption, distribution, metabolism, elimination
Pharmacodynamics
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What the drug does to the body – ie it’s effects
CVS, RS, GI, NS, Other , Side effects
2013 Anaesthesia
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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
Hypnosis: Propofol
Maintenance
Concepts of partial pressure and MAC
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Sevoflurane (SEVO) – MAC = 2.2
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Isoflurane (ISO) – MAC = 1.1
Desflurane (DES) – MAC = 6
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Used for gaseous induction.
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
Muscle Paralysis
Neuromuscular blockers
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Depolarising
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Suxamethonium
Non-depolarising
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Atracurium
Vecuronium
Rocuronium
Nicotinic ACh Receptor
Reversal of Paralysis
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Neostigmine
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Blocks cholinesterase
Stimulates nicotinic and
muscarinic
Given with an
anticholinergic
Sugammadex
Analgesia
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Systemic
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Simple- paracetamol 1g
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NSAID – Diclofenac etc
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Opioids eg morphine 2mg bolus
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Others – Ketamine
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Regional – spinal / epidural / blocks
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Local - infiltration
Uppers
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Anticholinergics
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Atropine
Glycopyrulate 200-600μg
Symatheto-mimetics
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 agonists
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Phenylepherine
Metaraminol 0.25-0.5 mg
Ephedrine
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A mixed  and  adreno agonist
3mg
Downers
More anaesthetic or opiate / analgesia
Short acting -blockers (labetalol, esmolol)
GTN
Clonidine - 2 agonist clonidine
Antiemetics
Antiemetics
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Cyclizine
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S/E – constipation + long QT
Prochlorperazine (‘Stematil’) –
DA and mACh receptor antagonist
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S/E – tachycardia and other anti-cholinergic effects
Ondansatron 5-HT3 receptor antagonists
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anti-histamine
S/E – extrapyramidal
Dexamethasone glucocorticoid
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S/E – deranged glucose control
Fluids and Gasses are drugs too!
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Oxygen is a ‘drug’
Intravenous fluids
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Colloids
Crystalloids
Blood and products
General Advice
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Can always give more – can’t take away
Caution in
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Unwell
Elderly
Hypovolaemic
Lots of ways to anaesthetise- don’t worry
Summary
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Classical Triad Anaesthesia
Temporal sequence
Usual sequence