any lipid-soluble agent the causes depression of the brain in a predictable order Cortex Midbrain Spinal cord Medulla

Oxygen as an anaesthetic agent - action - side- effects

generally good for you _Side- effects_ O2 free radicals CNS convulsions Pulmonary oxygen toxicity Retrolental fibroplasia CO2 narcosis

Nitrous oxide as an anaesthetic agent - action - side-effects/ contraindications

good analgesia but usually combined with other inhaled drugs for a good anaesthetic effect Fast induction/ recovery _Side-effects_ Cardio-respiratory depressant: diffusional hypoxia during recovery risk of bone marrow depression with prolonged use avoided in anaemic and 12 deficient patients can causes expansion in gaseous cavities contraindicated in pneumothorax, vascular air embolus or in an obstructed intestines

Anaesthetics and Analgesia Flashcards by A.M.C.T Kate

What is anaesthesia?

any lipid-soluble agent the causes depression of the brain in a predictable order
- Cortex
- Midbrain
- Spinal cord
- Medulla

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How do anaesthetics work?

Increase tonic inhibition
- increased action of GABA receptors
- Glycine
Inhibit excitatory synaptic transmission
- inhibiting ligand-gated ion-channels
- NMDA receptors
- opening K+ channels
- Nicotinic
- Serotonin

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How is anaesthesia administered?

Inhale
- Oxygen
- NO
- Isoflurane
Injected
- Propofol
- Thiopental
- Etomidate
- Ketamine

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Oxygen as an anaesthetic agent

action
side- effects

generally good for you

Side- effects

O2 free radicals
CNS convulsions
Pulmonary oxygen toxicity
Retrolental fibroplasia
CO2 narcosis

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Nitrous oxide as an anaesthetic agent

action
side-effects/ contraindications

good analgesia but usually combined with other inhaled drugs for a good anaesthetic effect
Fast induction/ recovery

Side-effects

Cardio-respiratory depressant: diffusional hypoxia during recovery
risk of bone marrow depression with prolonged use
- avoided in anaemic and 12 deficient patients
can causes expansion in gaseous cavities
- contraindicated in pneumothorax, vascular air embolus or in an obstructed intestines

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What chemical properties of inhalation need to be considered?

Non-irritant
Low blood-gas solubility
High potency (Minimum alveolar conc. | MAC)
Minimal side effects
bio-transmission
non-toxic

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Desflurane as a general anaesthetic agent

Fast induction/ recovery
- used for day-case surgery
moderately expensive and environmentally damaging
Sevoflurane is similar (expensive)

Side-effects

respiratory tract irritation
cough
bronchospasm

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Isoflurane as a general anaesthetic agent

a relatively cheap stable non-flammable halogenated ether
widely used and replaced halothane
medium induction/recovery rate

Side-effects

irritable to the airway
possible risk of coronary Ischaemia in susceptible patients

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Give an overview of Intravenous agents

they are usually induction agents/ iv opiate
rapid onset and pleasant sensations
Lipid soluble
short-acting, metabolised
cause CVS/RS depression

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Thiopentone as an anaesthetic agent

Powder
Smell of garlic
Antiepileptic
CVS/RS depression
Anaphylaxis/ arterial
Half-life 10 hours

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Propofol as an anaesthetic agent

Short-acting agent used for induction
maintenance of GA and sedation
onset within minutes of injection

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2,6-diisopropylphenol as an anaesthetic agent

Solvent
Redistribution half-life - 4 minutes
Elimination half-life - 4 hours
Minimal accumulation - TIVA
Antiemetic
Antiepileptic
Painful to inject
Abnormal movements
CVS/RS effects

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Give an overview the use of muscle relaxants

Dangerous drugs
Muscle paralysis
Facilitate intubation
Maintain paralysis for surgery/ventilation
Depolarising
Non depolarising
Anaesthetists only

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Give an overview of depolarising agents

Suxamethonium
Post-synaptic membrane
Mimics acetylcholine
Rapid onset offset
Short half life ~ 2min
Plasma cholinesterase
Multiple side effects

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Give an overview of non-depolarising blockers

Competitive with Ach
Ach moiety blocks Na channel with size
Duration is variable
Slower onset and slower offset
Steroid group: rocuronium
Benzylisoquinoliniums: atracurium

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Give an overview of the use of N-m blocking agents

Intubation
Surgery
Ventilation
Transfer
Side effects
Reversal

Gate theory - Pain

C fibres lets pain through
Ab fibres stimulate inhibitory neurons
Descending pathways prevent the central passage

Give an overview of Opioids

Act on opioid Receptor and antagonised by Naloxone
Naturally occurring eg Morphine ,Codeine
Semi-Synthetic eg Diamorphine
Synthetic eg Fentanyl
Weaker eg Codeine

What methods of administration are there for administration?

Intravenous pca/infusion
Intramuscualr
Oral
Intra nasal/aersol
EPidural/spinal

Where are Opioid receptors found?

POns and the Midbrain
Periaqueductal Grey Matter
Nucleus Raphe Magnus
Spinal COrd Posterior Horn 1 and 2
G.I.T
Peripheral tissues

Subtypes

Mu 1 and 2: OP3
Delta: OP1
Kappa: OP2

Give an overview of the use and effects of morphine

Effects: significantly reduces pain

Side effects

Resp. depression/ airway loss
N&V
Constipation/Pruritis
Miosis

What is Naloxone?

drug used to treat opioid overdose
needs to be regularly monitored and regulated

Give an overview of Ketamine and it’s effects

acts on NMDA Receptors
- Kappa and delta receptors
- Not GABA
Analgesic local/general
Anaesthetic
Sedative
SIDE EFFECTS: emergence phenomena

Give an overview of NSAIDS and their effects

Act by inhibiting Cyclooxygenase 1 and 2
Analgesic, Antipyretic, Anti-inflammatory
Side Effects
- Gastric Irritation
- Bronchospasm
- Renal Impairment
- Platelet function ASPIRIN

What is the effect of Aspirin in the body?

* Acetylsalycilic acid * causes Oxidative phosphorylation * causes Air Hunger * Reyes Syndrome

Give an overview of the effect Paracetamol has on the body?

* Mechanism of Action: Central prostaglandin effect/unknown * Side effectsOVERDOSE Hepatotoxicity/glutathione depletion * N acetylcysteine

Give examples of other Analgesia?

* Anxiolysis * Local anaesthetics * Antidepressants,antiepileptics * Guanethidine, ketamine, clonidine * Acupuncture * Inhalational Nitrous oxide/penthrane * Tramadol

What are anti-emetics give examples?

* drug used to treat nausea and vomiting * Cyclizine * Ondansetron * hyoscine * Metoclopramide * Steroids * Prochlorperazine * cannabinoids

The tiers of the Ramsay Sedation scale

* Patient Anxious * Cooperative * Responds only to commands * Brisk response to Glabellar Tap/Shout * Sluggish Response * No response

Give an overview of Benzodiazepines

* Midazolam, Diazepam, Lorazepam * Routes of administration * suppositories, IV injection(triazolam, flunitrazepam, and diazepam emulsion) * PHYSIOLOGY * Gabba- aminobutyric Acid * Inhibitory Neurotransmitter * Receptors A and B

What are the side effects of Benzodiazepines

used for * loss of airways * respiratory depression * ABC * Flumazenil can reverse the effects of benzodiazepines

Give examples of other sedatives

* Low dose vapours * Ketamine * Hyoscine * Propofol Low dose * Major Tranquilisers

What are the classifications of local anaesthetics?

* Amides * Lignocaine, Prilocaine, Bupivacaine * Esters * Cocaine, Amethocaine

Explain the mechanism of action of local anaesthetics

* Na channel blockade * Un-ionized drug through the membrane into the axoplasm * Protonated * Blocks channel--\> blocking the action potential

How are local anaesthetics administered?

* Anatomy Local Blocks /Ultrasound * Spinal Epidural Caudal * Skin * Aerosol/Nebulised * Combination with GA Part of Triad

How do side effects of local anaesthetics present?

- restlessness, disorientation, tremors, drowsiness - lightheadedness circumoral numbness, dizziness visual changes - respiratory depression

What effect does the toxicity of local anaesthetics cause in the - cardiovascular and - central nervous system

Cardiovascular * dysrhythmias, Cardiac depression CNS * fitting/ anxiety/ loss of consciousness * circumoral numbness

How is local anaesthetic toxicity treated?

* ABC * Oxygen * Lipid 20% * Dysrhythmias/fitting