Anaesthetics Basics Flashcards
Explain the purpose of induction agents
Used to induce loss of consciousness in one to two brain-arm circulations
Name the most commonly used induction agent
Propofol
What is the normal dosage for propofol?
1.5-2.5mg/kg
Positives of propofol?
Excellent suppression of airway reflexes
Reduces incidence of PONV (post-operative nausea/vomiting)
What induction agent is commonly used for rapid sequence induction?
Thiopentone
What is RSI?
Rapid sequence induction: an established method of inducing anaesthesia in patients who are at risk of aspiration of gastric contents into the lungs e.g trauma, when you don’t know whats in the stomach and need to be put under quickly
What is thiopentone codraindicated in?
Porphyria
Which induction agent has anti-epileptic properties and protects the brain?
Thiopentone
What occurs if thiopentone is injected into an artery?
Thrombosis and gangrene
What is the dosage of Thiopentone?
4-5mg/kg
What anaesthetic is recommended for short procedures/ use in the field?
Ketamine
What effect does Ketamine have on BP and HR?
Increases
A patient is confused, with anterograde amnesia, which induction agent have they been given?
Ketamine
Dosage of Ketamine?
1.0-1.5mg/kg
Which induction agent is recommended for haemodynamic stability? (good for cardiac sensitive situations)
Etomidate
What is the dosage of etomidate?
0.3mg/kg
Why does -etomidate have a high mortality rate in sepsis?
Adreno-cortical suppression
What is the purpose of inhalation agents?
Used to keep patients asleep after use of induction agents
When would an inhalation agent be used for induction?
Patients afraid of needles (paeds)
What is meant by MAC?
Minimum alveolar concentration (Concentration of the vapour that prevents the reaction to a standard surgical stimulus (traditionally a set depth and width of skin incision) in 50% of subjects.
Which inhalaton agent is recommended in children?
Sevoflurane (sweet smelling)
Which inhalation agent is recommended for long operations?
Desflurane
Which inhalation agent is known for a rapid onset and offset?
Desflurane
Which inhalation agent is recommended for organ retrieval and why?
Isoflurane due its minimal effect on organ blood flow
What is given prior to induction?
Analgesia
What is analgesia required for?
Insertion of airway Laryngeal mask airway Intubation Intraoperative pain relief Post-operative pain relief
Give three examples of short acting opiods
Fentanyl
Remifentanil
Alfentanil
What is the most commonly used analgesic?
Paracetamol
Diclofenac and Parcoxib are what types of painkiller?
NSAIDS
Explain the physiology of muscle contraction
As an action potential arrives at a neuro-muscular junction acetylcholine is released. This causes depolarisation of Nicotinic receptors leading to muscle contraction
How do depolarising muscle relaxants work?
Act on nicotinic receptors in the same way as acetylcholine, however are very slowly hydrolysed by acetylcholinesterase. This causes muscle contraction. The muscle then fatigues and relaxes.
What is the most common depolarising muscle relaxant?
Suxamethonium
Which muscle relaxant is used for RSI?
Suxamethonium
Adverse effects of Suxamethonium
Muscle pains fasciculations hyperkalaemia Malignant hyperthermia Rise in ICP, IOP and gastric pressure
Non-depolarising muscle relaxants have ….. onset and variable onset
slow
Name two short acting non-depolarising muscle relaxants
Atracurium
Mivacurium
Name two intermediate acting non-depolarising muscle relaxants
Vecuronium
Recuronium
Name a long acting non-depolarising muscle relaxants
Pancuronium
What is Neostigmine used for?
It is an anti-cholinerase used to reverse muscle relaxants by preventing breakdown of acetlycholinesterase
Glycopyrrolate is combined with what to reverse muscle relaxant
Neostigmine
What effect does ephedrine have on HR and contractility?
Rise in HR and contractility (this increases O2 required for heart) leading to rise in BP (direct and indirect action, alpha and Beta receptors)
Which two drugs cause a rise in BP by vasoconstriction?
Phenylephrine
Metaraminol
What medications are used to maintain BP in sever hypotension (sepsis, ICU)?
Noradrenaline
Adrenaline
Dobutamine
Why are anti-emetics used post operatively?
To prevent PONV
Name three anti-emetic agents
Ondansetron (commonly used)
Cyclizine (anti-histamine)
Dexamethasone (Steroids, given only in unconscious patients as causes stinging on administration)
Metoclopramide (anti-dopaminergic)
