Anaesthetics Flashcards
(123 cards)
Why doe sthe patient need to be fasted before general anaesthetic
Reduces the reflux of stomach contents into oropharynx (throat) then aspiration into trachea
How does reflux then aspiration lead to pneumonia
gastric contents in lungs creates aggressive inflammatory response
leads to pneumonitis - inflammation of lung tissue
then aspiration pneumonia
When is there the highest risk of aspiration during general anaesthetic
before, during intubation
at extubation
what are the fasting rules for operations under general anaesthetic
6 hours no food or feeds
2 hours no clear fluids - fully nil by mouth
What is preoxygenation
100% oxygen for a few minutes before being put under so they have a reserve for the period when they lose consiousness and are successfully intubated and ventilated
in case they are difficult to intubate or anaesthetist has difficult
What are the three classic classes of medications that patients may be given before anaesthetics
Benzodiazepines - relax muscles and reduce anxiety - midazolam
Opiates - fentanyl / alfentanyl - reduce pain and hypertensive response to laryngoscope
Alpha-2-adrenergic agonists - clonidine - help sedation and pain
What is used in emergency scenarios to get control of the airway
rapid sequence induction/intubation
What maneouvres can be used to prevent aspiration in RSI?
press down on cricoid cartilage (cricoid pressure) to press the oesophagus down
Position the patient pore upright
What is the triad of general anaesthesia
Hypnosis
muscle relaxation
analgesia
How can hypnotic agents be delivered
intravenous
inhalation
What do hypnotic agents do
make the patient unconscious
What are the intravenous options for hypnotic agents
propofol (most common)
ketamine
thiopental sodium (less common)
etomidate (rare)
What are the inhaled option for general anaesthetic
Sevoflurane (most common)
Desflurane (less favourable - bad for environment)
Isoflurane (rare)
Nitrous oxide (kids)
What are volatile anaesthetic agents
liquids at room temperature and need to be vapourised into a gas to be inhaled
e.g. sevoflurane, desflurane and isoflurane
What acts quicker, inhaled or IV general anaesthetic agents?
IV agents
Commonly, an intravenous medication will be used as an induction agent (to induce unconsciousness), and inhaled medications will be used to maintain the general anaesthetic during the operation. Inhaled medications need to diffuse across the lung tissue and into the blood, where it takes a while for them to reach an effective concentration. IV agents have a head start, as they are infused directly into the blood and so can quickly reach an effective concentration.
What is TIVA?
Total intravenous anaesthetia used for induction and maintenance - most commonly propofol
nicer recovery compared with inhaled options
What are the two classes of muscle relaxants
Depolarising
Non-depolarising
What are some examples of muscle relaxants?
Suxamethonium (depolarising)
Rocuronium and Atracurium (Non-depolarising)
What is the purpose of muscle relaxants in general anaesthetic?
To relax and paralyse muscles
Makes surgery and intubation easier
How can you reverse muscle relaxants
Neostigmine - cholinesterase inhibitor for depolarising muscle relaxants - for suxamethonium
Sugammadex for non-depolarising ones - rocuronium and vecuronium
Where do muscle relaxants act?
At the neuromusclular junction - Acetylcholine is blocked from stimulating a response from the muscle
Which opiates are most frequently used
Fentanyl
Alfentanil
Remifentanil
Morphine
Which antiemetics are given post-procedure for prophylaxis
Ondansetron
Dexamethasone
Cyclizine
What class of drug is ondansetron
5HT3 receptor antagonist