Anaesthetics Flashcards

1
Q

two many categories of anaesthesia

A
  • General anaesthesia – making the patient unconscious
  • Regional anaesthesia – blocking feeling to an isolated area of the body (e.g., a limb)
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2
Q

triad of general anaesthesia

A
  • Hypnosis
  • Muscle relaxation
  • Analgesia
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3
Q

since general anaesthesia involves patients becoming unconscious, patients must be

A

intubated or have a supraglottic airway device, and their breathing will be supported and controlled by a ventilator

  • Defintiibe airway- endotracheal tube
    • for high risk and long surgery
  • Supraglottic airway
    • most common
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4
Q

before general anesthesia is given patients are

A

pre-oxygenated

aim: replace nitrogen in the RBC with oxygen

Before being put under a general anaesthetic, the patient will have a period of several minutes where they breathe 100% oxygen. This gives them a reserve of oxygen for the period between when they lose consciousness and are successfully intubated and ventilated (in case the anaesthetist has difficulty establishing the airway)

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5
Q

medication which may be given before patient is put under to relax them and reduce anxiety, pain and make intubation easier

A
  • Benzodiazepines (e.g., midazolam) to relax the muscles and reduce anxiety (also causes amnesia)
  • Opiates (e.g., fentanyl) to reduce pain and reduce the hypertensive response to the laryngoscope
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6
Q

what is the idea behind rapid sequence induction/intuvation

A

successful intubation with an endotracheal tube as soon as possible after induction (when the patient is unconscious) to protect the airway.

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7
Q

biggest concern during rapid sequence induction/intubation

A
  • aspiration of stomach content into the lung
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8
Q

hypnotic agents help which which part of the triad of general anaesthesia

A

hypnosis

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9
Q

induction agents for general anaesthesia can either be

A

intravenous or inhaled

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10
Q

intravenous options for GA

A
  • Propofol (the most commonly used)
  • Ketamine
  • Thiopental sodium (less common)
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11
Q

inhaled options for GA

A
  • Sevoflurane (the most commonly used)
  • Desflurane (less favourable as bad for the environment)
  • Isoflurane (very rarely used)
  • Nitrous oxide (combined with other anaesthetic medications – may be used for gas induction in children)
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12
Q

what type of agents are sevoflurane, desflurance and isoflurane

A

volatile anaesthetic agents

  • must be vaporised into a gas to be inhaled
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13
Q

types of maintenance of GA

A
  1. induction: IV and maintenance: inhaled
  2. induction: IV and maintenance : IV (total intravenous anaesthesia)
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14
Q

total intravenous anaesthesia

A

IV medication for induction and maintenace of GA

e.g. propofol

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15
Q

benefit of TIVA

A

nicer recovery when waking up than inhaled options

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16
Q

muscle relaxants

A

lock the neuromuscular junction from working

  • paralyse muscles by blocking the activity of Axcetylcholine at the NMJ
17
Q

why give muscle relaxants

A

makes intubation and surgery easier.

18
Q

types of muscle relaxants

A
  • Depolarising (e.g., suxamethonium)
  • Non-depolarising (e.g., rocuronium and atracurium)
19
Q

reversing the effects of neuromuscular blocking medications after surgery

A

Cholinesterase inhibitors (e.g., neostigmine)

20
Q

analgesia

A

opiates are used most commonly during surgery

  • Fentanyl
  • Morphine
  • local anaesthetic- injected near the end of the surgey to prevent post operative pain*
  • lidocaine
21
Q

emergence - before waking the patient …

A
  • muscle relaxant needs to have warn off
    • can give neostigamine
  • then the inhaled anaesthetic is stopped
    • conc of anaesthetic in the body falls… pt regains consciousness
    • they are extubated when they are breathing for themselves
22
Q

after emergence many patients get

A

PONV

23
Q

PONV

A

post operative nauese and vomiting

24
Q

prophylaxis for PONV

A
  • Ondansetron (5HT3 receptor antagonist) – avoided in patients at risk of prolonged QT interval
  • Dexamethasone (corticosteroid) – used with caution in diabetic or immunocompromised patients
  • Cyclizine (histamine (H1) receptor antagonist) – caution with heart failure and elderly patients
25
Q

risks of GA

A

common

  • sore throat
  • PONV

significant

  • accidental awareness
  • aspiration
  • dental injury
  • anaphylaxis
  • cardiovascular events
  • malignant hyperthermia
  • death
26
Q

Malignant hyperthermia

A

is a rare but potentially fatal hypermetabolic response to anaesthesia. The risk is mainly with:

  • Volatile anaesthetics (isoflurane, sevoflurane and desflurane)
  • Suxamethonium
27
Q

malignant hyperthermia presentation

A
  • Increased body temperature (hyperthermia)
  • Increased carbon dioxide exhalation
  • Tachycardia
  • Muscle rigidity
  • Acidosis
  • Hyperkalaemia
28
Q

treatment if malignant hypertension

A

dantrolene

  • interferes with movement of calcium ions in skeletal muscle
29
Q

phases of GA

A

Phases of GA

  • Induction
    • send patients to sleep
  • Maintenance
    • keeping them asleep
  • Emergence
    • waking them up
  • Recovery
    • Managing them until “ward ready”
30
Q

phases of GA

A

Phases of GA

  • Induction
    • send patients to sleep
  • Maintenance
    • keeping them asleep
  • Emergence
    • waking them up
  • Recovery
    • Managing them until “ward ready”
31
Q

other types of anaesthesia

A
  • peripheral nerve block
  • epidural anaesthesia
  • local anaesthetic
32
Q

peripheral nerve blocks

A

regional anaesthesia

  • patient conscious
  • local anaesthetic injected around specific nerves causing distal nerves to be anaesthesised
  • method: US guided with the help of nerve stimulator
  • sedation may be given to help patient relax
33
Q

epidural anaesthesia

A

involves inserting a catheters into the epidermal space in the lower back

  • outside dura mater, separate from the spinal cord and CSF
  • local anaesthetic are infused through he catheter into the epidural space where they diffuse to the surrounding tissues and through to the spinal cord

e.g. levobupivacaina

34
Q

adverse effect from epidural

A
  • Headache if the dura is punctured, creating a hole for CSF to leak from (“dural tap”)
  • Hypotension
  • Motor weakness in the legs
  • Nerve damage (rare)
  • Infection
  • Haematoma (may cause spinal cord compression)
35
Q

local anaesthesia in surgery

A

to numb specific areas where a procedure is being performed e..g lidocaine