Day two; Anaesthetics Flashcards

1
Q

What are the fasting guidelines?

A

2 hours- clear fluid, water, black tea, fruit juice without bits.
4 hours- breast milk
6 hours- non breast milk light meal (milk curdles with gastric juices therefore more or less the same as solids).

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2
Q

What are the causes of delayed gastric emptying that you need to consider pre-op in a patient?

A

DM- gastro pareisis, ESRF, pyloric stenosis, pregnancy, obesity, high fat content or anxiety. Head injury.

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3
Q

How long do induction agents take to work?

A

10-20 seconds

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4
Q

How long do induction agents last for?

A

4-10 minutes

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5
Q

How do induction agents work?

A

They induce loss of consciousness in one brain-arm circulation time (IV).

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6
Q

What are inhalational/volatile agents generally used for?

A

Maintenance of anaesthesia

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7
Q

What is the most commonly used induction agent?

A

Propofol (lipid based)

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8
Q

What are the good things about propofol?

A

It causes excellent suppression of the airway reflexes and it decreases the incidence of PONV

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9
Q

What are the bad side effects of propofol?

A

Marked drop in HR and BP
Pain on injection
Involuntary movements

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10
Q

What type of drug is thiopentone?

A

Barbituate

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11
Q

What is an advantage of thiopentone?

A

It works faster than propofol, it is mainly used for rapid sequence induction and it has anti-epileptic properties in that it protects the brain.

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12
Q

What are the unwanted effects of thiopentone?

A

Drops BP but rise in HR
Rash / Bronchospasm (causes histamine release)
Intraarterial injection: thrombosis and gangrene
Contraindicated in Porphyria** (causes hepatic enzyme induction).
It is the licensed drug for the death penalty in some states in america.

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13
Q

Which induction agent causes dissociative amnesia?

A

Ketamine, as well as Anterograde amnesia and profound analgesia

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14
Q

What dose of ketamine is used?

A

1 – 1.5 mg/kg

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15
Q

How long does ketamine take to work?

A

90 seconds

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16
Q

What does ketamine do?

A

Causes a rise in HR, BP and bronchodilation

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17
Q

What are the unwanted side effects of ketamine?

A

N&V, and the emergence or delirium phenomenon.

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18
Q

What are the advantages of using etomidate?

A

Rapid onset, haemodynamic stability, lowest incidence of hypersensitivity reaction.

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19
Q

Which induction agent is used in patients who have cardiovascular compromise?

A

Etomidate

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20
Q

What are the unwanted side effects of etomidate?

A

Pain on injection, spontaneous movements, adreno-cortical suppression, high incidence of PONV.

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21
Q

Cortisol levels have been reported to be suppressed up to 72 hours after a single bolus of….. (induction agent)

A

Etomidate
It could therefore increase mortality and should never be used in patients in septic shock.
This also means that they won’t be able to respond to stress and their bp will remain low.

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22
Q

A patient requiring a burn dressing change requiring an induction agent….

A

Ketamine (this provides amnesia and analgesia)

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23
Q

A patient undergoing arm operation under GA with an LMA requiring an induction agent….

A

Propofol

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24
Q

A patient with a history of heart failure requires a general anaesthetic….

A

Etomidate

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25
A patient with intestinal obstruction requires an emergency laparotomy.
Thiopentone
26
A patient with porphyria comes for an inguinal hernia repair
Propofol (not thiopentone!!)
27
Name the four inhalational agents (used for amnesia)..
Isoflurane Sevoflurane Desflurane Enflurane
28
Which inhalational agent is sweet smelling and ideal for needle phobic children?
Sevoflurane (Sevo is 2)
29
Which inhalational agent has a rapid onset and offset?
Desflurane
30
Which inhalational agent has the least effect on blood flow to the organs and is good for transplants?
Isoflurane
31
What is MAC?
Minimum alveolar concentration is the concentration of a vapour in the lungs that is needed to prevent movement (motor response) in 50% of subjects in response to surgical (pain) stimulus. MAC is used to compare the strengths, or potency, of anaesthetic vapours.
32
What is the MAC for Nitrous oxide?
104%
33
What is the MAC for Sevoflurane?
2%
34
What is the MAC for isoflurane?
1.15%
35
What is the MAC for desflurane?
6% (des is 6)
36
What is the MAC for enflurane?
1.6%
37
What is the best inhalational agent for a long operation?
Desflurane
38
Which are the short acting analgesics and what are they used for?
Fentanyl, remifentanil and alfentanil. These are used for intra-op analgesia to suppress the response to laryngoscopy and surgical pain. They have a high potency and a rapid onset.
39
What are the long acting analgesics and when are they given?
Morphine and oxycodone and they are given as intra-op and post-op analgesia. (morphine is ideally started 1/2 hour before procedure ends).
40
IV NSAIDS?
Ketorolac, Parecoxib
41
Most commonly used oral opioid?
Codeine (you can't give codeine IV NB)
42
Most commonly used analgesic?
Paracetamol
43
What are the two groups of muscle relaxants?
Depolarising and non-depolarising
44
How do depolarising agents work?
They act similar to acetylcholine on nicotinic receptors but are very slowly hydrolysed by acetylcholinesterase. Therefore they cause muscle contraction, muscle then fatigues and relaxes.
45
How do non-depolarising agents work?
They block the Nicotinic receptors therefore muscle relaxes.
46
Name the depolarising muscle relaxant used for rapid sequence induction?
Suxamethonium
47
What is the dose of suxamethonium?
1 -1.5 mg/kg (same as ketamine)
48
What are the adverse effects of suxamthonium?
``` muscle pains, fasciculations, hyperkalemia malignant hyperthermia, rise in ICP,IOP and gastric pressure ```
49
Name the non-depolarising muscle relaxants...
Short acting: Atracurium, mivacurium Intermediate acting: Vecuronium, rocuronium Long acting: Pancuronium
50
Which drugs are used for muscle relaxant reversal by non-depolarising agents?
Neostigmine and Glycopyrolate
51
How does neostigmine work?
So its an acetyl choline esterase inhibitor, enzyme inhibition leads to a reduction in the breakdown of ACh and potentiates its action.
52
How do non-depolarising muscle relaxants work?
Slow onset and variable duration, less side effects Compete with Ach for nicotinic receptors and block the receptors. Non-depolarizing drugs are competitive antagonists of ACh at the postsynaptic nicotinic receptor. he binding of antagonists to the receptor is reversible and repeated association and dissociation occurs. Neuromuscular blockade starts to occur when 70-80% of receptors are antagonised, to produce a complete block over 90% of receptors must be occupied
53
Name side effects of anti-cholinesterases?
Bradycardia, miosis, GI upset, nausea, bronchospasm, increased bronchial secretions, sweating and salivation (Combined with antimuscarinic agent: Glycopyrrolate)
54
What type of agent is Glycopyrrolate?
Antimuscarinic
55
What are the MAIN side effects of reversal drugs?
Nausea and vomiting
56
Which anti-emetic agents are used post-surgery?
``` 5HT3 blockers: Ondansetron Anti-histamine: Cyclizine Steroids: Dexamethasone Phenothiazine: Prochlorperazine (Stemetil) Anti-dopaminergic: Metoclopramide ```
57
Which vaso-active drugs are commonly used to treat hypotension?
Ephedrine Phenylephrine Metaraminol
58
Which drugs are used in severe hypotension/ICU?
Noradrenaline Adrenaline Dobutamine
59
How does ephedrine work?
Rise in HR and contractility leading to rise in BP (direct and indirect action, alpha (α) & β receptors
60
How does phenylephrine work?
Rise in BP by vasoconstriction (Direct action, α receptors), drop in HR
61
How does meteraminol work?
Rise in BP by vasoconstriction (Direct and indirect action, predominant α receptors)
62
Best vaso-active agent for low bp and low HR
Ephedrine
63
Best vaso-active agent for low bp and high HR
Phenylephrine, Meteraminol
64
Best vaso-active agent in ICU for severe sepsis
Noradrenaline and adrenaline
65
What does the number beside the CO2 concentration mean on an anaesthetics monitor?
The maximum co2 concentration in expired air.
66
What is the order you do things in when giving an LMA?
Oxygen, opioid (fentanyl/afentanyl), propofol (induction agent), turn on volatile agent (sevoflurane), bag mask ventilation then insert the LMA.
67
What is the order you do things when doing intubation?
Oxygenation, fentanyl, propofol, muscle relaxant, sevoflurane, bag valve mask, ET intubation.
68
Describe the rapid sequence induction...
``` Pre-oxygenation: tight fitting mask for 3 mins or 5 full volume capacity breaths so that all the NO2 is washed out and replaced with o2. Thiopenone (4-5mg/kg) Propofol (1.5-2.5) Sux (1-1.5mg/kg) Technique: cricoid pressure COME BACK TO THIS?? ```
69
What is the maximum dosage of lignocaine without and with adrenaline?
3mg/kg and 7mg/kg | Over doubles with adrenaline
70
Which local anaesthetic has the same maximum dosage with or without adrenaline?
Bupivicaine 2mg/kg
71
What is the maximum dosage of prilocaine without and with adrenaline?
6mg/kg and 9 mg/kg | So increases by 50% with adrenaline
72
What is the equation to remember??
1% = 10ml/kg
73
Where does the spinal cord end?
L2
74
Where does the subarachnoid space end?
S2
75
Name the layers the needle goes through to get to the subarachnoid space....
Skin, sub cut fat, supraspinous ligament, interspinous ligament, ligamentum flavum, epidural space, dura and arachnoid and sub arachnoid space.
76
What is the benefit of having an epidural over a spinal?
You can top up an epidural using a catheter
77
If the CSF leaks out through the space caused by the needle what may happen?
Post dural headache
78
How long does an epidural take to work?
15-30 mins