Volatile anaesthetic agents Flashcards
1
Q
What is the molecular weight of halothane?
A
197
2
Q
What is the molecular weight of isoflurane?
A
184.5
3
Q
What is the molecular weight of enflurane?
A
184.5
4
Q
What is the molecular weight of desflurane?
A
168
5
Q
What is the molecular weight of sevoflurane?
A
200.1
6
Q
What is the molecular weight of nitrous oxide?
A
44
7
Q
What is the molecular weight of xenon?
A
131
8
Q
What is the boiling point of halothane?
A
50.2
9
Q
What is the boiling point of isoflurane?
A
48.5
10
Q
What is the boiling point of enflurane?
A
56.5
11
Q
What is the boiling point of desflurane?
A
23.5
12
Q
What is the boiling point of sevoflurane?
A
58.5
13
Q
What is the boiling point of nitrous oxide?
A
-88
14
Q
What is the boiling point of xenon?
A
-108
15
Q
What is the SVP of halothane?
A
32.3
16
Q
What is the SVP of isoflurane?
A
33.2
17
Q
What is the SVP of enflurane?
A
23.3
18
Q
What is the SVP of desflurane?
A
89.2
19
Q
What is the SVP of sevoflurane?
A
22.7
20
Q
What is the SVP of nitrous oxide?
A
5200
21
Q
What is the SVP of xenon?
A
unknown
22
Q
What is the MAC of halothane?
A
0.75
23
Q
What is the MAC of isoflurane?
A
1.17
24
Q
What is the MAC of enflurane?
A
1.68
25
What is the MAC of desflurane?
6.6
26
What is the MAC of sevoflurane?
1.8-2.2
27
What is the MAC of nitrous oxide?
105
28
What is the MAC of xenon?
71
29
What is the blood:gas partition coefficient of halothane?
2.4
30
What is the blood:gas partition coefficient of isoflurane?
1.4
31
What is the blood:gas partition coefficient of enflurane?
1.8
32
What is the blood:gas partition coefficient of desflurane?
0.42
33
What is the blood:gas partition coefficient of sevoflurane?
0.7
34
What is the blood:gas partition coefficient of nitrous oxide?
0.47
35
What is the blood:gas partition coefficient of xenon?
0.14
36
What is the blood:oil partition coefficient of halothane?
224
37
What is the blood:oil partition coefficient of isoflurane?
98
38
What is the blood:oil partition coefficient of enflurane?
98
39
What is the blood:oil partition coefficient of desflurane?
29
40
What is the blood:oil partition coefficient of sevoflurane?
80
41
What is the blood:oil partition coefficient of nitrous oxide?
1.4
42
What is the blood:oil partition coefficient of xenon?
1.9
43
What is the odour of halothane?
Sweet
44
What is the odour of isoflurane?
Irritant
45
What is the odour of enflurane?
non-irritant
46
What is the odour of desflurane?
Pungent
47
What is the odour of sevoflurane?
non-irritant
48
What is the odour of nitrous oxide?
odourless
49
What is the odour of xenon?
odourless
50
Which factors increase MAC?
Infancy Hyperthermia Hyperthyroidism Catecholamines Sympathomimetics Chronic EtOH Chronic opiate use Acute amphetamine use Hypernatraemia
51
Which factors decrease MAC?
Neonatal period Advanced age Pregnancy Hypotension Hypothermia Hypothyroidism Alpha-2 agonists Sedatives Acute EtOH Acute opiate use Chronic amphetamine use Lithium
52
Which factors decrease the time taken to reach equilibrium of anaesthetic agent?
Increased alveolar ventilation Decreased FRC Increased FiAA Reduced cardiac output Reduced blood:gas partition coefficient Second gas effect
53
Which metabolic system is responsible for metabolising the C-(halogen) bond?
CYP450
54
In which order do volatile agents affect cardiac contractility (most -\> least)
Halothane \> Enflurane \> Isoflurane \> Sevoflurane \> Desflurane
55
What is xenon?
An inert, odourless, noble gas that makes up about 8.7 x10-6% of the atmosphere.
56
How is xenon produced?
By fractional distillation of air
57
How expensive is xenon?
Very. Over 2000x the cost of an equivalent amount of N20
58
What is the atomic number of xenon?
54
59
What is the critical temperature of xenon?
16.6
60
What is the mechanism of action of xenon?
Inhibition of glutamate at the NMDA receptor producing anaesthesia and analgesia. Also blocks 5HT3 receptors, although is hasn't been shown to have an effect on PONV.
61
What are the effects of xenon on the cardiovascular system?
Minimal effects on CO, although mildly vagolytic producing a small decrease in HR. Has some ischaemic preconditioning properties
62
What are the effects of xenon on the respiratory system?
Reduction in RR Increase in TV Overall unchanged MV Will produce apnoea in high enough concentration
63
What are the effects of xenon on the CNS?
Likely neuroprotective Small variable increases in CBR, so not recommended for neurosurgery.
64
What is the critical pressure of N2O?
72 bar
65
Is N2O a vapour or a gas?
Both, it is inhaled as a vapour, and exhaled as a gas.
66
How is N2O produced?
Thermal decomposition of ammonium nitrate (NH4NO3) at 250°C
67
What other compounds are produced alongside N2O?
Nitric oxide Ammonia Nitrogen dioxide Nitrogen Nitric acid Water
68
How are the unwanted side products removed during N2O production
Acid/Alkali wash.
69
How is N2O stored?
As a liquid with a pressure of 52 bar (the SVP of the vapour above the liquid)
70
What colour cylinders are used to store N2O?
French blue
71
Define filling ratio?
The ratio of the mass of liquid N2O compared to if filled with water.
72
What is the filling ratio of N2O?
0.75 in the UK 0.67 in the tropics
73
What is the mechanism of action of N2O
Inhibition of NMDA receptor resulting in analgesia and sedation.
74
What are the effects of N2O on the cardiovascular system?
Decreased myocardial contractility offset by increase in central sympathetic outflow. In heart failure this can cause decompensation. No sensitisation to catecholamines.
75
What are the effects of N2O on the respiratory system?
Small reduction in TV Small increase in RR no net change in MV
76
What are the effects of N2O on the CNS?
Increase in CRF and CMRO2 - avoid in neurosurgery and head injury.
77
Give some undesirable side effects of N2O.
Inhibition of B12 -\> The cobalt ion at the centre of B12 is oxidised making it unsuitable to act as a cofactor in methionine synthesise. This can lead to reduced DNA synthesis and megaloblastic anaemia. Subacute combined degeneration of the cord occurs by a similar mechanism.
78
What is entonox?
a 50:50 mix of N2O and O2
79
How is entonox stored?
French blue cylinders with a white and blue checkered shoulder at 137 bar
80
What is the metabolism of isoflurane?
0.2%
