Inhalation Sedation II Flashcards

(35 cards)

1
Q

What is the spectrum of pt management?

A
TLC
LA
Suggestion/ hypnosis
IHS
Oral sedation 
IV sedation
GA
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2
Q

Advantages IHS?

A
Non-invasive
Rapid onset and recovery
Minimal impairment of reflex
No fasting required
Adult pt don't need escort
Some analgesic effect
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3
Q

Disadvantages IHS?

A
Lack of potency of nitrous oxide
Expensive equipment
Requires clear nasal airway
Intrusion make into operating field 
Chronic staff exposure 
Lack operator control
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4
Q

What patients are suitable?

A
Unpleasant tx
Anxious pt
Needle phobics
Those gag easily - reflex dulled
Medically compromised - unsuitable IV
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5
Q

What are general contraindications?

A
Nasal obstruction - can't breath in nitrous oxide
Severe pulmonary conditions
Cyanosis due cardaic/ respiratory diseae
Inability to communicate/ co-operate
Pregnancy 
Masks interrupt operative work
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6
Q

What drug contraindicates use of IHS?

A

Methotrexate

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7
Q

Why is methotrexate a contraindication to providing IHS

A

Nitrous oxide increase risk of methotrexate toxicity - drug interaction

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8
Q

When is methotrexate used?

A

Autoimmune conditions e.g rheumatoid, psoriasis, neoplastic disease

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9
Q

What medical conditions contraindicate IHS?

A

Muscle wasting - myasthenia gravis
Claustrophobia
Recent ophthalmic surgery using gas
Any air entrapment in body e.g head injury/ pneumothorax

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10
Q

Why is muscle waisting contraindication IHS?

A

Drug relax muscle to point respiratory depression

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11
Q

Why are those w/ psychiatric disorders contraindicated to have IHS?

A

Struggle understand expectations

Hard breath through nose calm and consistently

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12
Q

Ideal properties sedating agent

A
Alleviate anxiety
Degree amnesia and analgesia
Maintain protective reflex
Prolong operating time
Rapdily effective
Easily eliminated
No side effects
Easily administered
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13
Q

What is oxygen?

A

Clear, colourless and odourless gas

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14
Q

What state is oxygen in when in the cylinder?

A

Gaseous

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15
Q

What colour is oxygen cylinder?

A

Black w/ white shoulder

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16
Q

What is nitrous oxide?

A

Sweet smelling, colourless gas

17
Q

What colour is nitrous oxide cylinder

18
Q

What state is nitrous oxide in in cylinder?

A

Liquid when under pressure

19
Q

How know amount of nitrous oxide in cylinder?

20
Q

MAC nitrous oxide?

A

105% - weak anaesthetic

21
Q

What are systematic effects nitrous oxide?

A

Depression CNS

Slight depression CVS at high []

22
Q

Effects chronic exposure to nitrous oxide?

A

Increased risk of miscarriage
Decreases fertility
Pernicious anemia due issue via B12 synthesis

23
Q

What is entonox?

A

50% oxygen and 50% nitrous oxide

24
Q

Why doe entonox need to be used at room temp?

A

Cause uneven distribution of gas within cylinder

25
What are diff planes of nitrous oxide analgesia?
Plane 1 - moderate sedation Plane 2 - dissociation sedation and analgesia Plan 3 - total analgesia
26
What % for plane 1?
5-25%
27
What % for plane 2?
20-50%
28
What % for plan 3?
50%+
29
What is MAC?
Minimum alveolar concentration - measure anaesthetic potency
30
What is MAC of nitrous oxide?
105%
31
When is MAC reduced?
elderly | by other sedative - alcohol, antihistamines, benzodiazepine
32
What is theory of diffusion hypoxia?
Rapid elimination of nitrous oxide into lungs dilutes oxygen within alveolus lowering alveolar oxygen concentration, reduces ventilatory drive causing hypoxia/ hyperventilation
33
How to prevent diffusion hypoxia?
Routine administration 100% oxygen for 3-5 mins post -op
34
How to reduce occupations exposure?
Improve ventilation Active and passive scavenging Regular machine chekcs
35
Safety features of IHS?
``` Pinned system Colour coded cylinders and tubing Oxygen fail-cut out 30% minimum oxygen Oxygen flush Reservoir bag Scavenging ```