nitrous oxide [Entonox]

Question 1

Classification

N₂O

Answer 1

inhaled anesthetic

analgesic

Question 2

INDICATIONs

N₂O

Answer 2

EMR
moderate to severe pain 2nd to
- extremity injs
- burns // other injs
- clinical conditions [cardiac ischemia] NOT including inhalation inj

Question 3

CONTRAINDICATIONs

N₂O

Answer 3

• ALOC
• inability to comply with intructions
• inhalation injuruy
• pneumothorax
• air ebolism
• decompresion sickness
• gross abdominal distension
• severe bullous emphysema
• NTG use - past 5mins

Question 4

CDCPAIN

N₂O

Answer 4

C - ability to Comply
D - Decompression sickness
C - altered level of Consciousness
P - Pneumothorax
A - Air Emboli
I - Inhalation injury
N - Nitroglycrin use within 5 mins

Question 5

SADCF

N₂O

Answer 5

S - Shock
A - Abdominal distention
D - Depressant drugs
C - COPD
F - Facial injuries

Question 6

Warnings // Precautions

N₂O

Answer 6

• eliminated and unchanged from the body mostly by the lungs
• blood/gas partition co-efficient of nitrous oxide at 37 C is 0.46 compared with that of nitrogen of 0.015 causing nitrous oxide to expand into the internal gas spaces
• NOT be used in a confined space that cannot be adequately ventilated; when used inside an ambulance always operate the exhaust fan and or open windows to allow for the ventilation of expired gas
• NOT be used in aircraft due to the potential that expired gases may impact the pilots

Question 7

Pharmacodynamics (Oxygen)

N₂O

Answer 7

characteristics of oxygen (O₂) are:

- odourless, colourless gas
- molecular weight 32.00
- boiling point - 183.1 C (at 1bar(g))
- density 1.335kg/m3 (at 15 C)

Oxygen is present in the atmosphere at 21% and is an absolute necessity for life

At the concentrations in ENTONOX, oxygen has no discernible pharmaceutical effect other than the beficial effects of oxygen enriched mixture in certain cases

Question 8

Phmaracodynamics (Nitrous Oxide)

N₂O

Answer 8

Characteristics of nitrous oxide (N₂O) are:

- sweet smelling, colourless gas
- molecular weight 44.00
- boiling point - 88.6 C (at 1bar(g))
- density 1.875kg/m3 (at 15C)

• a potent analgesic and weak anaesthetic

Endorphins are probably involved in the analgesic effect; a concentration of 25% nitrous oxide is usually adequate to provide a marked reduction in pain

Question 9

Pharmacokinetics

N₂O

Answer 9

Inhaled
onset - rapid <1min (4/5 breaths)
peak - immediate
duration - requires continuous use

Question 10

ADVERSE EFFECTs

N₂O

Answer 10

• lightheadedness
• dizziness
• sedation
• drowsiness
• disorientation
• nausea // vomiting

Question 11

DRUG INTERACTIONs

N₂O

Answer 11

Depressant effects are potentiated by other CNS depressants
- ETOH
- sedatives
- antihistaminics
- psychotropic drugs

Question 12

Dosage - Adult

N₂O

Answer 12

EMR
self-administered to effect

Question 13

Dosage - Pediatric

N₂O

Answer 13

EMR
self-administered to effect

Question 14

Special Notes

N₂O

Answer 14

Ensure ENTONOX cylinders are maintained at a temperature above 10C to ensure the gases are mixed correctly. If this is not possible, D, CD, ED size cylinders may be used immediately if inverted 3 times before use to ensure mixing

• Always use a bacterial/viral filter between the patient and the Entonox demand valve regulator

Question 15

Brand Names

N₂O

Answer 15

Entonox
Nitraglin
Nitronox