Transcript Nitrous Oxide gas in A&E

Nitrous Oxide gas in A&E
Medical meeting 16 may 2012
Dr. David Tran
A&E department FVHospital
Tooth extraction in XVII century
History of Nitrous Oxide
• Azote protoxyde or Nitrous Oxide (N2O) was synthesized
on XVIIe century by Mayo, an English chemist, and purified
by Pristley in 1772.
• 1799, Davy describes the analgesic and dysphoric effects
(laughing gas).
• 1867: first use in France for anesthesia (interest of the
association with O2)
• 1990: beginning of the use of N2O in emergency
departments in France (MEOPA, KALINOX)
• XXI century: explanation of anti-NMDA and antihyperalgesic effects
Use of Nitrous Oxide in France
• Inhalation through a
simple mask with storage
balloon.
• Pre mix of N2O & O2
(50%-50%) in the same
bottle (Kalinox®, Meopa®)
Main indications in emergency
• In the relief of severe pain, usually in emergency
situations, by inhalation with 50% oxygen
• In short-term procedures which inevitably involve
pain, such as wound and burn dressing, wound
debridement and suturing, shoulder dislocation
reduction. Administrated with 50% oxygen
• In dental work to provide short-term analgesia for
tooth extraction and other brief procedures,
administered with 50% oxygen
Special warnings
• In patients taking other centrally acting medication, such
as morphine derivatives and/or benzodiazepines,
concomitant administration of nitrous oxide may result in
increased sedation, and consequently have effects on
respiration, circulation and protective reflexes. If nitrous
oxide is to be used in such patients, this should take
place under the supervision of appropriately trained
personnel.
• At the end of a nitrous oxide/oxygen anaesthesia,
withdrawal of the mask leads to an outpouring of nitrous
oxide from the lung and consequent dilution of oxygen in
incoming air. This results in "diffusion hypoxia" and is
counteracted by giving 100% oxygen for a few minutes
when the flow of nitrous oxide is stopped.
Several indications for N2O in A&E
Other indications
• In pediatric patients
• At the dentist
• At the veterinarian
Contra-indications
Nitrous oxide should not be used with any condition where
gas is entrapped within the body and where its expansion
might be dangerous, such as:
•
•
•
•
•
•
•
•
•
Head injuries with impairment of consciousness
Traumatic or spontaneous pneumothorax
Decompression sickness
Following a recent underwater dive
Severe bullous lung emphysema
Gross abdominal distension
Intoxication
Maxillofacial injuries
Recent intraocular injection of gas (such as SF6).
Note that Asthma (out of acute crisis) and pregnancy are not a contra-indication
Side effects of N2O
• Events such as euphoria, disorientation, sedation,
nausea, vomiting, dizziness are commonly described.
These events are generally minor and rapidly
reversible.
• Prolonged (several hours) or frequent use of nitrous
oxide, including heavy occupational exposure and
addiction, may result in megaloblastic anaemia.
How to use Nitrous Oxide
Nitrous Oxide protocole in A&E
Description of the device
Manometer
for N2O
Manometer
for O2
Mixer O2 / N2O
50% / 50%
Auto
administration
system
Nitrous Oxide
cylinder
Oxygen
cylinder
Materiel needed
• The N2O/O2 trolley with
mixer (50%)
• Different sizes of mask
(child, young adult, adult,
big adult)
• Saturometer + pulse
• Oxygen (on wall) + nasal
canula or facial mask
Procedure (1)
• Explain the procedure to the
patient
• Install the patient and
monitor his pulse & SpO2
• Choose the good mask and
start administration of N2O
by pressing the button
• Ask the patient to breath
normally and wait for 2 min.
Procedure (2)
• Insure that the patient feels
drowsy (but still awaked=talk)
• Start the procedure
• When procedure is finished,
remove the mask N2O (turn
off)
• Replace by pure O2
administration during 5 min.
(mask or nasal canula)
General precautions
• Nitrous oxide is non-flammable but strongly supports combustion and
should not be used near sources of fire.
• Smoking should be prohibited when using nitrous oxide.
• Under no circumstances should oils or grease be used to lubricate
any part of the nitrous oxide cylinder or the associated equipment
used to deliver the gas.
• Check that hands are clean and free from any oils or grease.
• Where alcohol gels are used to control microbiological crosscontamination, ensure that all alcohol has evaporated before
handling nitrous oxide cylinders or equipment.
• Nitrous oxide is stored in high pressure gas cylinders as a liquid
under pressure. Rapid opening of the valve can cause the discharged
gas to re-liquefy. This liquid can cause cold burns if in contact with
the skin. Cylinders should only be used in the vertical position with
the valve uppermost. If not, liquid may be discharged when the valve
is opened.
Daily check up of the device
• Turn on the 2 cylinders
(N2O & O2)
• Insure the pressure in O2
cylinder is enough.
• Insure that the flow of N2O
is 15l/min.
• Insure the pressure at the
way out of the 2 cylinders is
sufficient
• Don’t forget to turn off the 2
cylinders after checking
15 l/min.
Monthly check up of O2 concentration
• Once a month, O2
concentration at the
way out of the device
must be checked.
• Oxygen monitor
Oxiquant MC is used
to insure that mixed
gas result is 50% O2
• The result is written
on a dedicate form
with date and
signature.
Calibration in the
air: 21% O2
Measure at the
way out 50% O2
Consent form and Survey form
Conclusion
• Nitrous Oxide is an efficient and easy way
to manage pain during short procedure
• Nitrous Oxide (mixed with 50% O2) is safe
if you follow good practice (respect contraindications, monitor SpO2)
• Nitrous Oxide should be proposed
systematically for painful minor procedure
particularly for children (but not only)