Nitrous Oxide gas in A&ENitrous Oxide gas in A&EMedical meeting 16 may 2012Medical meeting 16 may 2012

Dr. David Tran

A&E department FVHospital

Tooth extraction in XVII centuryTooth extraction in XVII century

History of Nitrous OxideHistory of Nitrous Oxide• Azote protoxyde or Nitrous Oxide (N2O) was synthesized

on XVIIeXVIIe century by Mayo, an English chemist, and purified

by Pristley in 1772.

• 17991799, Davy describes the analgesic and dysphoric effects

(laughing gas).

• 18671867: first use in France for anesthesia (interest of the

association with O2)

• 19901990: beginning of the use of N2O in emergency

departments in France (MEOPA, KALINOX)(MEOPA, KALINOX)

• XXIXXI century: explanation of anti-NMDA and anti-

hyperalgesic effects

Use of Nitrous Oxide in FranceUse 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 emergencyMain 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 warningsSpecial 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&ESeveral indications for N2O in A&E

Other indicationsOther indications

• In pediatric patients

• At the dentist

• At the veterinarian

Contra-indicationsContra-indicationsNitrous 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 pneumothoraxTraumatic or spontaneous pneumothorax• Decompression sickness• Following a recent underwater dive• Severe bullous lung emphysema• Gross abdominal distension• Intoxication• Maxillofacial injuriesMaxillofacial 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 N2OSide effects of N2O

• Events such as euphoria, disorientation, sedation, euphoria, disorientation, sedation,

nausea, vomiting, dizzinessnausea, vomiting, dizziness are commonly described.

These events are generally minor and rapidly minor and rapidly

reversible.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 OxideHow to use Nitrous Oxide

Nitrous Oxide protocole in ANitrous Oxide protocole in A&&EE

Description of the deviceDescription of the device

Nitrous Oxide cylinder

Oxygen cylinder

Manometer for N2O

Manometer for O2 Mixer O2 / N2O

50% / 50%

Auto administration

system

Materiel neededMateriel 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)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)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 precautionsGeneral precautions• Nitrous oxide is non-flammable but strongly supports combustion and

should not be used near sources of fireshould 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 cross-contamination, 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 Cylinders should only be used in the vertical position with the valve uppermostthe valve uppermost. If not, liquid may be discharged when the valve is opened.

Daily check up of the deviceDaily 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 concentrationMonthly 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.

Measure at the way out 50% O2

Calibration in the air: 21% O2

Consent form and Survey formConsent form and Survey form

ConclusionConclusion

• Nitrous Oxide is an efficient and easyefficient and easy way to manage pain during short procedure

• Nitrous Oxide (mixed with 50% O2) is safe safe if you follow good practice (respect contra-indications, monitor SpO2)

• Nitrous Oxide should be proposed proposed systematically for painful minor proceduresystematically for painful minor procedure particularly for children (but not only)