3History 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 anti-hyperalgesic effects
4Use 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®)
5Main indications in emergency In the relief of severe pain, usually in emergency situations, by inhalation with 50% oxygenIn short-term procedures which inevitably involve pain, such as wound and burn dressing, wound debridement and suturing, shoulder dislocation reduction. Administrated with 50% oxygenIn dental work to provide short-term analgesia for tooth extraction and other brief procedures, administered with 50% oxygen
6Special warningsIn 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.
8Other indications In pediatric patients At the dentist At the veterinarian
9Contra-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 consciousnessTraumatic or spontaneous pneumothoraxDecompression sicknessFollowing a recent underwater diveSevere bullous lung emphysemaGross abdominal distensionIntoxicationMaxillofacial injuriesRecent intraocular injection of gas (such as SF6).Note that Asthma (out of acute crisis) and pregnancy are not a contra-indication
10Side effects of N2OEvents 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.
13Description of the device Manometer for O2Manometer for N2OMixer O2 / N2O50% / 50%Auto administration systemOxygen cylinderNitrous Oxide cylinder
14Materiel needed The N2O/O2 trolley with mixer (50%) Different sizes of mask (child, young adult, adult, big adult)Saturometer + pulseOxygen (on wall) + nasal canula or facial mask
15Procedure (1) Explain the procedure to the patient Install the patient and monitor his pulse & SpO2Choose the good mask and start administration of N2O by pressing the buttonAsk the patient to breath normally and wait for 2 min.
16Procedure (2)Insure that the patient feels drowsy (but still awaked=talk)Start the procedureWhen procedure is finished, remove the mask N2O (turn off)Replace by pure O2 administration during 5 min. (mask or nasal canula)
17General precautionsNitrous 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 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 the valve uppermost. If not, liquid may be discharged when the valve is opened.
18Daily 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 sufficientDon’t forget to turn off the 2 cylinders after checking15 l/min.
19Monthly check up of O2 concentration Calibration in the air: 21% O2Once 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% O2The result is written on a dedicate form with date and signature.Measure at the way out 50% O2
21ConclusionNitrous Oxide is an efficient and easy way to manage pain during short procedureNitrous Oxide (mixed with 50% O2) is safe if you follow good practice (respect contra-indications, monitor SpO2)Nitrous Oxide should be proposed systematically for painful minor procedure particularly for children (but not only)