​Nitrous oxide is a colorless, odorless to sweet-smelling inorganic gas that was first used in surgical and dental anesthesia in the mid-1800s. Today, the combination of inhaled nitrous oxide and oxygen, when used appropriately, can be a safe and effective means of managing pain and anxiety in dentistry.  Referred to as “conscious sedation,” “relative analgesia,” or “nitrous oxide-oxygen sedation,” inhaled nitrous oxide-oxygen is the most used gaseous anesthetic in the world and a 2007 survey by the ADA estimated that 70% of dental practices using any form of sedation employed nitrous oxide-oxygen sedation.

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Dental Best Practices for Nitrous Oxide-Oxygen Use

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Adopting appropriate work practices and following recommendations from the Council on Scientific Affairs (CSA) may help dental offices safely use nitrous oxide-oxygen.

Following are recommendations developed by the Council on Scientific Affairs:

• Every nitrous oxide delivery system should be equipped with a scavenging system. A flow meter (or equivalent measuring device) should be easy to see and well maintained to ensure accuracy. The system also should have a vacuum pump with the capacity for up to 45 liters of air per minute per workstation. The system also should come with masks in various sizes to ensure a proper fit for individual patients.

• Vent the vacuum and ventilation exhaust fumes outside (for example, through a vacuum system). Do not place exhaust system in the vicinity of the fresh-air intake vents. Ensure that the general ventilation provides good room-air mixing. Chronic occupational exposure—several hours a week—to unscavenged nitrous oxide has been associated with adverse health effects.3

• Test the pressure connections for leaks every time the nitrous system is first turned on and each time a gas cylinder is changed. High-pressure line connections should be tested for leaks at least quarterly. You can use a soap solution applied to the lines and connections to test for leaks. Alternatively, you can purchase a portable infrared spectrophotometer to test these connections.

• Before the initial use of the system for the day, inspect all of the system components—reservoir bag, tubings, masks, connectors—for wear, cracks, holes or tears. Replace any damaged pieces.

• Once all of the components have passed inspection, you can connect the mask to the tubing and turn on the vacuum pump. Ensure that the flow rate is correct—up to 45 liters per minute or according to the manufacturer’s recommendation.

• The mask should be properly fitted to each patient. Check that the reservoir bag does not over- or underinflate while the patient is breathing oxygen, before the nitrous is administered.

• Ask the patient to limit talking during administration of the nitrous and to try to breathe through his or her nose—avoid breathing through the mouth if possible.

• During administration, watch for changes in the tidal volume of the reservoir bag also keep an eye on the vacuum pump flow rate.

• After the procedure, deliver 100% oxygen to the patient for 5 minutes before removing the mask. This will purge the system of any residual nitrous oxide and will help the patient clear the drug.

• Periodically (semiannually is suggested), personnel—particularly those who work with the nitrous oxide delivery—can be assessed for exposure. This can be done by asking the staff members to wear personal dosimetry badges or by placing an infrared spectrophotometer in the room.

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