How is nitrous oxide given?

How is laughing gas administered?


Nitrous oxide, or laughing gas, is the most common inhalation sedation used in dentistry. It is easy to administer given proper training. Nitrous oxide is effective, nonallergenic, and it does not restrict patient activity once they leave the dental office.

Most dental offices use a continuous-flow unit. The units contain these basic components: 1) compressed gas cylinders which contain the nitrous oxide and oxygen gases; 2) valves; 3)pressure gauges; 4) flowmeters; 5) a reservoir bag; 6) conduction tubing; 7) a scavenging system; and 8) a nasal hood. There are also some safety features designed to prevent the delivery of less than normal atmospheric levels of oxygen.

The rubberized nasal hood is first placed over the nose, and the patient is asked to breathe through their nose. Two conducting tubes bring the gas to the patient and a second set of tubes carry the exhaled gases away. These extra tubes, in addition to a double nosepiece, are known as a scavenging system. This system helps prevent the chairside personnel from breathing the nitrous oxide exhaled into the ambient air as the dental work is done.

The mechanism of action of nitrous oxide is unknown, but most forms of sensation are depressed (e.g. hearing, touch, and even some forms of pain). The nitrous oxide gas produces a mild depression of the central nervous system, primarily in the cerebral cortex. While a slight depression of the contraction of muscle surrounding the heart can occur at extremely high levels of nitrous oxide, these dosages are not used in dentistry; therefore, there is no clinically significant effect on the cardiovascular system. Nitrous oxide gas is non-irritating to the lungs and is safe for other systems in the body.

Nitrous oxide gas has a rapid onset, usually relaxation begins within three to five minutes of onset of administration. The recovery time is also as short. A patient should be placed on pure oxygen for three to five minutes prior to leaving the chair. If pure oxygen is not provided, the nitrous oxide will still clear fairly rapidly from the lungs, but the patient could experience some adverse effects, such as headache, nausea, and lethargy. Once the patient has recovered after breathing the pure oxygen, he or she may leave the office, drive a car, and resume normal daily activities.

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