Characteristics and Properties of Nitrous Oxide
The characteristics and properties of nitrous oxide are as follows:
It reduces or eliminates anxiety.
It cannot produce profound surgical anesthesia. It can be used as a substitute to local anesthesia in minor procedures (small restorations and a supplement to local anesthesia) but not in extensive procedures (extractions).
It reduces the gag reflex but not the cough reflex.
There is minimal or nonexistent toxicity when used on healthy patients for a reasonable length of time.
It is highly insoluble in blood and water (resulting in quick absorption and elimination by the patient).
Ninety-nine percent of its elimination from the body is through the lungs without significant biotransformation (has minimal effect on other organ systems).
It is not metabolized through the liver (little interaction with other drugs except for enhancing the effects of sedative and anti-anxiety drugs).
It is heavier than air with a specific gravity of 1.53. This property is helpful when introducing nitrous oxide/oxygen to an extremely anxious patient by placing the nasal hood a few inches above an anxious patient with the nitrous oxide to descending into the patient’s nose, enabling gradual desensitization to the experience.
Is gas at room temperature, but when compressed into a cylinder becomes a liquid.
Is non-flammable, however, it can support combustion. (If placed near an open flame, will burn brighter.)
At extreme altitudes (above 10,000 feet), there is a need for an increase in concentration (~5%) to obtain the same effect.
Nitrous oxide is a colorless and virtually odorless gas with a faint, sweet smell. It causes central nervous system (CNS) depression and euphoria with little effect on the respiratory system.
The analgesic effect appears to be initiated by neuronal release of endogenous opioid peptides with subsequent activation of opioid receptors and descending Gamma-aminobutyric acid type A (GABAA) receptors and noradrenergic pathways that modulate nociceptive processing at the spinal level. The anxiolytic effect involves activation of the GABAA receptor either directly or indirectly through the benzodiazepine binding site.
Nitrous oxide has rapid uptake, being absorbed quickly from the alveoli and in a simple solution in the serum.
It is relatively insoluble, passing down a gradient into other tissues and cells in the body, such as the CNS.
As nitrous oxide is 34 times more soluble than nitrogen in blood, diffusion hypoxia may occur and administering 100% oxygen to the patient for minimum of 5 minutes once the nitrous oxide has been terminated is important.
Nitrous oxide causes minor depression in cardiac output while peripheral resistance is slightly decreased, thereby maintaining blood pressure.
The objectives of nitrous oxide/oxygen inhalation include:
Reduce or eliminate anxiety.
Reduce untoward movement and reaction to dental treatment.
Enhance communication and patient cooperation.
Raise the patient’s pain reaction threshold.
Increase tolerance for longer appointments.
Aid in the treatment of the mentally/physically disabled or medically compromised patient.
Potentiate the effects of sedatives.3