# Conscious Inhalation Sedation with Nitrous Oxide and Oxygen in Children: A Retrospective Study
###### Abstract
Although the etiology of dental anxiety disorders is multifactorial, negative and traumatic dental experiences have been shown to be one of the most common causes [23; 24; 25; 26], making avoidance of negative experiences that may exacerbate a preexisting anxiety state essential for clinicians to ensure high levels of oral health in young patients. In 2018, the American Academy of Pediatric Dentistry (AAPD) recommended the use of nitrous oxide (N\({}_{2}\)O) and oxygen (O\({}_{2}\)) as a safe, appropriate, and prudent approach for treating uncooperative children, children with dental anxiety during dental procedures, prolonged dental procedures, or uncomfortable procedures where the patient is not allowed to move [27; 28]. The mechanism of action of nitrous oxide is characterized by a triple action: anesthetic, analgesic, and anxiolytic. The first, i.e., the anesthetic effect, is due to the non-competitive inhibition of NMDA in the central nervous system; the second, the analgesic effect, is due to the release of endogenous opioids that act on opioid receptors and achieve comparable results to morphine, while the third, i.e., the antianxiety effect, is due to the activation of GABA-A [29]. At concentrations less than 50%, N\({}_{2}\)O is recommended to reduce anxiety and provide analgesia while maintaining a normal patient response to the dentist's instructions and allowing rapid recovery of mobility without loss of protective reflexes [28], with success rates ranging from 73 to 97% [30]. The success rate of nitrous oxide decreases slightly in patients younger than 5 years (91.8%) [31], which is due to the mixed breathing typical of younger children, which prevents complete inhalation of the nitrous oxide administered. N\({}_{2}\)O, a colorless and virtually odorless gas with a faint, sweet odor, is a potent analgesic/anxiolytic that depresses the central nervous system and induces euphoria but has little effect on the respiratory system [27]. Because N\({}_{2}\)O has very low gas solubility in the blood, it rapidly reaches therapeutic levels in the blood, and conversely, blood levels decrease rapidly when N\({}_{2}\)O is discontinued. In addition, compared with general anesthesia, N\({}_{2}\)O has a low adverse event rate (0-0.3%) [32], rapid resolution of symptoms, lower cost [33], and is considered physiologically safe for the patient when administered with adequate O\({}_{2}\). The most common adverse effects, which are very transient, are nausea and vomiting, which are thought to be due to prolonged administration of nitrous oxide/oxygen, fluctuations in nitrous oxide levels, lack of titration, increased nitrous oxide concentrations, and a heavy meal prior to nitrous oxide administration [27]. Poor technique with high concentrations can also lead to an \"excitement phase\" in which the patient may feel uncomfortable, uncooperative, and delirious, which is similar to a transitional stage to general anesthesia. Several studies conducted have shown that conscious sedation with N2O elicits a positive behavioral response in children with dental anxiety [31; 34; 35; 36]. In a recent cross-sectional study of 171 children (6-11 years) with moderate to severe dental anxiety and who required pulp treatment on one of their deciduous molars, [PERSON] et al. (2022) showed that a mixture of N2O and O2 played an important role in reducing dental anxiety in the short term (\(p\leq 0.001\)) [34]. Although, as previously described, dental anxiety is strongly related to demographic and psychosocial factors, children's cooperative behavior during treatment with nitrous oxide is not influenced by these factors, except for an authoritative parenting style, which may promote cooperative behavior [36].