# Conscious Inhalation Sedation with Nitrous Oxide and Oxygen in Children: A Retrospective Study
## 2 Materials and Methods  
A retrospective study was conducted from January 2019 to December 2020. The study was conducted at one clinical center in conformity with the Good Clinical Practice Guidelines and according to Declaration of Helsinki ethical principles for medical research involving human subjects, as revised in Fortaleza (2013). Informed consent was obtained by all parents. Children who needed conservative treatment of deciduous elements (carious lesions limited to enamel or superficial dentine which did not involve the pulp) for a maximum duration of 30 min and who had previously reported cases of dental anxiety during dental therapies or refused to perform them were included in the study. According to the AAPD guidelines, patients with chronic obstructive pulmonary diseases, ongoing infections of the upper respiratory tract, recent surgery or ongoing middle ear pathologies, disorders of the psychic sphere, treatments with bleomycin sulfate, methylene-tetrahydroofolate reductase deficiency, and vitamin B12 deficiency were excluded [27]. All patients were given the standard history/self-assessment questionnaire at the first visit according to the AAPD guidelines, and if there was any doubt about a possible exclusion condition, the pediatrician was consulted for information and clarifications. After parents received verbal and written explanations of the whole procedure and were informed about the benefits and the possible risks of the procedure and its alternatives, signed written consent to the dental treatment and authorization to process data were obtained for each child. At the end of the information interview, parents were asked not to give food in the 3 h before dental treatment. The operating protocol was followed in accordance with the approach protocols applied by [PERSON] et al. [35]. For each patient, two appointments were scheduled: first, cognitive visit, and second, session of pedodontics treatment. The parents accompanied the children and remained silent in the operating room during both the sessions. In the first session, the room, the dental unit, all the equipment, and the machinery were shown, telling the children that it was necessary to only breathe through the mask in the second session. All patients were examined, and the medical record was compiled, all the information was provided to the parents, and signatures were collected for the authorizations as per the law. At the second appointment, the patient, fasting for at least 3 h, underwent a conservative treatment on a deciduous element with the help of dispensing the N2O/O2 mixture through a disposable, scented nasal mask at a size suitable for the face. The protocol used for administering the combination of N2O and O2 complies with the requirements of the AAPD [27]. For the first 2 min, 100% O2 was supplied; then, N2O was titrated gradually by increasing 10% every 2 min up to 35%. After a 5 min induction period,pedodontics treatment began. The flow delivered was between 5 and 6 L per minute and was adjusted by monitoring the reservoir bag that had to pulsate cyclically with each breath without remaining hypo- or hyper-expanded. At the end of the treatment, 100% pure O\({}_{2}\) was delivered for 5 min. All patients were asked to breathe through their noses during treatment that lasted a maximum of 30 min while behavioral approach and guidance techniques were still applied. Composite fillings were performed on deciduous teeth with the help of a rubber dam. Although the percentage of nitrous oxide administered did not exceed 50%, which is the maximum concentration recommended by the AAPD to avoid harmful effects of nitrous oxide [28], the maximum dose did not exceed 35%, which has been proved the typical N\({}_{2}\)O dose to achieve ideal sedation in children [37]. To ensure high safety standards, patients were monitored every 10 min during the procedure using pulse oximetry, which allowed continuous control of heart rate and blood oxygen saturation.