Adverse Events and External Factors Affecting Nitrous Oxide Dental Sedation in an Academic Center

Abstract

Sedation with nitrous oxide in oxygen (N₂O–O₂) is a prevalent technique in dental procedures, known for enhancing patient comfort and satisfaction. Despite its reputation for safety, the technique involves specific risks, underscoring the necessity for proper training and precautions. Although complications are rare, they can lead to significant issues, such as aspiration of gastric contents, potentially resulting in serious consequences. Proper management and adherence to preoperative fasting guidelines are crucial to minimize these risks. Currently, no global consensus exists regarding preoperative fasting protocols for dental sedation, making it essential to understand their impact on sedation outcomes. The primary aim of this study was to assess the incidence of perioperative nausea and vomiting in pediatric and young patients undergoing dental procedures with varying concentrations of N₂O–O₂ over an 8-year period at our academic institution. Secondary objectives included evaluating the success rate of the sedation technique, respiratory and other sedation-related complications, and factors influencing procedural success. This retrospective study received approval from the institutional ethics committee and focused on patients sedated with 50% N₂O–O₂ at the dental teaching clinic of Pontificia Universidad Católica de Chile (CODUC) from 2016 to 2023, with more than 41.000 procedures/year and 112 dental chairs. Patients or their guardians provided informed consent for treatment and data usage for research purposes. The study adhered to STROBE guidelines. The study population included patients aged 2–23 years with an American Society of Anesthesiology (ASA) physical status I or II, undergoing dental procedures under N₂O–O₂ sedation for less than 1 h. Sedation was primarily indicated for patients with limited cooperative capacity due to factors such as young age, autism spectrum disorder, Down syndrome, intellectual or motor disabilities, dental anxiety, or gag reflex issues. Exclusion criteria encompassed patients older than 23 years, those with contraindications to N₂O sedation, severe obstructive pulmonary disease, severe emotional disorders, recent tympanic drainage, or noncompliance with preoperative fasting. Preoperative instructions included fasting guidelines of 2 h for clear liquids and 4 h for solid foods, in line with Chilean standards [1]. Patients underwent various dental procedures including rehabilitation, pulp treatment, scaling, periodontal treatment, and simple surgeries such as extractions and frenectomies. All patients were accompanied by one or two individuals during the procedure. Sedation was administered with 100% oxygen for 1–2 min, followed by titration of N₂O–O₂ to a maximum of 50%, starting at 10% and increasing incrementally. The aim was to achieve adequate sedation while maintaining patient consciousness and responsiveness. A gas flow rate of 6–9 L/min was typical. Postprocedure, 100% oxygen was given for 5 min until the patient was fully awake and ready for discharge. Each procedure was recorded in a specialized clinical file, noting procedure type, vital signs, and any adverse events. Success was rated on a 5-point Likert scale, with “Very good” or “Good” considered successful. Adverse events included nausea, vomiting, oxygen desaturation below 90%, and seizures. From 2016 to 2023, 248 patients were treated, comprising 44% females and 56% males. They underwent 692 dental procedures with N₂O–O₂, with most patients having one procedure (35.9%) and others undergoing between 2 and 15 procedures. Procedure duration ranged from 10 to 85 min, with a median of 36 min. The overall success rate was 80.6% (95% CI: 77.4–83.9) based on complete records. The median age of patients was 7 years, with a range of 2–23 years. Successful procedures had a median patient age of 7 years, while unsuccessful procedures had a median age of 5 years. A total of 178 patients (71.8%) had a history of neurological disorders (44%), asthma, or allergies that did not contraindicate sedation. Fourteen patients with autism spectrum disorder, with a median age of 10.5 years (IQR 7–17 years), underwent 56 dental procedures. Of these, 78.5% (n = 11) were male, a trend previously described [2]. Four patients vomited (0.58% of all procedures), all of whom were male. No aspiration of gastric contents was reported. There were no cases of hypoxia or seizures. Statistical analysis revealed no significant difference in procedure success based on sex, whether sedation and the procedure were performed by the same individual, or the number of teeth treated. Younger patients (2–5 years) had lower success rates. Procedures for patients with autism spectrum disorder had a higher success rate compared to other patients (92.7% versus 79.3% respectively, Kruskal–Wallis χ2: 4.26, df: 1, n = 427, p = 0.039). Additionally, the presence of a mother as a companion was associated with a lower success rate (77.9%) compared to other companions (86%) (p = 0.045, odds ratio: 0.57 [95% CI 0.33–0.99]). The study confirms that N₂O-O₂ sedation for dental procedures is effective with a low rate of complications. N20 inspired concentration of 50% or less and the maintenance of consciousness and responsiveness, the loss of protective airway reflexes is an unlikely occurrence, and thus the risk of aspiration is considerably low. The overall success rate of 80.6% is slightly lower than some literature reports but remains within an acceptable range [2]. The lower success rates observed in younger patients, and when a mother accompanied, the patient warrant further investigation. Patients with autism spectrum disorder experienced better outcomes, likely due to their older age and less severe symptoms. The impact of companion type on procedural success, though intriguing, requires further exploration. This study's findings, while informative, are limited by its retrospective nature and lack of data on some influencing factors. Future prospective studies could provide more definitive insights and help refine preoperative guidelines and sedation practices. Institutional Review Board approval: 240314001 (May 9, 2024). The authors declare no conflicts of interest. The data and material that support the findings of this study are accessible upon reasonable request from the corresponding author.