Sedation for out-patient dental procedures in a child with recent upper respiratory inflammatory problems: Usefulness of high-flow nasal cannula.

Upper respiratory inflammation (URI) is the most frequent illness in children, especially infants and preschoolers. Children usually present a concurrent or recent URI before surgery and anesthesia. It potentially increases risk of perioperative adverse respiratory events, such as desaturation, laryngospasm and apnea. These events may cause the delay in procedures or morbidity in pediatric patients for dental sedation. The use of sedatives may further cause hypoventilation and hypercapnia. The use of oxygen at all levels of sedation is indicated as a safeguard against such complications. However, the traditional oxygen delivery devices are constrained by low flow rate, less humidity, and low fraction of inspired oxygen (FiO2), which limits satisfactory oxygenation and also can not resolve the associated hypercapnia.

Here, we reported a case using the high-flow nasal cannula (HFNC) for airway management during intravenous sedation. A 5-year-old female (weight 15 kg, height 96 cm) was diagnosed with caries and pulpitis. She was timid and agitated and could not receive dental care under local anesthesia. After consultation with our anesthesia department, the child was scheduled for dental treatment (including resin filling, root canal treatment, placement of crowns for primary teeth, and placement of pit and fissure sealant) under intravenous sedation with midazolam and target control infusion (TCI) with propofol. It was postponed for five weeks, because she had URI symptoms. On the day of dental procedure, she was pre-medicated with midazolam 7 mg in 15 ml grape juice, 30 min prior to intravenous catheter insertion. Propofol was infused with TCI system, and set effect-site concentration (Ce) in the range of 1.6–2.0 μg/ml. The sedation level was targeted at observer's assessment of alertness/sedation level of four. We then applied HFNC (Optiflow™) with FiO2 1.0 and flow rate 10 L/min. We did not observe any airway obstruction nor desaturation during the treatment.

HFNC delivers warm and humidified gas up to a flow rate of 60 L/min, and is considered to have several physiological effects, such as decreased anatomical dead space, a mild distending pressure, and constant FiO2. Some studies also showed impact on carbon dioxide elimination with HFNC. This HFNC O2 delivery system improves functional residual capacity thereby reducing work of breath. It is rarely applied in dental sedation. For children with recent URI, they have higher risk of adverse respiratory events, and are more sensitive to hypoxia. The period of dental sedation may be long, thus, HFNC provides better oxygenation, comfort and safety. However, a consideration of HFNC in dentistry is spark, which may appear during the use of a high-speed drill; a high FiO2 forms in the oral cavity and in the presence of sparks can cause combustion. Therefore, while using high-speed drills, stopping the oxygen supply for a short period of time is suggested to prevent airway combustion. Nevertheless, HFNC can prolong apneic time than traditional nasal cannula. It can provide accurate FiO2 with a longer apneic oxygenation, and warm and humidified oxygen-enriched air for airway sensitive patients during dental procedure, particularly for children with recent URI (see Fig. 1).

Figure 1

Photos of nasal cannula and high-flow nasal cannula (HFNC, Optiflow TM). A. Nasal cannula can only provide oxygen at low flow rates ranging from 1 up to 6 L/min—delivering FiO2 of 24–44%. Rates above 5 L/min can result in dryness in the nose and nasopharynx, and possibly nose bleeds. B. Oxygen is heated and humidified through an active heated humidifier. Oxygen gas flow can up to 60 L/min, optimizes preoxygenation (C, D), it prolongs apnea time compared with nasal cannulas, and also enhances carbon dioxide (CO2) clearance.

Conflicts of interest

The authors have no conflicts of interest relevant to this article.