Managing general anesthesia for low invasive dental procedures while maintaining spontaneous respiration with low concentration remifentanil: a cross-sectional study

BACKGROUND: We assessed the relationship between patient age and remifentanil dosing rate in patients managed under general anesthesia with spontaneous breathing using low-dose remifentanil in sevoflurane. METHODS: The participants were patients with an American Society of Anesthesiologists Physical Status of 1 or 2 maintained under general anesthesia with low-dose remifentanil in 1.5-2.0% sevoflurane. The infusion rate of remifentanil was adjusted so that the spontaneous respiratory rate was half the rate prior to the induction of anesthesia, and γ(H) (µg/kg/min) was defined as the infusion rate of remifentanil under stable conditions where the respiratory rate was half the rate prior to the induction of anesthesia for ≥ 15 minutes. The relationship between γ(H) and patient age was analyzed statistically by Spearman's correlation analysis. RESULTS: During dental treatment under general anesthesia using low-dose remifentanil in sevoflurane, a significant correlation was detected between γ(H) and patient age. The regression line of y = −0.00079 x + 0.066 (y-axis; γ(H), x-axis; patient's age) was provided. The values of γ(H) provide 0.064 µg/kg/min at 2 years and 0.0186 µg/kg/min at 60 years. Therefore, as age increases, the dosing rate exhibits a declining trend. Furthermore, in the dosing rate of remifentanil when the patient's respiratory rate was reduced by half from the preanesthetic respiratory rate, the dosing rate provided was around 0.88 mL/h in all ages if the remifentanil was diluted as 0.1 mg/mL. EtCO(2) showed 51.0 ± 5.7 mmHg, and SpO(2) was controlled within the normal range by this method. In addition, all dental treatments were performed without major problems, such as awakening and body movement during general anesthesia, and the post-anesthetic recovery process was stable. CONCLUSION: General anesthesia with spontaneous breathing provides various advantages, and the present method is appropriate for minimally invasive procedures.