2018 Volume 39 Issue 4 Pages 395-401
Nitrous oxide inhalation sedation is widely used in dental practice as an effective means of mental sedation to reduce stress during dental treatment. Circulation dynamics are maintained and adjusted by baroreflex, but there is no information available regarding the sensitivity of baroreflex during N2O inhalation. Therefore, we evaluated whether sympathetic baroreflex sensitivity（Sympathetic BRS）is decreased by nitrous oxide inhalation sedation. Arm cuff and beat-to-beat BP（finger plethysmography）, HR, cardiac output（CO）, stroke volume（SV）, and MSNA（microneurography）were measured during inhalation of room air, 100％ oxygen, 30％ and 40％ nitrous oxide, and recovery（room air）for 20 min through a mask, respectively, in 10 young men［age 31±2（SD）yrs］. Sympathetic BRS was analyzed from the spontaneous changes in beat-by-beat diastolic BP and corresponding MSNA（burst incidence）during the last 5 minutes of each condition. Systolic and diastolic BP did not differ among the inhalation conditions. HR, CO, and MSNA（burst frequency and total MSNA）were also similar between all conditions. Sympathetic BRS remained unchanged by inhalation sedation with any nitrous oxide concentration（burst incidence）. These results suggest that baroreflex function is maintained during nitrous oxide inhalation sedation and nitrous oxide itself does not directly affect BP regulation.
