• Yuuya Kohzuka, Shiroh Isono, Sayaka Ohara, Kazune Kawabata, Anri Kitamura, Takashi Suzuki, Fernanda R Almeida, Yasunori Sato, and Takehiko Iijima.
• From the Department of Anesthesiology, Graduate School of Medicine, Chiba University, Chiba, Japan (Y.K., S.I.) the Department of Anesthesiology, Showa University Koto Toyosu Hospital, Tokyo, Japan (Y.K., T.S.) the Department of Perioperative Medicine, Division of Anesthesiology, Showa University School of Dentistry, Tokyo, Japan (Y.K., S.O., A.K., T.I.) the Department of Dental Anesthesiology and Orofacial Pain, Graduate School of Dentistry, Kyusyu Dental University, Fukuoka, Japan (K.K.) the Department of Oral Health Sciences, Faculty of Dentistry, University of British Columbia, Vancouver, Canada (F.R.A.) the Department of Preventive Medicine and Public Health, Keio University School of Medicine, Tokyo, Japan (Y.S.).
• Anesthesiology. 2019 Jun 1; 130 (6): 946-957.

What We Already Know About This TopicDental procedures under sedation can cause hypoxic events and even death. However, the mechanism of such hypoxic events is not well understood.What This Article Tells Us That Is NewApnea and hypopnea occur frequently during dental procedures under sedation. The majority of the events are not detectable with pulse oximetry. Insertion of a nasal tube with small diameter does not reduce the incidence of apnea/hypopnea.BackgroundIntravenous sedation is effective in patients undergoing dental procedures, but fatal hypoxemic events have been documented. It was hypothesized that abnormal breathing events occur frequently and are underdetected by pulse oximetry during sedation for dental procedures (primary hypothesis) and that insertion of a small-diameter nasopharyngeal tube reduces the frequency of the abnormal breathing events (secondary hypothesis).MethodsIn this nonblinded randomized control study, frequency of abnormal breathing episodes per hour (abnormal breathing index) of the patients under sedation for dental procedures was determined and used as a primary outcome to test the hypotheses. Abnormal breathing indexes were measured by a portable sleep monitor. Of the 46 participants, 43 were randomly allocated to the control group (n = 23, no nasopharyngeal tube) and the nasopharyngeal tube group (n = 20).ResultsIn the control group, nondesaturated abnormal breathing index was higher than the desaturated abnormal breathing index (35.2 [20.6, 48.0] vs. 7.2 [4.1, 18.5] h, difference: 25.1 [95% CI, 13.8 to 36.4], P < 0.001). The obstructive abnormal breathing index was greater than central abnormal breathing index (P < 0.001), and half of abnormal breathing indexes were followed by irregular breathing. Despite the obstructive nature of abnormal breathing, the nasopharyngeal tube did not significantly reduce the abnormal breathing index (48.0 [33.8, 64.4] h vs. 50.5 [36.4, 63.9] h, difference: -2.0 [95% CI, -15.2 to 11.2], P = 0.846), not supporting the secondary hypothesis.ConclusionsPatients under sedation for dental procedure frequently encounter obstructive apnea/hypopnea events. The majority of the obstructive apnea/hypopnea events were not detectable by pulse oximetry. The effectiveness of a small-diameter nasopharyngeal tube to mitigate the events is limited.

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