Figure 3: Changes in TC-CO2 and ETCO2 using a mouth-nose cannula during intravenous sedation The TC-CO2 increased after midazolam injection and tended to decrease after flumazenil injection. The ETCO2 using the nasal cannula tended to decrease after injection, and that uses the mouth-nose cannula intended to increase immediately after injection. The accuracy increased after midazolam injection and decreased after flumazenil injection. The mean accuracy ranged from 3 to 6 mmHg during sedation using the mouth-nose cannula (n=8).