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Respiratory rate is an inadequate parameter of ventilation in non-intubated sedation

  • Keiko Morimoto
  • Shin Ogura
  • Kenichiro Shinohara
  • Katsuhisa Sunada
Original Article


We compared the respiratory rate (RR) and transcutaneous carbon dioxide pressure (\({\text{Pt}}{{\text{c}}_{{\text{C}}{{\text{O}}_{\text{2}}}}}\)) during intravenous sedation (IVS), to determine whether RR is a useful parameter for monitoring ventilation. This was a prospective cohort study. The study sample comprised dental patients who received IVS via propofol or midazolam administration at Nippon Dental University Hospital. We simultaneously measured RR (through capnography), \({\text{Pt}}{{\text{c}}_{{\text{C}}{{\text{O}}_{\text{2}}}}}\) (using the \({\text{Pt}}{{\text{c}}_{{\text{C}}{{\text{O}}_{\text{2}}}}}\) monitor), and percutaneous oxygen saturation (SpO2). RR was the predictor and the outcome variable was \({\text{Pt}}{{\text{c}}_{{\text{C}}{{\text{O}}_{\text{2}}}}}\). Data were analyzed by Dunnett’s test and Pearson’s correlation coefficient. P < 0.05 was considered statistically significant. The study sample consisted of 15 patients. No significant changes were identified in the RR and SpO2 measurements over time. However, \({\text{Pt}}{{\text{c}}_{{\text{C}}{{\text{O}}_{\text{2}}}}}\) values obtained from 20 to 40 min after induction of sedation were significantly higher than baseline values (P < 0.05). A correlation was found between RR and \({\text{Pt}}{{\text{c}}_{{\text{C}}{{\text{O}}_{\text{2}}}}}\) (P < 0.05), but the correlation coefficient was low (r = 0.22), indicating a weak correlation between these two factors. The results of this study suggest that RR is an inadequate parameter for monitoring ventilation during IVS; however, \({\text{Pt}}{{\text{c}}_{{\text{C}}{{\text{O}}_{\text{2}}}}}\) may be useful for monitoring.


Intravenous sedation Non-intubated sedation Respiratory rate Transcutaneous carbon dioxide pressure 



We thank the research staff at the Department of Dental Anesthesiology, The Nippon Dental University School of Life Dentistry, Tokyo, for their support. We would like to thank Editage ( for English language editing.


This study did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.

Compliance with ethical standards

Conflict of interest

The authors declare that they have no conflict of interest.


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Copyright information

© The Society of The Nippon Dental University 2018

Authors and Affiliations

  1. 1.Department of Dental AnesthesiologyThe Nippon Dental University School of Life Dentistry at TokyoTokyoJapan
  2. 2.Division of Oral ImplantNippon Dental University Hospital at TokyoTokyoJapan

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