Inhalational conscious sedation with nitrous oxide enhances the cardiac parasympathetic component of heart rate variability
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Updated: Jun 28, 2026

Recording Brain Electromagnetic Activity During the Administration of the Gaseous Anesthetic Agents Xenon and Nitrous Oxide in Healthy Volunteers
Published on: January 13, 2018
Koki Okushima1, Atsushi Kohjitani, Yoko Asano
1Department of Dental Anesthesiology, Kagoshima University Medical and Dental Hospital, Kagoshima, Japan.
Objective:
We investigated the effects of conscious sedation by 30% nitrous oxide inhalation on the cardiac autonomic nervous system in the absence or presence of music listening.
Study Design:
The power spectral analysis of heart rate variability (HRV) and cardiovascular parameters were measured in 26 healthy volunteers, who were divided into the control and N(2)O groups.
Results:
Nitrous oxide inhalation attenuated the increase in relative low frequency (LF) power in the control group, but relative high frequency (HF) power remained constant compared to a decreased value in the control group. Nitrous oxide inhibited the increase in the LF/HF ratio. These autonomic balance shifts were observed without hemodynamic changes. Additional music during sedation did not alter HRV variables.
Conclusions:
Inhalational sedation with nitrous oxide shifted cardiac sympathetic-parasympathetic balance toward a parasympathetic dominance via the suppression of sympathetic activity. Music listening during sedation did not provide further relaxing effects.
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