2024 Volume 45 Issue 2 Pages 77-83
Nitrous oxide （N2O） inhalation sedation is widely used during dental treatments in patients with intellectual disabilities and developmental delay of the brain, in whom management of cerebral circulation is extremely important. While previous studies have reported that cerebral blood flow （CBF） increases with high-dose N2O administered via a circular breathing system, few studies have reported the effects of low-dose N2O inhalation sedation on cerebral circulation. Additionally, no previous study has investigated the effects of low-dose N2O inhalation sedation on intracranial pressure （ICP）. Here, we non-invasively estimated ICP during N2O inhalation sedation in normal healthy individuals.
The present study is a follow-up on our earlier research series on N2O inhalation sedation, and is based on reanalysis of the data obtained from the previous research. Eight healthy male volunteers received 30％ N2O via a nasal cannula, with tonometric measurement of arterial blood pressure （ABP） waveforms in the radial artery, and transcranial Doppler ultrasonography measurement of CBF velocity waveforms in the middle cerebral artery. ICP was calculated offline using these waveforms, by the signal calculator of the nICP-Plugin of the ICM＋® software for brain monitoring.
CBF velocity increased significantly during 30％ N2O inhalation, but ICP did not. Further, there was no significant change in either ABP or end-tidal carbon dioxide.
These results suggest that although CBF increases slightly during 30％ N2O inhalation sedation, ICP does not show a significant difference in healthy male volunteers.
