Effects of nitrous oxide sedation on resting electroencephalogram topography.
Brett L Foster, David T J Liley
Clinical neurophysiology : official journal of the International Federation of Clinical Neurophysiology February 1, 2013 DOI: 10.1016/j.clinph.2012.08.007 via PubMed
Summary
Nitrous oxide reduces resting total brain wave power, especially delta waves at frontal-vertex sites, in healthy men. After inhalation stops, frontal theta power increases above baseline. Unlike other anesthetics such as propofol and sevoflurane, nitrous oxide does not shift slow wave activity to the front of the brain, challenging a single mechanism for loss of consciousness based on EEG patterns.
Study at a glance
| Characteristics | Observational cohort Peer reviewed |
|---|---|
| Sample size | 16 |
| Population | Healthy male participants |
| Intervention | Nitrous oxide |
| Dose | 20% or 40% |
| Key finding | Nitrous oxide reduces frontal delta power, and during washout increases frontal theta power, distinct from the anteriorization seen with other anesthetics. |
Abstract
To quantify the effects of nitrous oxide (N(2)O) gas on electroencephalogram (EEG) topography in healthy male participants. Healthy male participants were administered 20% (n=8) or 40% (n=8) N(2)O while having high-density (modified 10-20) noise minimized EEG recordings. Nitrous oxide was found to produce clear reductions in resting total power, particularly at frontal-vertex sites. These reductions were found to principally reflect reductions in band-limited delta power. Following the termination of N(2)O inhalation, during N(2)O washout, selective increases in frontal theta power were observed that increased above baseline values. Nitrous oxide does not produce the classical anteriorization of slow wave activity typically seen during anesthetic induction. Instead N(2)O reduces frontal slow wave (delta) activity, which during gas washout produces a withdrawal response of enhanced frontal slow wave (theta) activity. Attempts to characterize a unitary mechanism of loss of consciousness during anesthesia on the basis of the topographic electroencephalographic changes is challenged by the distinct EEG effects that N(2)O has when compared to other well known anesthetic agents that include propofol and sevoflurane.