Changes in the pattern reversal visual evoked potential as a function of inspired nitrous oxide concentration.

Area of Science:

• Neuroscience
• Anesthesiology

Background:

• Nitrous oxide (N2O) is commonly used in anesthesia and analgesia.
• Its effects on visual processing and neurophysiological markers require further investigation.

Purpose of the Study:

• To investigate the impact of varying inspired N2O concentrations on visual evoked potentials (VEPs).
• To assess the dose-dependent effects of N2O on specific VEP wave components and their latencies.

Main Methods:

• VEPs to pattern displacement were recorded in 10 healthy subjects at 10%, 20%, 30%, and 40% inspired N2O concentrations.
• Control subjects (10) breathed air only.
• Expired CO2 levels were monitored.

Main Results:

• A significant decrease in the N65-P95 VEP wave amplitude was observed at 10%, 30%, and 40% N2O.
• The P95-N125 wave amplitude showed significant reductions at 30% and 40% N2O.
• No significant changes in VEP latency were detected.
• A significant reduction in N65-P95 amplitude was noted at 40% N2O in group comparisons.
• Early VEP component amplitudes showed persistent reduction post-exposure.

Conclusions:

• Inspired N2O concentrations, particularly higher doses, significantly attenuate VEP amplitudes.
• The N65-P95 component is more sensitive to N2O than the P95-N125 component.
• N2O may induce lasting neurophysiological changes in visual pathways.