RESUMO
Inhalational anaesthetics inhibit somatosensory evoked potentials. The present study examined the effect of nitrous oxide in anaesthetic mixture with sevoflurane on the somatosensory evoked potential in children. Forty-five patients aged between 6 months and 6 years undergoing club foot surgery were studied to verify the influence of sevoflurane alone (21 patients) and sevoflurane with nitrous oxide (24 patients) on the somatosensory evoked potential. Fractional inspired concentration of nitrous oxide and fractional end-tidal (alveolar) sevoflurane were measured to estimate the multiples and submultiples of the minimal alveolar concentration (age corrected). The somatosensory evoked potential signals were obtained by stimulation of the median nerve. Nitrous oxide (FI = 0.63 +/- 2.5) with sevoflurane caused more reduction in the amplitude of somatosensory evoked potential waves and a greater increase in the latency of somatosensory evoked potential waves in comparison with sevoflurane alone. The results show that it is possible to obtain the inhibition of somatosensory evoked potential with smaller concentrations of sevoflurane, when it is used with nitrous oxide.
