• C Raymond Schaney, James Sanders, Phyllis Kuhn, Stephanie LaJohn, and Christopher Heard.
• Department of Orthopedic Surgery, Shriners Hospital for Children, Erie, PA, USA. rschaney@adelphia.net
• Spine. 2005 Mar 15;30(6):689-93.

Study DesignA repeat measures design.ObjectivesNitrous oxide significantly reduces cortical somatosensory-evoked potential amplitude in adults; however, its effect on children and adolescents is unknown. This study evaluates the effect of nitrous oxide combined with propofol on the amplitude of the cortical response in children and adolescents.Summary Of Background DataSomatosensory-evoked potential amplitude measurements are used to determine spinal cord function during spine surgery. A significant decrease in amplitude of the cortical response may indicate either a compromise of neural conduction in the spinothalamic tracts of the dorsal column medial lemniscus system or the effect of anesthesia, an innocuous event.MethodsTen consecutive participants were evaluated. The study group comprised 4 boys and 6 girls, ages 10 to 18 years, undergoing corrective spinal surgery at an orthopedic children's hospital in northwestern Pennsylvania. The tibial nerve was stimulated and responses recorded from the somatosensory cortex when anesthesia was administered with and without nitrous oxide. Results were compared using a paired t test (alpha = 0.05)ResultsA significant decrease of 42 +/- 17% (P < 0.05) occurred in the cortically recorded somatosensory-evoked potential amplitude from 1.63 +/- 0.59 uV without nitrous oxide to 0.92 +/- 0.47 uV with nitrous oxide. Responses were similar in right and left extremities.ConclusionsIn our study, nitrous oxide use during low-dose isoflurane anesthesia supplemented with titrated propofol infusion caused a significant reduction in cortically recorded somatosensory-evoked potentials that was comparable with the 50% decrease observed in adults.

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