RESUMO
Nitrous Oxide is used for relief of pain in children undergoing minor surgical procedures, however its effects on autonomic nervous system have not been studied. The objective of this study was to assess the cardiovascular autonomic activity induced by brief exposure of 50% nitrous oxide in children. Sixteen non- premedicated pre-pubertal children under going middle - ear surgery were studied. Our results show that brief exposure to 50% nitrous oxide in children results in: [a] Absence of effect on mean arterial pressure and systolic arterial pressure variability; [b] Attenuation of the low frequency component of heart rate variability with a shift of the sympathetic - parasympathetic cardiac balance towards a parasympathetic predominance; and [c] Absence of alteration of spontaneous baroreflex sensibility. We conclude, nitrous oxide has relatively few effects on cardiovascular sysem and has a depressent effect in children as opposed to that in adults