[The effects of hyperventilation upon spinal dorsal horn neuronal single-unit activities under nitrous oxide anesthesia].

BACKGROUND

The purpose of this study is to investigate the effects of hyperventilation upon spinal dorsal horn neuronal single-unit activities under nitrous oxide anesthesia.

METHODS

Eight decerebrated spinal cats with laminectomy were maintained with oxygen and pancuronium bromide. Following the control period of normocapnia, 50% nitrous oxide was administered for 30 minutes after a hypocapnia period of 20-25 mmHg for 20 minutes. The recoveries of activities followed with normocapnia and pure oxygen administration. The changes of spontaneous and evoked activities by the pinching were investigated every 5 minutes after control study.

RESULTS

Inhalation of 50% nitrous oxide suppressed the WDR neuronal activities and with hyperventilation the suppressions significantly increased.

CONCLUSIONS

These results were compatible with clinical reports on the effectiveness of hyperventilation as a maintenance method under N2O anesthesia.