High pressure, diazepam and pH influences on ketamine anaesthesia in the rat

Ketamine infusion anaesthesia was studied in rats breathing oxygen/helium under hyperbaric conditions from 1 to 90 ATA. No pressure reversal of the analgesic effect was found. Premedication with diazepam failed to improve the analgesic action of ketamine, but influenced the respiratory pattern. Blood-gas analyses showed a marked relationship between arterial pH and the ketamine dose requirement for stable anaesthesia.