Effects of sevoflurane with or without nitrous oxide on cardiac contractility and sinoatrial node rate.

Cardiac effects of sevoflurane (SE) with or without nitrous oxide were examined in the canine blood-perfused papillary muscle and sinoatrial node preparations. Although SE depressed developed tension (DT), mean arterial pressure (MAP) and heart rate of the donor dog (DHR) dose dependently, sinoatrial rate (SAR) was not changed significantly. No significant changes in MAP, DHR and SAR were observed with the addition of nitrous oxide to SE. However, the addition of nitrous oxide to SE resulted in significant decrease of DT. These results suggest that SE depresses BP and cardiac contractility dose dependently, but dose not change heart rate. The combination of nitrous oxide and SE may produce less cardiovascular depressant effect at a given MAC level than SE given alone.