BACKGROUND: A rapid increase in desflurane concentration induces tachycardia and hypertension and increases plasma catecholamine concentration. No clinical study is available as to whether the desflurane-induced circulatory responses is blunted by the rate of increase in inhaled desflurane concentration although there were many studies about methods to blunt the circulatory responses. The current study examined to compare desflurane-induced circulatory responses by the rate of increase in inhaled desflurane concentration.

METHODS: Unpremedicated sixty ASA physical status 1 patients, aged 20-60 years, scheduled for elective surgery under general anesthesia were randomly allocated into one of two groups. The inspired concentration of desflurane via mask was increased to 12.0 vol% abruptly (group 1), or during 120 seconds (group 2). The target was to produce an end-tidal concentration of desflurane (ETdesf) of 10.0 vol% which was maintained until the end of the study by adjusting the vaporizer setting, when necessary. Heart rate (HR), mean arterial pressure (MAP), cardiac index (CI), systemic vascular resistance (SVR), ETdesf, end-tidal concentration of carbon dioxide, and peripheral oxygen saturation were measured at baseline and every 30 seconds for 5 minutes after inhalation of desflurane and for 2 minutes after intubation.

RESULTS: HR, blood pressure, and CI were significantly increased in two groups compared with baseline, but significant differences in maximum values were not observed between two groups. There were no significant differences between groups of the ETdesf at the maximal HR and MAP. Incidences of hypertension and tachycardia were lesser in slowly increased inhaled desflurane concentration (group 2) than abruptly increased group (group 1).

CONCLUSIONS: The present study demonstrates that increasing inhaled desflurane concentration slowly for mask ventilation is partially effective in attenuating desflurane-induced circulatory responses.