To evaluate the effects of alfentanil doses on cardiovascular and respiratory function, changes in mean arterial pressure (MAP), heart rate (HR), respiratory rate(RR) and PaCO2 induced by alfentanil (5 and 10 ㎍/㎏) after intravenous
administration
over
10 s were measured in 20 young adult male patients (ASA physical status 1) who were scheduled for lower extremity operations under spinal anesthesia. After fixation of spinal anesthesia level and stabilization of vital signs, control measurements
were
done. MAP and HR were measured at 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 15, 20, 25, 30, min and, RR and PaCO2 were measured at 5, 10, 15, 20, 30, min after alfentanll administration. While there were no significant changes in MAP or HR in either of the
two
groups after alfentanil administration, RR and PaCO2 showed significant changes and returned to control values by 10 and 20 min, respectively, with low doses of alfentanil and by 30 and 30 min, respectively, with high doses of alfentanil.
These results suggest that 5 or 10 ㎍/kg of alfentanil has no influence on cardiovascular function but, as the administered dose is increased, RR and minute ventilation decrease more profoundly and recovery is delayed.
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