The use of
fentanyl by an incremental intravenous (IV) bolus technique was evaluated in eight pediatric patients (ages 4 months to 5 years, ASA III-IV) undergoing corrective surgery for
congenital heart defects.
Anesthesia was induced with 5 to 10 micrograms/kg of
fentanyl. Additional boluses of comparable size were given intermittently thereafter, in order that a total dose of 100 micrograms/kg was achieved just before instituting
cardiopulmonary bypass (CPB). Heart rate, systolic blood pressure, various measures of
anesthetic depth, and plasma
fentanyl levels measured by radioimmunoassay were compared at various points during
anesthesia, surgery, and recovery. Decreases in heart rate were observed at the time of sternal incision and at 30 minutes thereafter, when doses of
fentanyl were near-maximal. No changes from baseline in systolic blood pressure or in
anesthetic depth occurred at any of the intervals studied. The plasma concentration of
fentanyl was 30 +/- 8 ng/mL just after completion of the
fentanyl administration, immediately before CPB. With onset of CPB, the
fentanyl level fell to 13 +/- 9 ng/mL, a statistically significant difference from the baseline value. No further change occurred over the additional 231 +/- 74 minutes in the operating room. The
fentanyl concentration was 10 +/- 4 ng/mL upon entry into the recovery room. It is concluded that administration of
fentanyl in small, intermittent IV boluses, with dosing completed before the onset of CPB, produces satisfactory plasma levels,
anesthesia, and hemodynamic stability in children undergoing corrective surgery for congenital cardiac defects.