Stress response in infants undergoing cardiac surgery: A randomized study of fentanyl bolus, fentanyl infusion, and fentanyl-midazolam infusion

There have been significant changes in the management of neonates and infan ts undergoing cardiac surgery in the past decade. We have evaluated in this prospective, randomized, double-blinded study the effect of large-dose fen tanyl anesthesia, with or without midazolam, on stress responses and outcom e. Forty-five patients < 6 mo of age received bolus fentanyl (Group 1), fen tanyl by continuous infusion (Group 2), or fentanyl-midazolam infusion (Gro up 3). Epinephrine, norepinephrine, cortisol, adrenocortical hormone, gluco se, and lactate were measured after the induction (T1), after sternotomy (T 2), 15 min after initiating cardiopulmonary bypass (T3), at the end of surg ery (T4), and after 24 h in the intensive care unit (T5). Plasma fentanyl c oncentrations were obtained at all time points except at T5. Within each gr oup epinephrine, norepinephrine, cortisol, glucose and lactate levels were significantly larger at T4 (P values < 0.01), but there were no differences among groups. Within groups, fentanyl levels were significantly larger in Groups 2 and 3 (P < 0.001) at T4, and among; groups, the fentanyl level was larger only at T2 in Group 1 compared with Groups 2 and 3 (P < 0.006). The re were no deaths or postoperative complications, and no significant differ ences in duration of mechanical ventilation or intensive care unit or hospi tal stay. Fentanyl dosing strategies, with or without midazolam, do not pre vent a hormonal or metabolic stress response in infants undergoing cardiac surgery.