Induction of anesthesia with fentanyl or fentanyl plus etomidate in high-risk patients

Anesthetic doses of fentanyl (46 +/- 1.3 micrograms/kg) and oxygen (group I) were compared to a moderate dose of fentanyl (3 to 4.7 micrograms/kg; mean = 3.54 +/- 0.1 micrograms/kg) + etomidate (0.4 mg/kg) intravenously (IV) (group II) during the anesthetic induction-endotracheal intubation sequence to evaluate hemodynamic changes and the incidence of side effects in 23 New York Heart Association class III and IV patients. Chest wall rigidity only occurred in group I (27%), and pain on injection (8%) and myoclonus (25%) only in group II. Patients in group I experienced transient, small increases in central venous pressure (immediately after induction) and mean pulmonary artery pressure (after tracheal intubation). Patients in group II had small, transient decreases in heart rate, mean arterial blood pressure and cardiac index after induction which returned to baseline levels immediately after tracheal intubation. The data indicate that a modest dose of fentanyl with etomidate is similar to a large (anesthetic) dose of fentanyl in terms of avoiding cardiovascular depression and preventing hemodynamic stimulation during and following the induction-tracheal intubation sequence. Our findings also demonstrate that these doses of fentanyl before etomidate decrease but do not eliminate side effects of etomidate. The results suggest that a modest dose of fentanyl followed by etomidate may be an attractive alternative to high doses of fentanyl in patients with limited cardiovascular reserve, especially when prolonged postoperative respiratory depression secondary to high doses of an opioid is undesirable.