Continuous infusions of alfentanil and propofol for coronary artery surgery.

OBJECTIVE

To study the anesthetic efficacy of two different background infusion rates for alfentanil in a total intravenous anesthesia (TIVA) technique using propofol. Therefore, the effects of these infusions on hemodynamic stability and on the suppression of hemodynamic and somatic responses to noxious stimuli were compared.

DESIGN

Prospective and randomized.

SETTING

The study was performed in a university hospital setting. Two patient groups were compared.

INTERVENTIONS

Anesthesia was induced in group 1 (n = 16) with alfentanil 50 micrograms/kg and in group 2 (n = 14) with alfentanil 75 micrograms/kg, infused in 4 min, as well as with an infusion of propofol at a rate of 10 mg/kg/h in both groups. After 4 min, the alfentanil infusion was reduced to 1 microgram/kg/min in group 1 and to 2 micrograms/kg/min in group 2. The propofol infusion was reduced following sternal spread to 3 mg/kg/h. Responses indicating inadequate anesthesia were treated with additional alfentanil bolus doses.

MEASUREMENTS AND MAIN RESULTS

Induction of anesthesia in group 1 was associated with significant decreases in systolic and diastolic (-13%) blood pressures, cardiac index (-16%) and left ventricular stroke work index (-31%). Hemodynamic changes were similar in group 2, except for the greater fall in systemic vascular resistance during maintenance of anesthesia. There was no difference in the incidence of breakthrough hypertension between the two groups (in 44% and 43% of the patients, respectively) and in the number of alfentanil bolus supplements. There were also no differences in the incidence of ischemia, myocardial infarction or duration of postoperative ventilation.

CONCLUSIONS

Because both infusions provided equally stable anesthesia, the lower infusion regimen for alfentanil is the more appropriate technique. Using this technique, the administration of additional alfentanil boluses just before stressful surgical episodes will further improve hemodynamic stability.