Metoprolol infusion reduces fentanyl requirements during balanced general anesthesia for moderate amplitude surgery

C. Guran, Emilia Drăgulin, G. Stelea, Alida Moise, Natalia Mincu
Secţia Anestezie şi Terapie Intensivă, Spitalul MAI „Prof. Dr. D. Gerota”, Bucureşti

Abstract

Background and goal of study: Perioperative beta-blockade has been used both as a cardio-protective measure and as an adjuvant for decreasing anesthetic needs (reduces BIS, volatile and opioid demand). This study evaluates the influence of a per-operative infusion of the selective beta-blocker metoprolol on haemodynamic stability and opioid and sevoflurane requirements during balanced general anesthesia.

Methods: A prospective, randomized, double blinded trial was conducted, where 119 patients scheduled for moderate amplitude surgery received peri-operatively a continuous infusion of metoprolol 20 µg/kg/h (M group – 58 patients) or the same amount of normal saline (Control group – 61 patients). The infusion was started 10 minutes before induction and continued until 10 minutes after extubation.
General anesthesia was conducted in a similar fashion and postoperative analgesia prescriptions were similar. Intraoperatively, noninvasive haemodynamic data, MAC of sevoflurane and fentanyl, atropine, and ephedrine consumption were recorded, as well as the postoperative pain, pethidine consumption and the incidence of nausea, vomiting and respiratory depression.

Results: In comparison with the Control group, the M group received significantly lower doses of fentanyl (7.8 ± 1.9 vs 9.4 ± 2.1 µg/kg, p < 0.001), and the mean value of MAC of sevoflurane was significantly reduced (0.872 ± 0.163 vs 0.956 ± 0.273, p < 0.05). The metoprolol infusion was associated with a reduced heart rate on induction (p = 0.014) and lower systolic arterial pressure on extubation (p = 0.034). Atropine consumption was similar, but ephedrine consumption was higher in M group than in the Control group (3.1 ± 0.7 vs 2.7 ± 0.6 mg, p < 0.01). The intensity of postoperative pain, pethidine consumption and the postoperative side effects were similar in the two groups.

Conclusions: Peri-operative metoprolol infusion decreased the fentanyl and sevoflurane requirements during general anesthesia for moderate amplitude surgery, with a reduced effect on haemodynamic stability on the expense of increased ephedrine consumption.

Keywords: Metoprolol, continuous infusion, general anaesthesia, fentanyl, sevoflurane, haemodynamic stability

J Rom Anest Terap Int 2009; 16: 93-98

STUDII CLINICE

Perfuzia continuă de metoprolol reduce necesarul de fentanyl în timpul anesteziei generale pentru chirurgia de amploare medie