• Our objective is to clarify if metoprolol, in a dose range used for perioperative cardiac protection, decreases anesthetic requirement. [ Time Frame: During the procedure ] [ Designated as safety issue: Yes ]
  

• Administration of esmolol, a short-acting beta-receptor antagonist, might reduce the actual anesthetic requirement. [ Time Frame: During the procedure ] [ Designated as safety issue: Yes ]
  

Beta-receptor antagonists are commonly used in the perioperative setting. These agents have been shown to decrease the incidence of perioperative myocardial ischemia and are recommended by a recent practice guideline in certain patient groups.1 Besides protection from ischemia, there are other situations where beta-receptor antagonists are used intraoperatively such as control of the sympathetic response to tracheal intubation and certain types of surgical stimuli.

There is new evidence suggesting that administration of esmolol, a short-acting beta-receptor antagonist, might reduce the actual anesthetic requirement. This was initially shown by studies in which esmolol decreased the amount of anesthetic required to prevent movement after skin incision.2;3 Subsequent studies used bispectral index (BIS) as an endpoint and demonstrated decreased BIS values in subjects receiving esmolol during general anesthesia. 4;5

This anesthetic-sparing effect observed with esmolol has not been prospectively studied with other beta-receptor antagonists. Since perioperative beta-blockade is commonly achieved using longer acting agents such as metoprolol or atenolol, it is clinically relevant to understand the effects of these medications on anesthetic requirement. We aim to conduct a prospective, randomized, controlled, double-blind study to compare the anesthetic-sparing effect of metoprolol and esmolol administered intraoperatively.