Conditions: Myocardial Ischemia
Allocation: RANDOMIZED | Intervention model: PARALLEL
Enrollment: 60
Healthy volunteers: no

Brief summary:
We will compare three study groups receiving metoprolol, esmolol, or placebo. Level of anesthesia will be titrated to achieve the same range of BIS value in all groups. Our hypothesis is that the metoprolol and esmolol groups will require a lower level of anesthetic agent to achieve the targeted BIS range, compared to the placebo group.

Our objective is to clarify if metoprolol, in a dose range used for perioperative cardiac protection, decreases anesthetic requirement.

Detailed description:
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.

Arms:
arm 1: Patients were randomly assigned to Metoprolol Group. The drug was dispensed in 60ml \& 5ml syringes of 0.9% NaCl and 1mg/ml Metoprolol. Investigators and patients were blinded to the group assignment. arm 2: Patients were randomly assigned to Esmolol Group. The drug was dispensed in 60ml \& 5ml syringes of 0.9% NaCl and 10mg/ml Esmolol. Investigators and patients were blinded to the group assignment. arm 3: Patients were randomly assigned to this group. Patients received 0.9% NaCl only. To maintain the blind, 0.9% NaCl was also dispensed in 60ml \& 5ml syringes.

Interventions: intervention 1: Metoprolol intervention 2: Esmolol intervention 3: P-Group
Intervention descriptions: intervention 1: 60ml syringes of 0.9% NaCl, 5ml syringes of metoprolol at 1mg/ml concentration intervention 2: 60ml syringes of esmolol at 10 mg/ml concentration, 5ml syringes of 0.9% of NaCl intervention 3: 0.9%NaCl dispensed in 60ml \& 5ml syringes

Protocol document: