Both clonidine and metoprolol modify anesthetic depth indicators and reduce intraoperative propofol requirement

Beta-blockers have been used in the past to decrease the depth of anesthesia, but the results are conflicting. However, beta-blockers are known to suppress electroencephalographic activities. This study was carried out to assess the effect of metoprolol on anesthetic depth indicators. We also compared the effect of metoprolol in reducing propofol requirements.

Ninety healthy adult patients undergoing peripheral nerve injury repair were enrolled in three groups to receive either: a tablet containing clonidine 200 microg, a tablet containing metoprolol tartrate 100 mg, or a placebo; 1 h prior to surgery. Standard anesthesia technique was followed. The bispectral index was monitored to guide propofol infusion and was maintained between 40 and 60. The total duration of anesthesia and surgery, and the total propofol consumption, were noted.

Demographic variables were comparable in all three groups. Significantly less propofol was consumed by patients in the clonidine and metoprolol groups in comparison to that in the placebo group (P < 0.001). Heart rate and mean blood pressure values differed significantly in the placebo group in comparison to the values in the other two groups.

Our study showed that, like clonidine, metoprolol attenuated the hemodynamic response to intraoperative stimuli and also had a sparing effect on the propofol dose requirement.