Epidural ketamine for postoperative analgesia.

hypotension seen with spinal anesthesia.” I have difficulty in agreeing with this conclusion. There are two pharmacologically active drugs in the first group, namely tetracaine and epinephrine compared to only one drug in the second group, namely bupivacaine. If tetracaine caused hypotension and epinephrine counteracted this effect while bupivacaine did not affect the blood pressure, the results in the two groups would have been similar. Therefore, using this study design, it is wrong to conclude that the hypotensive effect of the two local anesthetics is the same. To reach such a conclusion, either epinephrine would have been omitted from the study, or four groups would have been compared: in groups 1 and 3, either tetracaine or bupivacaine alone would have been used, and in groups 2 and 4, epinephrine would have been added to the specific local anesthetic. It may be argued that the addition of epinephrine did not significantly alter the arterial blood pressure after spinal anesthesia (2 ) . However, the quotation of a different study, especially from a different institution, is not valid since the circumstances are different.