Clinical evaluation of clonidine added to lidocaine solution for epidural anesthesia

The effects of clonidine added to lidocaine solution used for epidural anesthesia were assessed in 92 women scheduled for surgery and premedicated with diazepam 10 mg po. Patients received 18 ml 2% lidocaine with clonidine 5 micrograms.ml-1 (group C-5, n = 26), with clonidine 10 micrograms.ml-1 (group C-10, n = 20), with epinephrine 5 micrograms.ml-1 (group E, n = 26), or plain (group P, n = 20). No significant difference in the number of segments of analgesia was found at any observation period among the four groups of patients. The decreases in mean blood pressure (BP) observed 20 min after epidural injection in those given clonidine (5 +/- 8% for C-5, 10 +/- 11% for C-10, mean +/- SD) were similar to those given plain lidocaine (7 +/- 12%) but significantly less than those given epinephrine (18 +/- 12%, P less than 0.01 vs. C-5 or P). The response of BP to ephedrine given for restoring BP during anesthesia was not attenuated in patients who received epidural clonidine. Heart rate (HR) decreased significantly in patients given clonidine 10 micrograms.ml-1 (7 +/- 8%, P less than 0.01), but not in those given clonidine 5 micrograms.ml-1, whereas HR increased significantly in those given lidocaine plain or with epinephrine (10 +/- 8% and 28 +/- 14%, respectively, P less than 0.01). The incidence of sinus bradycardia was similar among the four groups of patients. Significant differences were also observed in sedation score between clonidine groups and groups P or E; sedation appeared approximately 10-20 min after epidural injection in both clonidine groups.(ABSTRACT TRUNCATED AT 250 WORDS)