Background: There is little systematic research on the efficacy and tolerability of the addition
of adjunctive analgesic agents in paravertebral analgesia. The addition of adjunctive analgesics,
such as fentanyl and clonidine, to local anesthetics has been shown to enhance the quality and
duration of sensory neural blockades, and decrease the dose of local anesthetic and supplemental
analgesia.
Objectives: Investigation of the safety and the analgesic efficacy of adding 1 μg/kg
dexmedetomidine to bupivacaine 0.25% in thoracic paravertebral blocks (PVB) in patients
undergoing modified radical mastectomy.
Study Design: A randomized, double-blind trial.
Setting: Academic medical center.
Methods: Sixty American Society of Anesthesiologists physical status –I – III patients were
randomly assigned to receive thoracicPVB with either 20 mL of bupivacaine 0.25% (Group B, n =
30), or 20 mL of bupivacaine 0.25% + 1 μg/kg dexmedetomidine (Group BD, n= 30). Assessment
parameters included hemodynamics, sedation score, pain severity, time of first analgesics request,
total analgesic consumption, and side effects in the first 48 hours.
Results: There was a significant reduction in pulse rate and diastolic blood pressure starting at 30
minutes in both groups, but more evidenced in group BD (P < 0.001). Intraoperative Systolic blood
pressure showed a significant reduction at 30 minutes in both groups (P < 0.001) then returned to
baseline level at 120 minutes in both groups. There was a significant increase in pulse rate starting
2 hours postoperative until 48 hours postoperatively in group B but only after 12 hours until 48
hours in group BD (P < 0.001). The time of the first rescue analgesic requirement was significantly
prolonged in the group BD (8.16 ± 42 hours) in comparison to group B (6.48 ± 5.24 hours) (P =
0.04). The mean total consumption of intravenous tramadol rescue analgesia in the postanesthesia
care unit in the firtst 48 hours postoperatively was significantly decreased in group BD (150.19 ±
76.98 mg) compared to group B (194.44 ± 63.91 mg) (P = 0.03). No significant serious adverse
effects were recorded during the study.
Limitations: This study is limited by its sample size.
Conclusion: The addition of dexmedetomidine 1 μg/kg to bupivacaine 0.25% in thoracic PVB
in patients undergoing modified radical mastectomy improves the quality and the duration of
analgesia and also provides an analgesic sparing effect with no serious side effects.