Comparative Study of Retrobulbar Block versus Ketamine Infusion during Eye Enucleation/Evisceration (Randomized Controlled Trial)

Abstract

Background: The aim of this study is to compare the safety and efficacy of retrobulbar block versus intraoperative ketamine infusion in eye enucleation or evisceration under general anesthesia.

Materials and methods: Forty-five patients belonging to American Society of Anesthesiologists Physical Status I and II undergoing eye enucleation or evisceration were randomly allocated to three equal groups (15 patients each). General anesthesia was used as the standardized technique in all patients. Group R received a single retrobulbar injection, Group K received intravenous ketamine infusion, and Group C received normal saline with the same rate of ketamine infusion. Intraoperative heart rate and mean arterial pressure, recovery time, postoperative pain score, time to first rescue analgesic, number of patients who required rescue analgesia, and any adverse events were reported.

Results: Postoperative pain Visual Analog Scale was significantly lower in R and K groups in comparison to the C group and was significantly higher in K than R group at 3, 6, 12, and 24 h. In addition, the time to first rescue analgesic was significantly longer in R group (429 ± 54 min) than that in K group (272 ± 34 min), but compared to both groups, it was longer in C group (52 ± 7 min). In K group, the recovery time was longer with higher sedation score in comparison to the other two groups.

Conclusions: Single retrobulbar injection and low-dose ketamine infusion are safe and effective when used as adjuvants to general anesthesia, but retrobulbar block provides better control of postoperative pain with prolonged time to first rescue analgesic and reduced analgesic consumption.

Keywords: Evisceration; eye enucleation; ketamine; postoperative pain; rescue analgesia; retrobulbar block.

Figure 1

Consort diagram

Figure 2

The changes in mean blood pressure amongst the three groups. Group R = Retrobulbar, Group K = Ketamine, Group C = Saline, T0 = before Induction, T1 = Immediate after induction of retrobulbar and ketamine infusion, T2 = At incision, T3–T5 = At 15 min intervals

Figure 3

The changes in hear t rate amongst the three groups. Group R = Retrobulbar, Group K = Ketamine, Group C = Saline, T0 = Before Induction, T1 = Immediate after induction of retrobulbar and ketamine infusion, T2 = At incision, T3–T5 = At 15 min intervals