Effect of Addition of Fentanyl and Clonidine to Local Anesthetic Solution in Peribulbar Block

Efficacy of adjuvants in ophthalmic regional anesthesia: A systematic review and network meta-analysis

PURPOSE

This network meta-analysis aims to determine the differences between adjuvants that are used in combination with local anesthetics for ophthalmic regional anesthesia.

DESIGN

Systematic review and network meta-analysis METHODS: A systematic literature search for randomized controlled trials, comparing the impact of adjuvants in ophthalmic regional anesthesia, in Embase, CENTRAL, MEDLINE and Web of Science was performed. Risk of bias was evaluated using the Cochrane risk of bias tool. Frequentist network meta-analysis was performed using a random effects model with saline as the comparator. Primary endpoints were the onset and the duration of sensory block and globe akinesia, as well as the duration of analgesia. Summary measure was the ratio of means (ROM). Secondary endpoints were the rates of side effects and adverse events.

RESULTS

39 trials were identified as eligible for network meta-analysis, including 3046 patients. 17 adjuvants were compared in the most extensive network (onset of globe akinesia). The addition of fentanyl (F), clonidine (C) or dexmedetomidine (D) showed the best overall results. Onset of sensory block: F 0.58 [CI 0.47-0.72], C 0.75 [0.63-0.88], D 0.71 [0.61-0.84], onset of globe akinesia: F 0.71 [0.61-0.82], C 0.70 [0.61-0.82], D 0.81 [0.71-0.92], duration of sensory block: F 1.20 [1.14-1.26], C 1.22 [1.18-1.27], D 1.44 [1.34-1.55], duration of globe akinesia: F 1.38 [1.22-1.57], C 1.45 [1.26-1.67], D 1.41 [1.24-1.59], duration analgesia: F 1.46 [1.33-1.60], C 1.78 [1.63-1.96], D 1.41 [1.28-1.56].

CONCLUSION

The addition of fentanyl, clonidine or dexmedetomidine showed beneficial effects regarding onset and duration of sensory block and globe akinesia.

Effect of adding clonidine to lidocaine on ocular hemodynamics during sub-Tenon's anesthesia: randomized double-blind study

INTRODUCTION AND OBJECTIVES

Different regional anesthesia techniques for ophthalmology can have hemodynamic effects on the eye. We assessed the effects of adding clonidine to lidocaine on Intraocular Pressure (IOP), Ocular Pulse Amplitude (OPA), and Ocular Perfusion Pressure (OPP) after the sub-Tenon's technique for cataract surgery.

METHODS

The study included 40 patients randomly allocated into two groups: sub-Tenon's blockade with Lidocaine plus Saline Solution (LS) or Lidocaine plus Clonidine (LC). IOP, OPA and OPP were measured before anesthesia, and 1, 5 and 10 minutes after the injection of anesthetic solution.

RESULTS

There was no difference between the groups in IOP, OPA, and OPP baseline values. After the injection of the anesthetic solution, the IOP increased in both groups at minute one, with a mean difference of +4.67 mmHg (p = 0.001) and +2.15 mmHg (p = 0.013) at 5 minutes. The increase was lower in the LC group when compared to LS (p = 0.027). OPA decreased in both groups, with a baseline difference, after 1 minute, of -0.85 mmHg (p =  -0.85 mmHg (p = 0.001), and at 5 and 10 minutes with differences of -1.17 (p = 0.001) and -0.89 mmHg (p = 0.001), respectively. The highest decrease was observed in group LC in relation to group LS (p = 0.03). There was no difference in OPP in relation to baseline measurements.

CONCLUSIONS

Adding clonidine to lidocaine for sub-Tenon's anesthesia reduced IOP and OPA without significant changes in OPP.

Dexamethasone Compared to Dexmedetomidine as an Adjuvant to Local Anesthetic Mixture in Peribulbar Block for Vitreoretinal Surgery. A Prospective Randomized Study

BACKGROUND

Dexamethasone or dexmedetomidine may improve the quality of peribulbar block.

AIM

The aim of this study is to compare the effects of adding either dexamethasone or dexmedetomidine to peribulbar block on the efficacy, intraocular pressure (IOP), time to first analgesic request, total analgesic requirement, and side effects in patients undergoing vitreoretinal surgery.

DESIGN

This was a clinical prospective randomized study.

PATIENTS AND METHODS

One hundred and fifty adult patients scheduled for vitreoretinal surgery with peribulbar block were randomized into three groups (50 patients each). Group I received 3.5 ml of 0.5% bupivacaine and 3.5 ml of 2% lidocaine + 1 ml normal Saline. 4 mg dexamethasone and 25 μg dexmedetomidine in 1 ml were added to the local anesthetic mixture in Groups II and III respectively. Onset and duration of sensory and motor blocks, adequate time to start surgery, IOP, time to first request of rescue analgesia, total analgesic consumption, and side effects were recorded. The statistical software SPSS 16 was utilized for statistical analysis.

RESULTS

Dexamethasone and dexmedetomidine groups showed significantly prolonged duration of corneal anesthesia (234.07 ± 1.37 and 233.54.1.97 min respectively), prolonged lid and globe akinesia (194.27 ± 1.63 and 194.73 ± 2.35 min respectively) with prolonged time to first request of analgesia and less consumption of rescue analgesia as compared to control group (P < 0.05) with non significant differences between both groups (P > 0.05). The onset of corneal anesthesia as well as lid and globe akinesia were enhanced in dexmedetomidine group compared to the other two groups (P < 0.05). In addition, the measurement of IOP was significantly less in the dexmedetomidine group after 10 min. All the patients were hemodynamically stable with no side effects observed.

CONCLUSION

The addition of dexamethasone and dexmedetomidine to local anesthetic mixture in peribulbar block for vitreoretinal surgeries provided safe and effective block with prolonged duration and decreased requirements of postoperative analgesia with better quality for dexmedetomidine group regarding the fast onset of the block and reduced IOP.