Dexmedetomidine is an effective adjuvant to subtenon block in phacoemulsification cataract surgery

The effects of subtenon and intravenous dexmedetomidine on patients undergoing cataract surgery: A comparative randomized controlled double-blind study

Background and Aims

This prospective randomized study designed to evaluate the efficacy of dexmedetomidine either added to LA mixture or administered IV during subtenon block for cataract surgery.

Material and Methods

75 patients, undergoing cataract surgery with subtenon anesthesia, were assigned randomly into three equal groups, Group I received subtenon bupivacaine 0.5% (1 ml) + lidocaine 2% (1 ml) + saline 0.9% (0.5 ml) and IV infusion of normal saline. Group II received subtenon bupivacaine 0.5% (1 ml) + lidocaine 2% (1 ml) + 0.5 μg/kg dexmedetomidine (0.5 ml) and IV infusion of normal saline. Group III received subtenon bupivacaine 0.5% (1 ml) + lidocaine 2% (1 ml) + saline 0.9% (0.5 μl) and IV infusion of 0.5 mg/kg dexmedetomidine over 10 min. before subtenon block. We recorded onset and duration of sensory and motor block, pain during subtenon injection, intraoperative hemodynamics, intraocular pressure, sedation and postoperative pain score.

Results

There was a significant decrease in the onset of action and an increase in the duration of sensory block in Group II. Pain during subtenon injection was significantly less in group III. Sedation Score was higher in Group III, while heart rate showed a significant reduction in the same group. The VAS was significantly decreased in group II. After the end of surgery, the intraocular pressure was significantly decreased in Groups II and III.

Conclusion

Subtenon dexmedetomidine shortens onset time, prolongs sensory block durations and significantly decreases the postoperative pain score with hemodynamic stability, while, IV dexmedetomidine substantially reduces pain during subtenon block and produces intra-operative sedation.

Practical Considerations for Dexmedetomidine Sedation in Adult Cataract Surgery Under Local/Regional Anesthesia: A Narrative Review

Cataract surgery is predominantly performed under local/regional anesthesia, with or without sedation. The practice pattern of sedation is unknown and seems to vary significantly among institutions and countries, routinely administered in some parts of the world to the other extreme of none at all. The selection of sedative agents and techniques varies widely. Currently, there is no ideal sedative agent. Dexmedetomidine has gained recent attention for sedation in ophthalmic local/regional anesthesia due to its alleged advantages of effective sedation with minimal respiratory depression, decreased intraocular pressure, and reduced pain during the local anesthetic injection; however, they are subject to differing interpretations. Published literature also suggests that although dexmedetomidine sedation for cataract surgery under local/regional anesthesia is potentially useful, its role may be limited due to logistical difficulties in administering the recommended dose.

Effect of dexmedetomidine on intraocular pressure as an additive in peribulbar block during glaucoma surgery

Purpose:

The purpose of this study is to assess the effect of dexmedetomidine on intraocular pressure (IOP) as an additive in peribulbar injections in glaucoma surgeries.

Methods:

A prospective, randomized, double-blind, parallel assignment interventional study was conducted for patients undergoing glaucoma surgeries at a tertiary eye care hospital in North India. Patients were randomized to two groups, Dexmed group and Placebo group. In the Dexmed group, dexmedetomidine (0.4 μg/kg body weight) was given as an additive along with peribulbar block. The primary outcome was change in IOP pre- and postperibulbar injections (IOP before the block, and after 5 and 15 min of the block). Secondary outcome measures were onset of block, adverse effects (bradycardia, hypotension, respiratory depression, and level 4 sedation), and surgeon satisfaction.

Results:

A total of 104 patients were randomized, 52 each in the Dexmed group and Placebo group. The percentage decrease in IOP was significantly more in the Dexmed group than in the Placebo group both at 5 and 15 min' post block (P < 0.05). At 5 min, the mean percent decrease in IOP in Dexmed group was -10.48, whereas it was 2.85 in the Placebo group. At 15 min, the mean percent decrease in IOP was -22.59 and -9.42 in the Dexmed and Placebo group, respectively. There was no significant difference between the two groups in the onset of block and adverse effects. Surgeon satisfaction was significantly greater in the Dexmed group than the Placebo group (P < 0.05).

Conclusion:

Dexmedetomidine lowers IOP significantly in patients undergoing glaucoma surgeries with safe hemodynamic changes and sedative effect.

Efficacy of Dexmedetomidine as a Sole Sedative Agent in Small Diagnostic and Therapeutic Procedures: A Systematic Review

Dexmedetomidine is an upcoming agent with sedative, anxiolytic, and analgesic properties. This review summarizes empirical evidence for the efficacy of dexmedetomidine as a sole sedative agent, and its effectiveness for small diagnostic and therapeutic procedure, in comparison with other frequently used sedatives. All randomized controlled trials on the effect of dexmedetomidine were reviewed. Pain level, patient satisfaction, operator satisfaction, procedure duration, recovery time, and hemodynamic and respiratory characteristics were examined. A total of 1993 patients (1,621 adults; 372 children) from 35 studies were included. In the adult studies, dexmedetomidine yielded significantly lower pain levels compared to the other sedatives (in 31.25% of the included studies) and significantly more patient satisfaction (68.2%). In studies on children, more favorable results concerning respiratory safety and the level of adequate sedation were found compared to the control sedatives. Implications for future studies are discussed.