Effect of Addition of Clonidine to Local Anaesthetic Mixture for Peribulbar Block

Abstract

Clonidine added to local anaesthetics prolongs the duration of anaesthesia and analgesia of peripheral, neuraxial and retrobulbar blocks. The present randomized blinded controlled study was conducted to evaluate the effect of the addition of clonidine to local anaesthetic mixture on the quality, onset time, duration of peribulbar block, perioperative analgesia and patients' comfort. The study comprised two groups of 12 patients each. Group A (control) patients received 7 ml of a mixture of 2% lignocaine and hyaluronidase with 1 ml normal saline, while group B (clonidine group) patients had clonidine 1 µg/kg added to the above mixture. Onset and duration of lid akinesia, globe anaesthesia and akinesia, time to first analgesic medication and total analgesic requirement were assessed. Patients were monitored for heart rate, blood pressure, sedation and respiratory depression. Addition of clonidine to local anaesthetic mixture resulted in a significant increase in duration of lid akinesia (85.4±25.6 vs 173.3±35.3 min, P<0.001), globe anaesthesia (63.2±6.9 vs 78.8±17.5 min, P=0.012) and globe akinesia (161.3±24.3 vs 201.2±45.7 min, P=0.016). The onset time and quality of block were similar in both the groups. No significant haemodynamic, respiratory or sedative effects were recorded. The perioperative pain scores and the analgesic requirements were significantly (P<0.01) lower in group B patients. We found that addition of clonidine 1 µg/kg to local anaesthetic mixture significantly increases the duration of anaesthesia and analgesia after peribulbar block.

Supplementation of retrobulbar block with clonidine in vitreoretinal surgery: effect on postoperative pain

“…At a dose of 100-150 μg, clonidine resulted in a reduction in intraoperative stress associated with surgery and a decrease in IOP [17]. There are few studies using clonidine in ophthalmic blocks, most of them combining clonidine with local anesthetics for peribulbar blocks in cataract surgery [12][13][14]. Cataract surgery is recognized as a procedure associated with minimal pain; phacoemulsification is even performed with topical anesthesia [18].…”

“…Studies that used clonidine in ophthalmic blocks have reported contradictory results [11][12][13][14]22]. In a dose-response study of 2% lidocaine peribulbar block for cataract surgery, Madan et al found a dose-dependent prolongation of anesthesia and analgesia [12].…”

“…The addition of clonidine, an alpha(2)-agonist, to local anesthetics prolongs analgesia and akinesia in retrobulbar and peribulbar blocks for cataract surgery [11][12][13][14]. Our hypothesis was that the addition of clonidine to the local anesthetic mixture of the retrobulbar block would prolong the time to first analgesic request following vitreoretinal surgery (primary outcome).…”

Adjuvants to local anaesthesia in ophthalmic surgery

“…A randomised trial of 24 cataract surgery patients by Bharti et al 54 of peribulbar clonidine 1 μg/kg adjuvant to 7 ml lignocaine and hyaluronidase mixture showed that clonidine improved pain scores, increased time to first analgesia and increased duration of akinesia (173 min in clonidine group versus 85.4 min in control group). No episodes of bradycardia or hypotension were experienced at this dose.…”

Regional anesthesia for eye surgery

“…At a dose of 1 g/kg, it does not increase the incidence of systemic adverse events such as hypotension or excessive sedation. 65 Moreover, it may help to prevent intraoperative arterial hypertension and lower intraocular pressure.…”