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MF Gouvea Barioni, GR Lauretti, AL Filho, NL Pereira, GR Goncalves; Peribulbar Anesthesia for Ofthalmic Surgery: The Effects Analgesic and Anesthetic of Clonidine added to Local Anesthetic and Oral Clonidine Premedication . Invest. Ophthalmol. Vis. Sci. 2002;43(13):398.
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Purpose: The purpose of this study was to determine whether the administration of peribulbar or oral clonidine would enhance analgesia and anesthesia in ophthalmic surgery. Methods: 60 patients were assigned to one of 4 groups, and premedicated with oral 2 ml volume (clonidine or placebo). The peribulbar eye block consisted of local anesthetics plus 1 ml of the test drug. The Control group (CG) received oral saline as premedication and peribulbar saline as the test drugs. The Clonidine eye group (Clo-eye G) received oral saline and peribulbar 30 mcg clonidine. The Clonidine oral group (Clo- oral G) received oral 150 mcg clonidine and peribulbar saline. The Clonidine eye+oral group (Clo eye+oral G) had oral 75 mcg clonidine and peribulbar 15 mcg clonidine. Perioperative assessment included anesthesia, analgesia, blood cortisol; and adverse effects Results:The groups were similar. The latency time to the onset of the peribulbar block was shorter in the Clo-eye G compared to the CG (p<0.05). The CG presented higher blood pressure levels throughout surgery, compared to the others (p<0.05). The time to first rescue analgesics was longer to all patients who received peribulbar clonidine compared to the CG (p<0.05). Analgesic consumption was lesser in the Clo-eye G compared to the CG (p<0.05). The blood cortisol level was higher during the intraoperative period in all groups (preoperative versus intraoperative values) (p<0.01). Conclusion:Nevertheless the higher intraoperative blood cortisol levels, 30 mcg peribulbar clonidine decreased the onset time to anesthesia, while 15 and 30 mcg peribulbar clonidine prolonged the time to first rescue analgesics in patients under peribulbar block, without increasing the incidence of adverse effects. Conversely, oral administration of clonidine alone did not enhance anesthesia or analgesia following eye block, suggesting a local mechanism of action of clonidine.
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