Revista de Cirurgia e Anestesia

Abstrato

Addition of Clonidine in Peribulbar Anesthesia for Vitreoretinal Surgeries: Randomized, Double-Blind Clinical Trial

Livia Maria Campos Teixeira, Catia Sousa Goveia, Marco Aurelio Soares Amorim, Denismar Borges de Miranda, Larissa Goveia Moreira, Luis Claudio Araujo Ladeira, Edno Magalhaes

Objective: The study evaluated the influence of clonidine on Intraocular Pressure (IOP), quality of the block and postoperative analgesia, as an adjunct to peribulbar block for vitreoretinal surgery.

Methods: Randomized, double-blind clinical trial, approved by the Research Ethics Committee, with 62 adults undergoing vitreoretinal surgery, under peribulbar block. They were randomly assigned to 2 groups: Control (0.875% ropivacaine) and Clonidine (0.875% ropivacaine+1 μg/kg clonidine). Ocular Anesthetic Scoring System, Ramsay sedation score, IOP and hemodynamic parameters were checked before, 5, 10 and 20 minutes after peribulbar block. Degree of akinesia (Nicoll Score) was tested 10 minutes after the block. Postoperative analgesia was assessed 30 minutes after surgery and 24 hours after block. Statistical analysis by Student’s t test or Mann-Whitney U test, according to the type of variable.

Results: Groups were similar regarding demographic variables, length of surgery, hemodynamic parameters, akinesia, sedation and analgesia 30 minutes after surgery. A lower IOP was observed in the Clonidine group compared to the Control at 5, 10 and 20 minutes. The reduction in IOP may be due to the vasoconstrictor effect of clonidine in the ciliary vessels, decreasing the production of aqueous humor. There was no arterial hypotension, which could contribute to this finding. With the addition of clonidine to the block, there was a lower frequency of pain complaints and less pain intensity, corroborating previous studies that found improvement in postoperative analgesia. There were no adverse effects.

Conclusion: Clonidine 1 μg/kg associated with 0.875% ropivacaine in peribulbar block for vitreoretinal surgeries reduces IOP, the frequency of pain complaints and pain intensity, without causing side effects.