Preoperative intravenous clonidine in the surgical treatment of cataract: evaluation of the clinical benefits

Abstract

Background and objectives: Clonidine has been used in anesthesia for its sedative and analgesic properties, and to achieve greater hemodynamic stability with reduction in intra-ocular pressure. This study evaluated the clinical effects of intravenous clonidine (2.5 microg.kg(-1)) on the intra-ocular pressure (IOP), hemodynamic parameters, and post-anesthetic recovery in the surgical treatment of cataract.

Methods: This is a randomized, double-blind, placebo-controlled study that included patients undergoing cataract surgery under peribulbar block. After placement of monitoring devices, baseline (M0) values of IOP, mean arterial pressure (MAP), heart rate (HR), SpO2, and the degree of sedation (Ramsay) were determined. Afterwards, placebo (Group P) or clonidine (Group C) was administered intravenously. After 30 minutes, at Moment 1 (M1), measurements were repeated, and once again at the end of the surgery, at Moment 2 (M2).

Results: The change in IOP between M0 and M1 was different for both groups, 14.5% in Group C and 5.25% in Group P (p = 0.01), and the means remained reduced until M2. Mean arterial pressure in Group C showed a 17% reduction from M0 to M1 and increased 3.5% in Group P (p < 0.001) and in Group C it showed a recovery at M2 (p = 0.17). The heart rate decreased 6.4% in Group C and 1% in Group P (p = 0.1) from M0 to M1. There was a greater sedation in Group C when compared with Group P (p < 0.001) but there was no cases of respiratory depression. The relative risk of intraoperative hypertension was 0.657 (CI 95% 0.517 to 0.835) in Group C, p < 0.01. Differences in the incidence of tachycardia, hypoxemia, hypotension, and increased hospital staying were not observed between both groups.

Conclusions: Clonidine, under the conditions of the present study, showed to be a safe drug and decreased IOP and the intraoperative risk of hypertension without delaying hospital discharge.