Preoperative intravenous clonidine in the surgical treatment of cataract: evaluation of the clinical benefits.
OBJECTIVE
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.
Serviço de Anestesia e Medicina Perioperatória do Hospital de Clínicas de Porto Alegre, Porto Alegre, RS. tocchett@gmail.com
Eduardo Tocchetto
ET
Lemes
Fábio
F
Van Der Fritz
Paulo Henrique Poti
PH
Homrich
Andressa Prestes
AP
Stolz
Julio César Mercador
JC
de Freitas
Elaine A Felix
EA
Fortis
D000368:Aged; D000959:Antihypertensive Agents / Q000008:administration & dosage* / Q000494:pharmacology; D002387:Cataract Extraction; D003000:Clonidine / Q000008:administration & dosage* / Q000494:pharmacology; D004311:Double-Blind Method; D005260:Female; D006801:Humans; D007275:Injections, Intravenous; D007429:Intraocular Pressure / Q000187:drug effects; D008297:Male; D008875:Middle Aged; D011300:Preoperative Care
D000959:Antihypertensive Agents; D003000:Clonidine