Low-dose oral clonidine as premedication before intraocular surgery in retrobulbar anesthesia

PURPOSE. We investigated whether low-dosed oral clonidine premedication bef ore elective intraocular surgery in retrobulbar anesthesia is effective in terms of anxiolysis, sedation, stable hemodynamics, lower intraocular press ure and perioperative endocrine stress response. METHODS. In a prospective, randomised, double-blind study, 44 patients sche duled for elective intraocular surgery received either 0.15 mg clonidine (n =22) or a matched placebo (n=22) orally 60 minutes before retrobulbar anest hesia. The main study parameters were sedation, anxiolysis, hemodynamics an d intraocular pressure. Additionally, mediators of endocrine stress respons es were measured five times, in 13 patients after clonidine and 12 after pl acebo. RESULTS. After clonidine 86% of the patients showed sedation and after plac ebo 90.9% showed no sedation (p<0.01). Clonidine produced effective anxioly sis (Erlanger-Anxiety-Scale: 31.6 +/- 2.6 points vs. 38.1 +/- 8.5 points) b efore the operation (p<0.01). Systolic blood pressure was significantly low er after clonidine. Effects on mean and diastolic blood pressure were small but statistically significant. Norepinephrine and cortisole plasma concent rations were significantly lower after clonidine. Intraocular pressure was significantly lower too (p<0.05). No clinically relevant adverse effects we re observed e.g. inappropriate sedation, hypotension (<100 mmHg), bradycard ia (<50 bpm) or hypoxemia (SpO(2)<90%). CONCLUSIONS. Oral low-dose clonidine produces light sedation, significant a nxiolysis and stable hemodynamics, and attenuates the endocrine response to perioperative stress. Thus, clonidine seems sufficient to increase patient comfort for intraocular surgery and might even offer clinically worthwhile benefits such as stable hemodynamics and a reduced response to perioperati ve stress.