title: Low-dose oral clonidine as premedication before intraocular surgery in retrobulbar anesthesia.
abstract: OBJECTIVE
  We investigated whether low-dosed oral clonidine premedication before elective intraocular surgery in retrobulbar anesthesia is effective in terms of anxiolysis, sedation, stable hemodynamics, lower intraocular pressure and perioperative endocrine stress response.
  
  
  METHODS
  In a prospective, randomised, double-blind study, 44 patients scheduled for elective intraocular surgery received either 0.15 mg clonidine (n=22) or a matched placebo (n=22) orally 60 minutes before retrobulbar anesthesia. The main study parameters were sedation, anxiolysis, hemodynamics and intraocular pressure. Additionally, mediators of endocrine stress responses were measured five times, in 13 patients after clonidine and 12 after placebo.
  
  
  RESULTS
  After clonidine 86% of the patients showed sedation and after placebo 90.9% showed no sedation (p<0.01). Clonidine produced effective anxiolysis (Erlanger-Anxiety-Scale: 31.6 +/- 2.6 points vs. 38.1 +/- 8.5 points) before the operation (p<0.01). Systolic blood pressure was significantly lower after clonidine. Effects on mean and diastolic blood pressure were small but statistically significant. Norepinephrine and cortisol plasma concentrations were significantly lower after clonidine. Intraocular pressure was significantly lower too (p<0.05). No clinically relevant adverse effects were observed e.g. inappropriate sedation, hypotension (<100 mmHg), bradycardia (<50 bpm) or hypoxemia (SpO2<90%).
  
  
  CONCLUSIONS
  Oral low-dose clonidine produces light sedation, significant anxiolysis 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 perioperative stress.
authors.affiliation: Department of Ophthalmology, University of the Saarland, Homburg, Germany.
authors.forename: J
authors.initials: J
authors.lastname: Weindler
authors.forename: R T
authors.initials: RT
authors.lastname: Kiefer
authors.forename: A
authors.initials: A
authors.lastname: Rippa
authors.forename: K
authors.initials: K
authors.lastname: Wiech
authors.forename: K W
authors.initials: KW
authors.lastname: Ruprecht
mesh_terms: D000284:Administration, Oral; D000368:Aged; D000700:Analgesics / Q000008:administration & dosage*; D000772:Anesthesia, Local / Q000379:methods*; D000779:Anesthetics, Local / Q000008:administration & dosage; D002387:Cataract Extraction; D003000:Clonidine / Q000008:administration & dosage*; D016292:Procedural Sedation; D004311:Double-Blind Method; D005260:Female; D006439:Hemodynamics / Q000187:drug effects; D006801:Humans; D007429:Intraocular Pressure / Q000187:drug effects; D008297:Male; D009915:Orbit; D011292:Premedication; D011446:Prospective Studies; D013732:Test Anxiety Scale
chemical_list: D000700:Analgesics; D000779:Anesthetics, Local; D003000:Clonidine