Clonidine is a preferential alpha-2 agonist drug that has been used for over 35 years to treat hypertension. Recently, it has also been used as a preoperative medication and as a sedative/anxiolytic drug. This randomized, double-blind, placebo-controlled crossover clinical trial characterized the effects of oral clonidine pretreatment on intravenous catheter placement in 13 patients. Parameters measured included the bispectral index (BIS), Observer's Assessment of Alertness/Sedation Scale (OAA/S), frontal temporal electromyogram (EMG), 30-Second Blink Count (Blink), Digit Symbol Substitution Test (DSST), State Anxiety Inventory (SAI), fingertip versus forearm skin temperatures, and multiple questionnaires. Oral clonidine significantly decreased SAI scores, OAA/S, EMG, and Blink, but did not cause statistically significant BIS or DSST reductions. Subjects preferred oral clonidine pretreatment prior to venipuncture compared to placebo. Questionnaires also indicated that clonidine provided minimal sedation, considerable anxiolysis, and some analgesia. Fingertip versus forearm skin temperature differentials were decreased. Reduced fingertip versus forearm temperature differentials suggest increased peripheral cutaneous blood flow prior to venous cannulation. Oral clonidine pretreatment not only helped control patient anxiety and pain but also provided cardiovascular stability.Key Words: Clonidine; Venous cannulation; BIS; SAI; DSST.I ntravenous (IV) catheters have become the accepted standard of care for general anesthesia and IV sedation. 1 Catheterization of peripheral veins can be made more comfortable using a variety of techniques, including local anesthesia infiltration, 2,3 nitrous oxide inhalation, 2,4,5 ethyl chloride topical, 4,6 eutectic mixture of local anesthetics (lidocaine-prilocaine) cream, 7,8 tetracaine patches, 9 and even midazolam nasal spray. 10 The goals of these methods are pain and anxiety reduction with minimal invasiveness and lack of significant complications. An additional benefit of some cannulation pretreatments is cutaneous vasodilation.Previous medical anesthesia/sedation studies have indicated that clonidine administration prior to surgery decreases pain 11,12 and anxiety 12 and also stabilizes blood pressure and heart rate by reduction of central sympathetic outflow. [13][14][15] Additional investigations have shown that clonidine pretreatment also increases skin temperature 16 and decreases the difference between fingertip and forearm temperatures. 17 These results suggest an increase in cutaneous blood flow. 18 The purpose of this randomized, double-blind, placebo-controlled crossover clinical trial was to characterize the sedative/anxiolytic effects and changes in skin temperatures of oral clonidine pretreatment prior to IV catheter placement. METHODSThe study protocol and informed consent form were approved by The Ohio State University Institutional Review Board. Inclusion criteria were (a) adults with American Society of Anesthesiologists ASA1 or ASA2 health status, (b) severe ...

Clonidine has recently been used as a pre-operative medication and sedative/anxiolytic drug. Its extended duration of action makes it suitable for longer procedures. In this randomized, crossover, placebo-controlled clinical trial, we characterized the effects of oral clonidine pre-treatment on intravenous diazepam/meperidine sedation using the bi-spectral index (BIS) in 13 participants. Clonidine significantly increased the numbers of BIS-depressed readings and percent memory loss during sedation, while reducing total diazepam and post-operative analgesic dosages by 44% and 55%, respectively. Systolic, diastolic, and mean arterial blood pressures, as well as pulse rates, were reduced. Respiratory rate, oxygen saturation, end-tidal CO(2), and recovery from sedation were unchanged. Participants, surgeons, and sedationists preferred clonidine over the placebo. Clonidine pre-treatment increased and prolonged sedation and amnesia and stabilized vital signs while significantly decreasing diazepam and post-operative analgesic usage. These results suggest that pre-operative clonidine administration could be a useful supplement to intravenous sedation for dental procedures of long duration.