The investigators' clinical practice makes use of oral clonidine as a means of transitioning from intravenous dexmedetomidine following prolonged infusions (more than 3-5 days). Although this is common clinical practice, there is limited clinical data to demonstrate the efficacy of this technique and to provide clonidine dosing guidelines. The purpose of this study is to retrospectively review the investigators' experience with the use of oral clonidine to prevent withdrawal following the prolonged administration of dexmedetomidine.