Study Evaluating Safety and Efficacy of Dexmedetomidine (DEX) in Intubated and Mechanically Ventilated Pediatric Intensive Care Unit (PICU) Subjects

An estimated 175 subjects will be enrolled at approximately 40 investigative sites. Subjects will be divided into two treatment groups to receive either high dose or low dose Dexmedetomidine (DEX). The loading and maintenance doses in both groups will be stratified according to the presence or absence of cardiopulmonary bypass. The level of sedation will be assessed using the University of Michigan Sedation Scale (UMSS). Score 0 (awake/alert); Score 1 (sleepy/responds appropriately); Score 2 (somnolent/arouses to light stimuli); Score 3 (deep sleep/arouses to deeper); Score 4 (unarousable to stimuli). Based on these scores and clinical judgment, additional sedation with intravenous midazolam will be administered according to the label. The UMSS scores must be documented before the administration of every midazolam (MDZ) dose and within five minutes after each dose of MDZ. Fentanyl or morphine may be administered to treat pain. Subjects may be extubated after beginning of study drug but are not required to be as part of the study. The efficacy and safety parameters that will be monitored include sedation levels, heart rate, blood pressure and ventilation indicators. Once subjects have met site-specified respiratory criteria, they will undergo tracheal extubation. The dexmedetomidine infusion may be continued during and after extubation if further sedation is required post-extubation. The continuous infusion of dexmedetomidine must be administered for a minimum of 6 hours and a maximum of 24 hours. Sedation levels, heart rate, blood pressure, respiratory rate, ventilator settings, SpO2 and if available transcutaneous carbon dioxide (TcCO2) and/or arterial blood gases (ABG) will be monitored and recorded in the peri-extubation period.