Propofol Dosage

The most common imaging procedure requiring sedation/anesthesia for the pediatric population is magnetic resonance imaging (MRI). However, the optimal anesthetic/sedation plan has not been determined for these procedures. Historically, common medications have included the use of pentobarbital and propofol, but in 2015, publication in the New England Journal of Medicine highlighted the accumulating evidence for the possible neurotoxic effects of these types of anesthetics in animal models and a collection of epidemiologic studies in humans. Although these initial possibilities have since been proven as less of a concern, in the interim, data has shown that alternative sedative agents, such as dexmedetomidine, may not have the same neurotoxic effect and could possibly even provide neuroprotection. Dexmedetomidine also possesses other beneficial traits such as reducing risks of pulmonary atelectasis or upper airway collapse, typically found with the administration of propofol. A concern raised by previous studies has been the possibility that the addition of dexmedetomidine could increase recovery times, leading to disruptions in workflow. Although it has been shown that large doses of dexmedetomidine exposure may lead to longer PACU stays, it is uncertain whether a small dose of dexmedetomidine would have such a significant impact. Based on the investigators' pilot trial6, the investigators found that a bolus of 1 mcg/kg dose of dexmedetomidine with a bolus of titrated propofol of 2-3 mg/kg and an infusion of propofol of 100 mcg/kg/min provided adequate sedation for successful scans, reduced propofol (infusion) exposure by 60%, and did not significantly increase recovery times. Finally, there is a paucity in literature for studies examining a range of doses subsequently; often, a control group is compared to a single, self-selected dose of choice. Here, the investigators hope to provide a range of doses to minimize selection bias in our study design and determine the dose that would provide the optimal sedation for these scans and minimize excess anesthetic exposure.

The goal of this prospective, randomized, single-blinded is to learn if there is an ideal sedation protocol in cataract surgery in adults. The main questions it aims to answer are: * Does the combination of Dexmedetomidine and Propofol affect significantly Ramsay sedation scale, compared to Dexmedetomidine and compared to Propofol? * How does each sedation protocol affect hemodynamics? (Heart rate and blood pressure) * Are respiratory events more common in a certain group? * Is the surgeon's satisfaction similar among groups? * Are adverse effects (bradycardia, hypotension, nausea) more common in a certain group? Researchers will compare 3 sedation protocols : Dexmedetomidine versus Propofol versus the combination of these 2 drugs and to see if one protocol is overall superior to the others. Fentanyl will also be used in all 3 sedation protocols. Participants will : * Receive one of these three protocols * Be operated for one or both eyes * Monitored during the whole surgery and in the recovery room * Be evaluated by the Ramsay sedation scale by a trained Anesthesiologist or CRNA during surgery and in the recovery room Surgeons will be asked about how much they were satisfied.