After confirming eligibility, written informed consent will be obtained by a trained team member who is not involved in assigning treatment or giving the study medication. Each participant will receive a unique study number to protect privacy. Participants will be randomly assigned to receive one of the study medications using a chance-based method.The study medication will be administered through a vein before placement of the breathing tube. Blood pressure and pulse rate will be measured before the procedure and at several time points after the breathing tube is inserted.