hypothermia, thrombus, and tension pneumothorax were ruled out upon admission to the hospital emergency department. However, the cardiac arrest occurring in this case was most likely multifactorial. 1 – 4 Hypovolemia was a likely causative factor, as the patient had been NPO for more than 15 hours, excluding his morning medications taken with a small sip of water. Medication overdose was another potential cause, specifically propranolol and guanfacine, as the patient had a history of serotonin syndrome attributed to overmedication for behavioral problems by his caregiver