Mr. Haycock is a 20-year-old student who presented to ER with a 5 day history of diarrhea and vomiting which started at the end of his trip to the Caribbean. Past medical history is significant for epilepsy controlled with carbamazepine. Vital signs: HR – 100/min, RR – 15/min, BP – 80/50 mmHg, Saturation – 99% in room air. Physical examination revealed dry mucous membranes, prolonged capillary refill time of 4 seconds.