A 17-year-old boy comes to the emergency department because of severe thirst and weakness and a 4-kg (1.8-lb) weight loss over the past 36 hours. He began having voluminous painless watery diarrhea on the airplane while returning from a trip to Thailand 36 hours ago. He has not vomited. While supine, pulse is 110/min and blood pressure is 110/60 mm Hg. While standing, pulse is 170/min and blood pressure is 70/40 mm Hg. His abdomen is nontender and bowel sounds are increased. Which of the following treatments is most appropriate at this time?
C. Exploratory laparotomy
D. Potassium chloride
Correct answer : E. Rehydration
The boy is dehydrated as a result of the watery diarrhoea. This explains the tachycardia, low BP and postural hypotension. The first thing to be done is immediate re-hydration. This can be followed by specific antibiotic therapy.