Final answer:
A decrease in blood pressure (BP) to 140/80 should alert the nurse that the patient might be hemorrhaging.
Step-by-step explanation:
The vital sign change that should alert the nurse that the patient might be hemorrhaging is a decrease in blood pressure (BP) to 140/80. A decrease in BP can indicate blood loss and decreased perfusion to the body's organs. The other vital sign changes listed - an increase in heart rate (HR) to 88/min, an increase in respiratory rate (RR) to 20/min, and a slight increase in body temperature to 37°C/ 98.6°F - are all within normal ranges and may not necessarily indicate hemorrhaging.