A nurse in an emergency department is caring for an infant who has a 2-day history of vomiting and an elevated temperature. Which of the following should the nurse recognize as the most reliable indicator of fluid loss?

For a child with hemophilia experiencing a joint injury, the best home treatment and therapy would be elevation and the application of ice to the affected joint. This approach helps reduce swelling and minimize bleeding in the joint.
Option A (factor VIII concentrates) is a treatment for hemophilia but is typically administered intravenously to replace the deficient clotting factor in the blood. It is not a home treatment for joint injuries.
Option C (nonsteroidal anti-inflammatory drugs - NSAIDs) may be used to manage pain and inflammation, but they do not address the underlying bleeding disorder in hemophilia or directly treat joint injuries.
Option D (DDAVP - synthetic vasopressin) is used in some types of hemophilia to temporarily raise factor VIII levels, but it is not typically used for joint injuries or as a home treatment.

D. A client's blood pressure changes from 112/60 mm Hg to 90/54 mm Hg when standing.
A significant drop in blood pressure when changing positions from lying to standing may indicate orthostatic hypotension, which can be a sign of dehydration, blood loss, or other underlying medical issues. This can be a cause for concern, especially if the client is an adolescent, as it may lead to decreased perfusion of vital organs and may require immediate medical attention.

The other options are as follows:
A. A client who has a burn injury to an estimated 5% of his leg and is crying - While it's essential to assess and address the client's pain and comfort, this finding does not indicate an immediate need for medical attention. Pain management and wound care can be addressed based on the severity of the burn and the client's pain level.
B. A client who has an ankle fracture reports a pain level increase from 3 to 5 after initial ambulation - This finding is concerning, and the nurse should notify the provider to reassess pain management and evaluate for potential complications related to the fracture. However, it may not require immediate medical attention unless there are signs of severe pain or complications.
C. A client who is 1 day postoperative and has a temperature of 37.5° C (99.5° F) - A slight increase in temperature in the immediate postoperative period may not be unusual and can be attributed to the normal inflammatory response after surgery. The nurse should continue monitoring the client's temperature and report any further changes or additional signs of infection or complications to the provider.
Overall, while all findings should be addressed and managed appropriately, the significant drop in blood pressure (option D) should be reported immediately due to the potential implications for the client's overall health and well-being.