A nurse is preparing to measure an infant's vital signs. The nurse should use which of the following sites to assess a heart rate?

For a 6-month-old infant who has undergone the repair of an intussusception, the nurse should select an oral electrolyte solution. This solution is specifically designed to replace lost fluids and electrolytes due to vomiting or diarrhea, which is crucial in preventing dehydration in infants.

Options A, B, and C are not suitable choices for an infant in this situation:

A. Half-strength orange juice: Citrus juices, including orange juice, are not recommended for infants under 12 months old. They are acidic and may cause stomach upset or diarrhea.

B. Sterile water: Sterile water does not contain the necessary electrolytes, and offering plain water to an infant after surgery or during an illness can lead to electrolyte imbalances and further dehydration.

C. Half-strength infant formula: Diluting infant formula can lead to inadequate nutrition for the infant. The baby requires appropriate nutrition to support recovery after surgery, and diluting formula can be harmful.

D. An oral electrolyte solution is the best choice as it helps maintain proper hydration and electrolyte balance in the infant's body during the recovery period. If the infant tolerates the oral electrolyte solution well and is not at risk for aspiration, the healthcare provider may gradually advance the diet to include other clear liquids and then slowly reintroduce regular infant formula or breast milk as appropriate. The healthcare provider's instructions should be followed carefully to support the infant's recovery and ensure adequate nutrition.

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.