If the new TPN solution is delayed, which solution should the nurse infuse until it arrives?

When total parenteral nutrition (TPN) is delayed, it is essential to maintain appropriate carbohydrate intake to prevent hypoglycemia and other metabolic complications. Dextrose 10% in water serves as an effective temporary measure because it provides a readily available source of glucose. This solution can help sustain blood sugar levels until the TPN solution, which contains not only glucose but also proteins and fats, arrives.

The other options do not provide sufficient carbohydrates or may have other effects on fluid and electrolyte balance. For instance, Lactated Ringer's solution is primarily an electrolyte solution and does not provide glucose, which is crucial when TPN is not immediately available. Similarly, 3% sodium chloride is a hypertonic saline solution that would pose risks of hypernatremia and fluid overload, and it lacks carbohydrates. Finally, 0.9% sodium chloride is used for fluid replacement but does not address the need for carbohydrates either, thus would not be suitable for this particular situation.

In summary, Dextrose 10% in water is the best choice for maintaining carbohydrate availability and preventing hypoglycemia while waiting for TPN.