Final answer:
The best indicator that a toddler is responding well to fluid replacement for hypovolemia is an adequate urine output, in this case, 48 mL for the past 4 hours. A CVP of 2 mm Hg is typically low, and an apical heart rate of 130 bpm needs to be considered in context with other vital signs. Urinary specific gravity by itself is less indicative of fluid status.
Step-by-step explanation:
A nurse is caring for a toddler who is being treated for hypovolemia. The desired response to fluid replacement in this scenario would be an adequate urine output, which indicates that the kidneys are functioning properly and the body is starting to return to homeostatic balance. An example of such a response is a urine output of 48 mL for the past 4 hours (indicating a rate of approximately 1 mL/kg body weight/hour, considering the average toddler's weight), as this would demonstrate that the child's kidneys are producing urine at an expected rate following fluid replacement. A central venous pressure (CVP) of 2 mm Hg, on the other hand, is typically low and may indicate ongoing hypovolemia. An apical heart rate of 130 beats per minute (bpm) can be within the normal range for a toddler, but by itself, it is not as indicative of fluid status as urine output. A urinary specific gravity of 1.025 shows concentration, but in the absence of other values, does not clearly indicate adequate fluid repletion. Therefore, urine output of 48 mL for the past 4 hours is the best indicator among the options given that the fluid therapy is having the desired effect.