A physician orders magnesium sulfate, 6 grams loading dose to be administered over 30 minutes. There are 40 grams of magnesium sulfate in the IV bag. What is the rate per hour to administer the loading dose?

This is the most commonly used method for calculating pediatric doses, especially for medications that are weight-based. The pediatric dose is typically calculated as a fraction or percentage of the adult dose based on the child's weight. For example, if the adult dose is 100mg and the child weighs 50kg, the child's dose may be calculated as 50mg (50% of the adult dose). Actual body weight takes into account the child's current weight, which can be an important factor in determining the appropriate dose.

Reasons why the other choices are not answers:

A. Body surface area is a method for calculating pediatric doses, but it is typically used for medications that are associated with toxicity or have a narrow therapeutic index.

C. Ideal body weight is an estimate of what a person's weight should be based on their height and gender, rather than their actual weight. It may be used in situations where a child is significantly overweight or underweight, but it is rarely used for pediatric dosing.

D. Actual body height is rarely used for pediatric dosing, as it does not take into account the child's weight or other important factors. It may be used in certain situations, such as when dosing growth hormone therapy.

To calculate the infusion rate in mL/hr, we need to divide the total volume to be infused by the time for infusion and convert the units appropriately.

First, we need to convert the time of infusion from hours to minutes, since most IV pumps use minutes as the time unit.

2 hours x 60 minutes/hour = 120 minutes Next, we can calculate the infusion rate:

500 mL ÷ 120 minutes = 4.17 mL/minute

To convert mL/minute to mL/hour, we multiply by 60:

4.17 mL/minute x 60 minutes/hour = 250 mL/hour

Therefore, the correct answer is B. 250 mL/hr. The nurse should set the IV pump to deliver the LR infusion at a rate of 250 mL/hr to infuse 500 mL over 2 hours.