A physician ordered magnesium sulfate 2 grams per hour for a maintenance dose. There are 40 grams of magnesium sulfate in 1 liter of lactated Ringers solution.
What is the rate per hour to administer the maintenance dose?

To answer this question, we need to understand the principles of pediatric dosage calculations and the factors that affect them. Pediatric dosages are usually calculated based on the child's weight or body surface area, and sometimes adjusted for age, organ function, or disease severity¹. However, not all medications that are used in adults are safe or effective in children. Some medications may have different pharmacokinetics, pharmacodynamics, adverse effects, or interactions in children than in adults².

Therefore, it is important to check the drug insert or label for any contraindications, warnings, or precautions for pediatric use before prescribing or administering a medication to a child. If the drug insert states that the medication is not for pediatric use, it means that the medication has not been tested or approved for use in children, or that it has been shown to be harmful or ineffective in children. In this case, a pediatric dose calculated from an adult dose should be avoided, as it may result in serious toxicity or therapeutic failure. The healthcare provider should consult a pediatric specialist, a pharmacist, or a reliable drug reference for alternative medications or dosing recommendations.

The other options are not correct because they do not necessarily warrant avoiding a pediatric dose calculated from an adult dose.

Option a. If the drug insert does not specify a pediatric dose, it means that there is insufficient data or evidence to support a specific pediatric dose, but it does not mean that the medication is contraindicated or unsafe in children. The healthcare provider should use clinical judgment and available resources to determine the appropriate dose for the child³.

Option b. If the child has an elevated temperature that has not responded to treatment, it means that the child may have an infection or inflammation that may affect the absorption, distribution, metabolism, or excretion of some medications. The healthcare provider should monitor the child's condition and adjust the dose accordingly, but it does not mean that the medication should be avoided altogether⁴.

Option c. If the child has gained or lost weight in the past month, it means that the child's weight may have changed significantly since the last dose calculation. The healthcare provider should weigh the child and recalculate the dose based on the current weight, but it does not mean that the medication should be avoided altogether.

To answer this question, we need to calculate the infusion rate in mL per hour, then multiply it by the total time in hours, and finally divide it by 1000 to get the volume in litres.

The infusion rate in mL per hour is the amount of fluid that is given to a patient over a period of time. It can be calculated by dividing the total volume of fluid in mL by the total time in hours². In this case, the infusion rate is:

2.75 mL/min × 60 min/h = 165 mL/h

The total volume of fluid in mL is the infusion rate multiplied by the total time in hours. In this case, the total volume is:

165 mL/h × 7 h = 1155 mL

The volume in litres is the volume in mL divided by 1000. In this case, the volume in litres is:

1155 mL / 1000 = 1.16 L

Therefore, the correct answer is d. 1.16 L.