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?

QD is an abbreviation for "quaque die" which means "every day" in Latin. However, QD is on the official "Do Not Use" list of the Joint Commission because it can be mistaken for QOD, which means "every other day" in Latin¹². This can lead to medication errors and patient harm. Therefore, the Joint Commission recommends writing "daily" instead of QD.

The other options are not on the official "Do Not Use" list of the Joint Commission. OS, PO, and OD are abbreviations for "oculus sinister" (left eye), "per os" (by mouth), and "oculus dexter" (right eye) respectively. They are commonly used in ophthalmology and pharmacy³. However, they should be used with caution and only when appropriate, as they can also be confused with other abbreviations or symbols.

To calculate the infusion rate, we need to convert the patient's weight from kilograms to milligrams.

Patient's weight: 65 kg

Dose required: 200 mcg/kg/min

First, let's calculate the total dose required for the patient per minute: Dose required = 200 mcg/kg/min * 65 kg

= 13,000 mcg/min

Next, we need to convert the dose from micrograms to milligrams:

13,000 mcg/min = 13 mg/min

Now, let's determine the infusion rate. We have 2,500 mg of esmolol in 250 mL of fluid. Therefore, the concentration of esmolol in the fluid is:

Concentration = 2,500 mg / 250 mL

= 10 mg/mL

To find the infusion rate, we divide the dose required by the concentration: Infusion rate = 13 mg/min / 10 mg/mL

= 1.3 mL/mi

Since the options are in mL/hr, we need to convert the rate from mL/min to mL/hr:

1.3 mL/min * 60 min/hr = 78 mL/hr

Therefore, the correct answer is:

a. 78 mL/hr