Obstetric Dosages
LEARNING OBJECTIVES
On completion of the materials in this chapter, you will be able to perform computations accurately by mastering the following mathematical concepts:
1 Calculating the intravenous (IV) rate of oxytocin (Pitocin) ordered in milliunit per minute
2 Calculating the IV rate of magnesium sulfate ordered in milligrams per minute
In obstetric nursing, oxytocin (Pitocin) and magnesium sulfate are commonly used. Oxytocin is used to either augment or induce labor. Magnesium sulfate is used to prevent seizures in mothers diagnosed with preeclampsia and is also used “off label” to control preterm labor contractions. Both these medications can be titrated, which means that the medication can be adjusted up and down based on patient status.
IV ADMINISTRATION OF MEDICATIONS BY MILLIUNITS/MINUTE
EXAMPLE 1: The physician has ordered 1000 mL 5% dextrose in water (D5W) with 10 units IV oxytocin. Begin at 1 mU/min and then increase by 1 mU/min every 30 minutes until regular contractions occur. Maximum dose is 20 mU/min.
What Is the IV Rate (mL/h) for the Beginning Infusion?
Using the D A × Q Method
Using the Ratio-Proportion Method
a. Convert total units in the IV bag to milliunits.
Therefore 0.1 mL/min of oxytocin is infusing.
What Is the Maximum IV Rate the Oxytocin Infusion May Be Set for?
Using the D A × Q Method
EXAMPLE 2: The physician has ordered 500 mL D5W with 10 units IV oxytocin. Begin at 1 mU/min and then increase by 1 mU/min every 30 minutes until active labor begins. Maximum dose is 28 mU/min.
What Is the IV Rate (mL/h) for the Beginning Infusion?
Using the D A × Q Method
Using the Ratio-Proportion Method
a. Convert total units in the IV bag to milliunits.