Dosage Calculation 3.0 Critical Care Medications Test
A nurse is preparing to administer epinephrine 10 mcg/min by continuous IV infusion. Available is epinephrine 1 mg in 250 mL dextrose 5% in water (DsW). The nurse should set the IV pump to deliver how many mL/hr? (Round the answer to the nearest whole number. Use a leading zero if it applies. Do not use a trailing zero.)
The Correct Answer and Explanation is:1
To solve this dosage calculation problem, we need to determine the mL/hr rate for delivering epinephrine 10 mcg/min when the available concentration is 1 mg in 250 mL D5W.
Step 1: Convert 1 mg to mcg
$$
1 \, \text{mg} = 1000 \, \text{mcg}
$$
So, the concentration is:
$$
1000 \, \text{mcg} \, \text{epinephrine} \, / \, 250 \, \text{mL} = 4 \, \text{mcg/mL}
$$
Step 2: Use the formula
To find the infusion rate in mL/hr, use the formula:
$$
\text{mL/hr} = \left( \frac{\text{Desired dose in mcg/min}}{\text{Concentration in mcg/mL}} \right) \times 60 \, \text{min/hr}
$$
Plug in the known values:
$$
\text{mL/hr} = \left( \frac{10 \, \text{mcg/min}}{4 \, \text{mcg/mL}} \right) \times 60
$$
$$
\text{mL/hr} = (2.5) \times 60 = 150 \, \text{mL/hr}
$$
Final Answer:
$$
\boxed{150} \, \text{mL/hr}
$$
Explanation (300+ words):
This dosage calculation is a common task in critical care nursing where medications such as epinephrine are given via continuous IV infusion. Epinephrine is a potent vasopressor used to manage cardiac arrest, anaphylaxis, or severe hypotension. The nurse must ensure the correct dose is administered, as even small deviations can cause significant effects on the patient’s cardiovascular status.
In this scenario, the ordered dose is 10 micrograms (mcg) per minute. However, IV pumps are set in mL per hour, so we must convert this dosage to match the delivery rate. First, the concentration of the epinephrine solution is calculated. Since 1 mg equals 1000 mcg, we determine the solution contains 1000 mcg in 250 mL, which simplifies to 4 mcg per mL.
Next, we determine how many milliliters per minute will provide the required 10 mcg/min:
$$
10 \, \text{mcg/min} \div 4 \, \text{mcg/mL} = 2.5 \, \text{mL/min}
$$
Then, convert this to mL/hr because infusion pumps are programmed in hours:
$$
2.5 \, \text{mL/min} \times 60 \, \text{min/hr} = 150 \, \text{mL/hr}
$$
This calculation ensures the accurate delivery of medication. Rounding is not necessary here since the result is already a whole number. Also, per medical standards, a leading zero is used when applicable (e.g., 0.5), and trailing zeros are avoided (e.g., not 150.0) to prevent dosage errors.
Precise calculations like this one are essential to patient safety and effective critical care nursing.