A critically ill client weighing 154\text{ lbs} is prescribed a continuous intravenous (IV… — NCLEX-RN

A critically ill client weighing $154\text{ lbs}$ is prescribed a continuous intravenous (IV) infusion of milrinone at $0.55\text{ mcg/kg/min}$ for the management of severe heart failure. The pharmacy supplies a premixed IV bag containing $20\text{ mg}$ of milrinone in $100\text{ mL}$ of $5\%$ dextrose in water ( $D_5W$ ). The client's current heart rate is $118\text{ beats/min}$ and blood pressure is $96/58\text{ mmHg}$ . What should the nurse set the infusion pump rate to in $\text{mL/hr}$ ? Record your answer to the nearest tenth.

Answer: 11.6 mL/hr

Answer

11.6

To determine the correct IV pump rate, a multi-step calculation is required. First, convert the weight to kilograms:

154\text{ lbs} \div 2.2 = 70\text{ kg}

. Next, find the minute dose:

70\text{ kg} \times 0.55\text{ mcg/kg/min} = 38.5\text{ mcg/min}

. Convert this to an hourly dose:

38.5\text{ mcg/min} \times 60\text{ min/hr} = 2310\text{ mcg/hr}

. Then, determine the concentration of the IV bag:

20\text{ mg}

is equal to

20,000\text{ mcg}

. Calculate the concentration:

20,000\text{ mcg} \div 100\text{ mL} = 200\text{ mcg/mL}

. Finally, divide the required hourly dose by the concentration to find the volume:

2310\text{ mcg/hr} \div 200\text{ mcg/mL} = 11.55\text{ mL/hr}

. Rounding to the nearest tenth gives

11.6\text{ mL/hr}

Step-by-Step Solution

Convert the client's weight from pounds to kilograms.

154\text{ lbs} \div 2.2\text{ lbs/kg} = 70\text{ kg}

The medication is prescribed in

\text{mcg/kg/min}

, requiring the weight to be in kilograms.

Calculate the required dose in

\text{mcg/min}

70\text{ kg} \times 0.55\text{ mcg/kg/min} = 38.5\text{ mcg/min}

This determines the exact amount of medication the client should receive each minute based on their body weight.

Convert the per-minute dose to an hourly dose.

38.5\text{ mcg/min} \times 60\text{ min/hr} = 2310\text{ mcg/hr}

Infusion pumps are programmed in hours (

\text{mL/hr}

), so the hourly medication requirement must be calculated.

Determine the concentration of the supplied medication in

\text{mcg/mL}

20\text{ mg} = 20,000\text{ mcg}

. Then,

20,000\text{ mcg} \div 100\text{ mL} = 200\text{ mcg/mL}

The prescribed dose is in micrograms, but the supplied medication is in milligrams. Converting to a common unit allows for accurate volume calculation.

Calculate the infusion pump rate in

\text{mL/hr}

and round to the nearest tenth.

2310\text{ mcg/hr} \div 200\text{ mcg/mL} = 11.55\text{ mL/hr}

. Rounded to the nearest tenth:

11.6\text{ mL/hr}

Dividing the required hourly dose by the concentration yields the exact fluid volume required per hour.

Key Concept

Weight-based continuous intravenous infusion dosage calculation

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