A rapid response nurse is managing a client who experienced a severe extravasation of a co… — NCLEX-RN

A rapid response nurse is managing a client who experienced a severe extravasation of a continuous norepinephrine infusion from a peripheral intravenous catheter. Following the facility's extravasation management protocol, the primary health care provider prescribes phentolamine mesylate $0.15\text{ mg/kg}$ to be infiltrated subcutaneously around the ischemic site.

The client weighs $191.4\text{ lbs}$ .

The pharmacy dispenses phentolamine in lyophilized vials, which the nurse reconstitutes to yield a concentration of $5\text{ mg/mL}$ .

The protocol mandates that the exact calculated phentolamine dose must be further diluted with $0.9\%$ sodium chloride to achieve a final total syringe volume of $12\text{ mL}$ prior to administration.

How many milliliters ( $\text{mL}$ ) of $0.9\%$ sodium chloride must the nurse draw up to mix with the phentolamine? Record your answer to the nearest tenth.

Answer: 9.4 mL

Answer

The nurse must draw up 9.4 mL of 0.9% sodium chloride.

To determine the correct amount of diluent, the nurse must first convert the client's weight to kilograms (

191.4\text{ lbs} \div 2.2 = 87\text{ kg}

). Next, calculate the total medication dose (

87\text{ kg} \times 0.15\text{ mg/kg} = 13.05\text{ mg}

). Then, determine the volume of the medication using the available concentration (

13.05\text{ mg} \div 5\text{ mg/mL} = 2.61\text{ mL}

). Finally, subtract the medication volume from the required total syringe volume to find the amount of diluent needed (

12\text{ mL} - 2.61\text{ mL} = 9.39\text{ mL}

). Rounding

9.39\text{ mL}

to the nearest tenth yields

9.4\text{ mL}

Step-by-Step Solution

Convert the client's weight from pounds to kilograms.

87\text{ kg}

The prescribed dose is weight-based in mg/kg, so the weight must be converted.

191.4\text{ lbs} \div 2.2 = 87\text{ kg}

Calculate the total required dose in milligrams.

13.05\text{ mg}

Multiply the client's weight in kilograms by the prescribed dosage.

87\text{ kg} \times 0.15\text{ mg/kg} = 13.05\text{ mg}

Calculate the volume of the phentolamine medication.

2.61\text{ mL}

Divide the total required dose by the available concentration.

13.05\text{ mg} \div 5\text{ mg/mL} = 2.61\text{ mL}

Determine the volume of diluent required.

9.39\text{ mL}

Subtract the medication volume from the target final syringe volume to find the amount of diluent needed.

12\text{ mL} - 2.61\text{ mL} = 9.39\text{ mL}

Round the final volume to the nearest tenth.

9.4\text{ mL}

Standard rounding rules dictate that a hundredth value of 9 rounds the tenth value up.

9.39\text{ mL} \approx 9.4\text{ mL}

Key Concept

Calculating complex weight-based medication dosages and diluent volumes for parenteral administration.

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