A patient with septic shock, weighing 165\text{ lbs}, is receiving a continuous intravenou… — NCLEX-RN

A patient with septic shock, weighing $165\text{ lbs}$ , is receiving a continuous intravenous infusion of norepinephrine via a dedicated central venous catheter to minimize the risk of extravasation. The current infusion rate delivers $0.05\text{ mcg/kg/min}$ . The patient's mean arterial pressure (MAP) is currently $58\text{ mmHg}$ . The hemodynamic titration protocol prescribes increasing the dose by $0.02\text{ mcg/kg/min}$ every $5\text{ minutes}$ until the MAP is $\ge 65\text{ mmHg}$ . The medication is supplied as $4\text{ mg}$ of norepinephrine in $250\text{ mL}$ of 5% dextrose in water (D5W). The nurse prepares to initiate the first titration increment. What should the new infusion pump rate be set at in $\text{mL/hr}$ ? (Round to the nearest tenth)

Answer: 19.7 mL/hr

Answer

19.7

To find the correct infusion rate, the nurse must first convert the patient's weight to kilograms (

75\text{ kg}

) and determine the new dose rate (

0.07\text{ mcg/kg/min}

). By multiplying the dose by the weight and

60\text{ minutes}

, the total hourly requirement is found (

315\text{ mcg/hr}

). Dividing this by the medication concentration (

16\text{ mcg/mL}

) yields

19.6875\text{ mL/hr}

, correctly rounded to

19.7\text{ mL/hr}

Step-by-Step Solution

Convert the patient's weight from pounds to kilograms.

165 \div 2.2 = 75\text{ kg}

Weight-based critical care medication dosing requires metric units.

Calculate the new required dose according to the titration protocol.

0.05\text{ mcg/kg/min} + 0.02\text{ mcg/kg/min} = 0.07\text{ mcg/kg/min}

The MAP is subtherapeutic (

58\text{ mmHg}

), so the infusion must be increased by the specified increment.

Calculate the total required micrograms per hour.

0.07\text{ mcg/kg/min} \times 75\text{ kg} \times 60\text{ min/hr} = 315\text{ mcg/hr}

Infusion pumps are programmed in

\text{mL/hr}

, so the time unit must be converted from minutes to hours, and the weight factored in.

Determine the concentration of the supplied medication in

\text{mcg/mL}

4\text{ mg} = 4000\text{ mcg}

;

4000\text{ mcg} \div 250\text{ mL} = 16\text{ mcg/mL}

The prescribed dose is in micrograms, so the medication supply must be converted to matching units to find the volume.

Calculate the final infusion rate in

\text{mL/hr}

and round to the nearest tenth.

315\text{ mcg/hr} \div 16\text{ mcg/mL} = 19.6875\text{ mL/hr}

, which rounds to

19.7\text{ mL/hr}

Dividing the hourly dose by the concentration yields the volume per hour required for the pump setting.

Key Concept

Weight-Based Continuous IV Infusion Titration

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