A nurse in the intensive care unit is caring for a client who weighs 187\text{ lbs} and is… — NCLEX-RN

A nurse in the intensive care unit is caring for a client who weighs $187\text{ lbs}$ and is receiving a continuous intravenous infusion of norepinephrine for septic shock. The medication is supplied as $4\text{ mg}$ of norepinephrine in $250\text{ mL}$ of $5\%$ dextrose in water ( $D_5W$ ). The infusion is currently running at $17\text{ mL/hr}$ .

The client's current vital signs include a heart rate of $112\text{ bpm}$ and a blood pressure of $82/46\text{ mmHg}$ (mean arterial pressure [MAP] $58\text{ mmHg}$ ).

The provider's prescribed titration parameters state: "Titrate norepinephrine infusion by $0.02\text{ mcg/kg/min}$ every 5 minutes to maintain a MAP $\geq 65\text{ mmHg}$ ."

Based on the client's current MAP, the nurse performs one titration increase. What should the nurse set the new infusion pump rate to in $\text{mL/hr}$ ? (Record answer to the nearest tenth.)

Answer: 23.4 mL/hr

Answer

The new infusion pump rate should be set to 23.4 mL/hr.

The client's mean arterial pressure (MAP) is

58\text{ mmHg}

(

[82 + 2(46)] \div 3

), indicating the need to titrate the norepinephrine upward per the provider's parameters (MAP less than

65\text{ mmHg}

). First, the weight is converted to

85\text{ kg}

(

187 \div 2.2

). The ordered increase is

0.02\text{ mcg/kg/min}

, which equals an additional

1.7\text{ mcg/min}

(

0.02 \times 85

) or

102\text{ mcg/hr}

(

1.7 \times 60

). The concentration of the IV bag is

16\text{ mcg/mL}

(

4,000\text{ mcg} \div 250\text{ mL}

). The required increase in fluid volume is

6.375\text{ mL/hr}

(

102 \div 16

). Adding this to the baseline rate of

17\text{ mL/hr}

yields

23.375\text{ mL/hr}

. Rounding to the nearest tenth provides the final correct rate of

23.4\text{ mL/hr}

Step-by-Step Solution

Assess the clinical situation to determine the necessary intervention.

The client's MAP is

58\text{ mmHg}

, which is below the target of

\geq 65\text{ mmHg}

. Therefore, a titration increase of

0.02\text{ mcg/kg/min}

is required.

Vasopressor infusions must be titrated according to prescribed parameters based on objective hemodynamic data.

Convert the client's weight from pounds to kilograms.

187\text{ lbs} \div 2.2\text{ lbs/kg} = 85\text{ kg}

Critical care medication dosing parameters are strictly weight-based in kilograms.

Calculate the concentration of the norepinephrine solution in

\text{mcg/mL}

4\text{ mg} = 4,000\text{ mcg}

. Then,

4,000\text{ mcg} \div 250\text{ mL} = 16\text{ mcg/mL}

You must know the concentration of the fluid in micrograms to calculate the volume needed.

Calculate the required titration dose increase per minute based on the client's weight.

0.02\text{ mcg/kg/min} \times 85\text{ kg} = 1.7\text{ mcg/min}

This establishes the exact additional amount of medication the client needs every minute.

Convert the per-minute dose increase to an hourly rate.

1.7\text{ mcg/min} \times 60\text{ min/hr} = 102\text{ mcg/hr}

IV pumps are programmed in

\text{mL/hr}

, so the medication dose must be converted to an hourly metric.

Determine the volume of fluid per hour required to deliver the dose increase.

102\text{ mcg/hr} \div 16\text{ mcg/mL} = 6.375\text{ mL/hr}

Dividing the hourly dose by the concentration yields the physical volume increase.

Calculate the new total infusion rate.

17\text{ mL/hr} + 6.375\text{ mL/hr} = 23.375\text{ mL/hr}

The calculated delta must be added to the baseline continuous rate to achieve the new prescribed dose.

Round the final calculated rate to the requested decimal place.

23.375

rounds to

23.4\text{ mL/hr}

Standard rounding rules apply; because the hundredths digit is 7, round the tenths digit up.

Key Concept

Weight-based vasopressor titration and complex hemodynamic dose calculations

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