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Zorluk: Çok zorPharmacological and Parenteral Therapies

A nurse in the intensive care unit is caring for a client who weighs 187 lbs187\text{ lbs} and is receiving a continuous intravenous infusion of norepinephrine for septic shock. The medication is supplied as 4 mg4\text{ mg} of norepinephrine in 250 mL250\text{ mL} of 5%5\% dextrose in water (D5WD_5W). The infusion is currently running at 17 mL/hr17\text{ mL/hr}.

The client's current vital signs include a heart rate of 112 bpm112\text{ bpm} and a blood pressure of 82/46 mmHg82/46\text{ mmHg} (mean arterial pressure [MAP] 58 mmHg58\text{ mmHg}).

The provider's prescribed titration parameters state: "Titrate norepinephrine infusion by 0.02 mcg/kg/min0.02\text{ mcg/kg/min} every 5 minutes to maintain a MAP ≥65 mmHg\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 mL/hr\text{mL/hr}? (Record answer to the nearest tenth.)

Cevap: 23.4 mL/hr

Cevap

The new infusion pump rate should be set to 23.4 mL/hr.
The client's mean arterial pressure (MAP) is 58 mmHg58\text{ mmHg} ([82+2(46)]÷3[82 + 2(46)] \div 3), indicating the need to titrate the norepinephrine upward per the provider's parameters (MAP less than 65 mmHg65\text{ mmHg}). First, the weight is converted to 85 kg85\text{ kg} (187÷2.2187 \div 2.2). The ordered increase is 0.02 mcg/kg/min0.02\text{ mcg/kg/min}, which equals an additional 1.7 mcg/min1.7\text{ mcg/min} (0.02×850.02 \times 85) or 102 mcg/hr102\text{ mcg/hr} (1.7×601.7 \times 60). The concentration of the IV bag is 16 mcg/mL16\text{ mcg/mL} (4,000 mcg÷250 mL4,000\text{ mcg} \div 250\text{ mL}). The required increase in fluid volume is 6.375 mL/hr6.375\text{ mL/hr} (102÷16102 \div 16). Adding this to the baseline rate of 17 mL/hr17\text{ mL/hr} yields 23.375 mL/hr23.375\text{ mL/hr}. Rounding to the nearest tenth provides the final correct rate of 23.4 mL/hr23.4\text{ mL/hr}.

Adım Adım Çözüm

1
Assess the clinical situation to determine the necessary intervention.
The client's MAP is 58 mmHg58\text{ mmHg}, which is below the target of ≥65 mmHg\geq 65\text{ mmHg}. Therefore, a titration increase of 0.02 mcg/kg/min0.02\text{ mcg/kg/min} is required.
Vasopressor infusions must be titrated according to prescribed parameters based on objective hemodynamic data.
2
Convert the client's weight from pounds to kilograms.
187 lbs÷2.2 lbs/kg=85 kg187\text{ lbs} \div 2.2\text{ lbs/kg} = 85\text{ kg}.
Critical care medication dosing parameters are strictly weight-based in kilograms.
3
Calculate the concentration of the norepinephrine solution in mcg/mL\text{mcg/mL}.
4 mg=4,000 mcg4\text{ mg} = 4,000\text{ mcg}. Then, 4,000 mcg÷250 mL=16 mcg/mL4,000\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.
4
Calculate the required titration dose increase per minute based on the client's weight.
0.02 mcg/kg/min×85 kg=1.7 mcg/min0.02\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.
5
Convert the per-minute dose increase to an hourly rate.
1.7 mcg/min×60 min/hr=102 mcg/hr1.7\text{ mcg/min} \times 60\text{ min/hr} = 102\text{ mcg/hr}.
IV pumps are programmed in mL/hr\text{mL/hr}, so the medication dose must be converted to an hourly metric.
6
Determine the volume of fluid per hour required to deliver the dose increase.
102 mcg/hr÷16 mcg/mL=6.375 mL/hr102\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.
7
Calculate the new total infusion rate.
17 mL/hr+6.375 mL/hr=23.375 mL/hr17\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.
8
Round the final calculated rate to the requested decimal place.
23.37523.375 rounds to 23.4 mL/hr23.4\text{ mL/hr}.
Standard rounding rules apply; because the hundredths digit is 7, round the tenths digit up.

Anahtar Kavram

Weight-based vasopressor titration and complex hemodynamic dose calculations
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