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Zorluk: OrtaPharmacological and Parenteral Therapies

An intensive care nurse is managing a male patient diagnosed with cardiogenic shock. The patient's body weight is recorded as 198 lb198 \text{ lb}. The medical team orders an intravenous infusion of dopamine at a rate of 5 mcg/kg/min5 \text{ mcg/kg/min} to support cardiac output. The available medication from the pharmacy is a premixed bag containing 400 mg400 \text{ mg} of dopamine dissolved in 250 mL250 \text{ mL} of 5%5\% dextrose in water (D5W).

Determine the appropriate infusion pump setting in mL/hr\text{mL/hr} to deliver the prescribed dose. Round the final answer to the nearest tenth.

Cevap: 16.9 mL/hr

Cevap

16.9
To safely program the infusion pump, the nurse must systematically convert the patient's weight to kilograms, find the total dose required per minute, convert that value to milligrams per hour, and finally divide it by the concentration of the dopamine bag (mg/mL). This mathematically yields the exact fluid volume required per hour.

Adım Adım Çözüm

1
Convert the patient's weight from pounds to kilograms.
198 lb÷2.2 lb/kg=90 kg198 \text{ lb} \div 2.2 \text{ lb/kg} = 90 \text{ kg}
Weight-based critical care drug dosing requires the patient's weight to be expressed in metric units (kilograms).
2
Calculate the total required dose per minute.
5 mcg/kg/min×90 kg=450 mcg/min5 \text{ mcg/kg/min} \times 90 \text{ kg} = 450 \text{ mcg/min}
This establishes the exact amount of medication the patient must receive every minute based on their specific body mass.
3
Convert the per-minute dose in micrograms to an hourly dose in milligrams.
450 mcg/min×60 min/hr=27,000 mcg/hr450 \text{ mcg/min} \times 60 \text{ min/hr} = 27,000 \text{ mcg/hr}. Then, 27,000 mcg÷1,000 mcg/mg=27 mg/hr27,000 \text{ mcg} \div 1,000 \text{ mcg/mg} = 27 \text{ mg/hr}
Since the infusion pump is programmed in mL/hr and the drug concentration is usually calculated in mg/mL, unifying these units simplifies the final calculation step.
4
Determine the concentration of the available medication bag.
400 mg÷250 mL=1.6 mg/mL400 \text{ mg} \div 250 \text{ mL} = 1.6 \text{ mg/mL}
This identifies how many milligrams of dopamine are present in a single milliliter of the IV fluid.
5
Calculate the final infusion rate and round to the nearest tenth.
27 mg/hr÷1.6 mg/mL=16.875 mL/hr27 \text{ mg/hr} \div 1.6 \text{ mg/mL} = 16.875 \text{ mL/hr}. Rounded to the nearest tenth, this yields 16.9 mL/hr16.9 \text{ mL/hr}.
Dividing the total required hourly dose by the fluid concentration provides the volume that the infusion pump must deliver per hour.

Anahtar Kavram

Weight-Based Continuous IV Medication Calculations
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