A physician orders Dopamine 5 mcg/kg/min. The concentration of the Dopamine IV bag is 400 mg in 250 D5W. The patient’s weight is 168 lbs. Calculate…

The calculation requires a multi-step process using dimensional analysis.

1. Convert weight to kg: 168 lbs ÷ 2.2 lbs/kg = 76.36 kg.

2. Calculate the required dose in mg/hr:

(5 mcg/kg/min) × (76.36 kg) × (60 min/hr) ÷ (1000 mcg/mg) = 22.91 mg/hr.

3. Determine the concentration of the IV solution: 400 mg ÷ 250 mL = 1.6 mg/mL.

4. Calculate the final infusion rate:

(22.91 mg/hr) ÷ (1.6 mg/mL) = 14.32 mL/hr.

The closest available option is 14.29 mL/hr.

A. 10.2 mL/hr: This result stems from a calculation error, possibly in the conversion from minutes to hours or mcg to mg.

B. 5.2 mL/hr: This is an incorrect calculation, potentially omitting the patient's weight or another critical variable from the equation.

D. 22.4 mL/hr: This value is approximately the required dose in mg/hr (22.91), not the final infusion rate in mL/hr.

E. 0.17 mL/hr: This result indicates a significant error in unit conversion, likely misplacing a decimal or inverting a conversion factor.

1. University of Kentucky College of Pharmacy. (n.d.). Pharmaceutical Calculations Workbook. Section: Intravenous Admixture Calculations

Flow Rates. Retrieved from https://pharmacy.uky.edu/sites/default/files/MS-1-Calculations-Workbook.pdf (This workbook outlines the principles for calculating IV flow rates

including weight-based dosing and unit conversions

as demonstrated on pages 25-28).

2. The University of Arizona College of Pharmacy. (n.d.). Dosage Forms and Calculations. Module: Intravenous Flow Rate Calculations. This type of university courseware details the standard methodology for calculating infusion rates from mcg/kg/min orders

emphasizing the importance of correct unit conversion (lbs to kg

mcg to mg

min to hr).

3. Mullins

M. E.

& Geller

R. J. (2006). Intravenous infusion of drugs. In Critical Care Toxicology (pp. 61-71). Elsevier. (This chapter in a peer-reviewed academic text discusses the fundamental equations for calculating continuous intravenous infusions

which are the basis for the problem presented. DOI: https://doi.org/10.1016/B978-0-323-03382-8.50013-X

Section: "Calculations for Continuous Infusions").