Question

Your patient is to receive dopamine 5 mcg/kg/min. He weighs 176 lb. You have dopamine 400 mg in 500 mL D5W. You will infuse this at which rate? A. 20 ml/hr B. 30 mL/hr 0.35 mL/hr D. 50 ml/hr When assessing for diovascular effects of an

solve using dimensional analysis.

Answer 1

ANSWER.

* Calculation of ml/hr

        ml/hr = Volume(ml) /Time(hr)

Calculation of volume(ml)

      Formula = Desired dose(D)/Dose in hand(H) * Quantity(Q).

Here

    Ordered dose = 5 mcg/kg/min.

    Weight of the patient = 176 lb

Convert lb to kg for calculation

          1 lb = 0.454 kg

   So

     Weight of the patient = 176 * 0.454

                                       = 79.9 kg

        Desired dose (D) for this patient = 5 * 79.9

                                                            = 399.5 mcg

         Dose in hand (H) = 400 mg

   Convert 400 mg to mcg for calculation

                  1 mg = 1000 mcg

         So

             Dose in hand (H) = 400 * 1000

                                         = 400000 mcg.

                 Quantity(Q) = 500 ml

As per above formula

           Volume(ml) of drug required = D/H * Q

                                                         = 399.5/400000 * 500

                                                         = 0.0009 * 500

                                                         = 0.49

                                                         = 0.5 ml

                                       Time(min) = 1 min

         Convert ml/min to ml/hr by multiplying with 60

               So

                       ml/hr = 0.5 * 60

                             B = 30 ml/hr