Calculation of intravenous medications can be time consuming, but once you become familiar with the conversion formulas it will be second nature. Although most pumps can calculate drips based on dosage and weight, the astute caregiver will always recheck these calculations with their own math. Intravenous dopamine can only be administered by a trained medical provider, usually a registered nurse.
Obtain the patient's weight in kilograms using a medically approved scale. The weight must be taken on the same day that the drip will be started, since Dopamine dosage calculations are weight based. If the weight is in pounds, then divide the weight by 2.2 to obtain the weight in kilograms. For this example we will use a 50 kilogram patient.
Review the doctor's prescription and familiarize yourself with the ordered dose. Compare this dose with your pharmacist to ensure that it is safe for your patient. Read back the ordered dose to the physician. For this example we will say the doctor ordered Dopamine at 5mcg/kg/minute.
The Dopamine concentration must be obtained to proceed. Obtain the medication concentration by dividing the milliliters of saline into the milligrams of medication. For instance, if you put 400 milligrams of Dopamine into a 250 milliliter bag of 0.9% Normal Saline, you will divide 400 by 250 and get 1.6 (this is the preferred concentration according to Merck, 2007). The physician's order is in micrograms (mcg); you will need to convert the concentration from milligrams to micrograms by multiplying this result by 1000 (1.6 x 1000= 1600mcg/ml).
Enter your patient's weight, ordered dose of Dopamine, and medication concentration into the formula as follows: Ordered dose x patient weight in kilograms x 60 minutes divided by the solution concentration.
Here is what our example looks like so far: (5mcg x 50kg x 60 minute) =15000. Divide this result by the medication concentration of 1600mcg/ml = 9.375 milliters per hour (round up to 9.4ml/hr).
Document your drip by using both the micrograms/kilogram/min and the actual drip rate. Always include the medication concentration. For our example, the documentation would read as follows:
Dopamine 400mg/250ml 0.9% Normal Saline infusing at 5mcg/kg/min with a rate of 9.4 ml/hr.