Dosage Calculation in Critical Care Settings

 

Some medications such as Dopamine, Nitroglycerin, or Versed are calculated based on

mcg/kg/min, mcg/min, or mg/kg/hr

To calculate the hourly rate (ml/hr), you may utilize the following formulas:


Dose (in mcg/kg/min) x wt (in kg) x drug volume in ml x 60 (min/hr) = ml/hr

drug concentration in mcg

Or

Dose (in mcg/min) x drug volume in ml x 60 (min/hr) = ml/hr

drug concentration in mcg

Or

Dose (in mg/kg/hr) x wt (in Kg) x drug volume in ml = ml/hr

drug concentration in mg


Reminder:

If the dosage calculation is in mg/min or mcg/min add 60 minutes into the formula.

If the dosage calculation is in mg/hr or mg/kg/hr, remove 60 minutes from the formula.

If the dosage calculation does not require wt, remove wt from the formula.

Example: Administer Dopamine 5 mcg/kg/min. Patient weighs 210 lb (95 kg). Available is Dopamine 200 mg in 250 ml Normal Saline.

How many ml/hr will the nurse administer?

Round ml/hr to the whole number.


Plug in the information into the formula:

5 mcg/kg/min x 95 kg x 250 ml x 60 min = 36 ml/hr

200,000 mcg

Example: Administer Nitroglycerin 10 mcg/min. Available is Nitroglycerin 50 mg in 250 ml NS

How many ml/hr will the nurse administer?


Plug in the information into the formula:

10 mcg/min x 250 ml x 60 min = 3 ml/hr

50,000 mcg

Example: Administer Versed 0.05 mg/kg/hr. Patient weighs 40 kg. Available is Versed 100 mg in 100 ml NS.

How many ml/hr will the nurse administer?


Simply plug in the information into the formula:

0.05 mg/kg/hr x 40kg x 100 ml = 2 ml/hr

100 mg