dobutamine drip at 7 mcg/kgk/min. weight is 100 kg. how many milligrams per hour

Question

 Please show set up. Thank you.

Answer 1

Drip rate: 7mcg/kg/min

Pt weight: 100kg

Find out mg/hr?

Total dose: 7mcg/kg/min x 100kg = 700mcg/min --> convert mcg to mg (dividing the result by 1000)

(700mcg/min)/1000 mcg/mg = 0.7mg/min --> calculate per hour rate (by multiplying the answer by 60)

(0.7mg/min) x 60 min/hr = 42mg/hr

Answer 2

Question: dobutamine drip at 7 mcg/kg/min. weight is 100 kg. how many milligrams per hour

What we know:

drip rate = 7mcg/kg/min

pt wt = 100kg

What we want:

rate in mg/hr ... so we need solve the rate using the patient's known weight (instead of a weight based rate) and then convert into the requested units.

conversions we can use:

mcg to mg = 1000mcg = 1mg

min to hour = 60min = 1 hr

X mg/hr = 7mcg/kg/min *(100kg)*(1mg/1000mcg)*(60min/hr)

broken down:

1) multiply by 100kg to get rate for this specific pt = 7mcg/kg/min * 100kg = 700mcg/min

2) want to convert from mcg to mg = 700mcg/min*(1mg/1000mcg) = 0.7mg/min

3) want to convert from minutes to hours = 0.7mg/min*(60min/hr) = 42mg/hour

Answer 3

7mcg X 100 Kg x 60 minutes/hr =  42,000 mcg/hr  / 1000mcg/mg   = 42mg/hr  

 

I find if I work this out in a  linear fashion, it is much easier to see what I am solving for, i can cancel out my units as I go along.   

 

You can check it like this:

 

42mg/hr X 1000mcg/mg = 42,000 mcg/hr

 

42,000mcg/hr  / 60minutes/hr   = 700mcg/minutes / 100kg   = 7mcg/kg/minute

 

Rather you prefer to work out the problem in a linear matter or using dimensional analysis, always go back and check your work, make sure you WRITE down the units you are solving for and cancel them out appropriately.  If you follow all of those steps, you will succeed at Pharm math!!

 

Trina Belair, MSN, FNP-C