math review

chare · Jan 20, 2010

dobutamine 500 mg/500ml d5w at 24 ml/hr pt weights 80 kg

what is the dose mcg/kg/min?

rate x concentration / 60 x 80

isoproterenol 1mg/500ml d5w at 150 ml/hr

what is the dose mcg/min?

rate x concentration / 60

nitroglycerin 100mg/250ml d5w at 3.75 ml/hr

what is the dose mcg/hr?

rate x concentration

CRIMSON · Jan 22, 2010

i have searched through the math websites and have figured out most of my problems. however, i am having trouble finding out how to work the problems that are looking for mcg/min or mcg/hr or mcg/kg/min
dobutamine 500 mg/500ml d5w at 24 ml/hr pt weights 80 kg
what is the dose mcg/kg/min?
isoproterenol 1mg/500ml d5w at 150 ml/hr
what is the dose mcg/min?
nitroglycerin 100mg/250ml d5w at 3.75 ml/hr
what is the dose mcg/hr?
i have the answers already. i was hoping someone can help me find a formula for working these problems. dimensional analyasis is too confusing for me. any help would be appreciated! :heartbeat

here is dimensional analysis on these 3:

mcg= 1000mcg/1mg x 500mg/500ml x 24ml/hr x 1hr/60min x wt/80kg =

kg/min

12,000,000/2,400,000 = 5mcg/kg/min

mcg/min= 1000mcg/1mg x 1mg/500ml x 150ml/1hr x 1hr/60min = 150,000/30,000 = 5mcg/min

mcg/hr= 1000mcg/1mg x 100mg/250ml x 3.75ml/1hr =375,000/250 = 1500mcg/hr

hope this helps.

AugustRain · Jan 22, 2010

I have searched through the math websites and have figured out most of my problems. However, I am having trouble finding out how to work the problems that are looking for mcg/min or mcg/hr or mcg/kg/min
Dobutamine 500 mg/500ml D5W at 24 ml/hr pt weights 80 kg
what is the dose mcg/kg/min?
Isoproterenol 1mg/500ml D5W at 150 ml/hr
what is the dose mcg/min?
Nitroglycerin 100mg/250ml D5W at 3.75 ml/hr
what is the dose mcg/hr?
I have the answers already. I was hoping someone can help me find a formula for working these problems. Dimensional analyasis is too confusing for me. Any help would be appreciated! :heartbeat

I have a hard time with dimensional analysis too, so I just try to break things down logically instead. Here's how I figure out these types of problems:

There are basically 3 steps

1. Set up a ratio with the info you already have

2. Convert to the units of measure the answer is looking for (is. mg vs mcg & hr vs min)

3. Divide by kg when needed

Dobutamine

1. You know the concentration, so set up a ratio to find the missing piece

500(mg):500(ml) = 24(mg):x(ml)

500x = 12000

x = 24 mg/hr

2. Convert from mg to mcg

24 mg/hr = 24000 mcg/hr

3. Convert from mcg/hr to mcg/min

2400 mcg/60 min = 400 mcg/min

4. Divide by kg to get to the starting unit

400 mcg/80 kg = 5 mcg/kg/min

Isoproterenol

1. Have concentration, set up a ratio

1(mg):500(ml) = x(mg):150(ml)

150 = 500x

x = 0.3 mg/hr

2. Convert from mg to mcg

0.3 mg/hr = 300 mcg/hr

3. Convert from mcg/hr to mcg/min

300 mcg/60 min = 5 mcg/min

Nitroglycerin

1. Have concentration, set up ratio

100(mg):250(ml) = x(mg):3.75(ml)

250x = 375

x = 1.5 mg/hr

2. Convert from mg to mcg

1.5 mg/hr = 1500 mcg/hr

You can always check your answers by working backwards.

Hope this helps!

myrose · Jan 30, 2010

Thank you for the help. I hads my test last week and passed! I actually tried to learn both ratio/proportion and dementional analysis to double check myself. That is one less stress I have to worry about this last semester!:smiley_aa