Need help on this basic med math problem?

  1. I have a med math exam tomorrow morning and I cannot figure this problem out:

    The patient is to receive Pitocin (oxytocin) at a rate of 8 milliunits per minute. The IV
    contains 10 units of Pitocin in 1000 ml Lactated Ringers. How many ml/hr to be set on
    the pump to infuse the required dose?

    I keep getting the wrong answer because I was never taught units and it's throwing me off.
  2. Visit OsceanSN2018 profile page

    About OsceanSN2018, CNA

    Joined: Jun '17; Posts: 207; Likes: 177


  3. by   OsceanSN2018
    I did: 10 units/1000ml = 1min/.008 units but I guess this is not how your supposed to set this up.
  4. by   meanmaryjean
    1 unit = 1000 milliunits (just as 1 gram = 1000 milligrams)

    Does that help?
  5. by   OsceanSN2018
    Quote from meanmaryjean
    1 unit = 1000 milliunits (just as 1 gram = 1000 milligrams)

    Does that help?
    Yes, that helps some. But what about the ml/hr? Can you show me how to set this up? I'm not looking for the answer because I have it, I just don't know how to set it up. I asked my classmates in group meet but they told me the exact same thing you just told me.

    So, I just took another shot at the problem and set it up like this=

    .008 units/0.17 hr= 1000ml/10 units.

    I got 40 as my answer but the right answer is 48....
  6. by   hon918
    Close, you lost a 0 converting min to hours, should be 0.017 hr. Here's how I would set this up:

    (0.008 units/1 min.) x (1000ml/ 10 units) x (60 min./ 1 hr) = 48 ml/hr
  7. by   OsceanSN2018
    Thank you! I finally get it now. This will be my 2nd week in OB and we have not learned this at all.
  8. by   bjwojcik
    You are starting with a rate of 8 milliunits/min and you have to change that to mL/h. Start off by writing the given and the units of the answer. This way you can fill in the ratios easier.
    8 milliunits/min = mL/h
    You will have to change milliunits to mL and min to h. The ratios used to change milliunits to mL are 1000 mL/10 units and 1 unit/1000 milliunits.
    The ratio to change min to h is, of course, 60 min/h.
    Just line everything up so you cancel out the unwanted units and end up with mL/h.
    8 milliunits/min (1000 mL/10 units)(1 unit/1000 milliunits)(60 min/h) = 48 mL/h
    Note: all the ratios equal 1, so you are only multiplying by various forms of 1 to change the units of the given into the units of the answer.

    Brad Wojcik, PharmD
  9. by   PrereqTaker89
    Hey there here's what I'd do:

    1000ml/10,000 milliunits X 8 milliunits/1 minute X 60 minutes/ 1 hour

    Cancel units and multiply straight across to get 48 ml/hr

    Love these problems!