Another med calc question

[semester1kid]

Here's something that showed up on a practice test. We were given the answer, which is 20 gtt and I did concoct a manner of figuring it out for myself. First I'll type out the question then my calculations of how I figured it out, then a couple of questions I still have (because even thought I figured something out, I'm still lost on this one)

*Give 800 units/hr of Heparin IV. Consider that 500L of D5W is available with 20,000 units of heparin added. The drop factor is 60gtt/min (***I don't think she meant to put 'min' after 60gtt???). Give (blank) gtt/min.

My calculation that worked to get 20 gtt/min was 800 units over 1 hour x 500 mL over 20,000 units. That gave me an answer of 20. Now for my question, I'm not clear as to why the 60gtt (micro drops) wasn't a factor in this calculation and I'm not sure if or how I could add 'gtt/min' to after the 20 when that type of unit was never in the equation. My thoughts are that I did it wrong but just happened to stumble onto a number that matches what she gave us as an answer....Thoughts???

[semester1kid]

One thing I didn't consider is that 60 minutes in an hour and 60 gtt could cross each other out - is that my missing piece of the puzzle? Since they cross each other out, my answer would still be 20 and it would add 'gtt' and 'min' to the calculation

[Mandychelle79, ASN, RN]

500ML/20,000 *( 800 units /1 hr) * (1hr/60 min) *( 60 gtt/ml)

ml cross out, as do units and do hr and the 60's leaving you with gtt/min

Your math is right

[semester1kid]

Thanks a lot - we have the actual test on Tuesday and wasn't certain how to handle that one, even though I had inadvertently come up with the right answer:)