Help Med Calc - please validate

[begosh]

A question on NCLEX RN Q&A Flash Card states:

Client admitted with DVT is prescribed heparin by constant infusion after an initial dose of 5,000 units IV push. The heparin comes prepared 20,000 units in 500 ml D5W. The bolus heparin was administered at 8am and the infusion initiated per protocol at 25 ml/hr. At 7pm, how much heparin had been administered?

My calculation are as follows:

25,000 units/500 ml = 40 units/ml

40 units/ml x 25 ml/hr = 1,000 units per hour

1,000 units per hour x 11 hours = 11,000 units for 11 hours

11,000 units + 5,000 units bolus = 16,000 units of heparin total (my answer)

However, the correct answer listed was 5,440 units administered during the said shift. Which I don't think is right. Maybe I'm thinking too much? Would appreciate your feedback. Thank you!

[dragon_lady]

Initial dose=5000 units

2nd dose= 20,000 units/500 ml=40 units *11=440

Add 1st and 2nd dose( 5,000 units+ 440 units=5,440 units)

[dragon_lady]

Your answer was my first answer too,then Iooked for some answers..

[begosh]

Thank you dragon_lady! I think I found where I got confused....I was thinking that the "25 ml/hr" was for the entire 20,000 units. Now I see that I read too much into the question.

Thanks bunches!!!

[akulahawkRN, ADN, RN, EMT-P]

As above, you have to look at the units per mL first. It's not 25,000U/500mL, it's 20,000U/500mL = 40U/mL. As the question is written, the answer is 5000+(11*1000)= 16,000U. The answer given doesn't match... so something isn't correct in the question (orders...) versus how they may have actually calculated the answer. It may have been calculated as 5000+(11*40)=5440U total dose. That calculation doesn't match how the question is written. Point is that errors can happen in all of these materials, either in how the question/problem is presented OR in how the answer is calculated.

I'd say, going by how the problem was presented, your answer is correct. Whether or not it's a safe dose is a whole different problem.

[begosh]

Thank you, akulahawk! My calculation above should have read 20,000 units (25,000 units was a typo).

I definitely read too much into the question when I multiplied 40 units x 25 ml (