medication calculations

Im completely stuck on this question and studying for med exam. I've used formula but im doing something wrong can anyone please guide me in the right direction.
on admission to the ward Mr A is ordered a heparin infusion. The rate of infusion is 2ml/hr. APPT returns back low and therefore you must increase the unfusion by 250 units/hr. the syringe comes preprepared at a concentration of 25000 units of heparin in 50 ml syringe. what is the new rate in mls/hr of the infusion. 

Jun 16Joined: Jan '18; Posts: 128; Likes: 249There are a few ways of doing this. Probably the easiest way right now is to calculate the units of heparin/mL in the syringe. Then it will be pretty simple to see how much you have to increase the infusion.


Jun 16Joined: Jan '18; Posts: 128; Likes: 249There is 25,000 units in 50 mL, so that works out to 500 units/mL, which would be 250 units/0.5 mL. You are at 2 mL/h now, so you would have to increase it 0.5 mL per hour, bringing it 2.5 mL/h. Does that make sense?

Jun 16Joined: Oct '10; Posts: 9; Likes: 3yes this defiently makes sense. but what nursing standard formula would you also use to help with these type of questions. because using the ml/hr formula didnt work? thank you very much for your help xxx

Jun 16Joined: Jan '18; Posts: 128; Likes: 249Well, the way I have always taught this stuff is to not use formulas. If you look at my article and download my book, I think it will help you. The article is in prenursing and called Master your Dosage Calculations Before you get to Nursing School
Master Your Drug Calculations BEFORE You Get to Nursing School
The book is under one of the comments calles Dosage Calculations PDF. This problem was a little different than what your formulas will cover because you have to calculate the increase then add it to the original rate. The direct way to calculate the increase is 250 units (50 mL/25,000 units) = 0.5 mL. The units cancel out leaving mL. Feel free to PM me if you need help.
Brad 
Jun 16Joined: Oct '10; Posts: 9; Likes: 3Thanks Brad very much. will definitely look at your book.

Jun 16Joined: Jan '18; Posts: 128; Likes: 249Ok, great. It was written for pharmacy technicians, but the calculations are still the same. Most of the material you will need is in Chapter 2. Let me know if you have any questions.