"The protocol for a continuous heparin drip is 25,000 units per 250 mL of D5W. A loading dose of 70 units per kilogram is ordered. What you have available is 10,000 units per mL. The patient weighs 154 pounds. The patient's aPTT is 90 and protocol is to reduce the dose by 100 units per hour. What is the drip rate of the new heparin dose?"

The above problem is an example of a question on our math final - the final that we have to pass with a 70 or better or get kicked out of the program. You cannot advance to next semester regardless of the rest of your grades. Even if you have an A in fundamentals, you are out of the program.

In a way I understand - pharmacology math is a big deal. But come on! Talk about pressure.

I have spent the past month practicing drug calculations for at least an hour a day. I wanted to make sure that I pass this thing no matter what. So I haven't exactly felt like blogging. I have been entirely focused on getting the hang of this.

And good news! I did! I'm still a nursing student - for now.

A few years ago I attended a Different Community College and didn't pass the pharmacology math exam. Coincidentally I got the same score on that test that I did on this test, but because the schools have different criteria, this time I got by. But I'm not bitter. Life is like that. I've learned to adapt to whatever is required of me wherever I am. I'm over trying to argue what works someplace else.

People ask why drug calculations are so difficult. I wish I could answer that. After all, the math itself isn't difficult. We do basic math functions - add, subtract, multiply and divide. But look at the problem above and you tell me why it's so hard. The first thing that comes to my mind is that you have to know what information in the problem is essential to the calculation and what information is just there to distract you.

The second problem is knowing what numbers calculate and where. Which number goes on top of the equation? Which goes on the bottom? What gets multiplied first and with what? What gets divided from what and when?

I don't feel bad because I showed this problem to my sweetie, who has a two degrees and thinks math is fun, and she couldn't figure it out at first. I had to explain which numbers go with what and only then could she do it. My classmates and I had gone to the tutoring center at the college to get help with this, and the tutors were scratching their heads too. Finally the nursing program chose one tutor and she is now the dedicated pharmacology math tutor. They sat her down and explained pharmacology equations to her so now she can explain it to us. She, too, was clueless at first. As absurd as this situation sounds, I'm just grateful that they have made this resource available to us.

Now the semester is over. I passed fundamentals. I passed math. Now if you'll excuse me I have some important sit-on-my-butt time I need to catch up on.

Oh, in case you're wondering, the answer is 10 mL/hour. If you're dying to know how I got that answer, you'll have to wait until tomorrow when my headache is gone and I can explain the problem adequately.

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## 6 comments:

If I read the question correctly, the rate of administration is 100 Units per hour at the dilution of 25,000 Units in 250 mL D5W. This will give you the flow rate of 1 mL/hr. (BTW, the standard infusion rate is 1,000 Units per hour, which will give you 10 mL/hr drip rate.)

The rest of the info is irrelevant to this question. Although it's all very important in delivering the correct dose to the pt.

It seems to me that your instructors made the questions unnecessarily complicated, instead of breaking them down into easily understandable chunks. Drug calculations is really no different than most basic algebra.

Just finished my first semester of nursing school, also a midlifer.

I always hated med math. I had to work at it just as you are. The pedes drug test was the worst for me. I took it the very last semester and had to pass it before I could graduate. I took it 3 times! Hang in there! It gets better.... plus the Guardrails function on the IV pump saves my life daily!

Helen wrote "It seems to me that your instructors made the questions unnecessarily complicated, instead of breaking them down into easily understandable chunks."

In their defense they did break it down into chunks up to this point. They are trying to teach us how to tease out the relevant information and ignore the stuff that doesn't matter.

I don't know why I defend my instructors so much. Must be Stockholm syndrome.

And you're right - it is 1,000 units per hour. That is a typo.

Thanks, Jeepgirl. I'm sure I'll be fine. It was just so incredibly nerve-wracking to think that with just the slightest of mistake, three semesters of nursing school would go down the drain.

The weird thing is I don't hate math and I do okay whenever I take a math class. I don't have test anxiety - never have. Dosage calculations are just vexing. As I mentioned, when I showed it to my partner, who has an extensive math history, it felt affirming when she couldn't even figure it out. I'm not crazy after all.

Another mid-lifer in final semester here. Just found your blog while googling dosage calculations. My school's criteria is 100% on each math test or yer out, thanks, buh-bye. Thus, the desperate, wee-hours internet search for elucidation.

I loved reading your posts so much that I momentarily forgot my math anxiety. You're brilliant, and hilarious, and you give me hope that I might run into a new nurse like you when I graduate. Thanks. Keep blogging.

Thanks Cass.

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