Math Problem

Can someone explain to me how to figure this question out? I have the answer already, it just doesnt make sense:

Heparin 10,000 units in 1000 ml D5W is infusing at 15 drops/min using a 10 drop/ml delivery system. How much heparin(units/hr) is the pt receiving.

I guess Im confused by the infusion @ 15 drops/min and the 10 drops/ml

Daytonite has shown you how to solve the problem. In case you don't fully understand what she's doing, I'm going to try to explain how I think about problems like this and what the problem statement actually means.

Heparin, 10,000 units: This is a measure of quantity and simply describes how much heparin is in the solution.

D5W, 1,000 mL: This is the volume of the solution.

Infusion @ 15 drops/min: How fast the IV set-up is dripping. You can stand there and watch the drops come out of the bag every minute and see this number.

10 drops/ml: This describes how large are the drops. 2 drops/ml would be big drops, 1 drop/ml even bigger, and 100 drops/ml would be tiny.

INTRO

Since you want to know how much heparin infused in one hour, it stands to reason that if you know how much medicine is in a drop and you know how many drops of medicine flow each minute (and hence, each hour), you've got your answer. Start by figuring the amount of medicine in each ml of solution and then combine that with what you know about how many drops flow each minute and how large is each of those drops.

AMT OF MEDICINE PER ML

Knowing the amount of heparin (10,000 units) and the volume of the solution (1,000 mL), you can determine the concentration of the solution. Concentration is a measure of how much material is dissolved in a given volume of solution. In this case, the concentration of the solution is 10,000 units of heparin in 1,000 ml or 10 units of heparin per ml (10,000 units/1,000 ml = 10 units per ml).

FLOW RATE

So, you know that for each ml that goes into the patient, they receive 10 units of heparin. Now you need to consider the rate (how fast) the medication is going in.

You know that you're getting 15 drops each minute. However, a drop could be any size, right? If you had little tiny droplets, each would contain a little tiny bit of heparin. If you had big, burly DROPS, each would have more heparin, right? However, the problem statement told you how big are the drops: It said that 10 drops make up 1 ml. If 10 drops make 1 ml then 5 drops make 1/2 ml and 2 drops make 1/5 ml and 1 drop makes 1/10 ml (0.1 ml)

So, if you have 15 drops per minute and each drop is 0.1 ml, you're getting 1.5 ml/min (15 drop/min x 1 ml/10 drops = 1.5 ml/min)

HEPARIN INFUSION RATE

In the first part of the problem, you determined how much heparin was in each ml of solution (10 units/ml) and in the second part of the problem you determined the volumetric rate at which the solution is flowing (1.5 ml/min). Now you just have to combine the two to determine the unit rate at which heparin is flowing in.

If your concentration were 1 unit per ml then how fast would heparin be infusing (remember, the solution is flowing at 1.5 ml/min)? Well, if each ml of solution had 1 unit of heparin and 1.5 ml is flowing each minute then you'd be infusing 1.5 units of heparin each minute, right?

Since the concentration is actually 10 units/ml and the volumetric flow rate is 1.5 ml/min, the infusion rate is 15 units per minute (10 units/ml x 1.5 ml/min).

Since the problem is asking for how much heparin is received each hour, just add up how much was added each minute. Each minute, another 15 units of heparin goes in so it goes:

Elapsed Time.....Total Amt of Heparin

1 min......................15 units

2 min......................30 units

3 min......................45 units

4 min......................60 units

5 min......................75 units

10 min...................150 units

20 min...................300 units

60 min...................900 units

(15 units/min x 60 min/hr = 900 units/hr)

This is a very long-winded way of getting to where Daytonite quickly got you. Does this help?

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