# Drug Calc problem, Help??

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Please help with these problems. They are on a review sheet that I don't have the key for. My test is tomarrow, any help greatly appreciated.

1. D5W 500 ml with 10,000 U Heparin. Infuse at 100 U/HR usina a microdrip set (60 gtt/ml).

2. The order reads: Add 100 u. regulat insulin to 250ml 0.9% NS, then administer 10 u. per hour of regular insulin. You will set the infusion pump at _________?

3. THe order reads: Heparin 1500 U. in 500 ml NSS to run at 120 u/hr. The flow rate is _________ ml/hr.

4. The physician orders D5W at 5 ml/hr. THe 500 ml bag was hung at 12 noon. THe drop factor is 15 gtts/ml. What time should the IV be finished.

Thanks for any help..

24 Posts

I believe these answers are all correct. However, you might rely on input of others to double check my work.

1. D5W 500 ml with 10,000 U Heparin. Infuse at 100 U/HR usina a microdrip set (60 gtt/ml).

500 ml 100 U 60 gtt 1 hour

--------- x ---------- x ---------- x -------------- = 5 gtt/min

10,000 U 1 hour 1 mL 60 minutes

2. The order reads: Add 100 u. regulat insulin to 250ml 0.9% NS, then administer 10 u. per hour of regular insulin. You will set the infusion pump at _________?

250 mL 10 units

---------- x -------------- = 25 ml/hour

100 units 1 hour

3. THe order reads: Heparin 1500 U. in 500 ml NSS to run at 120 u/hr. The flow rate is _________ ml/hr.

500 ml 120 units

-------- x ------------- = 40 ml/hr

1500 U 1 hour

4. The physician orders D5W at 5 ml/hr. THe 500 ml bag was hung at 12 noon. THe drop factor is 15 gtts/ml. What time should the IV be finished.

I think that 5 ml/hr is a typo and you must mean 50 ml an hour. Assuming you are looking at 50 mL per hour, you figure that it will take 10 hours for the 500 ml to be gone. Therefore, if it was started at 12 noon, the IV will be finished at 2200 (10 p.m.). See below.

500 ml 1 hour

--------- x ------- = 10 hours

1 bag 50 ml

866 Posts

Specializes in MICU, neuro, orthotrauma.

1. D5W 500 ml with 10,000 U Heparin. Infuse at 100 U/HR usina a microdrip set (60 gtt/ml).

10000(units total) /500(ml total) = 20

20 units in a ml

100(units an hour) /20(units in a ml) = 5

so you want 5 ml an hour.

5 (ml) * 60 (drops per ml) = 300 drops per hour or if they just want you to say how many ml per hour, then you would say 5.

2. The order reads: Add 100 u. regulat insulin to 250ml 0.9% NS, then administer 10 u. per hour of regular insulin. You will set the infusion pump at _________?

100 units / 250 ml = 0.4 units per ml

10 units / 0.4 units per ml = 25 ml per 10 units

set infusion pump at 25ml/hr

3. THe order reads: Heparin 1500 U. in 500 ml NSS to run at 120 u/hr. The flow rate is _________ ml/hr.

1500 units / 500 ml = 3 units per ml

120 units per hour / 3 units per ml = 40 ml per hour

4. The physician orders D5W at 5 ml/hr. THe 500 ml bag was hung at 12 noon. THe drop factor is 15 gtts/ml. What time should the IV be finished.

(drop factor is irrelevant here + this question is stupid)

500 ml \ 5 ml/hour = 100 hours so count 100 hours from twelve noon.

no one hangs a bag more than 24 hours so the answer is irrelevant as much as the question itself is inane.

24 Posts

Take 2 - sorry, my first attempt to show answers didn't work well. I believe these answers are all correct. However, you might rely on input of others to double check my work.

1. D5W 500 ml with 10,000 U Heparin. Infuse at 100 U/HR usina a microdrip set (60 gtt/ml).

5 gtt/min

2. The order reads: Add 100 u. regulat insulin to 250ml 0.9% NS, then administer 10 u. per hour of regular insulin. You will set the infusion pump at _________?

250 ml/unit * 10 units/hr = 25 ml/hr

3. THe order reads: Heparin 1500 U. in 500 ml NSS to run at 120 u/hr. The flow rate is _________ ml/hr.

500 ml/1500 U * 120 units/1 hour = 40 ml/hr

4. The physician orders D5W at 5 ml/hr. THe 500 ml bag was hung at 12 noon. THe drop factor is 15 gtts/ml. What time should the IV be finished.

I think that 5 ml/hr is a typo and you must mean 50 ml an hour. Assuming you are looking at 50 mL per hour, you figure that it will take 10 hours for the 500 ml to be gone. Therefore, if it was started at 12 noon, the IV will be finished at 2200 (10 p.m.). See below.

500 ml/1 bag * 1 hour/50 mL = 10 hours

866 Posts

Specializes in MICU, neuro, orthotrauma.

nurse in my browser, your answers are showing up clear as a bell. i can see that you do formulas. ive never been able to do them. i just have to figure out what theya re asking and answer it any way i can figure out how. formulas are HARD for me to remember.

4,491 Posts

Unusual orders here!. I would check with the pharmacy.

There are two Heparin orders at different concentrations and non standard rates. That said the math only:

1. D5W 500 ml with 10,000 U Heparin. Infuse at 100 U/HR usina a microdrip set (60 gtt/ml).

ANSWER: 500cc divided by 10,000 unots is 0,05 units per ml (cc). Multiply times 100 units per hour equals five ml per hour.

[i would find out if there is a standard at your hospital. In my city 50 units per cc is commonly used].

----------------------------

2. The order reads: Add 100 u. regulat insulin to 250ml 0.9% NS, then administer 10 u. per hour of regular insulin. You will set the infusion pump at _________?

ANSWER: The insulin question is similar. 100 units regular insulin in 250 cc. Divide the total fluid by the amount of the medication. This is 0.4 units of insulin per cc. 10 divided by 0.4 is 25 ml/hr.

[The hospitals where I work uses a standard on one unit per cc (ml). ] It is very important to constantly assess the patient and measure the glucose level at least once an hour. This is not a simple math question because a patient requiring an insulin drip is unstable. Hypoglycemis is always a possibility. Electrolytes, potassium (K+) must be monitored too.

--------------------------

3. THe order reads: Heparin 1500 U. in 500 ml NSS to run at 120 u/hr. The flow rate is _________ ml/hr.

ANSWER: Divide the total fluid by the number of units of Heparin. Ask for a policy. Seems that for the average patient a bolus followed by a drip with the PTT or APTT being drawn often would be therapeutic.

-----------------------

4. The physician orders D5W at 5 ml/hr. THe 500 ml bag was hung at 12 noon. THe drop factor is 15 gtts/ml. What time should the IV be finished.

ANSWER: It should never be finished. At 5 ml/hr 120 ml would have infused in 24 hours.

A policy for how long an IV may infuse should be written.

The questions here are illogical. The math only answer would place your patient at risk for potentially lethat sepsis by leaving the same IV bag running for 50 hours.

Please use this test to make sure your school or facility has safeguards in place. Patients need a nurse who is competent to do the math and advocate for their best interests!

ALWAYS CHECK INSULIN AND HEPARIN WITH ANOTHER LICENSED NURSE!

866 Posts

Specializes in MICU, neuro, orthotrauma.

*giggles at space nurse*

55 Posts

thanks everyone for your help. These questions have not been like any other sample problems or anything we have even done in class (I'm going in 2nd week of 2nd semester). Last minute Friday they handed these out. I'm not sure any will even be on our test like these.

And yes I think we would have hurt a lot of peopl if we were given the examples of medication doses that are in our Drug calculation module. One of my biggest gripes has been that the answers do not make since. Ex. Give 0.67 scored cap.

2,709 Posts

Im in the same boat. Algebra is Greek to me. I have to do it with long arithmetic. And even then Im not so sure.

The way I figure it is if you put 10,000 of something into 500 cc of something else, cross out the zeros that cancel each other & you get 100:5.... which, when simplified, is 20:1. So theres 20 units in each cc, but we want 100 units, so mulitply 20 by what to get 100? Answer = 5cc.

To me, Heparin 1500 units in 500 cc means there are 3 times as many units as there are ccs. So, to get 120 units/hr, divide by 3 & the answer is 40cc/hr.

And 100 units in 250 ccs means there is 2 and a half times more solution than medication in the bag. To get 10 units/hr, Id just say whats 2 and half times 10? 25cc/hr.

-----------------

866 Posts

Specializes in MICU, neuro, orthotrauma.

jt it seems like your brain likes the ratio way of sorting. my brain likes to break it down to the smallest element (how many units in ONE ml? is always my question) and then go from there.

i HAAAAAATE algebra. HATE HATE HATE it is the only subject that will drive me to tears. well no, thats not true... government will do the same, but only because people are so mean to each other and they lie in politics.

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